Table of Content

12 August 2009, Volume 35 Issue 8

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Complementary Effect of High Molecular Weight Glutenin Subumits on Bread-Making Quality in Common Wheat

YANG Yu-Shuang,PANG Bin-Shuang,WANG Lan-Fen,ZHANG Xue-Yong,YU Yuan-Jie

Acta Agron Sin. 2009, 35(8):  1379-1385.  doi:10.3724/SP.J.1006.2009.01379

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High molecular weight glutenin subunits (HMW-GS) play the major role in determining bread-making quality (BMQ). In this paper, effect of different HMW subunit compositions on bread making quality (BMQ) was evaluated using 10 near isogenic lines and Yanzhan 1 as recurrent parent. The results of correlation analysis showed that the composition of HMW-GS had great impact on bread score, and the variation coefficient between near isogenic lines with different HMW-GS compositions was 21.5%. Bread volume was significantly correlated positively with dough formation time (r = 0.90, P < 0.01), Zeleny sedimentation (r = 0.89, P < 0.01), dough stability time (r = 0.67, P < 0.05) and flour protein content (r = 0.52, P < 0.05). Therefore, bread score was significantly correlated positively with bread volume (r = 0.98, P < 0.01), Zeleny sedimentation (r = 0.93, P < 0.01), and dough formation time (r = 0.89, P < 0.01). The results of BMQ tests indicated that the expression of 1Ax1 at Glu-A1 locus could improve BMQ in most lines. Contribution of alleles at Glu-B1 to BMQ was 7+8>14+15>6+8>7 in lines with Null at Glu-A1and 5’+12 at Glu-D1. However, it was 6+8>14+15> 7 in the lines with 1 at Glu-A1 and 5’+12 at Glu-D1. When Null was at Glu-A1, lines with 14+15 and 5+10 subunits were slightly better than those with 14+15 and 5’+12. In addition, lines with 7+8 and 5’+12 were much better than those with 7+8 and 5+10. Compared to the 5+10 lines, silence of 1Dx5 caused significant BMQ decline. Therefore, it seems that there is complementary effect between X-type and Y-type of HMW-GS on BMQ, either absence will cause decline of BMQ.

Genetic Background Effect on QTL Expression of Heading Date and Plant Height and Their Interaction with Environment in Reciprocal Introgression Lines of Rice 

WANG Yun,CHENG Li-Rui,SUN Yong,ZHOU Zheng,ZHU Ling-Hua,XU Zheng-Jin et al.

Acta Agron Sin. 2009, 35(8):  1386-1394.  doi:10.3724/SP.J.1006.2009.01386

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Expression of quantitative trait is affected by genetic background and environment. Genetic background effect on QTL mapping and QTL by environment interaction for heading date (HD) and plant height (PH) in Beijing and Hainan environments were dissected using a large set of reciprocal introgression lines (ILs) derived from a japonica variety “Lemont” and indica variety “Teqing”. The two sets of ILs showed transgressive segregation for the two traits. Total 16 and 17 main-effect QTLs were identified for HD and PH in the two environments, respectively. Among them, only five main-effect QTLs (QHd2, QHd8a, QPh3, QPh5,and QPh12) were detected under the two backgrounds, indicating expression of most main-effect QTLs are specific to genetic background. Three main-effect QTLs (QHd8a, QHd9, and QHd10b) by environment interactions for HD were significantly detected under the two backgrounds, of which that of QHd8a had earlier heading for 2–3 days in Hainan, but delayed heading for 2–3 days in Beijing. Therefore, QHd8a could be considered as an important main-effect QTL for HD. By comparison with the QTL mapping results previously identified in the seven different mapping populations derived from the same parents in different environments, some stably expressed main-effect QTLs including QHd3, QHd8a, QPh3,and QPh4 were identified under different backgrounds and environments, suggesting these QTLs could be used in marker-assisted breeding for HD and PH. On the basis of the mapping information, marker-assisted improvement of HD for a rice variety under different environments was deeply discussed.

Molecular Dissection of Core Parental Cross “Triumph/Yanda1817”and Its Derivatives in Wheat Breeding Program

HAN Jun,ZHANG Lian-Song,LI Jing-Ting,SHI Li-Juan,XIE Chao-Jie,YOU Ming-Shan etal

Acta Agron Sin. 2009, 35(8):  1395-1404.  doi:10.3724/SP.J.1006.2009.01395

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Wheat landrace Yanda 1817 is one of the ‘core parental’ breeding lines for North China Winter Wheat Breeding Program during 1950–1960. The derivatives of cross Triumph/Yanda 1817 have been widely planted in the area and, thereafter, used as parental lines to make further crosses for new varieties development. In this study, the genetic contributions of core parental lines Yanda 1817 and Triumph to their derivative cultivars were analyzed using 175 polymorphic SSR markers randomly distributed on the 21 chromosomes of wheat genome with an average of 8.3 markers per chromosome. The results indicated that Triumph (43.6%) contributed more genetic components than Yanda 1817 (26.8%) to their derivatives on the whole genome level. On the A, B and D subgenome levels, triumph had the contribution ratio of 46.1%, 39.1% and 44.0%, While Yanda 1817 only had the contribution ratio of 25.9%, 25.7% and 26.4% to their derivatives, respectively. It revealed that exogenous germplasm played an important role in the improvement of wheat varieties in the North China Winter Wheat Breeding Program. As for single chromosomes, 20.0% (1A) to 63.3% (7A) of Triumph alleles and 7.5% (2A) to 44.2% (7D) of Yanda 1817 alleles could be detected on the derivative cultivars. Seven Yanda 1817 genomic (haplotypic) regions, Xwmc11-3A–Xcfa2262, Xbarc1073-7B–Xwmc475, Xgwm357-1AL–Xwmc312, Xbarc305-7DS–Xwmc506, Xgwm165-4AS–Xgwm610, Xwmc419-1B–Xwmc134, and Xcfd56-2D–Xbarc228, and eight Triumph genomic (haplotypic) regions, Xwmc105-6BS–Xwmc397, Xgdm72-3D–Xgdm8, Xgdm5-2DS–Xgwm455, Xbarc121-7AL–Xgwm332, Xgwm174-5DL–Xwmc161, Xgwm499-5BL–Xbarc308, Xbarc141-5A–Xgwm291, and Xgwm66-4BL–Xgwm251, were found to be significantly important in the Triumph/Yanda 1817 derivative cultivars. Genomic (haplotypic) regions Xwmc11-3A–Xcfa2262 derived from Yanda 1817 and Xwmc105-6BS–Xwmc397 derived from Triumph had the contribution ratio of 77.5% and 71.3%, respectively to the derivative cultivars of Triumph/Yanda 1817, indicating they are important targets for selection in breeding program. Agronomic important genes and QTLs relevant to yield, disease resistance, tolerance to abiotic stresses and adaptation to diversified environments located on these genomic (haplotypic) regions are important targets for new varieties development in the North China Winter Wheat Breeding Program.

