Table of Content

12 June 2009, Volume 35 Issue 6

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Breeding and Field Performance of Novel Soft and Waxy Transgenic Rice Lines without Selectable Markers

YU Heng-Xiu,LIU Qiao-Quan,XU Li,LU Mei-Fang,CAI Xiu-Lin,GONG Zhi-Yun,et al.

Acta Agron Sin. 2009, 35(6):  967-973.  doi:10.3724/SP.J.1006.2009.00967

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Amylose content is one of the important factors affecting rice cooking and eating quality, and controlled by the Waxy (Wx) gene which encoding a granule-bound starch synthase. High amylose levels are usually associated with poor cooking and eating quality. In our prevrious studies, in order to generate transgenic rice varieties with improved quality and without of the selectable marker, the antisense Wx gene was co-transformed together with a selectable marker gene, the hygromycin-resistant gene (HPT), to a high-yielding japonica rice cultivar, Wuxiangjing 9, mediated with Agrobacterium tumeficien. And some selectable marker-free (SMF) transgenic lines had been subsequently selected. In present study, several homozygous transgenic lines with soft or waxy grain property were selected from the offspring of these SMF transformants containing the antisense Wx gene. The results from Northern blot analysis indicated that the levels of both the Wx mature mRNA and unspliced transcripts were reduced differently in the endosperm of different transgenic lines. The Wx protein level in mature seeds of the transgenic lines was also reduced differently. The amylose content of two transgenic lines was reduced to that of soft rice (about 10%) and one line was reduced to that of waxy rice (lower than 2%). The gel consistency of these transgenic lines was softer than that of the wild type. The variance of gelatination temperature between the transgenic lines and the wild type did not reach to significant level. The most of the main agronomic traits of these transgenic lines were similar to that of the wild type. Therefore, three SMF transgenic homozygous lines with improved quality were successfully bred.

Genetic Background Effect on QTL Mapping for Salt Tolerance Revealed by a Set of Reciprocal Introgression Line Populations in Rice

YANG Jing,SUN Yong,CHENG Li-Rui,ZHOU Zheng,WANG Yun,ZHU Ling-Hua,CANG Jing......

Acta Agron Sin. 2009, 35(6):  974-982. 

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QTLs for salt tolerance (ST) related traits including score of salt toxicity of leaves (SST), survival days of seedlings (SDS), shoot K⁺ concentration (SKC) and shoot Na⁺ concentration (SNC) were detected using the reciprocal introgression lines (ILs) derived from a cross between japonica variety “Lemont” and indica variety “Teqing” under salt stress treatment with the concentration of 140 mmol L^-1 NaCL in green house and phytotron. Both genetic backgrounds of the two sets of ILs were similar to their respective parents. On the average, Lemont genome accounted for 83.8% in Lemont background-ILs whereas 88.9% of Teqing genome in Teqing background-ILs. Continuous variation and transgressive segregation for all ST-related traits were observed in the two IL populations with overlaps of frequency distributions for most traits, suggesting the gene effect of reciprocal introgression of the two parents on each ST-related trait was almost equivalent. Eighteen QTLs for all ST-related traits were identified for each of the two IL populations. No any a common QTL for the same trait was detected in the reciprocal IL populations, indicating there was a strong genetic background effect on expression of ST-QTLs, and also suggesting these ST-QTLs had relatively small phenotypic effect. Only one common QTL affecting SKC was identified in Teqing background-ILs under green house and phototron environments, indicating there was a strong interaction of ST-QTL with environment. Although the two parents are moderately susceptible to salt stress, QTL mapping results indicated that some favorable alleles beneficial to improvement of ST-related traits do exist in the parents. Therefore, it is possible to develop a new variety with improved ST by identifying and mining this kind of “hidden” ST-genes existed in the modern varieties through molecular marker technology and further pyramiding these non-allelic alleles via marker-assisted selection.

Genomic DNA Sequence,Gene Structure,Conserved Domains,and Natural Alleles of Gln1-4 Gene in Maize

WU Yong-Sheng,LI Xin-Hai,HAO Zhuan-Fang,ZHANG Shi-Huang,XIE Chuan-Xiao

Acta Agron Sin. 2009, 35(6):  983-991.  doi:10.3724/SP.J.1006.2009.00983

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Maize (Zea mays L.) cultivars with improved nitrogen use efficiency would be beneficial for low-input production systems and for environment since it would reduce the surface water pollution and the nitrate leaching into underground water. Glutamine synthetase genes families are the core elements for nitrogen assimilation and metabolism in maize plants. The objectives of this study were to isolate the genomic DNA sequence of Gln1-4, which is one of the important members of glutamine synthetase gene family, to analyze the gene structure, conserved domains and natural allelic variations and so that was to found basis for association analysis of the functional sites related to nitrogen use efficiency in maize. PCR walking strategy was applied to isolate the gDNA sequence of Gln1-4 and its flanking sequence. The gene structure was analyzed by aligning gDNA sequence and its’ mature mRNA sequence. The conserved domains were obtained by searching Conserved Domain Database (CDD) at NCBI. The natural allelic variations were evaluated by resequencing and aligning DNA sequences among 52 inbreds. A total of 3 724 bp gDNA sequence of Gln1-4 of Mo17 was assembled. The full length of the coding region was 2 858 bp, which was comprised of ten exons separated by nine introns. All 18 splicing sites were the conserved sequence of GU at 5' donor sites and AG at 3' acceptor sites. The sequence has been submitted to GenBank (Accession No.: EU369651) and annotated in details. Gln1-4 encodes a GS protein with molecular weight of 39.2 kD, which was comprised of 356 amino acids. Its isoelectric point (pI) was 5.202. Conserved domain searching results showed that the region from exon 2 to exon 6 at amino-terminal was an ammonium ion binding domain, and exon 8 to exon 9 at carboxyl terminal consisted of an ATPase activity domain. As compared with Gln1-3, the DNA sequence, amino acid sequence, gene structure and conserved domains for Gln1-4 were highly conserved with a 98.31% identity of amino acid sequence. A total of 318 types of natural DNA variation at important and target region of Gln1-4 gene were identified among 52 maize inbred lines, of which 242 was SNPs and 45 was small indels, comprising 90% of the total allelic variations. The analysis of the functional sites gene associated with nitrogen use efficiency of Gln1-4 in maize should focus on binding and catalyzing domains and splicing sites.

