Genes for resistance to stripe rust on chromosome 2B and their application in wheat breeding

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is one of the most damaging diseases of wheat worldwide. Growing resistant cultivars is the most economic and environmental friendly way to control the disease. There are many resistance genes to stripe rust located on wheat chromosome 2B. Here, we propose a strategy to construct the recombinant wheat chromosome 2B with multiple resistances to stripe rust by making crosses between wheat lines or cultivars carrying Yr genes and using marker-assisted selection, based on the reported information about resistance spectrum, chromosomal location, and linked markers of the genes. Pyramiding the resistance genes on 2B would afford a valuable strategy to control the disease by cultivating varieties with durable resistance. The possibility, efficiency, and prospect of the suggested strategy are reviewed in the paper.     

与小麦赤霉病抗性紧密连锁的基于AFLP片段的STS标记开发(英文)

DNA序列标签位点(STS)是一个操作简便和花费低的分子标记体系,将与某一性状密切连锁的AFLP(扩增片段长度多态性)片段转换成STS标记可直接用于分子育种工作中.本研究利用Ning 7840和Clark的重组自交系及AFLP技术,探测到一个与小麦赤霉病抗性紧密连锁的坐落在染色体3BS的主效数量特性位点(QTL),发现5个Pstl-AFLP片段与该QTL显著关联;其中2个片段与赤霉病抗性达到50%左右的表型变异解析度,一个为35个碱基的相引相片段,另一个为222个碱基的相斥相片段.222个碱基的DNA片段被克隆和测序,发现11个克隆中含有5种不同的DNA序列,其中一种序列在5个克隆中完全一致,该序列被用来作为设计STS标记的DNA模板.经多次实验,开发出了一个共显性STS标记.该STS标记与原222个碱基的AFLP片段谱带(banding pattern)完全一致,具有鉴别小麦育种材料赤霉病抗病强弱和加速抗病育种进程的潜力.     

Molecular mapping of a novel yellow rust resistance gene of wheat using microsatellite markers

Identification and genetic analysis of yellow rust resistance have suggested that wheat line R55 carries single dominant gene conferring yellow rust resistance. The bulked segregant analysis (BSA) for an F₂ population using microsatellite marker technique has indicated that the yellow rust resistance gene is located on the short arm of chromosome 1B, tightly linked to the microsatellite markers WMS11-193 bp and WMS18-184 bp, the linkage distance between the markers and the gene is 1.9 cM. This gene has been formally namedYr26. It is inferred from the pedigree, resistance and gene locus analysis that theYr26 has been transferred fromTriticum turgidum L. and is different from the other known yellow rust resistance genes.     

2002年大竹县小麦条锈病流行原因及综合治理

经分析2002年大竹县小麦条锈病突发流行的原因,主要是条中30、31和32上升为优势种群,导致绵阳系列的小麦品种持久抗病性丧失,以及2002年春季的持续低温天气和防治不力等因素.提出了大竹县今后小麦条锈病综合治理的措施.     

A combination of leaf rust resistance gene Lr34 and lesion mimic gene lm significantly enhances adult plant resistance to Puccinia triticina in wheat

Leaf rust caused by Puccinia triticina is an economically-important disease in wheat worldwide.A combination of different types of resistance genes may significantly enhance rust resistance under rust-favorable conditions.To investigate the interactions between the rust resistance gene Lr34 and the lesion mimic gene lm on 1BL in Ning 7840,a segregating F8-10 population of 180 recombinant inbred lines was developed from Ning 7840/Chokwang and evaluated for both lesion mimic expression and leaf rust response at the adult plant stage in a greenhouse.A major quantitative trait locus(QTL),derived from Sumai 3,was co-localized with Lr34 on chromosome 7D and explained 41.5% of phenotypic variations for rust severity and 22.1% for leaf tip necrosis(LTN).The presence of Lr34 was confirmed by Lr34-specific markers cssfr1 and cssfr2 in Ning 7840 and Sumai 3.Unlike Lr34,lm conditioned a spontaneous lesion mimic phenotype and had a significant effect on reducing uredinial size,and a smaller effect on severity.Additive effects were observed between lm and Lr34 for severity and LTN,and an epistatic effect was observed for infection type.Single marker analysis also identified several other QTL with minor effects on severity,infection type,or LTN.     