Genetic Analysis and Molecular Mapping of a Yellow green Leaf Gene（YGL4） in Rice （Oryza sativa L.）

LIU Meng-Meng,SANG Xian-Chun,LING Ying-Hua,DU Peng,ZHAO Fang-Ming,et al.

Acta Agron Sin. 2009, 35(8):  1405-1409.  doi:10.3724/SP.J.1006.2009.01405

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A leaf color mutant was obtained by EMS treating seeds of restorer line Jinhui 10, this mutation showed complete yellow green leaves during the life, and could be regenerated and inherited stably according to the observation of 5 generations. The content of its total chlorophyll ranged from 2.01 to 2.28 mg g^-1, which was only 38.2% to 50.5% of the original parent. Compared with the original parent, the mutation had no significant difference in the traits of main panicle length, first branch number, filled grain number of main panicle, seed setting rate and 1000-grain weight, except the effective panicle and plant height which were decreased significantly. Genetic analysis of F₂ populations confirmed that the mutational character was controlled by a single recessive nuclear gene, temporarily designated as YGL4. The gene was mapped between two microsatellite markers RM3123 and RM590, with genetic distances of 7.6 cM and 7.8 cM to the two markers respectively. New microsatellite markers were designed between RM3123 and RM590, and the YGL4 gene was final mapped between RM1162 and RM7093, with genetic distances of 1.8 cM and 4.0 cM to each of them respectively. This result provided a foundation of molecular marker-assisted breeding and map-based cloning of YGL4 gene.

Cloning of cDNAs for a Noval Sugar Transporter Gene,ZmERD6,from Maize and Its Expression Analysis under Abiotic Stresses

MA Xiao-Long,LIU Ying-Hui,YUAN Zu-Li,SHI Yun-Su,SONG Yan-Chun,WANG Tian-YU,LI Yu

Acta Agron Sin. 2009, 35(8):  1410-1417.  doi:10.3724/SP.J.1006.2009.01410

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Drought is one of the most important limiting factors for crop yield in the majority of agricultural regions around the world. Plants respond to drought stress at physiological, cellular and molecular levels. Carbohydrate substances as a nutrient and signal substances play an important role in plants throughout the life course. Carbohydrate has a variety of functions, such as providing energy for the cell life, a framework for proteins and nucleic acid molecules, and raw materials for new cells, regulating osmotically in plants to enhance tolerance, activating different signal transduction pathways and inhibition or activation of certain plant genes which regulate many physiological processes. Previous studies reported that ERD6 is a sugar transporter which widely exists in plants, belonging to Major Facilitator Super-family (MFS) which has a typical structure of MFS domain and sugar transport proteins signature. An EST with high similarity to ERD6 in Arabidopsis was found previously in maize. In the present study cDNAs for the gene homologous to ERD6, designated ZmERD6, was obtained through in silico and homology-based cloning techniques. ZmERD6 had two transcripts, i.e. ZmERD6-L (the large one) and ZmERD6-S (the small one). ZmERD6-L had an ORF of 1 515 bp and encoded 505 amino acids (AA) while ZmERD6-S had an ORF of 1 386 bp and encoded 463 AA. The deduced protein of ZmERD6-L and ZmERD6-S was predicted to contain 12 and 11 membrane spanning helices, respectively. Both of the two proteins had two MFS structural domain belonging to the sugar transporter sub-family of the MFS. Reverse transcription-PCR analysis was performed to investigate the expression pattern of the ZmERD6 in maize under various abiotic stresses. ZmERD6 was expressed at different stages through maize development and was also induced by different abiotic stresses. The promoter of ZmERD6 was cloned, which was about 2.5 kb upstream of ZmERD6 and was predicted to contain important regulatory elements including core promoter elements, enhancer elements, repressor elements and low-temperature and MeJA-responsive elements. These results suggest that the gene is a novel sugar transporter gene in maize and has important and diverse roles in tolerance to abiotic stresses.

An Integrated QTL Map of Growth Stage in Soybean[Glycine max(L.) Merr.]: Constructed through Meta-Analysis

WU Qiong,QI Zhao-Ming,LIU Chun-Yan,HU Guo-Hua,CHEN Qing-Shan

Acta Agron Sin. 2009, 35(8):  1418-1424.  doi:10.3724/SP.J.1006.2009.01418

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Soybean is one of the most important crops in the world, which is kept improving for its yield and quality. Growth stage is a critical trait in soybean development and production which is one of the quantitive traits depending on many loci. As far as the technology of QTL comes, quantitive traits mapping has becoming hot point. Located the QTL controlling soybean growth stage by genetic linkage, is very useful to molecular breeding and deeper understand the process of growth stage develop. Till now, a lot of QTLs related with soybean growth stage were mapped, but many pseudo-positive QTLs were included. To mining the true and major QTLs, meta-analysis were introduced in this study. According to the map of soybean soymap2 published in 2004, an integrated QTL map of soybean growth stages was constructed. The QTLs of soybean growth stage were collected in recent 12 years, and projected to the reference map from their own maps by the software BioMercator2.1. In total, 98 QTLs related with different growth stage of soybean were integrated, including the QTLs of vegetative growth and reproductive growth. A method of meta-analysis was used to narrow down the confidence interval. Seven R1 real QTLs and two R8 real QTLs as well as their corresponding markers were obtained respectively, and a known gene was found in a mapping interval in LG L, located on 93.26 cM. The shortest confidence interval is only 0.9 cM in LG C2, with the marker A397_1 on the left and the marker Satt263 on the right. And 10 QTLs in 5 linkage groups, including C2, D1a, D1b, F, and J, were related to several growth stages. In the combined analysis, a QTL on 55.89 cM in LG D1a controls 6 growth stages, which were R1, R2, R3, R4, R5, and R7. Another QTL on LG D1b, near the markers Bng047_1 and Sat_169, were partly related not only in vegetative growth but also in reproductive growth. The results offer a basis for gene mining and molecular breeding in soybean.

