普通小麦各染色体组有效利用土壤磷基因的遗传分析

以部分中国春双端体为材料用土培盆栽法对小麦各染色体组有效利用土壤潜在磷基因的遗传分析表明：小麦不同染色体臂上所携基因对小麦有效利用土壤潜在磷特性具有不同效应,在供试材料中,Ｂ组染色体所缺失的臂在缺磷下对籽粒产量的贡献较大,其中以４Ｂｓ、５Ｂｓ,效应最强,而Ｄ组所有缺失的染色体臂及大部分Ａ组所缺失的染色体臂在缺磷下则对籽粒产量有较强的抑制效应,其中以５Ｄｓ、３ＤＬ及２ＡＬ,１Ａｓ的效应最强。     

鹿科动物血清LDH同工酶的比较分析

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苏北麦田恶性杂草麦家公的生态习性研究

苏北麦田恶性杂草麦家公的生态习性研究钱希（江苏省国营黄海农场,响水县,２２４６２４）ＡＳＴＵＤＹＯＮＥＣＯＬＯＧＩＣＡＬＨＡＢＩＴＳＯＦＢＡＤＷＥＥＤＳＬＩＴＨＯＳＰＥＲＭＵＭＡＲＶＥＮＳＥＩＮＷＨＥＡＴＦＩＥＬＤＳＯＦＴＨＥＮＯＲＴＨＪＩＡＮＧＳＵ...     

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木材组成分子的侧壁纹孔式赵鹏（北京师范大学生物学系,北京１００８７５）ＴＨＥＬＡＴＥＲＡＬ－ＷＡＬＬＰＩＴＴＩＮＧＩＮＥＬＥＭＥＮＴＳＯＦＷＯＯＤＺｈａｏＰｅｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＢｉｏｌｏｇｙ,ＢｅｉｊｉｎｇＮｏｒｍａｌＵｎｉｖｅｒｓｉｔｙ...     

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植物生长调节剂防止温州蜜柑异常高温落花落果的效应童昌华李三玉（浙江农业大学园艺系,杭州３１００２９）ＥＦＦＥＣＴＳＯＦＰＬＡＮＴＧＲＯＷＴＨＲＥＧＵＬＡＴＯＲＳＯＮＦＬＯＷＥＲＡＮＤＦＲＵＩＴＬＥＴＤＲＯＰＯＦＷＥＮＺＨＯＵＭＩＧＡＮＣＡＵＳＥＤＢ...     

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小鼠2—细胞期经电融合后的早期胚胎发育

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吉林梅花鹿体尺,体重聚类与主成分分析

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STUDIES ON THE PATTERN OF MEGASPOROGENESIS AND MICROTUBULAR CYTOSKELETON CHANGES IN CYMBIDIUM SINENSE

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Chromosomal locations of genes that control major RNA-degrading activities in common wheat (Triticum aestivum L.)

Seventeen RNA-degrading enzymes of common wheat, with apparent molecular masses from 42.2 kDa to 16.3 kDa, were observed by the RNA-SDS-PAGE assay. To determine their chromosome locations, all chromosome arms of common wheat except 4BS were assayed in their null condition by using a set of ditelosomic or nullitetrasomic lines of the cultivar Chinese Spring. Our results showed that only one chromosome location each was identified for the 22.8-kDa and the 21.2-kDa enzymes, as well as for the 21.6 kDa enzyme, and they are on chromosome arms 2AS and 2DS, respectively. Loci controlling the 20.1 kDa activity were on chromosome arms 2AL, 4BS, 4DS and 6BS. The locus or loci coding for the gene(s) of the 42.2-kDa, 40.9-kDa and 39.2-kDa enzymes were probably ocated on chromosome arm 5AS, and their expression, in agreement with most other RNA-degrading enzyme activities were stimulated when chromosome arm 5AL was missing, indicating a inhibiting locus on 5AL. Our data suggested that the 31.9-kDa, 30.6-kDa and 29.6-kDa enzymes were possibly products of a common precursor which might be coded by a gene(s) on chromosome arm 6BS, and that the processing is co-regulated by loci on chromosome arms 2BS, 3DS, 6AL, 6BL and 7BS. The remaining of the enzyme activities were consistently found in all of the lines tested, and thus are presumably encoded by multiple loci. The only other possibility is that, their loci may be on chromosome arm 4BS which we have not assayed in its null condition.Contribution from Agriculture Research Division, University of Nebraska. Journal Series No. 11271 Current address: Dept. Bio/Microbiology, South Dakota State University, Brookings, SD57007, USA     

