Table of Content

12 October 2007, Volume 33 Issue 10

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ORIGINAL PAPERS

Breeding of the Restorer Line SWR78 with Wide Compatibility and Wide Restoring Ability

TANG Shu-Zhu;ZHANG Hong-Gen;KONG Xian-Wang;GU Shi-Liang; GONG Zhi-Yun; YAN Chang-Jie; LIANG Guo-Hua; GU Ming-Hong

Acta Agron Sin. 2007, 33(10):  1567-1574. 

Abstract ( 2067 )   PDF (522KB) ( 1115 )   Save

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Wide compatibility restorer line is an important parent material for utilizing the heterosis of inter- subspecies, i.e. indica and japonica rice. In production of hybrid rice, indica CMS lines mostly utilize the male sterile cytoplasm from Hainan male sterile wild rice (WA type) and partly from Hainan red awned wild rice (HL type), japonica CMS lines mostly utilize the male sterile cytoplasm from India Chinsurah Boro Ⅱ (BT type). These are so called 3 kinds of representative cytoplasm types. The different CMS lines need different restoring genes to restore their fertilities. So, it is very difficult for a line with single restoring gene to restore different CMS lines. Intention of this study was to breed a restorer line with wide compatibility and wide restoring ability and find a way to utilize the heterosis between indica and japonica rice in the three-line breeding program. In order to screen the restorer lines with wide restoring ability to different CMS lines, one set of isonuclear alloplasmic CMS lines with wide compatibility of Suqiu genetic background and above 3 kinds of cytoplasms were crossed with 9 indica restorer lines (include 136, 388, 6078, Minghui 63, 413, 559, 9311, Teqing, and 1001) and 10 japonica restorer lines(include T1950, C9083, 77302-1, Ninghui 3-2, C Bao, Wanhui 9, Xianghu 115, C9022, Pei C 311, and Lunhui 422). According to the appraisal result of spikelet fertility of F₁ between proposed restorer lines and CMS lines, restorer line 6078 had wide restoring ability to the above 3 kinds CMS lines. Afterward, wide compatibility gene S5n of Lemont was transferred into 6078, and SWR 78 (SWR is the abbreviation for Jiangsu wide compatibility restorer line) with wide compatibility and wide restoring ability was bred by successive back-crosses. By test-crossing and appraising, SWR 78 had wide restoring ability to 10 indica and japonica CMS lines with 4 different kinds of cytoplasm.

Identification of HWM-GS in Glu-B1 Loci by HPLC and the Effects of 7^OE on Wheat Dough Strength

ZHANG Ping-Ping ;ZHANG Qi-Jun ;LIU Li ;XIA Xian-Chun _;HE Zhong-Hu ;

Acta Agron Sin. 2007, 33(10):  1575-1581. 

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Correct identification of high molecular weight glutenin subunits (HMW-GS), and clarify their effects on wheat dough properties are very important in wheat (Triticum aestivum L.) quality study. Sixty-two cultivars or lines were used in present study to identify the composition of HMW-GS by SDS-PAGE and reversed-phase high-performance liquid chromatography (RP-HPLC). The results showed that combination of SDS-PAGE and RP-HPLC can effectively identify the composition of HWM-GS in Glu-B1 loci, especially for Glu-B1(7+8). Thirteen sib lines were used to study the effect of Glu-B1al (7^OE+8*) and protein fractions on wheat quality properties related to dough strength by RP-HPLC and size-exclusion high-performance liquid chromatography (SE-HPLC). The results showed that sib lines with Glu-B1al (7^OE+8*) significantly increased the quantity of HMW-GS, thus significantly improved dough strength, which could be used as high quality subunits in improving wheat gluten strength. Correlation analysis showed that the quantity of total glutenin, HMW-GS, LMW-GS and x-HMW were highly and positively correlated with extensograph maximum resistance (Rmax) with r of 0.76, 0.76, 0.77 and 0.72 (P＜0.01), respectively. The relative content of SDS-unextractable glutenin polymeric protein (UPP percentage) were highly and positively correlated with mixograph development time (MDT), farinograph development time (DT) and stability (ST), and Rmax with r of 0.77 (P＜0.01), 0.90 (P＜0.001), 0.89 (P＜0.001) and 0.87 (P＜0.001) , respectively. The ratio of gliadin to glutenin in quantity was negatively and significantly correlated with MDT, ST and Rmax with r of -0.69 (P＜0.01), -0.58 (P＜0.05) and -0.64 (P＜0.05) , respectively. HPLC is a useful tool for wheat quality breeding.

A Novel Line with HMW-GS 1Bx14+1By18 with Positive Effect on Processing Quality

PANG Bin-Shuang;ZHANG Xue-Yong;WANG Lan-Fen;HAO Chen-Yang;DONG Yu-Chen

Acta Agron Sin. 2007, 33(10):  1582-1586. 

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High molecular weight glutenin subunits (HMW-GS) are wheat endosperm storage proteins, which play an important role in the viscoelastic properties of dough. They are encoded by genes (Glu-1) located on the long arms of the group 1 chromosomes of hexaploid wheat (Triticum aestivum L.). Each locus consists of two tightly linked genes, an x-type and a y-type, which encode the high Mr x-type and the low Mr y-type subunit, respectively. Although 1Ax1, 1Ax2*, 1Bx7+1By8, 1Bx7^OE+1By8, 1Bx14+1By15, 1Bx17+1By18, 1Bx13+1By16, and 1Dx5+1Dy10 are recognized correlating with good bread-making quality, the x-type and y-type subunit genes at the same locus are very difficult to be separated in breeding. Therefore, it is very difficult to confer a score value for a single subunit. In breeding near-isogenic-lines (NILs) for HMW-GS of Xiaoyan 54 (1Ax1, 1Bx14+1By15, 1Dx2+1Dy12), an introduced variety, Prinqual was used as the donor of 1Bx17+1By18. A novel recombinant line 012912 with 1Bx14+1By18 was obtained. The recombinant (1Bx14+1By18) can stably inherit from generation to generation. Except the substitution of 1By15 by 1By18, all of the glutenin subunits and gliadin components of 012912 are consistent with those of Xiaoyan 54. The expression level of 1By18 was more than that of 1By15 by 29%, but the total protein content of the line 012912 was more than that of Xiaoyan 54 only by 0.29%. The SDS sedimentation of line 012912 was more than that of Xiaoyan 54 by 2.5 mL, and the mixing time and mixing tolerance were better than Xiaoyan 54. The results indicate that 1By18 has stronger positive effect than 1By15 on processing quality.

Genetic Diversity of Restorers of Three-Line Hybrid Rice in China

DING Li ;QI Yong-Wen ;ZHANG Dong-Ling ;Wang Mei-Xing ;LI Zi-Chao ;TANG Sheng-Xiang;

Acta Agron Sin. 2007, 33(10):  1587-1595. 