Molecular Mapping of Powdery Mildew Resistance Gene in Wheat Cultivar Jimai 22

YIN Gui-Hong,LI Gen-Ying,HE Zhong-Hu,LIU Jian-Jun,WANG Hui,XIA Xian-Chun

Acta Agron Sin. 2009, 35(8):  1425-1431.  doi:10.3724/SP.J.1006.2009.01425

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Wheatpowdery mildew, caused by Blumeria graminis f. sp. tritici, is one of the most important diseases of wheat (Triticum aestivum L.) worldwide. Breeding resistant wheat cultivars is the most economical and effective approach to control the disease. Jimai 22, a newly released wheat cultivar with high yield, broad adaptability, and good quality, is related to broad-sprectrum resistance to the isolates of B. graminis f. sp. tritici at both seedling and adult plant stages. To map the resistance gene of Jimai 22 on wheat chromosome, we used a highly virulent isolate E20 to screen the F₂ plants and F_2:3 lines derived from the cross of Jimai 22/Chinese Spring. Genetic analysis indicated that Jimai 22 carried a single dominant genefor resistance to powdery mildew, designated PmJM22 tentatively. Using bulked segregant analysis (BSA) with SSR and STS markers, PmJM22 was located to chromosome 2BL. Linkage analysis indicated that the resistance gene was linked to four SSR and five EST markers, with genetic distances from 7.7 (Xwmc149) to 31.3 cM (Xbarc101).Based on the origins, chromosome locations, and reaction patterns, PmJM22 is different from all the known powdery mildew resistance genes Pm6, Pm26, Pm33, and Mlzec1 on chromosome 2BL.

Developing a Method of Oligonucleotide Microarray for Event Specific Detection of Transgenic Maize（Zea mays）

LU Xing-Bo,WU Hai-Bin,WANG Min,LI Bao-Du,YANG Chong-Liang,SUN Hong-Wei

Acta Agron Sin. 2009, 35(8):  1432-1438.  doi:10.3724/SP.J.1006.2009.01432

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With the spread of genetically modified organism (GMO), the food and environment securities related to GMO attract great attention to the public. Genetically modified maize (Zea mays L.) is one of the most popular GMO varieties, which accounts for 22.5% of total planting area of transgenic crops. Currently, more than 40 countries and regions govern GMO food products with a compulsory tagging policy. Thus, technique for testing transgenic plants is of great importance, such as screening, gene specific, construct specific, event specific detection method, which have become a mainstay of GMOs detection. Event specific microarray shows a prosperous application due to its advantages of its high specificity, high sensitivity, automation and high efficiency. In this study, on the base of integrated DNA constructs of seven genetically modified maize varieties, Bt11, Bt176, Mon810, Mon863, TC1507, GA21, and NK603, event specific primers were designed for polymerase chain reaction (PCR) using Primer premier 5.0, and the PCR system and program were optimized. The results indicated that the sensitivity of PCR detection was 0.1%. In addition, based on unique and specific integration junction sequences between the host plant genome DNA and the integrated gene, a 40mer event specific oligo probe with high specificity was designed for each variety using Primer premier 5.0 and Oligo 6.0, all the event specific probes were developed in one microarray. To ensure the reliability of microarray detection, we used different kinds of positive and negative controls in oligonucleotide microarray. The results indicate that the sensitivity of microarray detection (0.01%) and the event specific oligonucleotide probes developed in this study meet the requirements of sensitivity and specificity for detecting and identifying genetically modified maize, which enhances the testing accuracy and efficiency.

Cloning and Differential Exprcssion of QM-Like Protein Homologue from Maize

WANG Hui-Wei,LI Hong-Jie,ZHU Zhen-Dong,WU Xiao-Fei,WANG Xiao-Ming

Acta Agron Sin. 2009, 35(8):  1439-1444.  doi:10.3724/SP.J.1006.2009.01439

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A full-length QM-like cDNA (designated ZmQM) was cloned from maize (Zea mays L.) leaf tissues using cDNA amplified fragment length polymorphism (cDNA-AFLP) and rapid amplification of cDNA ends (RACE) techniques. The expression of ZmQM was examined in leaves of the Ht2 isogenic lines Huangzaosi and HuangzaosiHt2 carrying gene Ht2 for resistance to northern corn leaf blight after inoculation with race 1 of Exserohilum turcicum (Pass.) Leonard et Suggs. Gene ZmQM contains an open reading frame 738 bp in length, which encodes 245 amino acids with a predicted molecular weight of 27.78 kD and an isoelectric point of 10.69. Scanning PROSITE motifs indicated that the amino acid sequence of ZmQM protein includes a Ribosomal protein Ll0e signature, an N-glycosylation site, four Protein kinase C phosphorylation site, a Casein kinase II phosphorylation site, a Tyrosine kinase phosphorylation site, an N-myristoylation site, and an Amidation site. The nucleotide sequence of ZmQM shared 66–92% identity to QM genes isolated from other species. RT-PCR analysis showed that the expression of gene ZmQM was up-regulated in Huangzaosi Ht2 at 12 h after inoculation with race 1 of E. turcicum compared with that in Huangzaosi. By inference, ZmQM protein may be involved in response of HuangzaosiHt2 to inoculation by E. turcicum race 1.

Expression of a Wheat Endosperm 14-3-3 Protein and Its Interactions with Starch Biosynthetic Enzymes in Amyloplasts

SONG Jian-Min,DAI Shuang,LI Hao-Sheng,LIU Ai-Feng,CHENG Dun-Gong,CHU Xiu-Sheng

Acta Agron Sin. 2009, 35(8):  1445-1450.  doi:10.3724/SP.J.1006.2009.01445

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Wheat endosperm starch is the major determinant of grain yield and processing quality. The quality and quantity of starch is controlled by a number of starch biosynthetic enzymes. 14-3-3 proteins, involved in many biological processes, are ubiquitous and important regulators in all eukaryotic cells from yeast to mammals and plants. Protein-protein interactions between a wheat endosperm 14-3-3 protein and starch biosynthetic enzymes from amyloplast were investigated in this study. A 14-3-3 gene was cloned from developing wheat endosperm and inserted into plasmid vectors pET29c and pET41c, respectively. The recombinant vectors were transformed into Escherichia coli strain BL21-CodonPlus (DE3)-RP and expressed at very high level. The fusion protein existed mainly as an insoluble inclusion body after extraction by BugBuster Protein Extraction Reagent. The soluble fusion protein was purified by bounding to S-protein agarose, while the inclusion body should be dissolved in 8 mol L^-1 urea and refolded firstly. Sucrose synthase activity was shown to be inhibited by exogenous recombinant 14-3-3 protein in a dosage-dependent manner, which suggested the refolded protein was successfully activated and can be used in the following research. The purified recombinant 14-3-3 protein was bound to S-protein agarose as a biochemical bait, and then incubated with wheat amyloplast extract. Proteins interacting specifically with the 14-3-3 protein and remaining on the resin were analyzed by SDS-PAGE and western blotting. These assays showed that starch synthase I (SSI), starch synthase II (SSII), starch branching enzyme IIa (SBEIIa), starch branching enzyme IIb (SBEIIb), and ADP glucose pyrophosphorylase large subunit (SH2) interacted with 14-3-3 protein, whereas SBEI, ADP glucose pyrophosphorylase small subunit (BT2), starch phosphorylase (SP), and D-enzyme (DE) did not bind with the 14-3-3 protein. The results suggest a role for the wheat endosperm 14-3-3 protein in regulation of grain starch biosynthetic enzymes.