Quantitative Trait Loci for Aluminum Resistance in Wheat Cultivar Chinese Spring

Aluminum (Al) toxicity is one of the major constrains for wheat production in many wheat growing areas worldwide. Further understanding of inheritance of Al resistance may facilitate improvement of Al resistance of wheat cultivars (Triticum aestivum L.). A set of ditelosomic lines derived from the moderately Al-resistant wheat cultivar Chinese Spring was assessed for Al resistance. The root growth of ditelosomic lines DT5AL, DT7AL, DT2DS and DT4DS was significantly lower than that of euploid Chinese Spring under Al stress, suggesting that Al-resistance genes might exist on the missing chromosome arms of 5AS, 7AS, 2DL and 4DL of Chinese Spring. A population of recombinant inbred lines (RILs) from the cross Annong 8455 × Chinese Spring-Sumai 3 7A substitution line was used to determine the effects of these chromosome arms on Al resistance. A genetic linkage map consisting of 381 amplified fragment length polymorphism (AFLP) markers and 168 simple sequence repeat (SSR) markers was constructed to determine the genetic effect of the quantitative trait loci (QTLs) for Al resistance in Chinese Spring. Three QTLs, Qalt.pser-4D, Qalt.pser-5A and Qalt.pser-2D, were identified that enhanced root growth under Al stress, suggesting that inheritance of Al resistance in Chinese Spring is polygenic. The QTL with the largest effect was flanked by the markers of Xcfd23 and Xwmc331 on chromosome 4DL and most probably is multi-allelic to the major QTL identified in Atlas 66. Two additional QTLs, Qalt.pser-5A and Qalt.pser-2D on chromosome 5AS and 2DL, respectively, were also detected with marginal significance in the population. Some SSR markers identified in this study would be useful for marker-assisted pyramiding of different QTLs for Al resistance in wheat cultivars.     

小麦旗叶早衰性状的QTL定位

为小麦旗叶早衰性状的精细定位和基因克隆奠定基础,该试验以普通小麦(Triticum aestivum L.)‘宁春4号’和‘宁春27号’杂交得到的128个F10代RIL群体为研究材料,利用307对多态性SSR标记对小麦旗叶早衰性状进行了QTL定位,并通过构建整合图谱的方法进行了标记加密。结果表明,共检测到1个控制旗叶早衰性状的加性QTL,位于2A染色体长臂的gwm526和gwm382标记区间内,可解释49.88%的表型变异。经遗传图谱整合后发现,gwm526和gwm382标记之间存在124个SNP标记。     

Genome-wide association mapping for resistance to leaf rust,stripe rust and tan spot in wheat reveals potential candidate genes

Key message

Genome-wide association mapping in conjunction with population sequencing map and Ensembl plants was used to identify markers/candidate genes linked to leaf rust, stripe rust and tan spot resistance in wheat.

Abstract

Leaf rust (LR), stripe rust (YR) and tan spot (TS) are some of the important foliar diseases in wheat (Triticum aestivum L.). To identify candidate resistance genes for these diseases in CIMMYT’s (International Maize and Wheat Improvement Center) International bread wheat screening nurseries, we used genome-wide association studies (GWAS) in conjunction with information from the population sequencing map and Ensembl plants. Wheat entries were genotyped using genotyping-by-sequencing and phenotyped in replicated trials. Using a mixed linear model, we observed that seedling resistance to LR was associated with 12 markers on chromosomes 1DS, 2AS, 2BL, 3B, 4AL, 6AS and 6AL, and seedling resistance to TS was associated with 14 markers on chromosomes 1AS, 2AL, 2BL, 3AS, 3AL, 3B, 6AS and 6AL. Seedling and adult plant resistance (APR) to YR were associated with several markers at the distal end of chromosome 2AS. In addition, YR APR was also associated with markers on chromosomes 2DL, 3B and 7DS. The potential candidate genes for these diseases included several resistance genes, receptor-like serine/threonine-protein kinases and defense-related enzymes. However, extensive LD in wheat that decays at about 5?×?10⁷ bps, poses a huge challenge for delineating candidate gene intervals and candidates should be further mapped, functionally characterized and validated. We also explored a segment on chromosome 2AS associated with multiple disease resistance and identified seventeen disease resistance linked genes. We conclude that identifying candidate genes linked to significant markers in GWAS is feasible in wheat, thus creating opportunities for accelerating molecular breeding.