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Restorer line is one of the key factors in hybrid rice production, and the knowledge about its genetic diversity may facilitate rice heterosis application. The restorer resources of three-line hybrid rice in China are rich in quantity, but the overall knowledge of these resources are less, although some results regarding the genetic diversity of restorers with a small quantity of materials have been reported since 1990s. To understand the genetic diversity of the restorers of three-line hybrid rice at a whole resource level, we collected 128 accessions of restorer line from the 6 rice eco-regions and 16 provinces in China in the present study, among which 101 were indica and 27 japonica. The materials could be divided into three types, WA (92), HL (8), and BT (28) types respectively, based on sterile-and-restoring relation. Thirty six pairs of microsatellite (SSR) markers covering the 12 rice chromosomes evenly and 9 phenotypic traits including days of heading, growth duration, plant height, spike weight, spike length, grains per spike, 1 000-grain weight, grain length, and grain length/width ratio were used to reveal the genetic diversity of the materials. The neighbor-jointing cluster diagram based on SSR results showed that the 128 accessions were distributed in 6 clusters, including 44, 42, 28, 3, 7, and 5 accessions in 1 to 6 clusters, respectively. Most of the indica (83.2%) and WA type (82.6%) were distributed in clusters 1 and 2, the japonica (81.5%) and BT type (78.6%) in cluster 3, and HL type (75%) in cluster 1. Materials of IR 24 progeny distributed in 4 clusters, while those of Minghui 63 progeny were all in cluster 1. In the 128 accessions, a total of 281 alleles were found with an average of 8.0 per locus by SSR markers. The alleles were 265 and 186 in indica and japonica subspecies with the average of 7.4 and 5.2 per locus, respectively. The average genetic diversity index (He) of total materials was 0.6190, in which indica (0.5770)>japonica (0.5656) with no significant difference (P>0.05), BT (0.5816)>WA (0.5705)>HL (0.4989) types with no significance (P>0.05) between BT and WA types. The He values lined as eco-region Ⅱ>eco-region Ⅲ>eco-region Ⅵ>eco-region Ⅰ>eco-region Ⅴ> eco-region Ⅳ, in which both eco-regions Ⅱ and Ⅳ were significant (P<0.01) with others. Two Hunan (0.5615) and Sichuan (0.5236), which had comparative sample size, showed significant (P<0.01) difference on He value. Detected by the 9 phenotypic traits, the Shannon-weiner indices (I) were 1.3746 (indica) and 1.3789 (japonica), BT (1.4026)>WA (1.3567)>HL (1.1732) types, rice region Ⅱ (1.3921)>region Ⅲ (1.1209)>region Ⅴ (1.0570)>region Ⅰ (0.9954)>region Ⅵ (0.7818)>region Ⅳ (0.7411). Phenotypic and SSR data showed similar results with the correlation coefficient of 0.9981* (by subspecies), 0.9418 (by sterile-restoring relation), and 0.8835** (by rice eco-regions), respectively, indicating the accordant evolution between genotype and phenotype.

Development and Application of Molecular Markers Specific to Chromosome 6VS of Haynaldia villosa

WANG Chun-Mei;BIE Tong-De;CHEN Quan-Zhan;CAO Ai-Zhong;CHEN Pei-Du

Acta Agron Sin. 2007, 33(10):  1595-1600. 

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The resistance gene of powdery mildew was introduced from Haynaldia villosa into common wheat (Triticum aestivum) and located on 6VS and designed as Pm21. In order to precisely map and clone Pm21, more molecular markers and chromosome structural variants need to be developed. RGA and STS markers, usually from expressed sequences, have proved to be very effective DNA markers. In order to development and application of molecular markers specific to chromosome 6VS of H. villosa, the DNA polymorphic analysis was performed on common wheat Yangmai 5, H. villosa and wheat-H. villosa 6VS/6AL translocation lines with 11 RGA and 17 pairs of STS primers. Two polymorphic fragments, about 1 000 bp and 800 bp, were amplified by a RGA primer Pto kin4 and a pair of STS primer, and then were cloned and sequenced, respectively. Based on the cloning sequences, two pairs of specific markers, CINAU17-1086 and CINAU18-723, were developed, and used to amplify common wheat Chinese Spring, Yangmai 5, Yangmai 158, H. villosa and T. durum-H. villosa amphiploid, wheat-H. villosa alien addition lines (1V-7V), wheat-H. villosa 6VS/6AL translocation line 92R137. The results indicated that two markers, CINAU17-₁₀₈₆ and CINAU18-₇₂₃, were located on chromosome 6VS because only the materials with 6VS chromosome could amplify the specific patterns. Furthermore, CINAU17-₁₀₈₆ was located between FL0.58 and FL0.70 and CINAU18-₇₂₃ between FL0.45 and centromere on chromosome 6VS by using 6VS deletion addition lines and translocation lines. The results obtained from these two markers were consistent with those from the cytogenetic identification to variant materials of chromosome 6VS obtained by radiating pollen. Therefore, CINAU17-₁₀₈₆ and CINAU18-₇₂₃ markers could be used to rapidly detect the correspondent chromosome segments of 6V in common wheat and primarily identify the breakage points of deletion lines.

Mapping of Genes Resistant to Bruchid in Mungbean Using Recombinant Inbred Lines Population

MEI Li;WANG Su-Hua;WANG Li-Xia;LIU Chang-You;SUN Lei;XU Ning;LIU Chun-Ji;CHENG Xu-Zhen;

Acta Agron Sin. 2007, 33(10):  1601-1605. 

Abstract ( 1863 )   PDF (324KB) ( 1400 )   Save

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Mungbean [Vigna radiate (L.) Wiclzek] is one of the main edible beans in China while bruchid are serious devastating stored pests of grain legumes causing considerable loss to mungbean. The most important of the bruchid beetle in Asian is Callosobruchus chinensis (L). Breeding for bruchid-resistant cultivars is a major goal in mungbean improvement. In this study, we analyzed the QTLs, using a Recombinant-inbred-lines (RIL) population from the cross between a highly susceptible economical parent Berken and a highly resistant wild parent ACC41. The RIL population together with their parents were planted in three sites (Australia, Beijing and Nanjing) and evaluated for their resistance by infesting with C. chinensis in 2005 and 2006 in our laboratory. We set the combination of a plant site and a year as an environment, so there are four environments (Australia 2005, Australia 2006, Beijing 2006, and Nanjing 2006). Chi-square analysis (χ²) of the RIL population showed that except for the accessions planted in Beijing field and tested for resistance in 2006, the accessions in other three environments supported the 1:1 segregation ratio. This clearly indicated there was a major resistant gene in ACC41 suitable for mapping. A genetic linkage map with 79 RFLP markers was constructed. Software WinQTLCart was applied to detect QTLs. As a result, a QTL named brI on group 9 steadily existed in the four environments and LOD was 12.99 to 115.12, explaining 74.05 to 79.27% of the phenotypic variations. It is a major QTL for bruchid resistance. The additive effect of the QTL was negative indicating that the allele of the loci from ACC41 promotes the resistance. It will be beneficial to bruchid-resistant breeding and plays an important role in mapping and cloning of the bruchid-resistant genes.