Construction of  Fingerprinting and Analysis of Genetic Diversity with SSR Markers for Eighty-Eight Approved Potato Cultivars(Solanum tuberosum L.)in China

DUAN Yan-Feng,LIU Jie,BIAN Chun-Song,DUAN Shao-Guang,XU Jian-Fei,JIN Li-Ping*

Acta Agron Sin. 2009, 35(8):  1451-1457.  doi:10.3724/SP.J.1006.2009.01451

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Potato (Solanum tuberosum L.) is one of the most important food crops in the world. Approved potato cultivars have contributed a lot not only to potato production but also to varietal improvement as germplasm resource, and about 110 potato cultivars were approved during 2000–2007 in China. It is necessary to make potato cultivar identification and genetic relationship analysis for seed production, germplasm management, plant variety protection and breeding practice. Currently, the simple sequence repeats (SSRs) are preferred as molecular markers due to their highly desirable properties. In this study, for the aim of cultivar identification and parents combination at the molecular level, SSR markers were employed to analysis on fingerprinting and genetic diversity of 88 potato cultivars approved in China during 2000–2007. Ten of one hundred and thirty-eight pairs of SSR primers were screened out based on sixteen accessions distinct in genetics. The 10 primer pairs amplified a total of 135 alleles (including 133 polymorphic alleles) among the 88 cultivars, and the ratio of polymorphism was as high as 98.52%.Alleles amplified by each pair of primers ranged from 7 (primer S7) to 22 (primer S189), with a mean of 13.5. The polymorphic information content values (PIC) ranged from 0.7604 (primer S192) to 0.9375 (primer S189), with a mean of 0.8501. The fragment sizes varied from 80 to 380 bp. The fingerprinting of 88 cultivars was constructed by 6 pairs of primers of S180, S25, S7, S151, S184, and S192. Eighty-seven out of eighty-eight cultivars were univocally identified by using only five SSR primers (S180, S25, S7, S151, and S184). UPGMA cluster analysis of genetic similarity showed that all the materials were clustered in to one group at the genetic similarity of 0.620, and 81.8% of the cultivars were still clustered together at the genetic similarity of 0.652.The genetic relationships of cultivars were identical to the family tree basically. It’s indicated that the genetic basis of potato cultivars in China is narrow, and the genetic relationship of the potato cultivars derived from the same district is similar. Thefingerprinting and analysis of genetic diversity in this studygave a basis for exploration and utilization of approved potato cultivars as germplasm resources.

EST-Aided Conversion of AFLP Marker Linked to Dominant Male Sterility Gene in Brassica napus into SCAR

SONG Lai-Qiang,YI Bin,YANG Ming-Gui,CHEN Lun-Lin,FU Ting-Dong

Acta Agron Sin. 2009, 35(8):  1458-1461.  doi:10.3724/SP.J.1006.2009.01458

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Dominant genic male sterility (Ms) in Brassica napus has been widely utilized in recurrent selection and in heterosis application. Recent genetical studies verified that its restorer gene is an allele locating at the Ms gene locus. According to this genetic pattern, a whole sterile population (Msms) can be acquired by crossing a homozygous male sterile line (MsMs) with a temporary maintainer (msms) and further used as a female parent in hybrid production, but trans-breeding of the sterile line or the temporary maintainer line that has the same nuclear background with the temporary maintainer line or the sterile line is critical to obtain uniform hybrid population and to maintain heterosis. Because of being laborious and time-consuming, an AFLP marker is usually converted to a PCR marker which is more efficient in molecular marker-assisted selection. In present study, we developed a SCAR marker with bioinformatics method from an AFLP marker SA12MG14 tightly linked to the Ms. Homologous sequences for this marker were obtained through Blast search (http://www.ncbi.nlm.nih.gov), and a corresponding accession of EST from Brassica napus was found from the Arabidopsis thaliana Integrated Database (http://atidb.org/cgi-perl/gbrowse/atibrowse). According to the combined sequence information of the AFLP fragment and the EST, a pair of primers was designed and analyzed on a backcross population Popu2. A dominant SCAR marker S6B3 was successfully identified and further detected consistently on the population with the original AFLP marker. The detected band was clear and steady. This marker is 0.3 cM away from the Ms, and its practical application will enhance work efficiency of breeding for homozygous sterile lines homologous to corresponding temporary maintainers.

Genetic Analysis of Waterlogging Tolerance for Germinated Seeds of Rapessed（Brassica napus L.） with Mixed Model of Major Gene Plus Polygene

CONG Ye,CHENG Yong,ZOU Cong-Shun,ZHANG Xue-Kun*,WANG Han-Zhong*

Acta Agron Sin. 2009, 35(8):  1462-1467.  doi:10.3724/SP.J.1006.2009.01462

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In China, over 85% of the rapeseed production is from the Yangtze River Basin. Rapeseed planted as rotation crop following rice from autumn to beginning of the second year summer, often encounters waterlogging stress because of enduring rainfall in autumn and humid paddy soil, which results in reduced field emergence and weaker seedlings. To reveal the genetic mechanism of waterlogging tolerance in rapeseed, we studied a genetic system of waterlogging tolerance in rapeseed by means of a joint segregation analysis in the multi-family generations (P₁, F₁, P₂, B₁, B₂, and F₂) derived from a cross of Zhongshuang 9×GH01. The results showed that waterlogging tolerance of Zhongshuang 9×GH01 was dominated by two pair of major genes with complete dominance effects plus polygenes with additive-dominance effects (E-5 model). Additive effect (d = 0.0696) was equal to dominance effect (h=0.0696) in the first major gene, and also the additive effect (d = 0.0530) was equal to dominance effect (h=0.0530) in the second major gene of the genetic system. Effect of polygenes acted in the manner of additive ([d]=0.3275) as well as dominant with a negative value ([h]= –0.2137). It indicated that there was heterosis for waterlogging tolerance found in the cross that played an important role in the genetic system of waterlogging tolerance. Heritability of major gene (h²_mg) in F₂ population was 73.57%; it suggested that it will be effective way for waterlogging tolerance breeding to select at early generations.

Expression of Critical Lignin Metabolism Genes in Flax(Linum usitatissimum)

WANG Jin,CHEN Xin-Bo,GAO Yuan,ZHANG Yan-Hong,LONG Song-Hua,DENG Xin et al.