     

Dissecting a wheat QTL for yield present in a range of environments: from the QTL to candidate genes

Previous studies with 95 bread wheat doubled haploid lines (DHLs) from the cross Chinese Spring (CS)xSQ1 trialled over 24 yearxtreatmentxlocations identified major yield quantitative trait loci (QTLs) in homoeologous locations on 7AL and 7BL, expressed mainly under stressed and non-stressed conditions, respectively. SQ1 and CS contributed alleles increasing yield on 7AL and 7BL, respectively. The yield component most strongly associated with these QTLs was grains per ear. Additional results which focus on the 7AL yield QTL are presented here. Trials monitoring agronomic, morphological, physiological, and anatomical traits revealed that the 7AL yield QTL was not associated with differences in flowering time or plant height, but with significant differences in biomass at maturity and anthesis, biomass per tiller, and biomass during tillering. In some trials, flag leaf chlorophyll content and leaf width at tillering were also associated with the QTL. Thus, it is likely that the yield gene(s) on 7AL affects plant productivity. Near-isogenic lines (NILs) for the 7AL yield QTL with CS or SQ1 alleles in an SQ1 background showed the SQ1 allele to be associated with >20% higher yield per ear, significantly higher flag leaf chlorophyll content, and wider flag leaves. Epidermal cell width and distance between leaf vascular bundles did not differ significantly between NILs, so the yield-associated gene may influence the number of cell files across the leaf through effects on cell division. Interestingly, comparative mapping with rice identified AINTEGUMENTA and G-protein subunit genes affecting lateral cell division at locations homologous to the wheat 7AL yield QTL.     

小麦新种质241千粒重的基因定位

以小麦新种质材料241为测定系,中国春单体系及双端体系作为测验系,对控制千粒重的基因进行了定位研究,结果表明,小麦新种质材料241的3A,2B,7B和6D染色体上具有控制千粒重的基因,其中3A,7B和6D染色体上的基因表现为强效, 2B染色体上的基因表现为弱效,通过双端体分析进一步将控制千粒重的基因定位到3AL,7BL和6DL上,其中6DL上可能具有控制241千粒重的新基因。     

A Novel STS Marker for Polyphenol Oxidase Activity in Bread Wheat

The enzyme activity of polyphenol oxidase (PPO) in grain has been related to undersirable brown discoloration of bread wheat (Triticum aestivum L.) based end-products, particularly for Asian noodles. Breeding wheat cultivars with low PPO activity is the best approach to reduce the undesirable darkening. Molecular markers could greatly improve selection efficiency in breeding programs. Based on the sequences of PPO genes (GenBank Accession Numbers AY596268, AY596269 and AY596270) conditioning PPO activity during kernel development, 28 pairs of primers were designed using the software ‘DNAMAN’. One of the markers from AY596268, designated as PPO18, can amplify a 685-bp and an 876-bp fragment in the cultivars with high and low PPO activity, respectively. The difference of 191-bp size was detected in the intron region of the PPO gene. The STS marker PPO18 was mapped to chromosome 2AL using a DH population derived from a cross Zhongyou 9507× CA9632, a set of nulli-tetrasomic lines and ditelosomic line 2AS of Chinese Spring. QTL analysis indicated that the PPO gene co-segregated with the STS marker PPO18 and is closely linked to Xgwm312 and Xgwm294 on chromosome 2AL, explaining 28–43% of phenotypic variance for PPO activity across three environments. A total of 233 Chinese wheat cultivars and advanced lines were used to validate the correlation between the polymorphic fragments of PPO18 and grain PPO activity. The results showed that PPO18 is a co-dominant, efficient and reliable molecular marker for PPO activity and can be used in wheat breeding programs targeted for noodle quality improvement.     