Regeneration of Transgenic Ramie Plants Expressing Green Fluorescent Protein Mediated by Agrobacterium tumefaciens

WANG Bo;PENG Ding-Xiang ;SUN Zhen-Xia;ZHANG Na;XING Xiu-Long

Acta Agron Sin. 2007, 33(10):  1606-1610. 

Abstract ( 1890 )   PDF (1458KB) ( 1185 )   Save

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Genetic improvement of crops can be achieved by biotechnological approaches such as Agrobacterium-mediated transformation. Unfortunately, there were only a few successful transformation experiments on ramie reported to date. In order to confirm its practical value of the green fluorescent protein (GFP), a visual marker, in ramie transformation, Agrobacterium tumefaciens-mediated transformation of ramie with the strain EHA105: pBIN m-GFP5-ER using cotyledon as explants excised from ‘5041-3’ was investigated. Ramie seeds were germinated on MS medium for 4–6 days followed by excised cotyledons from seedlings and inoculated with Agrobacterium tumefaciens cells (OD 0.5–0.8) for 5–10 min. The infected cotyledons were co-cultured on MS medium supplemented with 0.5 mg L^-1 thidiazuron (TDZ), 0.01 mg L^-1 indoleacetic acid (IAA), and 50 mg L^-1 acetosyringone (AS). Three days later, explants were transferred to MS medium supplemented with 0.5 mg L^-1 TDZ, 0.01 mg L^-1 IAA, 500 mg L^-1 cefotaxime (cef), and 30 mg L^-1 kanamycin (km) for selection. Putative transformed shoots were obtained in 4–6 weeks, which elongated on MS medium supplemented with 1.0 mg L^-1 6-benzylaminopurine (6-BA), 200 mg L^-1 cef, and 30 mg L^-1 km, and then rooted on MS medium supplemented with 0.025 mg L^-1 α-naphthalene acetic acid (NAA), 100 mg L^-1 cef, and 30 mg L^-1 km. Well rooted putative transformed plants were transplanted into plastic pots for acclimatization. Transformation efficiency of ramie plants above was 3.6% and the average number of resistant shoots per regenerated explant was 1.3. GFP detection was conducted during the transformation and strong GFP expression was observed in putative transformants, which indicated that GFP could be used in ramie transformation. Stable integration and maintenance of the transgenes in the genome of putative transformants were confirmed by Polymerase chain reaction and genomic Southern blot analysis. The transformation strategy described in this study will provide a practical protocol to generate diverse transgenic ramie plants.

Mining Favorable Salt-tolerant QTL from Rice Germplasm Using a Backcrossing Introgression Line Population

SUN Yong;ZANG Jin-Ping;WANG Yun;ZHU Ling-Hua;Fotokian M H ;XU Jian-Long ;;LI Zhi-Kang

Acta Agron Sin. 2007, 33(10):  1611-1617. 

Abstract ( 2003 )   PDF (485KB) ( 1241 )   Save

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Knowledge of the genetics of salt tolerance and mining of favorable alleles from germplasm should help develop rice varieties with high salt tolerance. QTLs affecting six salt-tolerance related traits including score of salt toxicity (SST), survival days of seedlings (SDS), shoot K⁺ concentration (SKC), shoot Na⁺ concentration (SNC), root K⁺ concentration (RKC), root Na⁺ concentration (RNC) were detected using 85 backcrossing introgression lines derived from a indica cultivar IR64 and a japonica upland cultivar Tarom molaii from Iran under salt stress with the concentration of 140 mmol L^-1 NaCl at the seedling stage. Continuous variation and transgression for all six traits were observed in the BIL population although there were only significant differences in SDS and SNC between the parents. Correlation analysis indicated that SDS had highly negative correlation with SNC and positive correlation with SKC but no correlations with RKC and RNC, suggesting that salt toxicity of leaves resulted from over-accumulation of Na⁺ in shoots. RKC highly positively correlated with RNC while both of them had no correlations with SKC and SNC, respectively, indicating different mechanisms in uptake of K⁺ and Na⁺ in roots and their transport from roots to shoots. Twenty-three QTLs for the six traits on the ten chromosomes except chromosomes 5 and 10 were identified by single-marker ANOVA using SAS PROC GLM, including 5 for SST, 6 for SDS, 4 for SKC, 4 for SNC, 1 for RKC, and 3 for RNC. Among them, the region of RM240-RM112 on chromosome 2 simultaneously affected SST, SDS, SKC, and SNC and the allele associated with improvement of salt tolerance was from Tarom molaii. This QTL could be useful for improvement of salt tolerance through marker assisted selection. The QTLs affecting SKC and SNC didn’t share the same genomic region with the QTLs for RKC and RNC, further confirming the view that different genetic mechanisms involved in uptake of K⁺ and Na⁺ between roots and shoots. By comparative mapping, 12 (52.2%) QTLs for the six related traits located in the same or near genome regions on chromosomes 1, 2, 3, 7, and 9 with the QTLs previously identified in different mapping populations. The advantages of mapping QTLs using BILs and strategy of mining ‘hidden’ salt-tolerant main-effect QTL from rice germplasm were discussed.

Improving Seedling Cold Tolerance of Japonica Rice by Using the “Hidden Diversity”in Indica Rice Germplasm in A Backcross Breeding Program

ZHANG Fan;HAO Xian-Bin;GAO Yong-Ming;HUA Ze-Tian;MA Xiu-Fang;CHEN Wen-Fu;XU Zheng-Jin;ZHU Ling-Hua;LI Zhi-Kang ;

Acta Agron Sin. 2007, 33(10):  1618-1624. 

Abstract ( 1818 )   PDF (482KB) ( 1174 )   Save

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Low temperature at the seedling stage has been an important factor limiting rice production in Northeast China. Developing rice cultivars with good seedling cold tolerance (CT) is the most effective approach to solve the problem. To efficiently discover and utilize useful genes from rice germplasm resources is the key to achieve new breakthroughs in rice improvement. In this study, C418, an elite japonica restorer (Oryza sativa L.), was used as the recurrent parent and 7 varieties of diverse origins (6 are indica lines) were used as donors to obtain BC2F2 bulks by crossing and continued backcrossing. Initial screening for CT under the low temperature of the field conditions resulted in 177 CT BC₂F₂ introgression lines (ILs). Replicated experiments under both normal (non-stress) and natural low-temperature (stress) conditions indicated that all donors had poor CT but there were transgressive segregations in all BC populations for CT, indicating the presence of ‘hidden genetic variation’ for improved CT in apparently cold-susceptible donors. Performances of BC₂F₆ ILs selected from 7 BC populations for traits related to seedling CT in replicated progeny testing under the controlled phytotron low-temperature conditions showed that a total of 93 promising ILs from the BC populations which had higher survival rates than C418. The BC populations involving donors BG300 and Zhong413 produced the highest number of CT progeny, including 28 ILs with a high level of CT, expressed as less affected seedling height and dry weight, and stronger root vigor under the low temperature of both the phytotron and field conditions. Our results indicate that backcross breeding coupled with efficient screening is a powerful way to exploit this hidden diversity and that using diverse indica germplasm as donors in BC breeding program can effectively improve CT of japonica rice varieties in Northeast China without loosing their high yield potential.