Acta Agron Sin. 2009, 35(8):  1468-1473.  doi:10.3724/SP.J.1006.2009.01468

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Flax (Linum usitatissimum) is an important bast fiber crop. High lignin content in the flax fiber greatly affects the performance and quality in the flax textile industry. CCoAOMT1, 4CL1, 4CL2, COMT, F5H1, F5H2,and F5H3 are putative genes coding the key enzymes involved in lignin accumulation. Expression patterns of these genes were analyzed by semi-quantitative RT-PCRin different flax tissues and in xylem and phloem (bark) at different development stages of the variety Baihua. The results revealed that All genes were detected to express in seedlings, roots, florescent xylem, florescent phloem, leaves, flowers and young fruits excluding F5H1 in roots. Expression of CCoAOMT1 was consistently high in all the tissues detected. There existed complementary expression between two 4CL genesand among the three F5H genes in various tissues. In the phloem, all genes lowly expressed except for 4CL2 at florescence and highly expressed after flowering. Expression of 4CL1 was high, and that of F5H3 was low in the phloem at all stages compared with that of other genes. In the xylem, expression of 4CL1 gene was low at all the developing stages, that of F5H1 reached a peak before flowering and that of the other genes in the xylem reached the highest at 30 d after emergence of seedlings and gradually declined at late growing stages, with a sharp decrease to very lower level after flowering. The expression of 4CL1compared with other genes was significantly higher in phloem than in xylem.

Comparison of Genetic Diversity between In-situ Conserved and Non-conserved Oryza rufipogon Populations in China

WANG Jia-Xiang,CHEN You-Tao,HUANG Juan,QIAO Wei-Hua,ZHANG Wan-Xia,YANG Qing-Wen

Acta Agron Sin. 2009, 35(8):  1474-1482.  doi:10.3724/SP.J.1006.2009.01474

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By the end of 2007, altogether 15 Oryza rufipogon in-situ conservation sites had been established in different parts of China. However, these sites were selected only on the basis of the scientists’ experience and the materials submitted by different provinces. Thus, the validity of the selected populations still needs to be verified. By virtue of 24 pairs of SSR markers, the research was conducted on genetic diversity for 427 accessions of Oryza rufipogon from the 15 in-situ conserved populations and 357 accessions from 15 non-conserved populations which were randomly selected according to their latitude, so as to clarify the genetic diversity and representativeness of the existing Oryza rufipogon in situ conserved populations in China. The results indicated that the average Ae and I of the 24 lociof the conserved populations were 5.98 and 1.90 respectively, which were both higher than those of non-conserved populations (5.85 and 1.86 respectively). However, the average He of the 24 loci of the conserved populations was 0.79, which was lower than that of the non-conserved populations (0.80). Besides, test of significance on the Ae, I, and He of the SSRloci showed that there was no significant difference between the two populations, demonstrating that the genetic diversity of the conserved populations could be representative of the Oryza rufipogon populations in China. Moreover, the number of specificalleles of the conserved populations was 40, which far exceeded that of the non-conserved populations(20), showing that the conserved populations possessed more unique genes which are worth conserved. In addition, based on previous research findings and in accordance with the geographic information of the conserved populations, we found that the 15 conservation sites covered all the typical geographic types in the Oryza rufipogon distribution areas in China. Thus, we may conclude that the 15 in-situ conservation sites were scientifically and rationally selected. On the basis of the analysis of the genetic structure of the Oryza rufipogon populations in China, it was recommended that future in-situ conservation sites should be established mainly in the southern part of Guangxi and in Guangdong.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Dynamic Analysis of Biomass Accumulation and Partition in Soybean with Different Yield Levels

HUANG Zhong-Wen,ZHAO Tuan-Jie,GAI Jun-Yi

Acta Agron Sin. 2009, 35(8):  1483-1490.  doi:10.3724/SP.J.1006.2009.01483

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The dynamic correlation between yield and above- and below-ground biomass and the dynamic partition of biomass of high, medium and low yield lines were studied by using the population of recombinant inbred lines NJRIKY derived from a cross between parents with different biomass and yield potential levels to obtain some information for dynamic control of biomass accumulation in high yield breeding and management of soybean. The results obtained were as follows: (1) Yield was significantly and positively correlated with above- and below-ground biomass accumulation, their correlation increased during the growing stages and the peak correlation occurred at seed filling stage (R5–R6) with r = 0.76 for below-ground biomass and 0.79 for above-ground biomass. (2) The high yield lines (2 500–2 800 kg ha^-1) had a significant higher below-ground and above-ground biomass accumulation than the medium yield and low yield lines. Both below- and above-ground biomass accumulation reached the peak at seed filling stage with the highest below-ground biomass of 660–700 kg ha^-1 and above-ground biomass of 720–780 kg ha^-1 at R5. (3) The composition of high yield lines was not consistent in the two years. Lines with decreased yield had also a decreased biomass, which demonstrated reduction of biomass accumulation caused by different environments was the reason for yield decrease. (4) The dynamic partition of biomass to stem and petiole during growing stages in high yield lines (30.8% and 10.6% at R5, respectively) was significantly higher than that in medium and low yield lines and the dynamic partition of biomass to leaf and root during growing stages in high yield lines (34.1% and 9.7% at R5, respectively) was significantly lower than that in medium and low yield lines. The results implied that the more increase of yield in the future depends on the comprehensive genetic improvement of both biomass and harvest index and the successive advancement of growth regulation technology in soybean.

Crosstalk of NO with Ca²⁺ in Stomatal Movement in Vicia faba Guard Cells

ZHANG Lin,ZHAO Xiang,WANG Ya-Jing,ZHANG Xiao*

Acta Agron Sin. 2009, 35(8):  1491-1499.  doi:10.3724/SP.J.1006.2009.01491

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Previous studies suggested that both NO and Ca²⁺ can serve as a signalling intermediate in ABA, H₂O₂-induced stomatal movement. However, Its mechanism(s) of action is not well defined in guard cells and, generally, in higher plants. In this study, extracellular 10 mmol L^-1 Ca^{2+ significantly inhibited stomatal opening, which was not alleviated by carboxy PTIO (c-PTIO, a NO scavenger). Sodium nitroprusside (SNP, a NO donor) showed effects of inhibition on stomatal opening at concentration of 10 or 100} µmol L^-1. However, 0.1 mmol L^-1Ca^{2+facilitated NO-inhibited stomatal opening, which was alleviated by LaCl₃ (a Ca2+channel inhibitor) at concentration of 1 mmol L-1. To gain further insights into Ca2+ function in NO-regulated stomatal movement, we patch-clamped Vicia faba guard cell protoplasts in a whole-cell configuration. In the absence of extracellular Ca2+NO inhibited inward rectifying K+ current at concentration of 10 or 100 ,} µmol L^-1, but have little effects on outward rectifying K⁺ current. NO significantly activated outward rectifying K⁺ current, when CaCl₂ was added to the bath solution, at concentration of 0.1 mmol L^-1, which was alleviated by LaCl₃. In contrast, 0.1 mmol L^-1 CaCl₂ alone had little effects on inward or outward rectifying K⁺ current. Extracellular Ca^{2+significantly inhibited inward rectifying K+ current and activated outward rectifying K+ current at concentration of 10 mmol L-1, which was not alleviated by c-PTIO. A single-cell analysis of cytosolic Ca2+ and NO using Ca2+specific fluorescence probe Fluo-3-AM and DAF-2DA revealed that 100 or NO} µmol L^-1 SNP evidently induced accumulation of Ca²⁺ in the guard cells，which was partially alleviated by LaCl₃, but 0.1 or 10 mmol L^-1 CaCl₂ had few effects on the accumulation of NO in the guard cells. These results indicated that NO promotes influx of Ca²⁺ into cytoplasm through Ca²⁺ channels to activate outward rectifying K⁺ channels and promotes K⁺ eflux, alternatively, NO inhibits inward rectifying K⁺ channels and blocks K⁺ influx, thus inhibiting stomatal opening and preventing the excessive loss of water in plants. In addition, extracellular Ca²⁺ at concentration of 10 mmol L^-1 modulatesstomatal movement and plasma membrane K⁺ channels of Vicia guard cells in a NO-independent signaling pathway.