Molecular characterization of RAPD and SCAR marker linked to the frog-eye leaf spot resistance gene in soybean

Two fragments SCS3₆₂₀ and SCS3₅₈₀ of the co-dominant marker OPS03_{620 & 580} that were linked to the resistance gene of soybean frog-eye leaf spot have been completely sequenced. A significant insertion of 30 bp is the main reason of the polymorphism between the two fragments. The results of Southern hybridization indicate that SCS3₆₂₀ derives from a single-or low-copy sequence and can be used as an RFLP probe. A co-dominant SCAR marker SCS3_{620 & 580} has been developed based on the sequences. The segregation of SCS3_{620 & 580} is similar to that of RAPD marker OPS03_{620 & 580}-Significant polymorphism has been shown between resistant and susceptible genotypes when 62 soybean genotypes were surveyed for the SCAR marker. Therefore, the marker can be used in the resistance breeding of soybean frog-eye leaf spot by marker-assisted selection.     

利用分子标记分析22种水稻10个抗稻瘟病基因的基因型

为了明确已克隆的部分稻瘟病抗性基因在上海市主栽水稻品种以及新培育的水稻品系中的分布,选取22份水稻为材料,利用分子标记检测技术,对10个已被克隆的抗稻瘟病基因进行基因型鉴定及分析.结果表明,22种水稻均含Pi36、Pi37、Pi-d2、Pib抗性基因,而Pi-kh、Pi9、Pi2、Pi-ta、Pikm抗性基因在22种水稻中分布各有不同,所有被测水稻中均不携带Pi25抗性基因.     

小麦抗叶锈病相关蛋白的初步分析

以小麦抗叶锈病近等基因系TcLr10和感病亲本Thatcher为植物材料.在未接种小麦叶锈菌之前提取二者叶片的蛋白质,并在接种小麦叶锈菌之后24h,48h,72h分别提取TcLr10与Thatcher叶片的蛋白质组,将提取的全部样品进行双向电泳.对所得蛋白质双向电泳图谱进行分析,结果表明,在未接种叶锈菌时TcLr10与Thatcher存在三个点的差异,其中有两个蛋白质点在TcLr10表达量明显高于感病亲本Thatcher,另一个点在TcLr10中有表达而在Thatcher中未发现;接种叶锈菌后TcLr10与Thatcher中均诱导产生一蛋白质点,但该点在Lr10中诱导产生的速度和量均明显高于感病亲本Thatcher.     

黄淮麦区26个小麦品种抗叶锈病初步鉴定

根据生物问遗传学原理，分析了26个黄淮麦区小麦品种对15个叶锈菌系的抗性状况，抗性最好的品种是徐州174，毒力频率为33．3％，毒力频率低于60％的仅有百农64、徐州8697等7个品种，2号和3号叶锈菌系的抗源品种最多，有22个，而14号和15号叶锈菌系无一抗源品种。总之，供试品种的抗叶锈性较差。     

Inheritance of resistance to race 7 of Cercospora sojina in soybeans and RAPD tagging of the resistance gene

Frog-eye leaf spot of soybean caused by Cercospora sojina Hara is a kind of worldwide disease. Resistance to race 7 of C. sojina was found to be due to a single dominant gene through analyzing resistant behavior of the cross NEAU91212 (susceptible to race 7) × NEAU9674 (resistant to all races). 3 RAPD markers linked to the resistant gene Rcsc 7 were identified using the BSA method. 2 fragments of OPS03620 and OPS03580 amplified with primer OPS03 co-dominantly segregated in the F2 individuals. The genetic distance between OPS03620 and the resistant gene is 8.7 cM. According to the co-dominant marker, the accuracy of predicting the homozygous and heterozygous resistant F2 individuals were 100% and 97.6% , respectively.     

Chromosomal location of yellow rust resistance gene(s) inTriticum aestivum-Lophopyrum elongatum substitution lines

A set ofT. aestivum-L. elongatum substitution lines were studied on yellow rust resistance at seedling stage, inheritance of the resistance and esterase-5 (Est-5) analysis. The results demonstrated thatL. elongatum carried a new yellow rust resistance gene(s), which was dominant and located on chromosome 3E ofL. elongatum. The biochemical locus encoding Est-5 was also located on chromosome 3E, and was tentatively named Est-E5, which was co-segregant with theYr gene(s) in wheat background. In addition, the transmission frequencies of chromosome 3E in 3A/3E and 3D/3E hybrids selfing were significantly higher than that of chromosome 3E in 3B/3E hybrid, which was probably due to the difference on genetic relationships among A, B, D and E genomes.     

