Table of Content

12 July 2008, Volume 34 Issue 07

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Molecular Characterization of Slow-Rusting Genes Lr34/Yr18 in Chinese Wheat Cultivars

YANG Wen-Xiong;YANG Fang-Ping;LIANG Dan;HE Zhong-Hu;SHANG Xun-Wu;XIA Xian-Chun

Acta Agron Sin. 2008, 34(07):  1109-1113. 

Abstract ( 2478 )   PDF (572KB) ( 1724 )   Save

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Lr34 and Yr18 are important slow rusting resistance genes that have been widely used in many countries. The aim of this study was to identify Lr34/Yr18 genes in 231 Chinese wheat cultivars and 422 landraces using an STS marker csLV34, which can amplify a 150-bp and a 229-bp fragment in the genotypes with and without Lr34/Yr18, respectively. The results indicated that only 14 genotypes carried the resistance genes Lr34/Yr18 in the improved wheat cultivars, with a frequency of 6.1%. Different frequencies were found in wheat cultivars from different zones, which were 0, 3.0%, 21.4%, 16.7%, and 33.3% in North Plain Winter Wheat Region (NPWWR), Yellow-Huai Facultative Winter Wheat Region (YHFWWR), Middle-Lower Yangtze Valley Winter Wheat Region (MLYVWWR), Southwest Winter Wheat Region (SWWR), and Northwest Spring Wheat Region (NSWR), respectively. Whereas, 85.1% of 422 landraces contained Lr34/Yr18, with the frequencies of 89.6%, 77.4%, 93.1%, 93.8%, 96.6%, and 61.1% in NPWWR, YHFWWR, MLYVWWR, SWWR, Southern China Winter Wheat Region (SCWWR) and NSWR, re-spectively. The marker csLV34 exhibited a good repeatability, and can be therefore used for the identification of Lr34/Yr18 in wheat breeding programs.

Genomic DNA Sequence, Gene Structure, Conserved Domains, and Natural Alleles of Gln1-3 Gene in Maize

WU Yong-Sheng;LI Xin-Hai;ZHANG Zheng;LI Ming-Shun;HAO Zhuan-Fang;ZHANG Shi-Huang;XIE Chuan-Xiao

Acta Agron Sin. 2008, 34(07):  1114-1120. 

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Glutamine synthetase gene family, the core elements of in vivo nitrogen use efficiency (NUE) and nitrogen recycle, encodes enzymes catalyzing the nitrogen assimilation from ammonium ion into protein in higher plant. Gln1-3 is a member of GS family that encodes the cytosolic isozyme expressed in mesophyll cells of maize (Zea mays L.). The knowledge about the genomic se-quence of the gene is the premise for the natural alleles, functional studies, and molecular marker development. In the present study, 4 571 bp of genomic region of Gln1-3 was sequenced using a maize inbred line Liaobai 371 with PCR walking strategy.
The 3 062 bp coding region of the gene was comprised of ten exons that were separated by nine introns. Totally, six out of nine
splice sites followed splicing mechanism with conserved GU sequences at 5′ donor sites and AG at 3′ acceptor sites. The se-
quence has been submitted to GenBank (Accession No.: EU338535) and annotated in details. Encoded GS1 protein, molecular
weight of 39.2 kD, is comprised of 356 amino acids. Its isoelectric point (pI) is 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 and exon 9 at carboxyl terminal consisted of an ATPase domain to fulfill the synthesis activity. A total of 364 sites of natural variation at impor-tant and target region of Gln1-3 gene were identified among 50 maize inbred lines, and 313 (86%) sites of the total (364) were SNP variations. The results provide a good basis for analyzing the key candidate genes associated with NUE and grain yield under different nitrogen supplies levels.

A Response of PvP5CS2 Gene to Abiotic Stresses in Common Bean

CHEN Ji-Bao;JING Rui-Lian;MAO Xin-Guo;CHANG Xiao-Ping;WANG Shu-Min

Acta Agron Sin. 2008, 34(07):  1121-1127. 

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Dramatic accumulation of proline under a variety of stress conditions such as drought, salt and cold has been documented in many plants. Understanding the molecular mechanism of the accumulation of proline in plants may be helpful for improving abiotic stress tolerance of crop plants. Δ¹-pyrroline-5-carboxylate synthetase (P5CS) catalyzed the first two steps of proline biosynthesis in plants, is encoded by P5CS gene in higher plants. In this paper, the responses of PvP5CS2 gene in common bean (Phaseolus vulgaris) seedlings to drought, salt and cold stresses were investigated by Real-time quantitative PCR (RT-qPCR) approach. The accumulation of proline in common bean seedling was measured using aqueous sulfosalicylic acid method. In addition, subcellular localization of PvP5CS2 in onion epidermal cells was studied. The results showed that abiotic stresses significantly triggered the expression of PvP5CS2 gene in leaves and roots of common bean seedling, and caused the accumulation of proine. PvP5CS2 mRNA transcript level in common bean seedling leaves steadily increased to the maximum that was 1.51 times of control under the 4 d drought stress and then rapidly decreased to below control level in later period of drought stress. The proline content in leaves increased from the second day and up to the maximum (300.14 μg g^-1 FW) at 8 d of drought stress. Treatment with 200 mmol L^-1 NaCl caused a dramatic up-regulation of PvP5CS2 expression to the peak value, 7.67 fold of control at 2 h in leaves and 6.14 fold of control at 6 h in roots. The peak of proline accumulation appeared at 6–9 h (2.5 fold) in leaves and 9 h (14.2 fold) in roots when salt stress. A significant expression of PvP5CS2 was detected at 2 h under cold (4℃) stress, which was 2.38 fold of control in leaves and 7.55 fold of control in roots. The accumulation of proline steadily increased to the maximum at 24 h of treatment in leaves (43.29 μg g^-1 FW) and at 12 h of treatment (28.90 μg g^-1 FW) in roots. In addition, the accumulation of PvP5CS2 mRNA preceded the accumulation of proline in three stress treatments. These results indicated that PvP5CS2 gene is an abiotic stress-inducible gene with different transcript levels in response to abiotic stresses, which regulates the accumulation of proline in common bean seedlings under drought, salt and cold stresses. Transient expression of PvP5CS2- GFP fusion gene in onion epidermal cells showed that PvP5CS2 protein was distributed in nucleus and plasmalemma.

Improvement of Rice Blast Resistance in TGMS Line by Pyramiding of Pi-1 and Pi-2 through Molecular Marker-Assisted Selection

LIU Wu-Ge;WANG Feng;JIN Su-Juan;ZHU Xiao-Yuan;LI Jin-Hua;LIU Zhen-Rong;LIAO Yi-Long;ZHU Man-Shan;HUANG Hui-Jun; FU Fu-Hong;LIU Yi-Bai

Acta Agron Sin. 2008, 34(07):  1128-1136. 