Genetic Mapping of Rll Gene Conferring Resistance to Late Blight in Potato(Solanum tuberosum)

XU Jian-Fei,HUANG San-Wen,JIN Li-Ping,DUAN Shao-Guang,QU Dong-Yu

Acta Agron Sin. 2009, 35(6):  992-997.  doi:10.3724/SP.J.1006.2009.00992

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Late blight caused by Phytophthora infestans is the most destructive disease for potato (Solanum tuberosum). A F₁ segregating population consisting of 83 genotypes, derived from R11 differential MaR11 and the susceptible potato cultivar Katahdin, was assessed for late blight resistance in detached leaves assay and genetically analyzed. The results showed that the distribution for R11 was clearly bimodal with the two peaks coinciding with the blight scores of the MaR11 (the resistant parent) and Katahdin (the susceptible parent), and the observed segregation with 39 resistant and 44 susceptible plants fitted a 1:1 ratio. It indicated that _R11 was inherited as a major dominant R gene and presented in the simplex condition in MaR11. There was a major late blight resistance locus (MLB) in potato on the long arm of chromosome 11, where R11 showed allelic versions of the R3 and R10 loci. Using the combination of comparative mapping and bulked segregant analysis, we developed six markers linked to R11 which was located on the end of the long arm of chromosome 11 with a distance of about 2.4 cM to marker C2_At5g59960. R11 was telomeric to the R3a and R10 gene. The genetic map constructed in this paper provides a basis for further construction of high-resolution genetic map of the R11 gene.

Molecular Mapping of Powdery Mildew Resistance Gene MlWE29 in Wheat Originated from Wild Emmer(Triticum turgidum var.dicoccoides)

ZHANG Lian-Song,HUA Wei,GUAN Hai-Ying,LI Gen-Qiao,ZHANG Hong-Tao,XIE Chao-Jie,YANG Zuo-Min.etal

Acta Agron Sin. 2009, 35(6):  998-1005.  doi:10.3724/SP.J.1006.2009.00998

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Powdery mildew, caused by Blumeria graminis f. sp. tritici, is one of the most important wheat diseases in many regions in the world. Breeding for the resistance is the most economical and effective method for controlling this disease. Wild emmer (Triticum turgidum var. dicoccoides) is the immediate progenitor of cultivated tetraploid and hexaploid wheats and has been proven to be an important resource of disease resistance improvement. In this study, a common wheat line 3D258 with powdery mildew resistance was developed by crossing wild emmer accession WE29 with common wheat landrace Yanda1817 and backcrossing with common wheat line 87-1 (Yanda 1817/WE29//5*87-1, F₆). Genetic analysis of the F₂ population and their F₃ families, developed from 3D258 and a susceptible common wheat cultivar Xuezao, indicated that the powdery mildew resistance in 3D258 was controlled by a single dominant gene, designated temporarily as MlWE29. Molecular markers and the bulked segregant analysis were used to characterize the powdery mildew resistance gene MlWE29. Six SSR markers (Xgwm335, Xgwm213, Xgwm639, Xwmc415, Xwmc289, and Xwmc75) and five EST-STS markers (BE494426, BE442763, CD452476, BE445282, and BE407068) were found to be linked to MlWE29. Using Chinese Spring nullisomic-tetrasomics, ditelosomics and deletion lines, MlWE29 was physically mapped on chromosome 5BL bin 0.59–0.79. The common wheat line 3D258 and its resistance gene linked molecular markers could be used in disease resistance genes pyramiding and marker-assisted selection in wheat breeding program.

Function Deletion Analysis of Light-Induced Gacab Promoter from G.arboreum in Transgenic Tobacco

WANG Xu-Jing,LI Wei-Min,TANG Qiao-Ling,JIA Shi-Rong,WANG Zhi-Xing

Acta Agron Sin. 2009, 35(6):  1006-1012.  doi:10.3724/SP.J.1006.2009.01006

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Genes encoding plant chlorophyll a/b binding proteins (CAB) are a typical group of light-inducible genes. It is well established that cab promoters in plants are light-inducible and tissue-specific. We cloned a 1009-bp promoter sequence of the Gossypium arboreum cab gene and clarified that this promoter (Gacab P) is light inducible. It is also verified that GUS transient expression driven by Gacab P promoter fragment from –504 to –1 bp was significantly higher than that of the CaMV35S promoter. Further work need to be conducted to testify whether this 500 bp segment still maintains light-inducible character. To find the shortest length of light-inducible Gacab promoter with strong transcription activity, the full-length Gacab P (pA) and 5' truncations with lengths of 197 bp (pB), 504 bp (pC), and 779 bp (pD) were fused with the gus (uid A) gene and ligated into plant expression vectors. All constructs were transformed into Nicotiana tabacum var. NC89 using the Agrobacterium-mediated transformation method. A total of 30 to 35 independent transgenic tobacco lines were generated with each of these constructs. To determine whether the various promoter constructs confer light-regulated expression to gus, F₁ progeny seeds of transgenic plants containing different Gacab promoter deletion constructs were geminated in either the dark or light. Ten days later, the seedlings grown in the dark were transferred to the light. GUS histochemical assay showed that gus expression of the pA construct was not detected in the dark, whereas its expression was measurable at green tissue for seedlings grown in the light. gus was expressed throughout seedlings containing pB, pC, or pD grown in either the dark or the light. PlantCARE analysis reveals that some light responsive elements are present between –1009 and –779 bp, including sequences similar to the I-box and the G-box. To analyze the effectiveness of different lengths of the Gacab promoter, GUS expression under the control of the Gacab promoter deletion constructs was examined by fluorometric assays of transgenic tobacco leaf protein extracts. Twenty independent lines for each construct were selected to monitor GUS activity. The average GUS activity is presented for each construct. GUS activity increased when the nucleotides between –1009 and –504 were deleted. Further deletions from –504 to –197 resulted in decreased promoter strength. The highest GUS activity was observed with construct pC, which contained the promoter fragment from –504 to –1 bp. In transgenic plants, the 5'-deletion Gacab promoter fragments A, B and D had relative activities of 50.2%, 60.0%, and 51.5% respectively (compared with pC). The –504 to -1 (C) fragment of the Gacab promoter had an activity of 160% compared with CaMV35S. The strength of the other Gacab promoter deletion constructs was similar to CaMV35S. According to these results, we can get conclusion that only the full-length Gacab promoter was light inducible and expressed in a tissue-specific manner, and the promoter fragment from –504 to –1 bp has the highest activity, 0.6-fold higher than that of the CaMV35S promoter.