Characteristics of Photosynthesis in Wheat Cultivars with Different Sensitivities to Ozone under O₃-Free Air Concentration Enrichment Conditions

CAO Ji-Ling,WANG Liang,ZENG Qing,LIANG Jing,TANG Hao-Ye,XIE Zu-Bingo，et al.

Acta Agron Sin. 2009, 35(8):  1500-1507.  doi:10.3724/SP.J.1006.2009.01500

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Ozone (O₃) has been recognized as a secondary phytotoxic air pullutant of serious concern in agriculture because of its effects on the physiology, growth, and yield of plants. Although the effects of elevated O₃ concentration on plant photosynthesis have widely studied with environment-controlled chambers, the conclusions are not certain due to the difference between free-air field and environment-controlled chambers. O₃-Free Air Concentration Enrichment (O₃FACE) can provide undisturbed field conditions and more reliable measurements in comparison with environment-controlled facilities. In this study, two winter wheat (Tritcium aestivum L.) cultivars (Yannong 19 and Yangmai 16) with different sensitivities to O₃ were used to investigate the responses of photosynthsis characteristics to elevated O₃ concentration with the Chinese O₃FACE platform. Under O₃ treatment for 75 d, the net photosynthetic rate (P_n), stomtal conductance (G_s), and transpiration rate (T_r) decreased significantly in both cultivars, whereas the intercellular CO₂ concentration (C_i) changed slightly. This indicated that the reduction of P_nresulted from stomatal and nonstomal factors with the major role of nonstomatal. The O₃-sensitive cultivar Yannong 19 showed larger reductions in P_n (61.1%), G_s (68.0%), and T_r (57.4%) than Yangmai 16 (27.9%, 37.5%, and 27.9%, respectively). In the chlorophyll fluorescence parameters, the maximal photochemical efficiency of PSII in the dark (F_v/F_m), the potential activity of PSII (F_v/F_o), the photochemical quenching (q_P), and the rate of photochemical reaction (P_rate) decreased in O₃ treatment, but the nonphotochemical quenching (NPQ) and the rate of thermal dissipation (D_rate) showed the upward tendency. The change tendency of total soluble protein content and the amount of Rubisco was similar to that of chlorophyll fluorescence parameters and P_n. The results implied that the major nonstomal factors responsible for P_n decrease under elevated O₃ concentration were the carboxylation limitation of RuBP and the damage of PSII. The change extents of all parameters were larger in Yannong 19 than in Yangmai 16. The high T_r value and slow reduction of Rubisco amount in Yangmai 16 are probably crucial reasons for its high photosynthetic rate.

Effects of Water Table on Rapeseed（Brassica. napus L.） Growth and Yield

SONG Feng-Ping,HU Li-Yong,ZHOU Guang-Sheng*,WU Jiang-Sheng,FU Ting-Dong

Acta Agron Sin. 2009, 35(8):  1508-1515.  doi:10.3724/SP.J.1006.2009.01508

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Adopting rice and rapeseed rotation system, the fields always have higher water table which is harmful to rapeseed at Yangzi river regions. To drain well for rapeseed in the post-rice field, we studied the suitable water table at four stages of the rapeseed growth and development with PVC tube. Agronomic traits of two rapeseed lines with different waterlogging tolerance were investigated to compare effects of different water table levels on rapeseed growth and yield. Four different water table level treatments (0, 30, 60 and 90 cm up to the soil surface) were carried out at the seedling, bud, flowering, and maturity stages, respectively. After the treatments, water level returned to 60 cm, a normal level. The results was at follows: (1) The water table determined roots depth, the development of roots, the growth of the above-ground parts and the yield; (2) The sensitivity to waterlogging different stages of rapeseed was bud stage and flowering stage > seedling stage, pod and mature period; (3) The suitable water table levels in bud stage, flowering stage/seedling stage and mature period were 30 to 90 cm, 30 to 60 cm and 30 to 90cm, respectively; (4) The water table from 30 to 60 cm may meet the requirements for growth and yield in the rapeseed , even in the more sensitive rapeseed lines to waterlogging.

Ultrastructure of Megasprogenesis in Faculative Apomictic Monosonic Addition Line M14  of Beta corolliflora of Sugar Beet

DING Chang-Hong,SHEN Jia-Heng,GUO De-Dong,SHANG Ya-Jia,LU Jun-Ping

Acta Agron Sin. 2009, 35(8):  1516-1524.  doi:10.3724/SP.J.1006.2009.01516

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Research on ultrastructure of megasporogenesis facultative apomictic monosonic addition line M14 of Beta corolliflora of sugar beet by TEM, in order to get the distinctions between the initial cells of sexual reproduction and apomixes. The embryo-sac development of M14 can be classified into three types: Allium odorum-type, Antennaria-type, and Polygonum-type. There was little difference between Allium odorum-type and Polygonum-type until the stage of dyads. At meiosis I, nuclear vacuoles, synaptonemal complexes showed up, cytoplasmic components underwent differentiation, callose deposited in the wall. The megasporocyte of Allium odorum-type only underwent meiosis I to form a dyad, and then the micropylar dyad cell of Allium odorum-type degenerated quickly, while the chalazal one developed into diploid functional megaspore. In Polygonum-type the micropylar dyad cell degenerated quickly, while the chalazal one finished meiosis II to form two unequal-sized megaspore. The megaspore at chalazal end developed into haploid functional megaspore. Antennaria-type was the only fashion of apomictic recreation of M14. Ultrastructure observation on M14 showed the signs of diploid apomictic recreation: no meiosis, no nuclear vacuoles, no cytoplasmic components differentiation, no callose deposition, and no plasmodesmata.