The Heterosis of Water Uptake by Single Root of Maize

LIU Xiao-Fang ;ZHANG Sui-Qi ;_;SHAN Lun ;YANG Xiao-Qing ;WU An-Hui

Acta Agron Sin. 2007, 33(10):  1625-1629. 

Abstract ( 1938 )   PDF (341KB) ( 991 )   Save

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The mechanism of heterosis in maize (Zea mays L.) has been studied mainly on kernel character to increase the growth and yield, but whether roots have heterosis on water uptake was not clear. Pressure probe techniques were extensively used to study water utiligation of plants, however, the feasibility of applying this technique to investigate the difference of water relation parameters among varieties of the same plant species has not been reported. In this study, the root pressure probe was employed to study hydraulic properties and interactions between water and solute flows of single primary root of three maize genotypes, 478, T4 and F₁ of hybrid HD4 (478×T4) under hydroponic conditions with two treatments (normal culture condition and water stress imitated by PEG-6000, ψs=－0.2 MPa). In the process of water flow across the single root, there are two different driving forces, hydrostatic pressure and osmotic pressure. Under hydrostatic pressure gradient, the pressure/time curves are monophasic, but in the presence of a permeable solution (50 mmol L^-1 NaCl), the curves are biphasic (water phase and solute phase). Under both normal and water stress conditions, hydrostatic hydraulic conductivity (Lp) (radial Lp and Lx) of single root was different among genotypes, F₁ was the highest and the male parent was the lowest. Osmotic Lp of single root in different genotypes showed the same trend with hydrostatic Lp and F₁ was significantly higher than the parents, but the difference between the two parents was indistinctively both under the two water levels. Compared with osmotic Lp, hydrostatic Lp was 30–53 times higher. Permeability coefficient (Ps) and reflection coefficient (σs) are important parameters in describing the interactions between water and solute flows. Ps means solute uptake ability by plant roots, and σs (0≤σs≤1) implies the passive selectivity of roots for given solute. Ps represented as F1>the female parent>the male parent, and σs showed the reverse trend. Water stress reduced both the hydrostatic Lp and the osmotic Lp, reduced the Ps indistinctively and enhanced the σs significantly. The results indicated that F₁ was prior to the parents to show the heterosis in water uptake ability by single root, and pressure probe techniques worked well in the study of genotype difference of water uptake by roots of plants. The above results also provide scientific references for breeding and selecting new genotypes of maize to improve the ability of water uptake by roots and drought-resistance.

Genetic Structure and Diversity of Both Enhanced Germplasms Developed during 10th Five Year Plan and Modern Cultivars Released during 1968–1995 in China

LI Ying-Hui; LIU Yan; GUAN Rong-Xia; LIU Zhang-Xiong; WEI Shu-Hong; YANG Guang-Yu; ZHOU Xin-An; ZHANG Meng-Chen; YANG Chun-Yan; ZHU Bao-Ge6; LI Wei-Dong7; LIU Xue-Yi <SUP

Acta Agron Sin. 2007, 33(10):  1630-1636. 

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To clarify the patterns of genetic structure, 22 relased modern cultivars and 22 new enhanced germplasms were analyzed with 24 SSR markers. Among the total of 231 alleles, 36 unique alleles were found only in new enhanced germplasms. At Satt309 locus, which closely linked with soybean cyst nematode resistance, an allele, which only was found in Chinese soybean landrace, was confirmed. Combining the results obtained by using UPGMA method and model-based method, four distinct clusters were discovered. Cluster Ⅰ was comprised of 13 new enhanced germplasms from Northeast region and Shanxi province. Cluster Ⅱ included 8 released cultivars from Northerneast region. Cluster Ⅲ consisted of 4 new enhanced germplasms and 4 released cultivars from Huanghuaihai and Southern region. Cluster Ⅳ contained 4 relased cultivars from Jilin, Heilongjiang, Shanxi and Henan provinces. The results of genetic diversity analysis showed that the new enhanced germplasms, which utilized foreign germplasms and wild species as parent, broadened the genetic base of released cultivars in northeast region.

A Comparative Study on Anther Proteomics between Cytoplasmic-Nuclear Male-Sterile Line NJCMS2A and Its Maintainer of Soybean

ZENG Wei-Ying; YANG Shou-Ping; YU De-Yue; GAI Jun-Yi

Acta Agron Sin. 2007, 33(10):  1637-1643. 

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Cytoplasmic-nuclear male sterility is a mojor tool in the hybrid seed production for utilization of heterosis in crops. The soybean cytoplasmic-nuclear male-sterile line NJCMS2A was developed through a consecutive backcross procedure with male-sterile plants of（N8855 ´ N1628）F₂ as donor parent and N1628 (designated as NJCMS2B afterwards) as recurrent parent. The present paper was aimed at the differential expressed proteins of anther at binucleate pollen stage between NJCMS2A and its maintainer NJCMS2B. The developmental stage of the anther was determined by both the external morphological performance of the flower bud and the microscopic observation of the microsporogenesis. Two-dimensional gel electrophoresis (2-DE) technique was used to separate the protein spots and the gels were stained with Coomassie Blue G-250. The obtained 2-DE maps were pretty consistent among replications. The difference between the protein maps of anthers from NJCMS2A and NJCMS2B was analyzed with the PDQuest image software. About 217 protein spots were detected within Mr 18.4–116.0 kD and pH 4–7. Total 25 spots out of 217 were found differentially expressed between NJCMS2A and NJCMS2B. Among these, 13 protein spots were present in the anther protein map of NJCMS2A but absent in that of NJCMS2B, and 10 protein spots present in that of NJCMS2B but absent in that of NJCMS2A, another two protein spots were up-regulated significantly in the map of NJCMS2B in comparison with that of NJCMS2A. The matrix-assisted laser-adsorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) technique was used to obtain the peptide mass fingerprinting of the differentially expressed proteins and the MASCOT software was used to search the protein database NCBInr. The results were as follows: 10 proteins were present in NJCMS2A anther at binucleate pollen stage but absent in NJCMS2B. These were heat shock 22 kD protein, AIG1-like protein, oligouridylate binding protein, cysteine proteinase, hypothetical protein MtrDRAFT_AC146570g8v1, vacuolar H+-ATPase A subunit, adenosine/AMP deaminase, translational initiation factor EIF-4A, cullin, and beta-amyrin synthase. Four proteins were absent in NJCMS2A anther but present in NJCMS2B. These were MADS box protein, starch branching enzyme, glutathione-s-transferase, and auxin-induced protein AUX28. According to the literature, the functions, especially those related to the male sterility of the major differentially expressed proteins, including heat shock 22 kD protein, cysteine proteinase, vacuolar H+-ATPase A subunit, MADS box protein, and starch branching enzyme were reviewed and discussed. It was inferred that the male sterility of NJCMS2A might be related to energy metabolism turbulence, the programmed cell death (PCD), starch synthesis suffocation and the disturbed function of the flower developmental gene. But the exact mechanism of the differentially expressed proteins above leading to the male sterility of NJCMS2A are to be further studied.