Isolation,Characterization and Mapping of Genomic Microsatellite Markers for the First Time in Sea-Island Cotton(Gossypium barbadense)

ZHANG Pei-Pei,WANG Xia-Qing,YU Yang,YU Yu,LIN Zhong-Xu,ZHANG Xian-Long

Acta Agron Sin. 2009, 35(6):  1013-1020.  doi:10.3724/SP.J.1006.2009.01013

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Sea-island cotton (G. barbadense) is one of the most important cultivated cotton species in the world. In order to explore the genetic diversity of this species, microsatellite loci were identified from G. barbadense cv. Pima3-79 (the genetic standard line). Microsatellite markers were developed using two different approaches: (i) cloning of ISSR amplified fragments and (ii) amplification using degenerate primers. Two hundred and thirty-nine unique clones were generated from 1447 recombinants, and 214 unique sequences were obtained. Eighty-six primer pairs were developed from 70 sequences that had flanking regions sufficient for primer design. The 86 SSR primer pairs were used to analyze 56 sea-island cotton accessions and 4 upland cotton cultivars, 16 primers had no amplification and 43 primers did not detect polymorphism between all the cultivars. Nineteen primers showed polymorphism between the sea-island cotton accessions. On the basis of Jaccard’s genetic similarity coefficient, these primers could distinctly distinguish sea-island cotton and upland cotton, and sea-island cotton accessions were separated into four groups. Nine interspecific polymorphic markers were mapped on the cotton genetic map with four mapped at A sub-genome and five at D sub-genome. These microsatellite markers will be useful for assessing the genetic diversity patterns within sea-island cotton as well as aiding in construction of genetic linkage maps.

ITS Region of rDNA in Common Wheat and Its Genome Origins

QIAN Jin，SUN Yi，DUAN Yong-Hong

Acta Agron Sin. 2009, 35(6):  1021-1030.  doi:10.3724/SP.J.1006.2009.01021

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Wheat, as an allohexaploid, is the most important cereal crop in the world. The origins of the three genomes have been a ‘hot spot’ for many geneticists and phylogeneticists since the famous Japanese geneticist Kihara suggested that wheat genome is composed of chromosomes of A, B and D genomes from three diploid progenitors. The studies on the origins of the three genomes have reported controversial results. Ribosomal DNA (rDNA) internal transcribed spacer (ITS) sequences are ubiquitous in most plants, they have been widely used in plant phylogenetics and systematics studies because of their unique characteristics compared with other types of DNAs. Specific primers were used to amplify the rDNA ITS sequences of common wheat (Triticum aestivum L.) by PCR. The amplified rDNA fragments were sequenced. Three types of ITS sequences were obtained. The results of cluster analysis by neighbor-joining method suggested that the sequence length of wheat ITS region was 602 bp, within which ITS1 and ITS2 had 8 and 20 variation sites, respectively. The range of genetic distances and genetic differentiation varied from 0 to 0.038, with the mean value of 0.021. The ITS sequences of common wheat resulted from this study were compared with those of its wild relatives, downloaded from GenBank, by MEGA, PAUP and PHYLIP programs, and the differentiation distances of ITS were calculated by Kimura-2 model program. A dendrogram was constructed with Bromus tectorum as the out-group. Based on the fact that common wheat had the ITS sequences highly similar to some of its wild relatives, we arrived at a conclusion that the formation of its genome is relatively recent events and the concerted evolution in its genome is incomplete, which provided the evidence at molecular level for that common wheat (Triticum aestivum L.) is an allohexaploid. By contrastive analysis to ITS sequences of common wheatandthe suspected donators of its genomes, we proposed that the most probable original donators of A, B, D genomes maybe T.urartu, T. speltoides, T. tauschii, respectively. We also proposed that the ‘concerted evolution’ is not concerted if we take various types of genes or DNA fragments into account.

Global Genome Expression Analysis of Transcription Factors under PEG Osmotic Stress in Rice Root System

MA Ting-Chen,CHEN Rong-Jun,YU Rong-Rong,ZENG Han-Lai,ZHANG Duan-Pin

Acta Agron Sin. 2009, 35(6):  1030-1037.  doi:10.3724/SP.J.1006.2009.01030

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Transcription factors play an important role in plant stress tolerance. The Affymetrix rice genome arrays were used to research the expression change of transcription factors and their families in two rice cultivars with different levels of drought tolerance under PEG osmotic stress. Results showed that a total of 95 transcripts encoding transcription factors (24 transcripts were down-regulated and 71 transcripts were up-regulated at the transcription level) in Xingfengzao 119 and 129 transcripts (69 transcripts were down-regulated and 60 transcripts were up-regulated at the transcription level) in Aihua 5 were affected by PEG osmotic stress. Transcription factors transcripts in response to PEG osmotic stresses were belonged to 30 transcription factors families for each of two cultivars, but there was a difference between the two 30 families. The transcription factors transcripts for expressed cultivar specific-response to PEG osmotic stress, with 72 transcripts for Xingfengzao 119 and 106 for Aihua 5. There was an overlap of transcripts in response to PEG osmotic stress between Xingfengzao 119 and Aihua 5, with the 16 and 7 up-regulated and the down-regulated at the transcription level, respectively. Distribution of PEG osmotic stress regulating genes of two cultivars on rice chromosome was different and their transcripts overlapped were located in 0.432 to 26.139 Mb of chromosome 2 and 0.076 to 20.597 Mb of chromosome 5.

Detection of Quantitative Trait Loci for Plant Height Using an Immortalized F₂ Population in Wheat

WANG Yan,LI Zhuo-Kun,TIAN Ji-Chun

Acta Agron Sin. 2009, 35(6):  1038-1043.  doi:10.3724/SP.J.1006.2009.01038

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To study the genetic mechanism of wheat plant height, a set of doubled haploid (DH) lines were used to construct an immortalized F₂ (IF₂) population comprising 168 different crosses. The IF₂ population was evaluated for plant height in 2007 cropping seasons in Tai’an and Liaocheng, Shandong province. Linkage map was constructed with 324 SSR markers covering the whole wheat genome, including 284 SSR, 37 ESTs loci, 1 ISSR loci and 2 HMW-GS loci, was constructed. This linkage map covered a total length of 2 485.7 cM with an average distance of 7.67 cM between adjacent markers. QTL analyses were performed using the software QTLNetwork version 2.0 based on the mixed linear model at P < 0.05. Four additive QTLs, 1 dominance QTL and pair of epistatic QTLs were detected, the total QTL effects detected for the plant height explained 20% of the phenotypic variation. One QTL qPh4D for plant height was identified on chromosome 4D, was identified on chromosome 2D, explaining 7.5% of the phenotypic variances. Dominance effect loci qPh2D was identified on chromosome 2D, explaining 1.6% of the phenotypic variances；Epistatic effects of loci was identified on chromosome 5B–6D, explaining 1.7% of the phenotypic variances . The results indicate additive effects, dominance effects and epistatic effects are important in genetics of wheat for plant height, which are also subjected to environmental modifications. These results further demonstrate that the use of IF₂ groups QTL positioning research methods contribute to the molecular marker-assisted breeding.