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Blast is one of the most serious diseases of rice worldwide, which usually leads to a sharp decline in rice production and even results in no yield. Breeding blast-resistant varieties is one of the most effective and economical ways to control the disease. In this study, the BL122 contained two blast resistance genes Pi-1 and Pi-2 was used as gene donor to be crossed and then backcrossed with the TGMS line GD-7S. Five improved TGMS lines with Pi-1 and Pi-2 homozygous genotype were successfully developed through molecular marker-assisted selection. The resistance frequency of the improved TGMS lines ranged from 94.12% to 97.06%, much higher than that of the check GD-7S, which was only 17.65%, by artificially inoculating 34 representa-tive blast isolates collected in Guangdong Province. The improved TGMS lines also displayed high resistance to leaf and neck blast in the epidemic areas. The critical temperature of fertility transformation for the improved TGMS lines from fertile to sterile was preliminarily identified in the phytotron with the regime of 12.5 h/23℃ and natural conditions. The results showed that the critical temperature point for the improved TGMS lines was likely consistent with that of the check GD-7S. The statistical analysis showed there was no significant difference in the agronomic traits between improved TGMS lines and GD-7S except the flag leaf length and number of panicles per plant. Moreover, there was also no significant difference in most of the agronomic traits be-tween the F1s derived from the crosses of the same restorer line L38 with both the check GD-7S and the improved TGMS lines, respectively. All these indicated that the improved TGMS lines retained almost the same agronomic traits and combining ability as the check.

Yield Trait Variation and QTL Mapping in a DH Population of Rice under Phosphorus Deficiency

MU Ping;HUANG Chao;LI Jun-Xia;LIU Li-Feng;LIU Ui-Ju;LI Zi-Chao

Acta Agron Sin. 2008, 34(07):  1137-1142. 

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To study the difference of QTLs for rice yield and its component traits under different phosphorus applications, a DH (doubled haploid) population including 116 lines, derived from a cross between phosphorus deficiency tolerant rice IRAT109 and phosphorus deficiency sensitive rice Yuefu, was evaluated for yield per plant (YP) and its components including 1000-grain weight (GW), seed-setting percentage (SP), panicle number per plant (PN), and grain number per panicle (GN) under phosphorus deficiency and normal conditions. No significant differences were found in GW and GN but significant differences were found in SP, PN, and YP for the DH population between the two conditions. This result indicted that SP, PN, and YP were more easily influenced by phosphorus deficiency than GW and GN. A total of seventeen QTLs were detected for plant yield and its components under phosphorus deficiency using the constructed molecular linkage map (including 94 RFLP and 71 SSR markers and covering 1 535 cM). Among them, there were twelve QTLs with general contributions of over 10% to phenotypic variation. Three tightly linked QTL regions on chromosomes 3, 6, and 7 were identified. These QTLs with high general contribution and tightly linked QTL regions might be useful for phosphorus deficiency tolerant and high yielding rice breeding by molecular marker assisted selection.

Expression of Special Genes Resistant to Powdery Mildew (Blumeria graminis f. sp. tritici) in Wheat Germplasm N9436

WU Jin-Hua;HU Yin-Gang;ZHANG Hong;WANG Chang-You;WANG Qiu-Ying;JI Wan-Quan

Acta Agron Sin. 2008, 34(07):  1143-1152. 

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Powdery mildew, caused by Blumeria graminis f. sp. tritici (syn. Erysiphe graminis f. sp. tritici), is one of the most important fungal diseases of common wheat (Triticum aestivum L.) worldwide and causes severe yield losses. Wheat germplasm N9436, developed by our research group, is a resistant material to powdery mildew. In the present study, a suppression subtraction hybridization (SSH) cDNA library was constructed with cDNA from N9436 leaf inoculated by Blumeria graminis as the tester and cDNA from N9436 healthy leaf as the driver. A total of 140 positive clones were randomly chosen from the SSH-cDNA library and were amplified with sp6 and t7 primers to examine the insert size. Their sizes ranged from 200 to 1 000 bp with an average of 238 bp. Among the 140 clones, 32.86% showed redundant and repeated sequences by sequence analysis. The most frequent se-quence was glutathione transferase and followed by ribulose-1,5-bisphosphate carboxylase/oxygenase small/large subunit. After screening repeat and redundant sequences, 94 ESTs were acquired. Nucleic acid and protein homology search were performed using the BLAST (Basic Local Alignment Search Tool) program with the default settings at NCBI website (http://www.ncbi. nlm.nih.gov). BlastX results in nr-protein database revealed that 49 ESTs were highly homologous with known proteins involved in disease resistance and defenses, energy metabolism, cell structure, protein synthesis and processing, transport and signal trans-duction. BlastNr results showed that 69 and 20 ESTs had high identities with known Unigene and function-unknown ESTs, re-spectively, and 5 ESTs matched none in the nr-database. Compared with BlastX and BlastNr analysis, 33 ESTs were both in the nucleic acid and protein databases including 22 ESTs associated with powdery mildew resistance, out of which 6 for signal trans- duction, 2 for hypersensitive necrosis reaction (HR) system, and 14 for systemic acquired resistance (SAR) system, respectively.

Cloning of HvBADH1 Gene from Hulless Barley and Its Transformation in Nicotiana tabacum

ZHAO Yu-Wei;HAO Jian-Gao;BU Huai-Yu;WANG Ying-Juan;JIA Jing-Fen

Acta Agron Sin. 2008, 34(07):  1153-1159. 

Abstract ( 2022 )   PDF (1199KB) ( 1335 )   Save

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Glycine betaine is a nontoxic osmolyte accumulated in the cytoplasm of salt or drought stressed plants, marine animals, and microorganisms. Betaine aldehyde dehydrogenase (BADH) catalyzes the final step in the synthesis of glycine betaine from choline in many plants. In order to reveal the relationship between the BADH expression and salt stress resistance of hulless bar-ley (Hordeum vulgare L. var. nudum Hook.f.), a 1 512 bp cDNA encoding BADH was cloned from hulless barley using the methods of RT-PCR and RACE. This cDNA encoded a 54.2 kD protein containing 232 amino acid residues and HvBADH1 was designated with the accession number of EF492983 in GenBank. HvBADH1 exhibited the highest homology (98.4%) in amino acid sequence with BBD2 gene encoding an isoenzyme of BADH from barley. It also shared highly homology of 97.0%, 84.7%, and 85.1% with BADH wheat, maize, and rice respectively. The HvBADH1 gene was inserted into pMAL c2x and transformed into E.coli cells (TB1) for expression. The recombinant TB1 (harboring pMAL c2x-HvBADH1) cells and control TB1 (harboring empty pMAL c2x) cells were then induced with IPTG. The results revealed that the recombinant E. coli cells could express a fu-sion protein with molecular weight of 96.3 kD. This fusion protein was fused by maltose binding protein (MBP, about 42.1 kD) and the peptide (about 54.2 kD) encoded by HvBADH1. The ORF of HvBADH1 was inserted between CaMV 35S promoter and NOS polyA in T-DNA region of binary expression vector pCAMBIA1301. The recombinant plasmid, designated as pCAM-ba, was transformed into Agrobacterium tumefaciens LBA4404. The HvBADH1 gene was transformed to tobacco mediated by Agro-bacterium. Two hygromycin B (Hyg) resistant regenerated plant strains were selected. PCR detection and Southern blot analysis indicated that all the Hyg resistant tobacco plants contained the alien BADH gene. RT-PCR analysis showed that HvBADH1 gene normally expressed on the mRNA level in the transgenic tobacco plants. The results suggest that HvBADH1 gene is related with the salt tolerance in hulless barley and can express in transgenic plants.