Isolation of Differentially Expressed Genes from Wheat Cultivars Jinan 17 and Yumai 34 with Good Bread Quality under Heat Stress during Grain Filling Stage

LI Hao ; ZHANG Ping-Ping ; ZHA Xiang-Dong ; XIA Xian-Chun ; HE Zhong-Hu ;;

Acta Agron Sin. 2007, 33(10):  1644-1653. 

Abstract ( 2303 )   PDF (1034KB) ( 993 )   Save

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Studies of gene expression patterns under heat stress during grain filling stage will provide important information for breeding wheat cultivars with high quality. In the present study, two wheat cultivars, Jinan 17 and Yumai 34 with different quality stability under various environments, were used to in the influence of high temperature on gene expression. The wheat plants were exposed to high temperature (38℃/25℃ day/night) for three days in the middle (from 15 to 18 days post-anthesis) and late stage (from 30 to 33 days post-anthesis) of grain filling in a climate chamber. Spikelets in middle of heads were harvested, and RNA of kernels was extracted with a combined technique of cold phenolic and Trizol single-step methods. cDNA was obtained by the reverse transcription of total RNA, and differential bands were detected subsequently in cDNA-AFLP analysis. In total, 410 and 316 differential bands were detected from Jinan 17 and Yumai 34, respectively. The differential fragments were cloned, sequenced and blasted in NCBI, and 85 and 99 positive fragments of differentially expressed genes under heat stress were obtained from Jinan 17 and Yumai 34, respectively. After the positive fragments were validated by reverse Northern blotting, 25 positive fragments isolated from Jinan 17 showed intense signal, and 22 of them were induced under heat stress, which were notablely homologous to stress response genes and heat shock protein of wheat. Meanwhile, 31 positive fragments showed intense signal were observed from Yumai 34, and 25 of them were suppressed, which were notablely homologous to stress response genes, ethylene forming enzyme, pyrroline-5-carboxylate synthetase. The rusults indicated that gene expression was more induced under heat stress in Jinan17, whereas suppressed more in Yumai 34, which might lead to differences in heat tolerance and quality stability. Five fragments from Jinan 17, and two fragments from Yumai 34 did not have any homology sequences in the BLAST analysis, while other fragments have homology protein or nucleic acid sequences in wheat or other crops. Two fragments induced in response to heat stress were notablely homologous to the storage protein genes, which might induce the expression of transcripts related to storage protein under heat stress. Fifteen differential fragments were detected from medium stage of grain filling in Jinan 17, whereas those from late stage were 10, while 29 and 2 differential fragments in Yumai 34 were observed in medium and late stages, respectively. This indicated that gene expression was more significantly affected by heat stress in medium stage than in late stage of grain filling, especially in Yumai 34. The difference of gene expression patterns between two wheat cultivars were observed, stress response genes were induced in Jinan 17, ethylene forming enzyme and pyrroline-5-carboxylate synthetase as well as stress response genes were suppressed in Yumai 34, which may result in the different responses in heat tolerance and quality stability. The identification and characterization of heat stress responsive genes in wheat may provide a molecular biological understanding of gene expression patterns and regulation involved in the heat stress in wheat.

Differential Expression Analysis of Genes at the Stage before Anther Abortion of NCa CMS System in Brassica napus L.

WEI Wen-Liang; WANG Han-Zhong; LIU Gui-Hua

Acta Agron Sin. 2007, 33(10):  1654-1661. 

Abstract ( 1789 )   PDF (931KB) ( 892 )   Save

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Previous studies showed that NCa CMS was a novel CMS and would be of great importance for rapeseed hybrid breeding and production. In this article, differentially expressed genes during pollen abortion among NCa cms, maintainer line and fertile F1 were analyzed by means of cDNA-AFLP. 224 pair of AFLP primers were used to analyze the cDNA of the above 3 materials. The transcript-derived fragments (TDFs) were cloned, and then 41 TDFs were sequenced after identified as positive clones. Most of the TDFs were cloned firstly in Brassica napus. Gene function analysis revealed that 82% of TDFs were related with metabolism processes of (1) cell formation and degradation, (2) protein synthesis, processing and transporting, (3) energy metabolism and (4) signal transferring, involving all the key metabolism processes during pollen development. The differential expression of seven key genes among these TDFs in young leaves and floral buds of NCa cms and maintainer line were further analyzed by RT-PCR. The pectin esterase gene and amino acid permease gene abundantly expressed in floral buds of NCa cms while pectin esterase gene showed no transcript either in young leaves of NCa cms or in the two tissues of maintainer line, and amino acid permease gene slightly expressed in the corresponding tissues. However, kinesin gene and aldehyde dehydrogenase (ALDH) gene expressed abundantly in floral buds of maintainer line but just slightly detected in young leaves of maintainer line and both tissues of NCa cms. The transcriptions of ZEP gene and mono-dehydroascorbate reductase were reverse to that of amino acid permease gene. The transcription of pollen-special oleosin-like protein gene was detected almost twice in abundance in floral buds of maintainer line than in those of NCa cms, whereas not detected in young leaves of the two materials. As for the gene transcription in the floral buds, the differentially expressed genes cloned from the NCa cms were detected abundantly in its floral buds but almost no transcription in those of maintainer line, and vice versa, which demonstrated that the authenticity and efficiency of cDNA–AFLP applied to reveal and clone differentially expressed genes. Further studies were underway in order to investigate the relationship between these genes with NCa pollen abortion.

Acquiring Nitrogen Quantity in Digital Image of Cotton Leaf by Artificial Neutral Network Model

LI Xiao-Zheng ; XIE Rui-Zhi; WANG Ke-Ru ; BAI Zhong-Ying ; LI Shao-Kun ; ; WANG Fang-Yong ; GAO Shi-Ju

Acta Agron Sin. 2007, 33(10):  1662-1666. 