Identification of Photothermal Responses in Soybean by Integrating Photoperiod Treatments with Planting-Date Experiments

FEI Zhi-Hong,WU Cun-Xiang,SUN Hong-Bo,HOU Wen-Sheng,ZHANG Bao-Shi，HAN Tian-Fu

Acta Agron Sin. 2009, 35(8):  1525-1531.  doi:10.3724/SP.J.1006.2009.01525

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Soybean [Glycine max (L.) Merr.] is a short-day crop that favors temperate weather. There have been a lot of studies on the responses to photoperiod, temperature or photothermal comprehensive regimes in soybean. However, little work has been conducted in the interactive effects of photoperiod and temperature on the development of soybean. To fully understand the photothermal responses of soybean and to identify the varietal variations in these traits, we designed two photoperiodic treatments of 12 h (short day or SD) and 16 h (long day or LD) integrated with two thermal conditions, high temperature (HT) (summer seeding in Beijing) and low temperature (LT) (spring seeding) in the current study. In 2007, the responses to the photoperiod, temperature, and photoperiod-temperature combinations of 10 spring sowing soybean varieties (lines) from the Northeast and 18 summer sowing varieties (lines) from Yellow-Huai-Hai River Valleys of China were identified in 4 photothermal regimes (LD+LT, LD+HT, SD+LT, SD+HT). In 2008, 50 varieties (lines) were used to test the photoperiodic responses. The results showed that SD promoted the developmental rate of soybean regardless of the temperature conditions; HT shortened the number of the days from emergence to flowering no matter whether the photoperiod was long or short. There was significant interaction between temperature and photoperiod from emergence to flowering. With the increase of temperature, the promotive effect of SD on developmental rate of soybean was enhanced, and the HT hastening effect was strengthened by SD as well. The apparent differences in photoperiod response sensitivity (PRS), temperature response sensitivity (TRS) and photothermal comprehensive response sensitivity (PTCRS) between ecotypes were observed. The above three indices of spring sowing soybean varieties from the Northeast were all lower than those of summer sowing varieties from Yellow-Huai-Hai River Valleys. However, the differences between TRS values under the two photoperiod treatments and that between PRS values under the two temperature conditions in spring sowing soybean varieties from the Northeast were both larger than those in summer sowing varieties from the Valleys, and it indicated that there was higher photoperiod × temperature interaction in the spring sowing varieties. The relationship between photothermal responses of soybean varieties and their ecological adaptability was discussed, and it proposed that, in breeding program, emphasis should be paid not only on the identification of responses of soybean varieties to the individual photoperiod or temperature factor but also on the photothermal interaction.

Effects of Sulphur Application on Grain Yield and Processing Quality in Medium-Gluten Wheat

XIE Ying-Xin,ZHU Yun-Ji*,ZHU Xiao-Jie,GUO Tian-Cai,WANG Chen-Yang,TIAN Wen-Zhong

Acta Agron Sin. 2009, 35(8):  1532-1538.  doi:10.3724/SP.J.1006.2009.01532

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Global sulphur (S) deficiency in farming lands is a problem in recent years, especially in the fields with high nitrogen (N) input. Unbalanced application of S and N fertilizers not only leads to low N use efficiency but also degrades the grain quality of wheat (Triticum aestivum L.) due to physiological S deficiency. To investigate the effects of sulphur application on grain yield and processing quality, two medium-gluten wheat cultivars (Yunong 949 and Lankao Aizao 8) were used in field experiments with different S and N fertilizer treatments in 2005–2007 growing seasons. Two N levels treatments (240 and 330 kg ha^-1) were combined with two S levels (0 and 60 kg ha^-1). In both cultivars, nitrogen combined sulphur treatments increased grain yield and the yield components. Comparing with no sulphur application, nitrogen combined sulphur application reduced the ratio of amylose/ Amylopectin, and increased farinograph quality parameters of flour. The extensibility parameters of flour such as extended area and extensibility of dough were increased, and the rheological properties of dough and the other main processing quality of wheat flour were improved by sulphur application. In addition, the brightness of flour and the quality identified by senses were improved by sulphur application. On the whole, there is an available measure of fertilizer use not only increasing grain yield and improving quality but also saving cost with applying N 240 kg combined with S 60 kg per hectare in high fertility field. Above results indicate that there is an urgent need to apply S fertilizer in some with high N application in China to achieve high grain yield and maintain high processing quality of wheat.

Effects of Long-Term Application of Different Fertilizer Patterns on Rice Paddy Soil Phosphorus and Rice Phosphorus Nutrition

ZHAO Qing-Lei,WANG Kai-Rong,MA Jia-Qing,YANG Lian-Qun,XIE Xiao-Li,et al.

Acta Agron Sin. 2009, 35(8):  1539-1545.  doi:10.3724/SP.J.1006.2009.01539

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16-year experiment was conducted for revealing the long-term impact mechanism of fertilization on soil fertility and crop nutrition. Five treatments including blank (CK), organic nutrient recycling without NPK fertilizer application (C), NPK fertilizer application (NPK), organic nutrient recycling combined with NPK fertilizer application (NPK+C) and reducing fertilizer application (F+1/2C) were selected, and soil phosphorus fertility indicators and rice plant phosphorus content were measured. The results showed that long-term application of different fertilizer patterns changed the phosphorus fertility characteristics in 0–20 cm soil and rice phosphorus nutrition significantly, while did not vary the phosphorus fertility in 20–40 cm soil remarkably. Compared with blank, NPK fertilizer application increased Olsen-P and total phosphorus content in 0–20 cm soil by 108.8% and 31.9% respectively, meanwhile, the phosphorus contents in rice plant and grains of the two treatments had significant difference in all growth periods. In contrast with NPK fertilizer application, organic nutrient recycling combined with NPK fertilizer application increased Olsen-P and total phosphorus content in 0–20 cm soil by 84.3% and 19.4% respectively, meanwhile, the soil phosphorus activation coefficient achieved 2.96, indicating that the phosphorus content of these two treatments in plant(except grains)had significant difference in all growth periods. There was no significant difference between treatments of organic nutrient recycling alone and blank onsoil fertility indicators and the phosphorus contents in plant and grains in all growth period. And also, there was no obvious difference between treatments of reducing fertilizer application and NPK fertilizer application on soil fertilizer characteristics and phosphorus contents of plant and grains. Compared with NPK fertilizer application, reducing fertilizer application decreased rice plant phosphorus content slightly. Organic nutrient recycling combined with NPK fertilizer application improved soil phosphorus fertility characteristics prominently, raised soil phosphorus activation degree, and promoted the absorbtion of phosphorus in rice.