Effects of Soybean Major Maturity Genes under Different Photoperiods

WANG Ying;WU Cun-Xiang;ZHANG Xue-Ming;WANG Yun-Peng;HAN Tian-Fu

Acta Agron Sin. 2008, 34(07):  1160-1168. 

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Maturity and its related traits are important for the yield, quality and adaptability of soybean [Glycine max (L.) Merr.]. Up to now, several major genes have been identified to control the flowering and maturity time in soybean. The understanding of the maturity gene effect under different photoperiods will facilitate the qualitative design of growth period traits in soybean variety development. In this study, 39 near-isogenic lines (NILs) derived from Clark and Harosoy were used to analyze the effects of 6 major maturity gene pairs including E1/e1, E2/e2, E3/e3, E4/e4, E5/e5, and E7/e7 on developmental periods of soybean. The re-sult showed that the dominant alleles tend to delay the flowering and maturity time in most of the genotypes studied. Gene effect was found to be dependent on the genetic background, and the dominant allele could strengthen the effect of other maturity genes, indicating that there were interactions between major genes. The major gene effects under long-day (LD) condition differed from those under short-day (SD). LD promoted the roles of dominant alleles and delayed the flowering and maturity while SD had the opposite effects. Additionally, the photoperiod effects were also varied in the developmental stages of soybean. E1 and E4 were sensitive to photoperiod before and after flowering respectively, whereas E3 was sensitive to photoperiod during both of the two stages.

Association Analysis of Agronomic and Quality Traits with SSR Markers in Glycine max and Glycine soja in China: I. Population Structure and Associated Markers

WEN Zi-Xiang;ZHAO Tuan-Jie;ZHENG Yong-Zhan;LIU Shun-Hu;WANG Chun-E;WANG Fang;GAI Jun-Yi

Acta Agron Sin. 2008, 34(07):  1169-1178. 

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Association mapping is a procedure for detecting QTLs as well as their alleles based on linkage disequilibrium (LD). The genotyping data of 60 simple-sequence repeat (SSR) markers on representative samples of 393 landraces of Glycine max (L.) Merr. and 196 wild accessions of Glycine soja Sieb. et Zucc. were used in the present study. Linkage disequilibrium of pairwise loci and population structure were firstly analyzed for the two populations, then the association analysis between SSR loci and 16 agronomic and quality traits was performed by using TASSEL GLM (general linear model) program. The different degrees of LD were detected not only among syntenic markers but also among nonsyntenic ones, suggesting that there had been historical re-combination among linkage groups. The cultivated soybean population had more LD loci pairs than wild soybean population, while the later had higher degree and slower attenuation of LD than the former. Genetic structure analysis showed that both of the cultivated and wild populations were composed of nine and four subpopulations, respectively, which associated with their geo-graphic eco-types, indicating the classification of geographic eco-types was of sound genetic bases. Twenty seven and thirty four SSR loci associated with the traits were screened out from cultivated and wild populations, respectively. Some loci were found to associate with a same trait in both populations, and there existed both consistent and inconsistent association between the culti-vated and wild populations. There were a few loci associated with two or more traits simultaneously, which might be the genetic reason of correlation among traits or pleiotropic phenomena. In addition, twenty-four associated markers were in agreement with mapped QTLs from family-based linkage mapping procedure.

Cloning and Functional Identification of the Two MYB Transcription Factors GmMYBJ6 and GmMYBJ7 in Soybean

DU Hai;YANG Wen-Jie;LIU Lei;TANG Xiao-Feng;WU Yan-Min;HUANG Yu-Bi;TANG Yi-Xiong

Acta Agron Sin. 2008, 34(07):  1179-1187. 

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Plant R2R3-myb genes are widely distributed in higher plants and comprise one of the largest known families of regulatory proteins. In the past decades, its biochemical and molecular characteristics were extensively studied and reported to be involved in many physiological and biochemical processes. On the based of its conserved DNA-binding domain, two MYB-like genes from soybean cultivar Jilin 3 were cloned by RT-PCR and RACE methods, named GmMYBJ6 and GmMYBJ7 (GenBank accession No. DQ902863 and DQ902864), which contained an ORF of 786 bp and 969 bp encoding 261 and 322 amino acids respectively. Genomic DNA sequences analysis showed that both the two genes contained two introns. Meanwhile, the transcription level of the two genes was investigated by semi-quantitative RT-PCR, and the result showed that the two genes were expressed in root, stems, leaves, flowers and immature seeds of soybean. Furthermore, the yeast one-hybrid assay showed that the two MYB proteins had transcriptional activation functions. But the levels of their transcriptional activity were lower when the introns existed. Fluorescence real-time quantification PCR analysis indicated that the expression of GmMYBJ6 and GmMYBJ7 genes could be induced by ABA and NAA, respectively. And their expressions were changed with the inducible time. In conclusion, GmMYBJ6 and GmMYBJ7 genes isolated from soybean are new members of MYB transcription factor family, which may play key roles in the signal transduction related to ABA and NAA in soybean.

Relationships among Genome A, B, and C Revealed by FISH and CAPS

KONG Fang;JIANG Jin-Jin;WU Lei;WANG You-Ping

Acta Agron Sin. 2008, 34(07):  1188-1192. 

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Physical localization of repetitive DNA sequence from genome A (151 bp) was carried out on the chromosomes of the selected Brassica species by FISH (fluorescence in situ hybridization). The signals distributed on all the chromosomes of A (Brassica rapa, 2n=20) or C genome (B. oleracea, 2n=18). For B. juncea (AABB, 2n=36), the signals were found on all the chromosomes of genome A and the strength of signal varied among different chromosomes, while the chromosomes of genome B showed weak or no signals. FAE1 gene is a rate-limiting gene for erucic acid synthesis in Brassica. The genes from six Brassica species of U-triangule were cloned by PCR. These PCR products were digested with different restriction endonucleases. Mbo I and Msp I were found to produce informative CAPS patterns of FAE1 gene. Three diploids displayed different patterns, the patterns of genome A was very similar to that of genome C, while the patterns of genome B was the most diverged out of the patterns of the A and C genomes. Three amphidiploids generally exhibited additive patterns of the progenitors, but not strictly in all cases, indicating that rearrangements and recombinations did occur in the formation and evolution of amphidiploids. Genetic relation-ships among Brassica species could be demonstrated through CAPS analysis of FAE1 gene and FISH method when repetitive DNA sequence (not ribosomal RNA genes) was used as a probe.