Abstract ( 1601 )   PDF (344KB) ( 958 )   Save

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Artificial Neutral Network (ANN) has some important features, such as self-study, acceptance-error, building math model rapidly. ANN has been widely used in many fields, some people have made a lot of findings in agriculture by ANN. The technology of digital image processing is also very important for agriculture, and people have found there are some relation between color information and the nitrogen quantity for maize, tomato. But nobody use ANN to found the relation. The objective of this research is to process the digital image of cotton leaf, and use ANN to select the best math model and input vectors for establishing the relation between the color information and nitrogen quantity of cotton leaf. So we can use the advantages of ANN and the technology of digital image processing, and select the most suitable result for this research automatically. We select three ANN models (line on network, BP network and radical basis function (RBF) network) and six pieces of input vectors for this research, and train each model with color information from 180 pieces of digital images, and use the better to forecast nitrogen quantity of 30 pieces of images. The results showed that linear network was not fit this research and the relation between color information and nitrogen quantity was not fit the linear models, and RBF network was better for this research than BP network. RBF network had a lot of advantages in calculating the quantity of nitrogen using vector (B, H, G-R, G/R). The precision of training result was very marked, with r = 0.9022**, and the precision of forecast was high, with r = 0.8674** by this ANN forecast using the 30 pieces of cotton digital image. Because of local smallest, simple framework, and rapid training, RBF network can get the nitrogen quantity in plant by digital image information, and enhance the application of ANN in agriculture.

Effects of Nitrogen and Potassium Application Levels on Flag Leaf Photosynthetic Characteristics after Anthesis in Winter Wheat

ZOU Tie-Xiang; DAI Ting-Bo; JIANG Dong; JING Qi; CAO Wei-Xing

Acta Agron Sin. 2007, 33(10):  1667-1673. 

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Grain yield limit is one of the main problems in medium or weak gluten wheat production in middle-lower reaches of the Yangtze River of China. Nitrogen and potassium are key factors affecting leaf photosynthesis, and previous researches have showed that the application of either of the two fertilizers can improve wheat organ construction, therefore, affect grain yield. However, the physiological mechanism of nitrogen and potassium interaction on photosynthetic characteristics in wheat needs to be revealed. In the present study, we used two winter wheat (Triticum aestivum L.) cultivars, ‘Ningmai 9’ (weak gluten) and ‘Yangmai 10’ (medium gluten) in a field experiment to investigate chlorophyll content (SPAD), net photosynthetic rate (P_n), chlorophyll fluorescence parameters of flag leaves and the relationship among those parameters and nitrogen and potassium fertilization levels. In the experiment, nitrogen was the main plot with 3 levels corresponding to 0, 112.5, and 225 kg N ha^-1 respectively, and potassium (0, 75, and 150 kg K₂O ha^-1) and cultivar (‘Ningmai 9’ and ‘Yangmai 10’) were the split plots. The results showed that SPAD and photosynthetic parameters (P_n, F_v /F_m, F_v /F_o, F_v’/F_m’, and Φ_PSⅡ) were increased with N and K supply, compared with CK (no N and K fertilization). Compared with potassium fertilization, the role of nitrogen on SPAD and photosynthetic parameters (P_n, F_v /F_m, F_v /F_o, F_v’/F_m’, and Φ_PSⅡ) was greater. The relationships between chlorophyll fluorescence parameters (F_v /F_m, F_v /F_o, F_v’/F_m’, and Φ_PSⅡ) and Pn were all significant (P < 0.01). Photosynthetic parameters except SPAD were higher in ‘Yangmai 10’ than in ‘Ningmai 9’. The results suggested that higher chlorophyll fluorescence parameters (F_v /F_m, F_v /F_o, F_v’/F_m’ and Φ_PSⅡ) affected by reasonable leaf N/K ratio at anthesis were the key physiological basis not only for higher Pn after anthesis, but also for getting almost the same yield of ‘Yangmai 10’ which needs more energy compared with that in ‘Ningmai 9’.

“Three Combination Structure” Quantitative Expression and High Yield Analysis in Crops

ZHANG Bin; ZHAO Ming ; ; DONG Zhi-Qiang; CHEN Chuan-Yong; SUN Rui

Acta Agron Sin. 2007, 33(10):  1674-1681. 

Abstract ( 1987 )   PDF (491KB) ( 1477 )   Save

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With the increase of crop yield, topping the highest yield becomes more difficult. Higher productivity requires better crop performance, which accordingly requires precise crop husbandry. However, there are still large gaps in understanding crop performance and their relevant physiological factors and furthermore the effective manipulation measures. As a consequence of which, quantified crop yield analysis is badly needed. On the basis of the secondary structure of “three combination structure” crop yield analysis model, which is the organic integration of photosynthetic property, source sink and yield component theory, the concept of “three combination structure quantitative expression” was put forward, and the parameters were calculated by means of field experiments and simulation method. With that the quantitative expressions of spring maize (Zea mays L.), summer maize, rice (Oryza sativa L.) and winter wheat (Triticum aestivum L.) were founded, respectively. And the causations for high yield and the restrictive factors for higher yield were analyzed. Improving average net assimilation rate (MNAR) would improve rice yield, and properly increasing average leaf area index (MLAI) or harvest index (HI) was the possible way for higher winter wheat yield. The mutative trends of each equation parameter were analyzed for different spring maize populations, the results showed that improving total grain number per unit land area (TGN) via increasing MCGR would result in higher maize yield. The definite function expressions between the parameters were also established. With the definite relationships between the parameters, one parameter can be expressed with other relevant parameter(s). The foundation of the “three combination structure” quantitative expression provided a new idea and new method for the quantitative analysis of crop production. With that one could understand yield formation processes systematically and make a good judgment on the critical factors for limiting higher yield and explore corresponding possible ways to settle them accordingly. So “three combination structure” quantitative expression might be a good guidance for higher crop production.

A Dynamic Model Simulating Photosynthetic Production and Dry Matter Accumulation for Alfalfa (Medicago sativa L.)

ZHU Yu-Jie; FENG Li-Ping ; ; YI Peng; YING Xiao-Guang; HU Yue-Gao

Acta Agron Sin. 2007, 33(10):  1682-1687. 

Abstract ( 1940 )   PDF (333KB) ( 1060 )   Save

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Photosynthetic production and dry matter accumulation are major determinants of the final yield in crop production. Early simulation model of photosynthetic production and dry matter accumulation for alfalfa is relatively simple and much depending on experience. On the base of the eco-physiological processes and biological characteristics of alfalfa (Medicago sativa L.), a simulation model for photosynthetic production and dry matter accumulation was established by the field experiment data and widely collected data. This model included the sub-models of photosynthesis, respiration, leaf area dynamic, dry matter production, assimilate partitioning, and yield. The model took into account of the effect of temperature. The model was parameterized with data from the literature and local experiments. Data from Beijing were used for calculation of the coefficients of dry matter allocation（C(d)_i）at different development stages. Data from literature were used for calculation of the coefficients of dry matter conversion (β). The photosynthetic parameters (a and P_max) for six alfalfa cultivars were determined based on the data from the field experiments at Beijing and Taiyuan. The verification and validation of the model were conducted. Data from Beijing were used for validation of leaf area dynamics and above-ground biomass. Data from Beijing and Taiyuan were used for validation of crop yields of 6 cultivars. The model simulated appropriately the growth of the crop. The adjusted linear correlation coefficient (R²) values between simulated and measured leaf area, above-ground biomass, stem biomass, and leaf biomass were 0.98, 0.95, 0.96, and 0.88 (n=20), respectively. The root mean squared error (RMSE) between simulated and measured yields was 103 kg ha^-1, and the normal root mean squared error (NRMSE) was 2.1 % (n = 102). The results indicate that the model has not only good mechanism in model building, but also good simulation capability.

