Reaction to powdery mildew and stripe rust in related species and landraces of wheat

Field and controlled environmental tests indicated that the 49 accessions of closely related species and 12 landraces of wheat (Triticum aestivum L. em. Thell.) from the National Gene Bank of China showed different reactions to powdery mildew (Blumeria graminis (DC.) E. O. Speer. f. sp. tritici) and stripe rust (Puccinia striiformis Westend f. sp. tritici) at adult and seedling stages. Unknown Pm genes or alleles were postulated with Triticum baeoticum Boiss. accessions BO 3 and Triticum monococcum L. MO 4 and MO 5 when inoculated with 21 powdery mildew isolates at seedling stage. Fourteen accessions of T. baeoticum, T. monococcum, Triticum durum, and wheat landraces were inoculated with 30 stripe rust isolates at seedling stage. Unknown Yr genes or alleles were postulated with T. baeoticum Boiss. accession BO 5, as well as wheat landraces Xiaobaimai, Laomangmai, and Shaanxibai. Heterogeniety in reaction to powdery mildew isolates and stripe rust races were observed in related species and landraces of wheat.     

Comparison of protein quality and mineral element concentrations in grain of spelt (Triticum spelta L.) and common wheat (Triticum aestivum L.)

The cultivation of Triticum spelta (spelt) has no tradition in Hungary. In recent years the interest towards this old species renewed in many countries. This high‐nutritional cereal, which has a high ash and fibre content, can be used in many health‐oriented grain‐based food products. Therefore, field experiments have been conducted for some years to test the performance of this species under home growing conditions. Here we report the results of analyses for some important quality parameters of grain samples from the 1996/97 season in comparison with those of older and new home‐grown bread wheat cultivars. Three common wheat cultivars and one advanced spelt line were grown on small plots fertilised with an NPK dose necessary to reach the highest yield and quality. Spikes were sampled weekly from the time of 70–77% grain moisture to full ripening. The grains were analysed for ash, N, P and K content and amino acid composition. Concentrations of 16 other macro + micro elements and in the ripe grains, baking quality parameters were also assessed. The grain development of spelt showed a remarkable time‐lag compared to that of the common wheat cultivars. However, the highest thousand‐grain‐masses, ash, N, and P concentrations were measured in this cultivar after milk ripening. The grains of spelt contained the macro‐nutrient Mg and four micro‐nutrients (Zn, Mn, Fe, Cu) in higher concentrations compared to those of the common wheat varieties. The total and essential amino acid concentrations measured in the ripe grains of spelt were also remarkably higher.

Although its wet gluten content (47.5%) was considerably higher than that of the bread wheat cultivars, its breadmaking quality was poor.     

Transfer of leaf rust and stripe rust resistance from <Emphasis Type="Italic">Aegilops umbellulata</Emphasis> Zhuk. to bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

Aegilops umbellulata acc. 3732, an excellent source of resistance to major wheat diseases, was used for transferring leaf rust and stripe rust resistance to cultivated wheat. An amphiploid between Ae. umbellulata acc. 3732 and Triticum durum cv. WH890 was crossed with cv. Chinese Spring Ph ^I to induce homoeologous pairing between Ae. umbellulata and wheat chromosomes. The F₁ was crossed to the susceptible Triticum aestivum cv. ‘WL711’ and leaf rust and stripe rust resistant plants were selected among the backcross progenies. Homozygous lines were selected and screened against six Puccinia triticina and four Puccinia striiformis f. sp. tritici pathotypes at the seedling stage and a mixture of prevalent pathotypes of both rust pathogens at the adult plant stage. Genomic in situ hybridization in some of the selected introgression lines detected two lines with complete Ae. umbellulata chromosomes. Depending on the rust reactions and allelism tests, the introgression lines could be classified into two groups, comprising of lines with seedling leaf rust resistance gene Lr9 and with new seedling leaf rust and stripe rust resistance genes. Inheritance studies detected an additional adult plant leaf rust resistance gene in one of the introgression lines. A minimum of three putatively new genes—two for leaf rust resistance (LrU1 and LrU2) and one for stripe rust resistance (YrU1) have been introgressed into wheat from Ae. umbellulata. Two lines with no apparent linkage drag have been identified. These lines could serve as sources of resistance to leaf rust and stripe rust in breeding programs.     