Molecular Mapping and Chromosomal Location of the Powdery Mildew Resistance Gene in Wheat Cultivar Tangmai 4

HU Tie-Zhu;LI Hong-Jie;XIE Chao-Jie;YOU Ming-Shan;YANG Zuo-Min;SUN Qi-Xin;LIU Zhi-Yong

Acta Agron Sin. 2008, 34(07):  1193-1198. 

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Powdery mildew, caused by Blumeria graminis f. sp. tritici, is one of the most important diseases in wheat (Triticum aestivum L.) worldwide. Breeding for resistance is the most economical and effective method for controlling the disease. Tangmai 4 carries a pair of T1BL·1RS wheat-rye (Secale cereale L.) translocated chromosomes and is resistant to a wide spectrum of wheat powdery mildew isolates. Genetic analysis indicated that a single semidominant gene in Tangmai 4 conferred resistance to powdery mildew, temporarily designated as PmTm4. Segregating F₂ population and their F₃ progenies derived from the cross between Tangmai 4 and Clement were used for bulked segregation analysis. Four SSR, one EST-SSR, and one EST-STS polymorphic markers were linked to the powdery mildew resistance gene PmTm4 in an order of Xcau12–Xgwm611–PmTm4–XEST92– Xbarc1073–Xbarc82–Xwmc276. Gene PmTm4 was physically mapped on the distal bin of chromosome 7BL using Chinese Spring nullisomic-tetrasomic, ditelisomic, and deletion lines. The results demonstrate that PmTm4 gene may be either allele at the Pm5 locus or else a member of closely linked cluster of genes.

Genetic Linkage Map Construction and QTL Mapping for Yield and Fi-ber Quality in Upland Cotton (Gossypium hirsutum L.)

CHEN Li;ZHANG Zheng-Sheng;HU Mei-Chun;WANG Wei;ZHANG Jian;LIU Da-Jun;ZHENG Jing;ZHENG Feng-Min;MA Jing

Acta Agron Sin. 2008, 34(07):  1199-1205. 

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Cotton is the world’s most important natural textile fiber. With the changes in spinning technology, the improvement of cotton fiber quality is becoming extremely important. The combination of conventional breeding techniques with MAS (mo-lecular-assisted selection) will become a basic approach for cotton fiber improvement. In the present study, 3 458 SSR primer pairs were used to screen the polymorphic primers between Zhong 35 and Yumian 1, and 173 polymorphic primer pairs were ob-tained. The polymorphic primer pairs were used to genotype the 180 individual plants of F₂ population derived from (Zhong 35 × Yumian 1), and 178 loci were obtained. A genetic linkage map with 148 SSR loci and 36 linkage groups was constructed, and the linkage map covered a whole length of 1 309.2 cM with an average interval of 8.8 cM between two markers, accounting for 29.5% of the cotton genome. 28 out of 36 linkage groups were located on 20 chromosomes, and 8 linkage groups were not located on any chromosomes. The data of yield and fiber qualities of the 180 F₂ plants and F_2:3 family lines were used to detect QTLs by interval mapping, and 9 QTLs controlling yield and fiber quality were identified, including two QTLs for lint percent (LP), one for boll weight (BW), one for seed index (SD), one for fiber length (FL), two for fiber strength (FS), and two for fiber fineness (FF). The five QTLs, LP1, BW, SD, FL, and FS1, were located on chromosome 7, and the other four QTLs, LP2, FS2, FF1, and FF2, on chro-mosome 15, 21, 9, and 20, respectively. The favorable alleles of all five QTLs for fiber qualities originated from Yumian 1.

Cytogenetical Studies on Sorghum (S. bicolor), Sudangrass (S. sudanense), and Their Hybrid

ZHAN Qiu-Wen;ZHU Li-Meng;WU Juan-Juan;ZHANG Wei;ZHANG Tian-Zhen

Acta Agron Sin. 2008, 34(07):  1206-1212. 

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Sudangrass (Sorghum sudanense) and sorghum (S. bicolor) are two members of the genus Sorghum (Gramineae). Their hybrids have exhibited favorable forage yields and overall improved quality and disease resistance. They are widely used in aquaculture, production of livestock food and environmental protection, but some disagreements exist as to whether they actually belong to the same species. The Karyotypes of two sudangrass varieties, two sorghum varieties, three sorghum-sudangrass F₁ hybrids were analyzed by the method of cell wall degradation and hypotonic treatment for chromosome preparations, and the meiosis behavior of three F₁ hybrids and the chromosome numbers of two F₂ hybrids were observed. The result showed that the karyotypic types of sorghum and sudangrass were 1A, and the karyotype formula was 2n=18m+2sm (sat) for Sa, 2n=20m for 3042A and 3042A×Sa F₁, and 2n=20m(sat) for the others. The difference of chromosomes among three groups (i.e. sudangrass, sorghum, and sor-ghum-sudangrass hybrid F₁) were not significant in terms of absolute long arm, absolute short arm, absolute total length, arm ratio (l/s), relative total length (P>0.05); the change of chromosome length was not obvious in sorghum and sudangrass. The paired chromosome configuration of sorghum-sudangrass hybrid F₁ in pollen mother cells at diakinesis and metaphaseIwas 2n=2x=20(10II) and the chromosome pairing behavior was regular, but the frequencies of rod bivalent of Tx623A×S722 F₁, 3042A×Sa F₁, and Tx623A×Sa F₁ were 4.887, 5.710, and 5.126, respectively; those of ring bivalent were 5.113, 4.290, and 4.874, respectively. At anaphase I, the paired chromosomes of sorghum-sudangrass hybrid F₁ could separate from each other. The chromosome numbers of F₂ hybrid were 20 (2n=20). Therefore, the sudangrass/sorghum relationship is sufficiently close.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Changes of Chloroplast Ultramicrostructure and Function of Different Green Organs in Wheat under Limited Irrigation

ZHANG Yong-Ping;WANG Zhi-Min;HUANG Qin;XIE Min

Acta Agron Sin. 2008, 34(07):  1213-1219. 