Effects of Population Density on Stalk Lodging Resistant Mechanism and Agronomic Characteristics of Maize

GOU Ling ; HUANG Jian-Jun; ZHANG Bin; LI Tao; SUN Rui; ZHAO Ming ;

Acta Agron Sin. 2007, 33(10):  1688-1695. 

Abstract ( 2133 )   PDF (494KB) ( 1434 )   Save

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Lodging is a major constraint to limit grain yield under increased planting density in modern maize (Zea mays L.) production. Effects of planting density on stalk mechanical and agronomic characteristics were investigated using three maize cultivars differing in lodging resistant ability,i.e. Jingke 519 (with a large spike under thinned planting density), Denghai 3719 (tolerant to high density) and Nongda 108 (a main local cultivar). Five levels of density treatment were imposed, 3.0, 5.25, 7.5, 9.25 and 12.0×104 plants ha^-1. Experiments were arranged in a split plot design with four replicates. The irrigation and fertilizer management in the experiment plot was consistent with typical agronomic practices in the local high-yield field. The results indicated that the increase of planting density would cause significant decreases in stalk crushing strength (SCS), rind penetration strength (RPS), internode diameter and dry weight (DW), percentage of dry matter and ratio of dry matter weight to length of internode (RDWL), and dramatic increase in internode length. The relationship between stalk mechanical characteristics and planting density fitted a exponential curve (y = ae^bx) significantly. The stalk mechanical characteristics were highly correlated with the agronomic characteristics. These characteristics of Jingke 519 were susceptive of the increasing planting density above 75 000 plant ha^-1, especially for these above the 4th internode was. The whole plant would have high lodging resistant ability if the dry matter accumulation was high in the 4th and above 4th internods. That the internod length enlarged slowly and diameter of internode decreased significantly with increasing plant density was an adaptability to high planting density for the resistant cultivar. When the percentage of DW of the 4th and above 4th internods was more than 7.5%, and its RDWL was more than 0.2 g cm^-1 at a week prior to anthesis, the plants would be resistant to lodging .The stepwise regression analysis revealed that the RDWL contributed positively the most to SCS and RPS. RDWL was definite as an agronomic indicator of maize stalk lodging resistant ability.

Genetic Diversity Analysis of Sesamum indicum L. Germplasms Using SRAP and EST-SSR Markers

ZHANG Peng; ZHANG Hai-Yang ; ; GUO Wang-Zhen; ZHENG Yong-Zhan; WEI Li-Bin; ZHANG Tian-Zhen

Acta Agron Sin. 2007, 33(10):  1696-1702. 

Abstract ( 1966 )   PDF (413KB) ( 1032 )   Save

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Sesame (Sesamum indicum L.), an important oil-yielding plant, is one of the most ancient crops in tropical and subtropical areas. Despite its nutritional value and importance, the research on sesame has been scarce. In this study genetic relationships among 134 Chinese sesames, 41 alien sesames, and 17 improved cultivars were analysed using SRAP and EST-SSR markers. Large genetic variability was found within all the germplasm collection. A total of 270 SRAP markers were recorded using 31 primer combinations, each primer detected 5.45 loci; While 25 pairs of SSR amplified 136 loci, each primer detected 3.04 loci. Mantel test revealed that the relation of genetic similarity matrix between SRAP and SSR was significant (r=0.7864, t=5.2571, P<0.01) for 192 species, so the UPGMA dendrogram was set up based on the integrated data of SRAP and SSR. The 192 accessions were grouped into three robust clusters, and cluster Ⅰ consisted of six groups, which was not revealed any association between genotype and geographical origin. Accessions came from one region were distributed throughout the dendrogram. The results revealed by the genetic distance and Shannor-weaver index of sesame germplasm resources from different regions that the genetic diversity of sesame was high, and in our nation the southern was higher than the others. We presumed that the sesame species was introduced to the Southern China firstly, of course it needs other evidence to be substantiated. The cluster result suggests that there was a considerable gene flow among different regions. So when we choose the parents in sesame breeding focusing on the genetic relationships is a good strategy.

Establishment of Multiplex-PCR for Quality Traits in Common Wheat

ZHANG Xiao-Ke ; XIA Xian-Chun ; WANG Zhong-Wei; WAN Ying-Xiu ; ZHANG Ping-Zhi; HE Xin-Yao; YANG Yan; HE Zhong-Hu ;;

Acta Agron Sin. 2007, 33(10):  1703-1710. 

Abstract ( 1941 )   PDF (959KB) ( 1168 )   Save

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Wheat (Triticum aestivum L.) quality properties are strongly affected by the compositions of high-molecular-weight glutenin subunits, kernel hardness, amylase content, pre-harvest sprouting tolerance and presence or absence of 1B/1R translocation. It is very important to develop multiplex PCR for wheat quality improvement in molecular marker assisted breeding to reduce the cost and improve the efficiency. Three types of multiplex PCRs were developed and validated with 13, 30, and 11 Chinese wheat cultivars and advanced lines with known genes, respectively. The first multiplex PCR was used to simultaneously detect genes ω-secalin (1B/1R), Vp1B3, and Pinb-D1b for improving wheat processing quality. The second one was to detect the genes ω-secalin, Ax2*, Bx17, and Dx5 for improving gluten quality and bread making quality. The third multiplex PCR included three markers for Wx-7A, Wx-4A, and Wx-7D to improve starch quality and breed waxy wheat cultivars. The genotypes of all tested wheat cultivars and advanced lines identified by three multiplex PCRs were in agreement with those detected by other methods. The primer-primer interactions in each multiplex PCR were not found. Genomic DNAs extracted from both wheat kernels and leaves were feasible for three multiplex PCR amplifications. The three multiplex PCRs were highly effective in the test of Chinese wheat cultivars, demonstrating good repeatability and low cost for the evaluation of wheat quality properties in wheat breeding program.

RESEARCH NOTES

Characteristics of ERF Transcription Factor of Thinopyrum intermedium in Transcription Activation and DNA-Binding

LIANG Hong-Xia ; LIU Hong-Xia ; ZHANG Zeng-Yan ; ; WANG Li-Li ; XIN Zhi-Yong

Acta Agron Sin. 2007, 33(10):  1720-1723. 