Heterosis of Water Uptake Ability by Roots of Maize at Cell Level

LIU Xiao-Fang,ZHANG Sui-Qi,YANG Xiao-Qing,SHAN Lun

Acta Agron Sin. 2009, 35(8):  1546-1551.  doi:10.3724/SP.J.1006.2009.01546

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Cell pressure probe technique has been extensively used to study plant water relations at cell level. Effect of numerous internal or external factors on water uptake by plant root cells has been studied. However, the feasibility of this technique for investigating the difference of water related parameters among varieties of the same plant species has not been reported. In this paper, the cell pressure probe was employed to study cortex cell water related parameters of primary roots among three different maize genotypes (F₁ hybrid of HD4, its female parent T4 and male parent 478) under normal and water stress conditions. The water stress was simulated with PEG-6000 with ψ_s value of –0.2 MPa. As to the size of root cortex cells, the diameter, length and volume of cells represented as F₁ > female parent > male parent under both conditions, and there was significant differences of volume among the three maize genotypes. Water stress reduced cell diameter and length obviously so as to decreased volume significantly. The root cortex cell turgor of the three maize genotypes was approximately 0.6 MPa and the genotypic difference was not noticeable under normal culture condition. By contrast to normal condition, cell turgor values of the three maize genotypes were decreased by 0.2–0.3 MPa under water stress condition and cell turgor of male parent was significantly lower than that of the other 2 varieties. The volumetric elastic modulus of the cell wall is a property of rigid cell wall which represents the change in turgorof a cell caused by a given change of the relative volume. Value ofelastic modulus represented as male parent > female parent > F₁ under the two water levels and enhanced by water stress significantly. Moreover, the differences of elastic modulusamong the three maize genotypes were significant under water stress condition. The half time of water exchange represented as male parent > female parent > F₁ under the two water levels, and water stressprolongedhalf time; 50 μmol·L^-1 HgCl₂ also prolongedhalf time, but 5 mmol L^-1 2-mercaptoethanol reversed the effect partly and the final half timewas even larger than the original value. The cell hydraulic conductivity represented as F₁ > female parent > male parent under the two water levels, and water stress noticeably decreased cell hydraulic conductivity. The results indicated that F₁ was better than the parents and showed heterosis in water uptake ability at cell level, and cell pressure probe worked well in the study of genotypic difference of cell water related parameters. The above results also provide scientific references for breeding and selecting new genotypes of maize with improved ability of water uptake by roots and with drought-resistance.

Effects of Super Absorbent Polymer Application Rate on Yield and Quality of Naked Oat(Avenue nuda L.) in Two Irrigation Systems

WU Na,ZHAO Bao-Ping,ZENG Zhao-Hai,REN Chang-Zhong,GUO Lai-Chun,et al.

Acta Agron Sin. 2009, 35(8):  1552-1557.  doi:10.3724/SP.J.1006.2009.01552

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Super absorbent polymer (SAP) and drip irrigation technique are water-saving measurements in several crops, such as wheat, maize, and tomato. Oat is a water-sensitive crop that requires a large amount of water during the growth period. Grain yield and quality of oat are affected by water condition. However, studies in this area are rare. In this study, the variation of grain yield, grain quality, mineral element contents and forage quality of naked oat were investigated under two irrigation systems (traditional irrigation and drip irrigation) and four levels of super absorbent polymer (0, 30, 60 and 90 kg ha^-1). Compared with drip irrigation, grain yield under traditional irrigation was 14.78% higher, but crude protein, crude fat, and β-glucan content of grain decreased by 1.22%, 2.73%, and 3.36%, respectively. The difference between two irrigation systems was significant (P < 0.05). Calcium, magnesium, potassium, zinc and iron contents in grains were significantly higher in drip irrigation system than in traditional irrigation system, except for the manganese content. Relative feeding value, which varied from 122.38% to 135.67% in drip irrigation system, was significantly higher than that in traditional irrigation system (118.75%–134.44%). SAP had positive effect on grain yield of naked oat. In drip irrigation system, the grain yield increased by 2.95% to 12.14% when SAP was applied; it in traditional irrigation system increased by 1.1% to 5.00%. The SAP application of 60 kg ha^-1improved most quality traits of naked oat including the contents of mineral elements in grains.

RESEARCH NOTES

Relationship between cpt1 Gene and the Negative Phototropism in Rice Roots

WANG Yue-Xia,WANG Zhong,LIU Quan-Jun,ZHAO Hui-Jie,GU Yun-Jie,et al.

Acta Agron Sin. 2009, 35(8):  1558-1561.  doi:10.3724/SP.J.1006.2009.01558

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With the purpose of studying the relationship between cpt1 gene and negative phototropism in rice roots, discussing the contribution of asymmetric distribution of IAA on negative phototropism in rice roots, CaCl₂, EDTA and IAA were assayed for their effects on the negative phototropism in rice roots, as well as effects on the expression of cpt1 gene on the basis of reverse transcription-PCR. The result showed that, the negative phototropism in rice roots was improved by the treatment with 1 mg L^-1 CaCl₂ and 0.001 mg L^-1 IAA in culture solution under light for 24 h but constrained by 1 mg L^-1 EDTA. A similar effect was shown from the analysis of cpt1 gene expression, which suggested CPT1 protein could be induced by CaCl₂ and IAA. The effects also showed a positive correlation between the expression of cpt1 and negative phototropism in rice roots. It could be supposed from present results that the asymmetric distribution of IAA is an important step for the negative phototropism process in rice roots, which probably is particularly associated with CPT1 protein as a carrier of IAA.

Effect of Cultivation Method of Broadcasting Rice Seedlings in the Field with Standing-Stubbles under No-tillage Condition on Senescence Characteristics of Leaves during Late Stages of Rice Development

XIAO Qi-Yin,REN Wan-Jun,YANG Wen-Yu,LU Ting-Qi,LIU Dai-Yin

Acta Agron Sin. 2009, 35(8):  1562-1567.  doi:10.3724/SP.J.1006.2009.01562

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Three panicle types of hybrid rice combinations Fuyou I, D you 527, and Gangyou 881 were used to investigate the effects of different tillage and cultivation methods on the senescence characteristics and mechanism in middle and latter periods of rice. The results showed that, the SPAD value and soluble protein content (SPC) of leaf after heading were increased by the treatment of broadcasting rice seedlings in the field with standing-stubbles under no-tillage condition (BSNT). Activity of peroxidase (POD) was decreased, but activities of superoxide dismutase (SOD) and catalase (CAT) in the late growth duration (21 days after heading) were enhanced by the treatment of BSNT. For BSNT, rate of reactive oxygen free radical (O₂^?) production speed and malondialdehyde (MDA) content were lower than those for other treatments. Therefore, treatment of BSNT effectively delayed senescence of plant.