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The green organs in wheat (Triticum aestivum L.) consist of leaf and non-leaf organs including ear, culm, and sheath. Understanding the structures and functions of these non-leaf green organs under abiotic stresses will help to explore the potential of photosynthesis of the whole plant. In order to identify the photosynthetic adaptation of different green organs to drought stress in winter wheat, the changes of chloroplast ultra-microstructure and function of the organ above were studied in a field experiment in the 2002–2003 growth season (a medium rain fall growth season) using cultivar Shijiajuang 8 with water treatments of no irri-gation (control), irrigating twice at jointing and anthesis stages, and irrigating 4 times at pseudostem erecting, booting, anthesis, and grain-filling stages. Each irrigation received 750 m³ ha^-1 water. Chloroplast ultramicrostructure of flag leaf blade and non-leaf organs (peduncle, flag leaf sheath, glume, and lemma) in response to different irrigation treatments were observed during late grain-filling period, and the net photosynthetic rate (Pn) and Fv/Fm values of different green organs were measured simultaneously. The results showed that the chloroplast number of non-leaf organs was less than that of leaf blade, and many starch grains were found in the chloroplasts of glume and lemma under sufficient water supplies (irrigating 4 times). Obvious senescence characteris-tics and differences in chloroplast ultramicrostructure were found in different organs of control, and the senescence was signifi-cantly severer in flag leaf than in non-leaf green organs. The chloroplast structure of flag leaf blade and lemma was destroyed under drought stress, while that of peduncle, sheath, and glume showed relatively stable in the late developmental stage under different irrigation regimes. Post-anthesis drought stress decreased P_n and F_v/F_m values in different green organs, but much less affected them in non-leaf organs (peduncle, sheath, and ear). The results indicated greater stability of chloroplast structure and photosynthetic activity in non-leaf green organs at the late grain-filling stage under water stress.

Characteristics of Drought Tolerance in ppc Overexpressed Rice Seedlings

FANG Li-Feng;DING Zai-Song;ZHAO Ming

Acta Agron Sin. 2008, 34(07):  1220-1226. 

Abstract ( 1928 )   PDF (368KB) ( 1478 )   Save

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Introducing enzymes involved in C₄ photosynthesis into C₃ crops is supposed to enhance the photosynthesis and crop productivity. Several attempts have been made to transfer phosphoenolpyruvate carboxylase (PEPC) gene from maize into rice, however, the relation of photosynthetic capacity, productivity and stress tolerance in transgenic rice was not analyzed. In the present research, the productivity and photosynthesis in T₄ offspring of ppc gene overexpressed rice were investigated under drought stress. The results indicated that the yield increased by 28% and 42%, and the number of tillers increased by 27% and 40%, respectively, in two transgenic lines T1 and T2 compared with those of the wild type under upland cultivation. Under drought stress, the transgenic rice seedlings maintained higher photosynthesis (A), stomatal conductance (G_s) and water use efficiency (WUE), as well as higher superoxide dismutase (SOD) activity and lower malondialdehyde (MDA) content than the wild type. It is suggested that the overexpression of ppc gene in rice makes higher antioxidation ability under drought stress. In addition, the transgenic lines T1 and T2 exhibited higher proline content and lower increase of osmotic potential under drought stress, suggesting that the ppc gene transgenic rice has the higher osmoregulation ability than the wild type. The similar results were also found in the ex-periments treated by PEG-6000. Therefore, the present results suggested that, the ppc gene overexpressed rice confers higher photosynthesis and drought tolerance under drought stress, which is helpful to increase the number of tillers, then contribute to enhance the rice yield.

Physiological Characteristics Related to Stress-Tolerance in Introgression Line “PD29” with IR64 Genetic Background at the Tillering Stage

ZHAO Xiu-Qin;XIE Xue-Wen;SUN Yong;DENG Jian-Li;ZHU Ling-Hua;LI Zhi-Kang

Acta Agron Sin. 2008, 34(07):  1227-1232. 

Abstract ( 2016 )   PDF (302KB) ( 1425 )   Save

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Drought tolerance (DT) or water-saving is becoming one of the most important target traits in rice breeding community under ever-increasing severe drought situation all over the world. The introgression line “PD29” with IR64 genetic background has promising yield performance under both drought (stress) and irrigation (control) conditions. In the present study, the physiological characteristics related to stress tolerance of the “PD29” were analysised with recurrent parent, IR64, and upland rice variety IRAT109 as control varieties under both drought and irrigation conditions. The results showed that “PD29” not only had higher leaf relative water content (RWC) under stress but also could recover RWC to a fully turgid (hydrated) state 2 h after re-watering which indicated that “PD29” has higher DT ability than control varieties at the tillering stage. Further analysis showed that “PD29” not only had higher maximum photochemical of FPS II efficiency (F_v/F_m), osmotic potential (Y), proline content (Pro), and antioxidants activity (AOA) than IR64 under drought condition but also presented less decrease in the F_v/F_m and RWC and more decrease in net photosynthetic rate (P_n), transpiration rate (T_r), stomatal conductance (G_s) and more increase in Pro and AOA. Furthermore, compared to IRAT109, “PD29” had higher Pro and more increase in the AOA under drought condition. Therefore, it was concluded that the promising DT-performance of “PD29” was related to the significant increase of AOA and proline under the drought. Moreover, the significant decrease of the P_n, G_s, and T_r under the drought condition indicated that “PD29”has strong plasticity in photosynthetic capacity which can keep the higher photosynthesis under the adaptive circumstance and decrease the water loss through transpiration under the stress condition.

Effects of Plant Growth Regulators (PGRs) on Endogenous Hormone Contents and Activities of Protective Enzymes in Soybean Leaves

ZHENG Dian-Feng;ZHAO Li-Ming;FENG Nai-Jie

Acta Agron Sin. 2008, 34(07):  1233-1239. 

Abstract ( 2266 )   PDF (341KB) ( 2032 )   Save

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The leaf senescence is one of the main problems at filling stage in soybean grain, affecting leaf photosynthetic physiology. Previous researches have showed that chemical growth regulators have been used to delay leaf senescence, therefore, to raise grain yield. In the present study, a soybean (Glycine max) cultivar, ‘Kennong4’ with three treatments by spraying SOD simulation material (SOD_M), Choline chloride (Cc) and Diethyl aminoethyl hexanoate (DTA-6) were employed to compare differences of several endogenous hormones and protective enzyme activities in soybean leaves in a field experiment. The results show that, compared with CK, 7–15% of yield increases were obtained with SOD_M and DTA-6 treatments. IAA, GA, and CTK contents significantly increased with SOD_M treatment from the 5th to the 30th day after spraying. DTA-6 improved the contents of IAA and CTK from the 15th to the 30th day after spraying, however, the contents of IAA and CTK reduced with Cc treatment in varying degrees. On the other hand, with the time elongation after spraying PGRs, three regulators increased SOD and POD ac-tivities in soybean leaves. SOD activity in leaves with DTA-6 spraying was higher than that with SOD_M spraying, although POD activity in leaves with DTA-6 spraying was lower than that with SOD_M spraying. In addition, SODM and DTA-6 also enhanced CAT activity in soybean leaves and slowed the increase of MDA. But the effect of Cc was not obvious. The results above indi-cated that it is effective to increase seed yield or delay leaf senescence, and regulate the level of endogenous hormones and physiological function of protective enzymes by spraying SOD_M and DTA-6 on soybean leaves.