Genetical Studies on Progenies of Somatic Hybrids between Brassica napus and Descurainia sophia

XIN Ru-Ying,GUAN Rong-Zhan,ZHANG Li-Jun,JIANG Shu-Hui,ZHANG Hong-Sheng,ZHENG Xiu

Acta Agron Sin. 2009, 35(6):  1044-1050.  doi:10.3724/SP.J.1006.2009.01044

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Somatic hybridization is an available way to create new germplasm and enrich breeding materials. Somatic hybridization between B. napus and D. sophia has been finished by the authors in 2005. Present research is to continue progeny studies of the somatic hybrids with the objective of carrying out desirable genes transfer from D. sophia to B. napus. Fertile progenies of the somatic hybrids between Brassica napus (2n=38) and Descurainia sophia (2n=38) selfed in three consecutive generations, resulting in F₂, F₃, and F₄ populations. The number of somatic chromosome, chromosome behavior and genetic components from D. sophia in these progenies were observed and analyzed by cytological and SSR analyse. The average number of chromosomes in F₂, F₃, and F₄ populations were 38.47±3.17, 37.65±3.23, and 36.66±2.95, respectively, and the maximum number was 56, 50, and 45, respectively, showing that chromosome number tended to reduction with the generation progression. Abnormal chromosome behaviors such as chromosome bridges, lagging chromosomes, meiotic cycle asynchrony, chromosome unequal distribution at meiosis stage were often observed in the three populations. SSR marker detections with 22 pairs of primers showed that the average frequency of plants with bands characteristic of D. sophia in the F₂, F₃, and F₄ populations was 9.62%, 2.99%, and 0.31%, respectively. Therefore, achieving germplasm of D. sophia filter into B. napus should attach importance to select progenies of the somatic hybrid in F₂ population.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Dynamic Changes of Photosynthetic Characteristics in Xiaoyan 54,Jing 411 and the Stable Selected Superior Strains of Their Hybrid Progenies

CHENG Jian-Feng,MA Wei-Min,CHEN Gen-Yun,HU Mei-Jun,SHEN Yun-Gang,et al.

Acta Agron Sin. 2009, 35(6):  1051-1058.  doi:10.3724/SP.J.1006.2009.01051

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Xiaoyan 54, derived from the cross between Triticum aestivum L. and Thinopyrum ponticum, has special features of inherent higher cyclic photophosphorylation activity during photosynthesis and its higher tolerance to stresses. Many hybrid progenies of Xiaoyan 54 and Jing 411 were produced in the Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, including several lines with stable characters. To explore their photosynthetic properties and provide theoretical basis or technical approaches for wheat breeding selection, the parents (Xiaoyan 54 and Jing 411) and the stable single-seed descent lines 6, 7, and 10 were planted in Shanghai in 2006–2008 growing seasons. Millisecond delayed light emission (ms-DLE) of their flag leaves during the heading stage was determined in 2007. The morpho-agronomic and yield traits of them were investigated in 2008. Net photosynthetic rate (P_n),chlorophyll content (Chl), specific leaf weight (SLW), F_v/F_m, ATP content, initial reduction rate of P700 in reciprocal first functional leaf of them during the different growth stages were determined for analyzing dynamic changes of photosynthetic characteristics in 2008. The morpho-agronomic traits of the line 6 and 7 were similar to Xiaoyan 54 and Jing 411, respectively, and varied markedly in line 10. Photosynthetic characteristics of the parents and stable single-seed descent lines were closely related to the growth stages and measured indexes. P_n decreased in the order of tillering stage > heading stage > grain filling stage > jointing stage; Chl content was different with grain filling stage ranking the first, followed by heading stage, tilleringstage and jointing stage; ATP content was the order of grain filling stage > jointing stage > tillering stage > heading stage; initial reduction rate of P700 was at grain filling stage > heading stage > jointing stage > tillering stage; F_v/F_m at various growth stages were similar without significant differences. The heterobeltiosis of photosynthetic characteristics in wheat changed with different growth stages, such as the heterobeltiosis of P_n or Chl in line 10 was at grain-filling stage, heterobeltiosis of ATP content was at heading stage, SLW and initial reduction rate of P700 in each growth stage were the medium between the parents. Photosynthesis capacity was superior in line 10 than in the parents because of the heterobeltioses on P_n and contents of Chl and ATP. In lines 6 and 7, the photosynthesis capacity was inferior to and between the parents, respectively.

Effects of Aluminum on Mitochondrial membrane Physiological Characteristics in Peanut Root Tips

ZHAN Jie,KOU Rui-Jie,LI Chuang-Zhen,HE Hu-Yi,HE Long-Fei

Acta Agron Sin. 2009, 35(6):  1059-1067.  doi:10.3724/SP.J.1006.2009.01059

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Mitochondria play a vital role in plant life. Peanut (Arachis hypogaea L.) culitivars LH11 (Al-resistant) and R1549 (Al-sensitive) were selected through root elongation experiment, hematoxylin dying and Al³⁺ concentration detection in root tips. The concentration of mitochondrial MDA in two cultivars root tips increased after Al³⁺ treatment that of R1549 was higher than that of LH11. The difference between two cultivars in mitochondrial MDA concentration was very significant in 20ΔΨ decreased significantly, mitochondrial Cyt c/a ratio reduced, which was more obvious in R1549 than in LH11 with Al³⁺ concentration increasing. To sum up, high Al³⁺ concentration treatment induced mitochondrial permeability transition pore opening, increased mitochondrial membrane permeability, decreased mitochondrial membrane Ca²⁺ transit system activity so that cytoplasm Ca²⁺ concentration increased, cytochrome c released into the cytoplasm, which might induce PCD(programmed cell death) in root tip, and inhibit root growth. Compared with Al-sensitive cultivar, Al-resistant cultivar has less Al³⁺ absorption and membrane lipid peroxidation level, higher control ability of Ca²⁺-ATPase activity, MPTP opening and ΔΨ_m maintaining so that is not easy to produce PCD under low Al³⁺ concentration stress. It may be one of reasons for Al resistance mechanism in plant.

Canopy Characteristics and Its Correlation with Photosynthesis of Super High-Yielding Hybrid Cotton Biaoza A₁ and Shiza 2

DU Ming-Wei,FENG Guo-Yi,YAO Yan-Di,LUO Hong-Hai,ZHANG Ya-Li,XIA Dong-Li,et al.