Generation of transgenic wheat resistant to wheat yellow mosaic virus and identification of gene silence induced by virus infection

The plasmid containing the promoter Act1, the coat protein (cp) gene of wheat yellow mosaic virus (WYMV) and the selectable bar gene, was delivered via particle bombardment, directly into immature embryos of a wheat cultivars. PCR and PCR-RFLP were employed to screen the existence of the cp gene in T0 and T1 generations. Seeds from the positive T1 plants were sowed in fields heavily contaminated with WYMV to detect their resistance. In field trial of virus infection, one of the transgenic wheat lines, P8-T2, exhibited highly disease-resistance. Western blot and RT-PCR analysis showed that the expression level of cp gene in the resistant transgenic line was reduced greatly compared to those susceptible to WYMV infection. This provided evidence to presume that the resistance obtained by the transgenic wheat line was stimulated by the mechanism of the virus induced gene silencing.     

Fine mapping of the <Emphasis Type="Italic">Ht2 (Helminthosporium turcicum</Emphasis> resistance 2) gene in maize

Fine mapping of Helminthosporium turcicum resistance gene Ht2 is extremely valuable for map-based cloning of the Ht2 gene,gaining a better knowledge of the distribution of resistance genes in maize genome and marker-assisted selection in maize breeding.An F2 mapping population was developed from a cross between a resistant inbred line 77Ht2 and a susceptible inbred line Huobai.With the aid of RFLP marker analyses,the Ht2 gene was mapped between the RFLP markers UMC89 and BNL2.369on chromosome 8,with a genetic distance of 0.9cM to BNL2.369.There was a linkage between SSR markers UMC1202,BNLG1152,UMC1149 and the Ht2 gene by SSR assay,Among the SSR markers,the genetic distance between UMC1149 and the Ht2 gene was 7.2cM,By bulked segregant analysis 7 RAPD-amplified products which were probably linked to the Ht2 gene were selected after screening 450 RAPD primers and converted the single-copy ones into SCAR markers.Linkage analysis showed that the genetic distance between the SCAR marker SD-06633 and the Ht2 gene was 0.4cM.From these results,a part of linkage map around the Ht2 gene was constructed.     

小麦赤霉病:从表型鉴定到抗性改良

 赤霉病已成为影响中国小麦安全生产的最重要病害之一。表型鉴定体系对赤霉病抗性准确评价和抗性改良至关重要。本文分析了赤霉病的危害和改良的迫切性、中国抗赤育种的现状、QTL的定位和利用进展等,讨论了赤霉病接种鉴定和评价方法、赤霉病抗源利用和抗赤分子标记辅助育种策略,提出赤霉病改良的思路和建议。     

甜菜抗根腐病基因ISSR分子标记的初步研究

以感病×抗病的甜菜种间杂交组合KWS9419×ZD204的F1代17个单株及ZD自交一代16个单株为试材,采用BSA法和ISSR技术,通过对155个随机引物的筛选,获得了一个与甜菜抗根腐病基因连锁的ISSR标记OPP0760,可以用作抗根腐病基因的分子辅助选择的依据。     

小麦抗穗发芽分子标记开发及育种应用

 综述了小麦收获前穗发芽的影响因素和应对策略、穗发芽抗性的QTL/基因研究进展、开发的分子标记及其育种应用,总结了利用分子标记开展抗穗发芽分子标记辅助育种取得的成效。结果表明,温度和降雨是影响小麦穗发芽发生的主要环境因素,培育抗穗发芽品种是解决该问题的有效途径。     

Gene expression profiling related to powdery mildew resistance in wheat with the method of suppression subtractive hybridization

“Bainong 3217 × Mardler” BC₅F₄ wheat line at the initial stage of inoculation with powdery mildew pathogen (Erysiphe graminis DC) was used to construct a suppression subtractive hybridization (SSH) cDNA library. Totally 760 ESTs were obtained through sequencing. Similarity analysis of ESTs based on BLASTn and BLASTx with the sequences in GenBank, in combination with macroarray differential screening, revealed that 199 ESTs of 65 kinds were known to be functionally disease resistance related. Based on the gene expression profiling in the present study, it is postulated that salicylic acid (SA) and MAP-related signal transduction pathways were involved in powdery mildew resistance in wheat. System acquired resistance genes were predominant in terms of kinds and quantity. With the initiation of cell defense reaction, the genes conferring anti-oxidation substances were largely expressed and thus cell protection mechanism was activated. Much evidence revealed that phenylpropanes metabolic pathway was involved in phytoalexin synthesis in wheat powdery mildew resistance. Genes conferring some enzymes of structural modification of cell walls and proteinase inhibitors inhibiting pathogen growth were also detected. The genes controlling a few proteinases (mainly cysteine proteinase) had a considerable redundancy of expression.