Responses of Plant Growth of Dwarf and Semi-Dwarf Soybean Mutants to Exogenous GA₃

LI Wei;ZHU Bao-Ge;XU Min-Xin;ZHANG Li-Ming;CHEN Xiu-Wen;MA Wen-Ping;ZHI Yan-Yang

Acta Agron Sin. 2008, 34(07):  1240-1246. 

Abstract ( 2134 )   PDF (353KB) ( 1497 )   Save

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Dwarf and semi-dwarf mutants are the valuable materials for investigating plant gene function and developing new crop variety with high seed yield and lodging resistance. In the present study, the developing plants of dwarf (df) and semi-dwarf (sdf) mutants and their wild-types (WTs) in different growth stages were treated with exogenous gibberellin A₃ (GA₃) in order to analyze responses of plant growth rate, plant height, and vertical cell length from the main stem to exogenous GA₃ (40 mg L^-1), as well as the endogenous GA₃₊₁ level differences between two types of mutants and their WTs. The results indicated that the responses of plant growth of the sdf and df mutants to the exogenous GA₃ were significantly different, demonstrating that GA₃ treatment led to the average rate (2.76 cm d^-1) of plant growth of the sdf mutant in different measuring-time intervals to be significantly higher than that (1.10 cm d^-1) of water treatment (control); but the average rate of plant growth (0.92 cm d^-1) of GA₃-treated df mutant was slightly higher than that (0.56 cm d^-1) of control, and moreover df mutant plants in the prophase of entire growth period only had a little response to exogenous GA₃. In addition, after GA₃ treatment the average plant height, internode length, and vertical cell length of the internode on the main stem of sdf mutant were much higher than those of df mutant, verifying the exogenous GA₃ treatment could recover plant height phenotype of WT-sd in sdf mutant, while not recover that of WT-d in df mutant. The node number on the main stem of two types of mutants was almost no response to GA₃. Based on above results we think that sdf is a GA₃-sensitive soybean mutant, and df is a GA₃-insensitive soybean mutant. Furthermore it was found that the endogenous GA₁₊₃ levels in sdf and df mutant plants were remarkably lower than that in their WT plants, which may be the physiological cause of dwarfism for sdf and df mutants.

Effects of Irrigation on Yield and Protein Content of Grains and Their Stability in Strong-Gluten Wheat

ZHAO Guang-Cai;WAN Fu-Shi;CHANG Xu-Hong;YANG Yu-Shuang;LI Shan-Shan;FENG Ming;LI Nai-Xin

Acta Agron Sin. 2008, 34(07):  1247-1252. 

Abstract ( 2046 )   PDF (154KB) ( 1687 )   Save

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In wheat (Triticum aestivum L.) high-yielding and high-quality production, a great attention has been gradually paid to the effects of environment and cultivation technique. Currently, many reports on the stability of yield and quality give different results and conclusions due to different cultivars and environments in different experiments. In this study, field experiments in 2005–2006 growing season were carried out in seven provinces with seven strong-gluten cultivars under four irrigation regimes to give further explanation on this topic. Grain yield and protein content in grains were evaluated at maturity. The results showed that the highest grain yields were obtained with no significant difference in the treatment of 3 irrigations (at emergence of the 2nd spring-leaf, emergence of the 5th spring-leaf, and anthesis, respectively, 600 m³ ha^-1 per irrigation) and 4 irrigations ( the above 3 irrigations plus 1 irrigation at grain-filling) with rainfall below the average. The grain yield in all the seven experimental sites showed an increasing trend with the increase of irrigation times and quantity, and the differences among eco-environments were also shortened. The effect of irrigation was larger in sites with lower “environmental index”, indicating that irrigation could strengthen the yield stability of strong-gluten wheat in different environments. Cultivars with higher environmental index had smaller variation coefficients(CV) of grain yield. The protein content was significantly different among irrigation treatments. The average protein content decreased with the increase of irrigation times, expect for Renqiu site in Hebei province where the rainfall was extremely scarce (43.9 mm in the growing season). The protein content in the same cultivar varied obviously in different sites, but showed better stability in cultivars with smaller CV values. It suggested that the ecological factors affect protein content greatly in wheat.

Effects of Basic Fertilizer Treatments and Nitrogen Topdressing at Joint-ing Stage on Starch RVA Characteristics of Waxy Maize

LU Da-Lei;LU Wei-Ping;ZHAO Jiu-Ran;WANG De-Cheng

Acta Agron Sin. 2008, 34(07):  1253-1258. 

Abstract ( 2047 )   PDF (198KB) ( 1201 )   Save

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Proper fertilizer managements can improve the starch pasting properties of waxy maize (Zea mays L. Ceratina Kulesh). To understand the starch Rapid Visco Analyzer (RVA) characteristics of waxy maize, we used Suyunuo 4 in a field experiment with different treatments of basic and topdressing fertilizers, especially the N fertilizer. The split design was employed with main plot of 4 basic fertilizer treatments (N 75 kg ha^-1, N 75 kg ha^-1 + K₂O 70 kg ha^-1, N 75 kg ha^-1 + P₂O₅ 65 kg ha^-1, and N 75 kg ha^-1 + P₂O₅ 65 kg ha^-1 + K₂O 70 kg ha^-1) and split plot of 3 N topdressing treatments (N 0, 150, and 300 kg ha^-1). The peak viscosity (PV), trough viscosity (TV), final viscosity (FV), breakdown (BD), and setback (SB) varied in different fertilizer treatments except peak time (PT) and pasting temperature (PTP). Compared with the treatment of only N applied in basic fertilizer, adding P or (and) K fertilizers decreased the PV and BD, but increased TV, FV, and SB. With larger amount of N topdressing at jointing stage, PV, TV, and FV increased gradually, SB rose first and fell later. BD showed no significant differences in treatments of top-dressing N 150 and 300 kg ha^-1. Among the RVA characteristics, PV was positively correlated with TV, FV, and BD (r = 0.80, 0.87, and 0.75, respectively, P<0.01), while PTP negatively correlated with PV, TV, and FV (r = -0.65, -0.62, and -0.60, respec-tively, P<0.05). The RVA characteristics of waxy maize starch were improved to be the better when the top dressing was N 300 kg ha^-1 at jointing stage on the basis of N 75 kg ha^-1 or N 75 kg ha^-1 + P₂O₅ 65 kg ha^-1 as the basic fertilizer, and the top dressing was N 150 kg ha^-1 at jointing stage on the basis of N 75 kg ha^-1 + P₂O₅ 65 kg ha^-1 + K₂O 70 kg ha^-1 as the basic fertilizer.