Acta Agron Sin. 2009, 35(6):  1068-1077.  doi:10.3724/SP.J.1006.2009.01068

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Alterations of canopy architecture improving photosynthesis may be a way to increase the yield of cotton. Study on the relationship between canopy characteristics and photosynthesis is of great significance to excavate yield potential and construct super high-yielding cultivation technique system. The present investigation was undertaken in the field experiment to evaluate the canopy characteristics, such as leaf area distribution, leaf angle and light distribution, and its correlation with canopy photosynthesis of super high-yielding hybrid cotton (lint 3 500 kg ha^-1). Two super high-yielding hybrid cotton cultivars, Biaoza A₁ and Shiza 2, were grown with Under-Mulch-Drip irrigation. The results revealed that super high-yielding hybrid cotton had higher leaf area index with longer duration during growth stages. Higher light absorption was observed with better light transmittance in the mid layer of canopy and less light leakage in the lower layer of canopy in super high-yielding hybrid cotton. Higher canopy photosynthetic rate with longer duration was also observed during growth stages. Furthermore, in the late growth stage, non-foliar organs, especially the stem of super high-yielding hybrid cotton remained higher photosynthetic capacity. The photosynthetic contribution rate of stem was 1.6-4.9 times that of the high-yielding traditional cotton, which is an important reason for hybrid cotton to remain superiority of canopy photosynthesis in the late growth stage. In the effective utilization of light energy and promotion of assimilations transport to boll promptly, super high-yielding hybrid cotton has higher anastomosis degrees among leaf, boll and light distributions in each layer of canopy, which is beneficial to enhancing hybrid cotton yield potential.

Effects of Nitrogen on Cotton（Gossypium hirsutum L.） Root Growth under Short-Term Waterlogging during Flowering and Boll-Forming Stage

GUO Wen-Qi,ZHAO Xin-Hua,CHEN Bing-Lin,LIU Rui-Xian,ZHOU Zhi-Guo

Acta Agron Sin. 2009, 35(6):  1078-1085.  doi:10.3724/SP.J.1006.2009.01078

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The flowering and boll development stage is the key period for cotton quality and yield. Waterlogging during this period significantly inhibits cotton development and reduces final yield. Nitrogen fertilizer is considered to be an effective up-regulatory element for crop growth. The objective of this investigation was to evaluate effects of nitrogen on cotton resistance to soil waterlogging in terms of the changes of root dry matter accumulation, antioxidant enzyme activities and root vigor under short-term waterlogging. A pot experiment wasconducted with three N levels (0, 3.73, and 7.46 g N pot^-1 equivalent to 0, 240, and 480 kg N ha^-1, respectively), waterlogging for eight days and then recovering for fifteen days. The results showed that the root dry matter weight and the Root/Shoot ratio of plants by waterlogged decreased, and the root dry matter weight reached a peak at the 240 kg N ha^-1 under waterlogging, but the root/shoot ratio decreased with the increase of N application. Under waterlogging, soluble protein content significantly decreased in comparison with well-watered cotton, and the reduced degree increased with increasing N application. Malondialdehyde (MDA) content in cotton roots was significantly (P <0.05) increased, with the lowest at the 240 kg N ha^-1 during waterlogging. Application of N increased the activities of peroxidase (POD) and catalase (CAT) of cotton roots, but decreased superoxide dismutase (SOD) activity during waterlogging. Both root vigor and CAP decreased by waterlogging, were the highest at the 240 kg N ha^-1. At the 15 d after terminating waterlogging, N application promoted root vigor and CAP, but decreased MDA content. These results suggest that appropriate N supply (240 kg N ha^-1 in this investigation) may contribute to waterlogging resistance of cotton plants through adjusting the antioxidant enzyme activities of roots, decreasing lipid peroxidation and enhancing root vigor during waterlogging (waterlogging for eight days in this investigation), excessive N supply (480 kg N ha^-1) has a deleterious effect on plant waterlogging resistance, however, more N should be supplied to waterlogged cotton pants after terminating waterlogging.

Characteristics of Accumulation and Distribution of Nitrogen and Dry Matter in Wheat at Yield Level of Ten Thousand Kilograms per hectare

ZHANG Fa-Quan,WANG Xiao-Yan,YU Zhen-Wen,WANG Xi-Zhi,BAI Hong-Li

Acta Agron Sin. 2009, 35(6):  1086-1096.  doi:10.3724/SP.J.1006.2009.01086

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Application of nitrogen (N) fertilizer is one of the most important cultivated measures to increase wheat (Triticum aestivum L.) yield in production. However, abuse of N fertilizer will not only reduce grain yield and economic profit but also cause environmental problems. The proper amount of N fertilizer applied in high-yielding production of winter wheat has been studied at the yield level of 9000 kg ha^-1. The objective of this study was to determine the effects of several N fertilizer rates on uptake, distribution, and translocation of nitrogen as well as grain yield, therefore, to suggest a reasonable application rate of N fertilizer in wheat production. Three rates of N fertilizer application (0, 180, and 240 kg ha^-1) without manure before sowing were designed in Experiment I in 2005–2006, only one treatment of N fertilizer (260 kg ha^-1) with 3 750 kg ha^-1 manure before sowing in Experiment II in 2005–2006, and six N fertilizer rates (0, 210, 240, 270, 300, and 330 kg ha^-1) with 3 750 kg ha^-1 manure in 2006–2007. Two wheat cultivars with medium protein content, Taishan 23 and Jimai 22, were used in the three experiments, i.e., Taishan 23 in Experiment I, Jimai 22 in the other two experiments. The results showed that the application of manure before sowing had minor effect in this study, and three experiments showed similar changing trends in N accumulation and translocation among various organs and growth stages as well as the grain yield. Take the example of Experiment III, with more input of N fertilizer, the grain yield first increased and later decreased during growth period compared with the control (no N fertilizer treatment), and the grain yields of N240 (240 kg ha^-1) and N270 (270 kg ha^-1) treatments were 9 954.73 and 10 647.02 kg ha^-1, respectively, by the increase percentages of 11.20% and 18.93%. Compared with the control, the nitrogen accumulation amount in plant and grain and the nitrogen translocation amount (nitrogen accumulation in vegetative organs at anthesis stage minus the nitrogen accumulation in vegetative organs at maturity, NTA) from vegetative organs to grains after anthesis significantly increased in treatments with N fertilizer application. With the increase of N fertilizer rate, the nitrogen accumulation amount in wheat plant showed a changing trend of first up and then down. The N270 treatment had the highest nitrogen accumulation amount at maturity. The NTA and nitrogen translocation efficiency (NTA/ nitrogen accumulation in vegetative organs at anthesis stage, TE) from vegetative organs to grain after anthesis also increased at first and then decreased. The N270 treatment had the highest nitrogen translocation amount, which was 213.78 kg ha^-1. The N 240 treatment had the highest TE of 67.98%. Similarly, the dry matter accumulation amount in various vegetative organs of wheat at maturity, the dry matter redistribution amount from vegetative organs to grain after anthesis, and the dry matter redistribution efficiency after anthesis were all largest in N270 treatment. Among the six N fertilizer treatments, the contribution of dry matter accumulation amount from vegetative organs to grains after anthesis was the largest in N240 treatment. The results of this study suggested that N fertilizer supplied at 240–270 kg ha^-1 is optimal in wheat production under similar conditions to those of the experiments to obtain the high-yielding level of 10 000 kg ha^-1.