Abstract ( 1537 )   PDF (514KB) ( 944 )   Save

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In order to investigate the transactivation activity and interaction characteristic of an ERF transcription factor TiERF1a isolated from Thinopyrum intermedium and its cis-acting element GCC box, we successfully constructed the yeast reporter vectors containing 3 tandem copies of GCC box or mutated GCC box fused upstream of lacZ gene, which had been integrated into the genome of the yeast strain YM4271 and the effecter expression vector pYepGAP-TiERF1a containing the full encoding region of TiERF1a gene. The TiERF1a expression vector pYepGAP-TiERF1a was transformed into the reporter yeast cells. The activity of lacZ gene expression product,β-galactosidase, was assayed qualitatively by X-gal colony-lifted filter, and analyzed quantitatively using o-nitrophenyl-β-D-galactopyranoside (ONPG) as substrate. The results indicated that TiERF1a could bind to GCC box sequence and possessed high transactivation activity. The method established can also be used to analyze the transcriptional regulation activity of other transcription factors in yeast cells.

Cloning of lyc-b Gene from Sweetpotato (Ipomoea batatas L.) and Transferring the Gene into Tobacco

CHEN Xuan-Yang ; YUAN Zhao-Nian ; ZHANG Zhao-Jian ; ZHENG Jin-Gui ;

Acta Agron Sin. 2007, 33(10):  1724-1728. 

Abstract ( 1906 )   PDF (497KB) ( 886 )   Save

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Lycopene β-cyclase, which catalyzes linear lycopene to cycle and become β-carotene, is one of key enzymes in the β-carotene biosynthesis pathway. Total RNA was purified from sweetpotato tuberous roots and was reverse-transcripted into cDNA, and the consensus sequence of the gene for lycopene β-cyclase (lyc-b) was amplified from the cDNA, then total cDNA sequence of lyc-b was obtained by the ways of Rapid Amplification of cDNA End (RACE). Sequence analysis showed that the complete sequence of lyc-b consists of 1 844 bp, which has an Open Reading Frame of 1 503 bp and encodes a protein of 501 amino acids. The gene was constructed into plant express vector p23-lyc-b，and was transferred into tobacco by Agrobacterium-mediated method. The results of PCR and Southern blot showed that the gene was integrated into tobacco genome.

Leaf Aging and Reactive Oxygen Species Metabolism of Winter Wheat in Different Cultivation Modes

YU Huan; FENG Bai-Li; ZHANG Ying; LIU Peng-Tao; HE Rong-Yan; DAI Hui-Ping; LI Sheng-Xiu

Acta Agron Sin. 2007, 33(10):  1729-1732. 

Abstract ( 1797 )   PDF (299KB) ( 1176 )   Save

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Chlorophyll and soluble protein break down and reactive oxygen species metabolism is maladjustment in the process of leaf aging. The damage action of reactive oxygen species is one of the reasons for plant leaf aging. Superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) are important defending enzymes that can eliminate reactive oxygen species and inhibit plant aging. The experiment was carried out to study the effects of three cultivation modes (flat planting, straw mulching, plastic film-mulching) with the 120 kg N ha^-1 application and planting density of 130–150×10⁴ plants ha^-1 on leaf aging of the winter wheat (Triticum aestivum L.) cultivar Xiaoyan 22. The results showed that leaf aging and reactive oxygen species metabolism varied with the cultivation modes. Compared with flat farming, straw mulching could increase leaf chlorophyll, slow the speed of leaf aging and the extent of declining metabolism. At the early filling stage, plastic film-mulching could increase leaf chlorophyll, enhance POD, CAT activities, and lower the malondialdehyde (MDA) content. At the late filling stage, there were a remarkable decline of leaf chlorophyll, a quick leaf aging and a marked increase of MDA. The POD and CAT were involved in leaf aging regulation, synergistically protecting the leaves by reducing the damage from reactive oxygen species, prolonging the functional period of leaves and increasing the yield. We can use straw mulching to regulate the leaf aging of winter wheat, and improve the yield and quality of winter wheat in the south of Loess Plateau.

Detecting Genetically Modified Soybean by Real-time Quantitative PCR Technique

WU Ying ; SONG Feng-Sun ; LU Xu-Zhong; ZHAO Wei; YANG Jian-Bo; LI Li ;

Acta Agron Sin. 2007, 33(10):  1733-1737. 

Abstract ( 1943 )   PDF (551KB) ( 1015 )   Save

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In this paper, fluorescence-labeled Taqman probes and SYBR dye were chosen to detect the amplified DNA fragments by PCR. Before special primers and probes were used to amplify the exogenous gene cp4-epsps, the endogenous gene Lectin was detected to avoid the fake negative result. Then, Two quantitative systems were optimized. And the standard curve of Ct vs. the GM content in the reference materials was generated and a linear regression equation was obtained to quantify GM soybean. The result showed that fluorescence signal appeared at the 24th cycles in Taqman-labeled, while at the 18th cycles in SYBR-labeled. It suggested that a little primer dimmers or other unspecific amplifications had cumulated before objective product formed in SYBR assay. The correlation coefficient (R²=0.993) of SYBR assay was lower than that of Taqman (R²=0.999). Finally, the two quantitative systems were tested respectively by using known samples with three GM contents. The results indicated that the precision of two systems were high, and the recurrences of the results were fine. Comparing the two quantitative assays, it has higher delicacy and precision in Taqman assay. The inferior limit of detection was less than 0.05%，and the Coefficient Variance was up to 0.09%. A very sensitive quantitative PCR method for the detection of genetically modified (GM) soybean was developed and validated. We also discussed the difference between Taqman assay and SYBR assay on detecting GMOs, and recommend the Taqman assay to use in transgenic product detection, especially in GMO food detection.

Method of ID Constitution for Wheat Cultivars

WANG Li-Xin; LI Yun-Fu; CHANG Li-Fang; HUANG Lan ;; LI Hong-Bo ; GE Ling-Ling; Liu Li-Hua ;; YAO Ji ;; ZHAO Chang-Ping ;

Acta Agron Sin. 2007, 33(10):  1738-1740. 

Abstract ( 2007 )   PDF (434KB) ( 1101 )   Save

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DNA fingerprint is a useful tool for identification new cultivars, cultivars’ authenticity and seed purity in wheat production and trade. In the present study, 15 SSR markers and 20 AFLP-SCAR markers were employed as DNA fingerprints of 455 wheat cultivars collected from 12 provinces and eco-regions of China. The fingerprints built by the two kinds of marker could explore the cultivars’ genetic diversity more reliably. Therefore, an approach to build wheat fingerprints was set up by connecting both SSR and AFLP-SCAR codes. In this paper, we exampled the way of constituting DNA fingerprints for wheat cultivars by 10 pairs of SSR marker and 10 pairs of AFLP-SCAR marker. The approach is put forward to converting DNA fingerprint code to bar code and give every wheat cultivar an ID number in the future.