Changes and Correlations between Yield and Partial Physiological Char-acters in Leaves of Soybean Cultivars Released from 1923 to 2005 in Jilin Province

ZHAO Hong-Xiang;XU Ke-Zhang;YANG Guang-Yu;YANG Chun-Ming;BIAN Shao-Feng;LU Jing-Mei

Acta Agron Sin. 2008, 34(07):  1259-1265. 

Abstract ( 1756 )   PDF (429KB) ( 1313 )   Save

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The yield and partial changes physiological characters in the leaves were measured at different growing stages using 42 soybean cultivars released from 1923 to 2005 in Jilin province, and the relationship between them was analyzed. The results showed that soybean seed yield was increased significantly in the process of cultivar released years, it increased by 95.94% in past 82 years (1.17% per year) according to the calculation of regression equation. At the same time, nitrate reductase activity (NRA), soluble sugar content, specific leaf weight (SLW), chlorophyll content, soluble protein content in leaves at V₄, R₂, R₄, R₆ stages increased and positively correlated with soybean yield. Among them, NRA was correlated significantly with soybean yield at three growth stages and could be used as a selection index for high-yielding soybean cultivars.

Effect of Selenium Application on Yield and Qualities for Nutrition and Health Care in Tartary Buckwheat

TIAN Xiu-Ying;WANG Zheng-Yin

Acta Agron Sin. 2008, 34(07):  1266-1272. 

Abstract ( 1838 )   PDF (189KB) ( 1492 )   Save

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Tartary buckwheat (Fagopyrum tataricum) products are regarded as health food due to their components of vitamin B1 and E, mineral elements, flavonoids (mainly rutin) and high content of proteins. The composition ratios of eight essential amino acids in tartary buckwheat seeds is similar to that in eggs, and rutin is approved to be effective in protecting humans against chronic diseases (e.g. cardiovascular diseases), heart diseases, and cancer. Selenium (Se) is an essential trace element for higher animals and humans with many physiological functions. To study the effect of Se application on growth, yield and quality of tartary buckwheat, a pot experiment was carried out in 2005. The contents of total Se, amino acid, flavonoids, and rutin were determined by atomic fluorescence spectrophotometer, automatic amino acid analyzer, A UV-VI 8500 spectrophotometer and HPLC respectively. The results showed that appropriate amount of Se (0.5 mg kg^-1 soil) significantly promoted the plant height, dry mat-ter weight of shoots, and the total weight of the plant. With the application of 1.0 mg Se kg^-1 soil, the yield, spikes, and grain number per plant were 1.42–2.32 times and about two times as many as those of untreated plants. The seed setting rate and 100-grain weight were increased by 0.6%–6.2% and 1.90%–5.85% respectively, and the contents of flavonoids and rutin in seeds improved by 3.7%–7.5% and 30.9%–59.6%, respectively. The most effective treatment occurred at the rate of 0.5 mg Se kg^-1 soil, which made the yield, all quality characters of seeds reach the peak. Excessive Se (1.0 mg kg^-1) obviously injured tartary buck-wheat plant, resulting in the decrease of yield, plant height and biomass. Except in the case where the treatment was 0.5 mg Se kg^-1 soil, the contents of N, P, K, Zn, Ca, Mn, crude protein, and fat were increased when the supply of Se was increased. The study showed that the application of Se to soil could significantly increase Se content, meanwhile, decrease starch content to a different extent. It is thus feasible to promote the growth, yield and qualities for nutrition and health care in seeds of tartary buck-wheat by adding appropriate Se to soil.

Comparison of Effects of Lanthanum Application on Growth by Spraying and Soil Dressing in Chamaecrista rotundifolia

JIANG Zhao-Wei;WENG Bo-Qi;HUANG Yuan-Fang;WANG Yi-Xiang;YING Zhao-Yang

Acta Agron Sin. 2008, 34(07):  1273-1279. 

Abstract ( 1707 )   PDF (177KB) ( 1226 )   Save

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Few studies have been concerned in physiological effects of REEs on forages, and the mechanism of action by rare earth elements (REEs) is still not clear. The studies on the action of REEs soil application to crop are still rare. A pot experiment was conducted to study the effects of spray application and soil application of lanthanum (La) on growth of leguminous grass Chamaecrista rotundifolia in order to provide theoretical reference for reasonable applications of REEs in agriculture. The results showed that both methods obviously increased the chlorophyll content of leaf, leaf area and dry matter weight of C. rotundifolia. At each sampling date, the shoot dry matter weight of Y2 treatment was the highest for spray application, with 15.91–20.03% (P<0.05) higher than the control. The shoot dry matter weight of Y8 treatment was the highest for soil application, with 14.28–17.42% (P<0.05) higher than the control. At each sampling date, the root dry matter weight of Y2 treatment was the highest for spray application, with 19.88–25.34% (P<0.05) higher than the control. The root dry matter weight of Y8 treatment was the highest for soil application, with 21.41–27.03% (P<0.05) higher than the control. At the same La application rate, the dry matter accumulation showed no significant difference between spray application and soil application. Furthermore, the highest dry matter accumulation also showed no significant difference between Y2 and Y8 treatments. Judging from this, spray application was more effective with lower application rate, lower cost and more environmental protection than soil application. The reasonable La ap-plication rate for soil application REEs was 1–2 times of that for spray application. The concentration of La in each part of C. rotundifolia plant increased with the increase of La application rate. The concentration of La in soil changed little, because the background concentration was high, the application rate was very low and the uptake rate by C. rotundifolia was low.

RESEARCH NOTES

Genetic Analysis and Molecular Mapping of Stripe Rust Resistance Gene in Wheat Cultivar Zhongliang 22

YANG Min-Na;XU Zhi-Bin;WANG Mei-Nan;SONG Jian-Rong;JING Jin-Xue;LI Zhen-Qi

Acta Agron Sin. 2008, 34(07):  1280-1284. 

Abstract ( 1943 )   PDF (316KB) ( 1645 )   Save

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To identify and tag new resistance genes to stripe rust (Puccinia striiform f. sp. tritici) in a wheat (Triticum aestivum L.) cultivar Zhongliang 22 (Zhong 5/S394//Xiannong 4), resistance identification with the F₂ population of Zhongliang 22/Mingxian 169 at seedling stage, monosomic analysis by Chinese Spring, and SSR Markers were employed in the current experiment. Genetic analysis indicated that one dominant nucleic gene (temporarily designated as Yrzhong22) and one recessive cytoplasmic gene conditioned stripe rust rust resistance in Zhongliang 22, and Yrzhong22 was located on chromosome 5B. Using the resistant and susceptible pools derived from a cross of Zhongliang 22 ´ Mingxian 169, SSR markers combined with bulked segregation analy-sis (BSA) revealed that four SSR markers located on chromosome 5BL were linked to Yrzhong22. The genetic distances between Yrzhong22 and its nearest makers Xwmc810 and Xgdm116 were 2.7 cM and 4.4 cM, respectively. Yrzhong22 is probably a novel resistance gene to wheat stripe rust donated from Elytrigia intermedium on the basis of pedigree analysis and molecular results.