Effect of Plant Density on Dynamic Characteristics of Leaf Area Index in Development of Spring Maize

SUN Rui,ZHU Ping,WANG Zhi-Min,CONG Yan-Xia,GOU Ling,FANG Li-Feng,ZHAO Ming

Acta Agron Sin. 2009, 35(6):  1097-1105.  doi:10.3724/SP.J.1006.2009.01097

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To provide further evidence for the regulatory effect of plant densities on the important characteristics of leaf area index (LAI), the important feature of the regulation role for the parameters, such as the velocity of LAI change, mean LAI, the maximum LAI and the time to maximum LAI was analyzed quantitatively. A field experiment using two spring-maize cultivars, Jidan 209 and Zhengdan 958, was conducted with five different densities from 4.5×10⁴ to 10.5×10⁴ plants ha^-1 in 2005 and seven different densities from 3×10⁴ to 12×10⁴ plants ha^-1 in 2006 in Jilin province, respectively. An extensively suitable LAIsimulation model for high yield population, y= (a+bx)/(1+cx+dx²) was adopted in the present research to simulate and analyze the effect of different densities on the dynamic characteristics of LAI in development of spring-maize in whole growth duration. The results indicated that maximum LAI was significantly increased with the increase of planting density from 3×10⁴ to 12×10⁴ plants ha^-1 and the time to the maximum LAI advanced with increasing plant densities. The relative LAI of different densities showed large difference between before and after reaching the maximum LAI. LAI of high density decreased more rapidly than that of low density. The mean LAI in whole growth duration increased while the ratio of mean LAI to the maximum LAI declined with increasing densities. The influence of density on each parameter of model equation by applying the relative model was different, that between intervals of 3×10⁴ plants ha^-1 was significant. The trend of changes on different parameters was different. The parameter a approached to 0, therefore, density has little effect on it. The parameters b and c reduced with increasing densities, but d increased with increasing densities. The velocity of LAI change in growing period showed the trend of a curve of N shape with variable speed, and the changed trend of LAI fit into growth at ages. The velocity of LAI change in high-density population increased or decreased larger than that in low-density population. The jointing period and the big flare periods were in response to density sensitively. The results above proved that some important indexes are more sensitive to different densities, such as the changing velocity of group LAI, the maximum LAI, the time to the maximum LAI, mean LAI, and the ratio of mean LAI to the maximum LAI. These characteristic indexes of LAI may serve as the reference for regulating plant density of spring maize population.

Population Characteristics of Super Japonica Rice Ningjing 1 and Ningjing 3 and Its Responses to Nitrogen

LI Gang-Hua,ZHANG Guo-Fa,CHEN Gong-Lei,WANG Shao-Hua,LING Qi-Hong,DING Yan-Feng

Acta Agron Sin. 2009, 35(6):  1106-1114.  doi:10.3724/SP.J.1006.2009.01106

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In order to study the super high-yielding population characteristics of super japonica rice and its responses to nitrogen, two field experiments with five N rate treatments and four N application ratio treatments of Ningjing 3 were carried out in 2008, the 6.7 ha demonstration fields of Ningjing 1 and Ningjing 3 in 2007 and 2008 were also investigated. Results showed that the dry matter accumulation of Ningjing 1 and Ningjing 3 after heading was 70–80% of the grain yield, and the apparent translocation ratio of dry matter from stem and leaves to grain was small, which resulted in the high and stable grain yield. Ample spikelets per square meter were the guarantee of super and stable high yield. To achieve the target yield of 11.0 t ha^-1, the spikelets per square meter must be above 42 000 m^-2; to achieve the target yield of 11.7 t ha^-1, the spikelets per square meter must be above 45 000 m^-2, as well as grain filling rate and grain weight must be above 90% and 26 mg. For super high-yielding rice population, the optimal LAI at heading should be 7.0–7.5, crop growth rate (CGR) from heading to maturity should be higher and the harvest index (HI) should be above 0.5. The appropriate N rate and relative more N topdressed at panicle initiation stage could not only ensure the optimal LAI at heading, but also maintain the plant type characteristics of super high-yielding rice, improve the LAI after heading, leaf area duration, CGR and HI, therefore achieve the super high grain yield.

Relationships among Water Use Efficiency,Carbon Isotope Discrimination,and Specific Leaf Area in Maize

ZHANG Cong-Zhi,ZHANG Jia-Bao,ZHAO Bing-Zi,ZHANG Hui,HUANG Ping,LI Xiao-Peng etal

Acta Agron Sin. 2009, 35(6):  1115-1121.  doi:10.3724/SP.J.1006.2009.01115

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Plant fractionates heavy carbon isotopes during photosynthesis, which usually occurs when CO₂ diffuses to the carboxylation site, and during carboxylation reaction. On account of CO₂ fixation process is coupled with water transpiration during the photosynthesis, it is possible to apply stable carbon isotope to study crop water use efficiency (WUE). At present, stable carbon isotope techniques have been widely studied and applied in C₃ plants, however, the relative studies are less reported in C₄ plants. In this way, a pot experiment was conducted from June 9 to September 25 in 2007 to study the variation of leaf area (LA), specific leaf area (SLA), water use efficiency (WUE), and carbon isotope discrimination (Δ¹³C) in maize (Zea mays L.) under different water deficit conditions. The objective was to understand the relationship among WUE, Δ¹³C and SLA. Maize were subjected to four water treatments, that is: 75–100% (W1), 50%–75% (W2), 30%–50% (W3), and 0–30% (W4) of field water-holding capacity of the soil. The WUE, SLA, and Δ¹³C values were measured at seedling, jointing, booting, tasseling, filling, and mature stages. The dry matter accumulation at jointing was obviously affected by W2 and W3 treatments, and decreased significantly in W4 treatment after booting. WUE increased with water stress during all growth stages in W2 and W3 treatments, but decreased significantly in W4 treatment after booting. SLA reached maximal value at booting. Leaf Δ¹³C decreased in W1, W2, and W3 treatments from jointing to mature, whereas leaf Δ¹³C value was greater in W4 treatment than in W2 and W3 treatments. Stem Δ¹³C significantly and positively correlated and presented no significant difference with leaf Δ¹³C, which indicated that carbon isotope was not fractionated during photosynthate transport from leaves to stems. Maize Δ¹³C was negatively correlated with WUE; SLA and Δ¹³C presented positive correlation and both negatively correlated with WUE.