Physiological basis of reduced Al tolerance in ditelosomic lines of Chinese Spring wheat

Aluminum tolerance was assessed in the moderately Al-tolerant wheat (Triticum aestivum L.) cultivar Chinese Spring and a set of ditelosomic lines derived from Chinese Spring. Three ditelosomic lines lacking chromosome arms 4DL, 5AS and 7AS, respectively, exhibited decreased Al tolerance relative to the euploid parent Chinese Spring based on reduced root growth in Al-containing solutions. The physiological basis of the reduced Al tolerance was investigated. Measurements by inductively coupled argon plasma mass spectroscopy of root apical Al accumulation demonstrated that two of these three lines had a decreased ability to exclude Al from the root apex, the site of Al phytotoxicity. As Al-induced malate exudation has been suggested to be an important physiological mechanism of Al tolerance in wheat, this parameter was quantified and malate exudation was shown to be smaller in all three deletion lines compared with Chinese Spring. These results suggest that the decreased Al tolerance in at least two of the three ditelosomic lines is due to the loss of different genes independently influencing a single Al-tolerance mechanism, rather than to the loss of genes encoding alternative Al-tolerance mechanisms. Received: 3 July 2000 / Accepted: 9 August 2000     

Reassessment of the evolution of wheat chromosomes 4A, 5A,and 7B

Key message

Comparison of genome sequences of wild emmer wheat and Aegilops tauschii suggests a novel scenario of the evolution of rearranged wheat chromosomes 4A, 5A, and 7B.

Abstract

Past research suggested that wheat chromosome 4A was subjected to a reciprocal translocation T(4AL;5AL)1 that occurred in the diploid progenitor of the wheat A subgenome and to three major rearrangements that occurred in polyploid wheat: pericentric inversion Inv(4AS;4AL)1, paracentric inversion Inv(4AL;4AL)1, and reciprocal translocation T(4AL;7BS)1. Gene collinearity along the pseudomolecules of tetraploid wild emmer wheat (Triticum turgidum ssp. dicoccoides, subgenomes AABB) and diploid Aegilops tauschii (genomes DD) was employed to confirm these rearrangements and to analyze the breakpoints. The exchange of distal regions of chromosome arms 4AS and 4AL due to pericentric inversion Inv(4AS;4AL)1 was detected, and breakpoints were validated with an optical Bionano genome map. Both breakpoints contained satellite DNA. The breakpoints of reciprocal translocation T(4AL;7BS)1 were also found. However, the breakpoints that generated paracentric inversion Inv(4AL;4AL)1 appeared to be collocated with the 4AL breakpoints that had produced Inv(4AS;4AL)1 and T(4AL;7BS)1. Inv(4AS;4AL)1, Inv(4AL;4AL)1, and T(4AL;7BS)1 either originated sequentially, and Inv(4AL;4AL)1 was produced by recurrent chromosome breaks at the same breakpoints that generated Inv(4AS;4AL)1 and T(4AL;7BS)1, or Inv(4AS;4AL)1, Inv(4AL;4AL)1, and T(4AL;7BS)1 originated simultaneously. We prefer the latter hypothesis since it makes fewer assumptions about the sequence of events that produced these chromosome rearrangements.

     

Characterization of phytoene synthase 1 gene (<Emphasis Type="Italic">Psy1</Emphasis>) located on common wheat chromosome 7A and development of a functional marker

Phytoene synthase (Psy), a critical enzyme in the carotenoid biosynthetic pathway, demonstrated high association with the yellow pigment (YP) content in wheat grain. Characterization of Psy genes and the development of functional markers for them are of importance for marker-assisted selection in wheat breeding. In this study, the full-length genomic DNA sequence of a Psy gene (Psy-A1) located on chromosome 7A, was characterized by in silico cloning and experimental validation. The cloned Psy-A1 comprises six exons and five introns, 4,175 bp in total, and an ORF of 1,284 bp. A co-dominant marker, YP7A, was developed based on polymorphisms of two haplotypes of Psy-A1, yielding 194 and 231-bp fragments in cultivars with high and low YP content, respectively. The marker YP7A was mapped on chromosome 7AL using an RIL population from cross PH82-2/Neixing 188, and a set of Chinese Spring nullisomic–tetrasomic lines and ditelosomic line 7AS. Psy-A1, co-segregating with the STS marker YP7A, was linked to SSR marker Xwmc809 on chromosome 7AL with a genetic distance of 5.8 cM, and explained 20–28% of the phenotypic variance for YP content across three environments. A total of 217 Chinese wheat cultivars and advanced lines were used to validate the association between the polymorphic band pattern and grain YP content. The results showed that the functional marker YP7A was closely related to grain YP content and, therefore, could be used in wheat breeding programs targeting of YP content for various wheat-based products. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.