Transgenetic Research of Antigen VP4 Gene into Peanut (Arachis hypo-gaea L.) via Agrobacterium tumefaciens

LIU Feng;WAN Shu-Bo;BI Yu-Ping;YAN Cai-Xia;LI Chun-Juan;Zhao Jin-Ping;SHAN Shi-Hua;

Acta Agron Sin. 2008, 34(07):  1285-1289. 

Abstract ( 1851 )   PDF (381KB) ( 1428 )   Save

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Peanut (Arachis hypogaea L.) is an important commercial crop worldwide and provides an excellent source of protein and other nutrients. So it is one of the ideal vectors in oral vaccine of transgenic plant. The Agrobacterium strain LBA4404 harboring the binary vector pBI121 was used for transformation. The plasmid carries genes for VP4 (2 350 bp) of the human rotavirus (HRV) driven by CaMV 35S promoter and neomycin phosphotransferase (npt II). Two peanut cultivars were used as source of cotyledon explants in this experiment. Efficient transformation of cotyledons by A. tumefaciens strain LBA4404 carrying nptII and VP4 gene on binary vectors led to the production of a large percentage of transgenic plants. Transformed individuals were obtained through selection on medium containing 125 mg L-1 Kan. Integration of the transgenes was assessed by PCR amplification and Southern blot hybridizations. Taking pBG1VP4 or pBG1VP4 plasmid as positive control, non-transformed peanut as negative control, 22 plants among 26 plants grown up through selection on medium containing 125 mg L-1 Kan were assessed by PCR amplification of 620 bp fragment of npt II gene. Then all of 22 plants were assessed by PCR amplification of 2 350 bp fragment of VP4 gene. Taking VP4 gene with a-32P-dCTP maker as probe, five plants selected randomly from 22 positive plants were analysed by PCR-Southern blot hybridizations and showed DNA bloting bands. Then the genomic DNA of 4 plants chosen from PCR-Southern positive plants was further analyzed with Southern blot hybridizations and showed correspondent DNA blotting bands. The results showed that the foreign gene was integrated into genome of transformated peanuts. The total RNA from 11 plants of Luhua 14 was assessed by RT-PCR analysis and evidenced the expression of G1VP4 gene. In addition, expression of critical protein in 30 kD was assayed with Western-blot method. An edible vaccine based on the VP4 of human rotavirus (HRV) could provide a means to protect children from severe acute diarrhea, enabling intact antigen to reach the gut associated lymphoid tissue, as the rigid walls of the plant cell protect antigenic proteins from the acidic environment of stomach. Elevated expression of the rotavirus VP4 antigen in transgenic peanuts is a critical factor in the development of a safe and effective rotavirus vaccine.

Cloning and Expression of AGPase Cytoplasmic Large Subunit Gene in Common Wheat

KANG Guo-Zhang;WANG Yong-Hua;LIU Chao;SHEN Bing-Quan;GUO Tian-Cai;ZHU Yun-Ji

Acta Agron Sin. 2008, 34(07):  1290-1293. 

Abstract ( 1905 )   PDF (407KB) ( 1023 )   Save

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The 1941-bp full cDNA sequence (GenBank No. DQ839506) of LSU I, the cytoplasmic large subunit gene I of adenosine 5’ diphosphate glucose pyrophosphorylase (AGPase), was cloned from a high 1000-grain weight wheat (Triticum aestivum L.) cultivar Yujiao 2. Semi-quantitive PCR analysis showed that LSU I expressed higher in leaves, glumes, sheaths, and grain than in roots and stems, indicating that LSU I expressed actively in photosynthetic and starch synthesis-related organs. During the primal period of grain development (5–10 d after thesis), there was no difference in transcript levels of LSU I gene between Yujiao 2 and Lankao Aizao 8 (low 1000-grain weight), but the transcript amounts in grains of Yujiao 2 was markedly higher than that of Lankao Aizao 8 at grain filling and maturity stages. The changes of LSU I gene expression were similar to the trend of starch accumulation in the two cultivars, suggesting that LSU I gene may be associated with starch accumulation in common wheat.

Integrated Effects of Reducing N Application and Cutting-Roots with K Top-Dressing on N, K Uptake, and Yield, Quality of Flue-Cured Tobacco

ZHAO Zheng-Xiong;YIN Hong-Hui;LI Hong-Guang;TANG Jia-Min;LI Shao-Ming

Acta Agron Sin. 2008, 34(07):  1294-1298. 

Abstract ( 2025 )   PDF (153KB) ( 1181 )   Save

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Cutting-roots with K top-dressing at topping of flue-cured tobacco plant, which was supplied with nitrogen fertilizer at the con-ventional rate, had been considered having positive effect on potassium uptake and leaf quality in flue-cured tobacco, due to the improvement of lateral roots’ development and activity. However, it could be inferred that nitrogen uptake of plant be improved simultaneously, which may result in higher concentration of nicotine and undesired quality of leaves. Therefore, we hypothesized that nitrogen fertilization rate during the whole growth period should be reduced in the case that the practice cutting roots with K top-dressing be adopted at the stage of decapitation of flue-cured tobacco, in order to get superior flue-cured leaves. Field experiments were conducted to compare dry matter accumulation (DMA), N and K uptake as well as leaf yield and economic returns for (a) normal fertilization at recommended N rate without cutting-roots and K top-dressing at decapitation (CK), (b) normal fertilization at recommended N rate coupled with cutting-roots and K top-dressing at decapitation (CK+C+K) and (c)
reducing nitrogen fertilization rate up to 80% coupled with cutting-roots and K top-dressing at decapitation (RN+C+K). The re-sults showed that the practice cutting roots with K top-dressing enhanced growth in later growth stage of tobacco, with RN+C+K and CK+C+K both showing significant advantages in terms of leaf area and SPAD value on upper and middle position of the stalk, DMA, N and K uptake, leaf yield and economic returns as well as leaf quality compared with CK. In addition, DMA, N and K uptake, leaf yield and economic value in RN+C+K were recorded 97.2%, 97.8%, 98.9%, 98.6%, and 102.0% of those in CK+C+K respectively, while nicotine concentration in upper leaves in RN+C+K were 6.7% and 4.5% less than CK and CK+C+K, and po-tassium concentration in upper leaves in RN+C+K 18.9% and 5.6% higher than CK and CK+C+K respectively. It suggested that
nitrogen rate applied to tobacco plant should be reduced in the case of coupling with the practice cutting roots with K top-dressing at
stage of decapitation, in order to obtain more desirable leaf quality, higher economic value and higher nitrogen fertilizer utilization efficiency.