Simulating Soil Water Dynamics and Its Effects on Crop Yield Using RZWQM-CERES in the North China Plain

FANG Quan-Xiao,YU Qiang,WANG Jian-Lin

Acta Agron Sin. 2009, 35(6):  1122-1130.  doi:10.3724/SP.J.1006.2009.01122

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Agricultural system model is an important tool for optimizing multi-objective managements and decisions in agriculture. However, due to the complex process with multiple parameters in the model, calibration and validation for system model are difficult. In the paper, the hybrid model RZWQM (Root Zone Water Quality Model)-CERES (Crop Environment Resource Synthesis) was calibrated and validated for simulating soil water dynamics and crop yield under various irrigation levels at Yucheng and Luancheng Experimental Stations in the North China Plain. The results showed that the root mean standard error (RMSE) and mean relative error (MRE) of simulated soil water storage in the 0–120 cm layer across different treatments at Yucheng Experimental Station ranged from 2.38 to 2.70 cm and from 2.8 to 3.3%, respectively. The RMSE and MRE of simulated leaf area index across treatments were ranged from 0.43 to 0.73 and from –12.8 to 4.2%, respectively, and the RMSE and MRE of simulated grain yield ranged from 550 to 580 kg ha^-1 and from –0.6 to 7.6 %, respectively. At Luancheng Experimental Station, the RMSE and MRE of simulated soil water storage in the 0–120 cm layer ranged from 3.49 to 3.73 cm and from –0.6 to 10.0 %, respectively. The RMSE and MRE of simulated grain yield were 670 kg ha^-1 and –6.6%, respectively. Generally, the simulated and measured grain yields showed similar responses to soil water changes across the irrigation treatments (R² = 0.83^***, n =22). Above results indicate that RZWQM-CERES can be used as a tool to simulate and investigate the effects of soil water on crop yield in the wheat-maize cropping system in the areas. The reasonable model parameters established for the cropping system are the basis of model application for optimizing multi-objective managements and decisions in agriculture. The model parameterization, model mechanism and its flexibility were also discussed.

Correlation between Canopy Spectral Vegetation Index and Leaf Stomatal Conductance in Rapeseed(Brassica napus L.)

SUN Jin-Ying,CAO Hong-Xin,HUANG Yun

Acta Agron Sin. 2009, 35(6):  1131-1138.  doi:10.3724/SP.J.1006.2009.01131

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It plays a very important role for improving water use efficiency of crops and predicting crop yield and quality to monitor leaf stomatal conductance with real time, non-destructively and quantitatively by using canopy spectral characteristics. In the paper, the spectral reflectance, leaf stomatal conductance, LAI (leaf area index), leaf fresh and dry biomass of two rapeseed varieties were determined in a field experiment by split-plot design with the main plot of N levels and the subsidiary plot of cultivars, 3 replications, and plot area of 4.3 m by 7.0 m in 2007–2008. The changes in leaf stomatal conductance and the correlation between leaf stomatal conductance and spectral vegetation index were analyzed based on the vegetation index combined with spectral reflectance in all kinds of bands. The estimating models for spectral vegetation index of leaf stomatal conductance were established according to the relationship between spectral vegetation index and leaf stomatal conductance. The results showed that there were two peaks in changes carve of leaf stomatal conductance, and one peak in the changes curve of LAI, leaf fresh and dry biomass in the whole growth period. There existed significantly positive correlation between spectral vegetation index and leaf stomatal conductance or canopy leaf stomatal conductance before flowering, and the spectral vegetation index better fitted into canopy average stomatal conductance than into leaf stomatal conductance. The quantitative relationships between spectral vegetation index and canopy leaf stomatal conductance laid the foundation for rapid and non-destructive stomatal conductance estimates in a large area of rapes in future.

RESEARCH NOTES

Comparison of Seed Structure of Progenies from Intergeneric Hybrids between Sinapis alba and Brassica napus

WEI Cun-Xu,LI Ai-Min,ZHANG Yong-Tai,ZHOU Wei-Dong,WANG You-Ping

Acta Agron Sin. 2009, 35(6):  1139-1145.  doi:10.3724/SP.J.1006.2009.01139

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Sinapis alba L. possesses desirable agronomic characters. The backcross progenies of intergeneric hybrids between S. alba and Brassica napus L. obtained the valuable agronomic traits from S. alba. Seed structure of some yellow and yellow-like seed lines, which were selected from backcross progenies, was observed under light microscopy and electronic microscopy. The morphologically anatomical structure of seed coat of backcross progenies resembled that of B. napus, but was different from that of S. alba. Seed coat of B. napus was composed of flattened epidermis, crushed subepidermis, U-shaped-a palisade layer and aleurone layer, while seed coat of S. alba was composed of intestine-shaped epidermis, ellipse subepidermis, U-shaped-b palisade layer and aleurone layer. The pigments of seed coat were mainly distributed in the palisade layer. There were pigments in seed coats of B. napus and some backcross progenies, but no pigments in those of S. alba and other backcross progenies. The palisade layer was thicker in B. napus, thinner in S. alba, and intermediate in hybrid progenies. Seed coat microsculpturing was observed with scanning electronic microscope. The reticulate-foveate pattern was the characteristics of B. napus and hybrid progenies, while the blister pattern of H₂O-immersed seed and the sulcate pattern of dry seed were the characteristics of S. alba. The area of cotyledon cell was larger in B. napus, smaller in S. alba, and intermediate in hybrid progenies. The area index of protein body in cotyledon cell was higher in S. alba, lower in B. napus, and intermediate in progenies. The observations of ultrastructure showed that protein bodies were heterogeneous with crystal globoids in parents and progenies. Oilbodies included large and small oilbodies, and their sizes were different from each other between parents and progenies. The above results showed that the anatomy of the progeny seeds was similar to that of B. napus, but the seed color, the thickness of palisade layer, cotyledon cell size, protein body and oilbody were affected by S. alba.

Drought and Salinity Tolerance in Transgenic Potato Expressing the Betaine Aldehyde Dehydrogenase Gene

ZHANG Ning,SI Huai-Jun,LI Liang,YANG Tao,ZHANG Chun-Feng,WANG Di

Acta Agron Sin. 2009, 35(6):  1146-1150.  doi:10.3724/SP.J.1006.2009.01146

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Glycine betaine (GB) is a common compatible solute in many different organisms including higher plants. Many plant species can accumulate GB in response to drought and salinity. GB is synthesized by conversion of choline to GB through a two-step oxidation via the intermadiate betaine aldehyde. In higher plants, the relevant enzymes are choline monooxygenase (CMO) and betaine aldehyde dehydrogenase (BADH). The fact that many important crops, such as rice, potato and tomato, are betaine-deficient has inevitably led to the proposal that it might be possible to increase drought and salinity tolerances by genetic engineering of GB synthesis. In the present study, the transgenic plants of potato cultivar Gannongshu 2 were obtained by Agrobacterium-mediated transformation of the expression vector pBIBB contained BADH gene under the control of the constitutive promoter CaMV 35S. PCR, Southern and Northern blot analyses showed that the BADH gene was integrated into potato genome, transcribed and expressed in the transgenic plants. The analysis of BADH activity of transgenic plant leaves revealed that the BADH activity ranged from 2 to 11 U, while it was not detectable in the control plants. There was a negative relationship (y= –3.7738x+57.083, r=0.989^**) between BADH activity and relative electric conductivity of the transgenic potato leaves. The transgenic potato plants grew normally under NaCl and polyethylene glycol (PEG) stresses with increase of 0.4–0.9 cm for plant height and 17–29% for fresh weight per plant compared with the control plants. This result demonstrated that the transgenic potato plants can improve tolerances to drought and salinity as a result of transformation and expression of BADH gene.

Genetic Analysis and Molecular Mapping of a Male Sterile Mutant in Rice

CHU Ming-Guang,LI Shuang-Cheng,WANG Shi-Quan,DENG Qi-Ming,ZHANG Jing,et al.

Acta Agron Sin. 2009, 35(6):  1151-1155.  doi:10.3724/SP.J.1006.2009.01151

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Male sterility is an important inheritance phenomenon in plants and widely used in hybrid seed production. The male sterile plant can't produce normal male gametophyte for reproduction, while the female counterpart is normal. So far, more than 100 of male sterile mutants or genes have been reported in rice. Ms-np is a male-sterile mutant derived from a spontaneous mutation. The filaments of the mutant are long and thin, and the withered anthers are white and transparent. Ms-np was confirmed to be a none-pollen type mutant of male sterility, for no pollen grains were stained with I₂-KI solution and the anther locules were always hollow. Genetic analysis of five F₂ populations and two BC₁F₁ populations revealed that the mutation was controlled by a single recessive gene. To uncover the molecular basis of ms-np, the F₂ population derived form the cross of ms-np/M63 was used for genetic mapping. Screening of 227 F₂ mutant individuals with simple sequence repeat (SSR) markers indicated that ms-np(t) was located between the molecular markers RM541 and RM343, on chromosome 6, with the distances of 15.2 and 7.9 cM, respectively. The results provide a basis for further gene cloning and understanding of the molecular mechanism underlying rice male fertility.

Expression of GMCHI gene，isolated from Soybean，Enhances the Survival in Prokaryotes to Low Temperature Stress

CHENG Li-Bao,LI Shu-Yan,HE Guang-Yuan

Acta Agron Sin. 2009, 35(6):  1156-1160.  doi:10.3724/SP.J.1006.2009.01156

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Low temperature during germination being a natural disaster usually occurs in North of China, which results in low germination rate and low seedling vigor, and even ultimately severe loss in yield. A gene was isolated from soybean Zhonghuang 22 cultivar (tolerant to low temperature in imbibition) for 24 h under 4℃ via cDNA-AFLP, name as GMCHI, GenBank accession No. EU699765. The full-length sequence of GMCHI which was 387 bp in nucleotide was obtained by RACE method. The sequence of gene shared low similarity with that of genes documented in NCBI, we inferred that GMCHI was a new discovered gene in soybean. Semi quantitative RT-PCR result revealed that GMCHI was induced by ABA and IPEG.. The gene ligated with Prokaryotic expression vector was transformed into prokaryotic cell, the result of 6% SDS-PAGE induced by IPTG was expressed in Prokaryotes. The E. coli carrying GMCHI survived and showed tolerance to low temperature under the treatment of –20℃ for 2 h. RT-PCR validated that GMCHI in Prokaryotes improved the adaptation to low temperature.

Cloning and Expression Analysis of an NBS-LRR Type Gene from Sugarcane

QUE You-Xiong,XU Li-Ping,ZHANG Mu-Qing,ZAHNG Ji-Sen,CHEN Ru-Kai

Acta Agron Sin. 2009, 35(6):  1161-1166.  doi:10.3724/SP.J.1006.2009.01161

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In the present study, a non-TIR-NBS-LRR type disease-related gene was cloned by rapid amplification of cDNA ends (RACE) using the high-resistant sugarcane variety NCo376.This gene was termed as SNLR, with the GenBank accession No. of EF155648. The full-length cDNA sequence of SNLR is 2 985 bp, including an open reading frame (ORF) of 2661 bp and the typical 29 bp poly-A. The SNLR gene contained all the four typical conserved motifs of the NBS: P-loop (GMGGVGGKTT), Kinase-2 (LIVLDD), Kinase3a (GSR/KILVIIR) and hydrophobic region (GLPLAL), plus six putative LRR regions. It can be deduced from the hydrophobic character, secondary structure and 3D model analysis of the corresponding coding protein that the SNLR protein was alkalescent, with pI of 7.76 and without any obvious hydrophobic domain; coil and helices were the framework of secondary structure; no transmembrane region was found in its protein 3D model. The gene expression profile under the treatment ofU. scitaminea, SA and H₂O₂ wereinvestigated by Real-time qPCR. Results showed that expression ofsugarcane SNLR gene was influenced by the fungus, SA and H₂O₂, with the expression patterns of “down-up”, “down in the whole process” and “up-down”, respectively. It was inferred that expression of SNLR gene occurs both via an H₂O₂- and SA-dependent pathway. At the same time, SNLR gene was found to be expressed highly in leaves, mildly in stalks and slightly in roots, which indicated its relation to resistance in this aspect.

Variation of Wheat Quality in Main Wheat-Producing Regions in china

HU Xue-Xu,ZHOU Gui-Ying,WU Li-Na,LU Wei,WU Li,LI Jing-Mei,WANG Shuang,et al.

Acta Agron Sin. 2009, 35(6):  1167-1172.  doi:10.3724/SP.J.1006.2009.01167

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In China, regional planning for wheat quality consists of three regions and 10 subregions. The main wheat-producing area is composed of several subregions, such as Northern part of North China (I), Northern part of Huang-Huai Region (II), Southern part of Huang-Huai Region (III), and Middle-to-Lower Reaches of Yangtze River (IV). Generally, wheat cultivars growing in the four subregions are characterized with strong gluten, strong-to-medium gluten, medium gluten, and medium-to-weak gluten, respectively. To study the distribution of cultivars with various quality types, a total of 2 571 samples of 174 wheat cultivars collected from the four subregions in 2003–2007 were analyzed with 14 quality traits. There were significant (P < 0.05 or P < 0.01) variations among the four subregions in each year. However, the variance trends were not consistent across years. Based on the averages of the five years, significant (P < 0.05 or P < 0.01) differences were observed among various subregions in kernel protein content, wet gluten content, forming time, stability time, loaf volume, and loaf score, which in the four subregions were sanked as I > II > III > IV. Cultivars from I and II subregions performed higher falling number, flour yield, sedimentation value, water absorption, extension area, extensibility, and maximum resistance to extensibility than those from III and IV subregions. Most of the strong-gluten cultivars were distributed in I and II subregions, and the medium-gluten and weak-gluten wheat were mainly planted in III and IV subregions, respectively.