小麦黄绿近等基因系主要生理特性及叶绿体形态结构的比较

探索小麦(Triticum aestivum)叶绿素合成及叶绿体形成发育的遗传和生理机制对小麦高光效育种具有重要意义.为研究叶色变异形成的生理机制及其对叶绿体形成发育的影响,本研究以新创制的3个黄绿小麦近等基因系(near-isogenic lines,NILs)(黄化系1-20YY、黄绿系1-20YG和绿色系1-20GG)为材料,研究不同发育时期的叶片可溶性物质含量和抗氧化酶系统活力等性状,并对其叶绿体形态结构进行了比较分析.结果表明,叶色黄化对叶片可溶性糖含量和可溶性蛋白质含量的影响远大于其对游离脯氨酸含量的影响,除苗期黄化系1-20YY的可溶性糖含量和可溶性蛋白质含量显著低于黄绿系1-20YG和绿色系1-20GG(P＜0.05),各发育期黄绿系1-20YG的可溶性糖含量和可溶性蛋白质含量与绿色系1-20GG的差异不显著.同时,叶色黄化对叶片抗氧化酶系统的活性有一定的影响,其中对过氧化物酶(peroxidase,POD)活性的影响大于其对超氧化物歧化酶(superoxide dismutase,SOD)和过氧化氢酶(hydrogen peroxidase,CAT)活性的影响.从3个NILs的叶绿体形态结构比较分析结果可以看出,黄化系1-20YY叶绿体多呈不规则状且分布趋向叶肉细胞中央,其基质类囊体和基粒类囊体不发达且联结不紧密,与绿色系1-20GG叶绿体形态结构差异明显;而黄绿系1-20YG叶绿体形态与绿色系1-20GG有差异,多呈近球形,但其超微结构与1-20GG系基本一致,基质类囊体和基粒类囊体较发达且联结较为紧密.研究结果为进一步探讨叶色黄化的生物学机制提供了基础资料.     

小麦T型细胞质雄性不育恢复基因Rf1和f4的SSR标记分析

为进一步探讨小麦(Triticum aestivum L.)T型细胞质雄性不育(T-CMS)育性恢复的遗传机理,并为利用T型不育系选育强优势杂交小麦分子辅助育种提供理论与技术支撑,本研究以小麦ms(S)矮抗58/R113的F2代分离群体中的极端可育株和极端不育株分别建立恢复池和不育池,采用分布于小麦第一染色体群(染色体1A、1B和1D)及第六染色体群(染色体6A、6B和6D)上的196对SSR引物进行扩增筛选.结果表明,(1)位于1AS染色体上的3个SSR标记和位于6BS染色体上的4个SSR标记均在亲本和基因池间扩增出了稳定的多态性差异条带;(2)定位群体验证结果表明,恢复基因Rf1与1AS染色体上Xgwm136、Xgpw7062和Xgdm33标记的遗传距离分别为4.8、9.6和13.7 cM,3个标记与Rf1之间的顺序依次为Xgdm33、Xgwm136、f1、Xgpw7062; (3)恢复基因Rf4与6BS染色体上的Xgpw1079、Xgwm193、Xgpw7011和Xgwm508标记的遗传距离分别为3.4、6.8、13.7和21.5 cM,4个标记与Rf4之间的顺序依次为Xgpw 011、Xgpw1079、Rf4、Xgwm19和Xgwm508.研究还表明,T-CMS恢复系R113的育性是由Rf1和f4两对主效恢复基因和多对微效基因共同控制的,筛选的上述7个SSR标记可直接用于T型或者类似T型,如S型杂交小麦分子标记辅助育种,可有效提高对应恢复系的选择效率.     

Chromosomal distribution and genetic expression of Lophopyrum elongatum (Host) A. Löve genes for adult plant resistance to stripe rust in wheat background

A set of wheat cv. Chinese Spring (CS)-Lophopyrum elongatum addition and substitution lines has been analyzed for its potential to offer new sources of stripe rust resistance for wheat. The adult plants of these lines, together with CS-L. elongatum amphiploid and CS, were inoculated by new physiological races CYR-30 and CYR-31 of stripe rust in China. The resistance investigation indicated that chromosome 7E1 of L. elongatum was responsible for the adult resistance in CS background. Moreover, the expression of the adults plant resistance derived from chromosome 7E1 in wheat background was dependent on the wheat genotype. In addition, the different rust resistance and glutenin composition were observed in 2 CS-L. elongatum amphiploids, indicating the genetic diversity existed in different origins of L. elongatum.     

Sources of resistance in primary synthetic hexaploid wheat (Triticum aestivum L.) to insect pests: Hessian fly, Russian wheat aphid and Sunn pest in the fertile crescent

Hessian fly, Mayetiola destructor (Say), Russian wheat aphid (RWA), Diuraphis noxia (Kurdjumov), and Sunn pest, Eurygaster integriceps (Puton), are among the most important insect pests of wheat in North Africa, West and Central Asia. Host plant resistance is the most economical, environmentally friendly and practical means of controlling insect pests. Through field and greenhouse screening, several sources of resistance to Hessian fly, RWA and Sunn pest have been identified in wheat and its wild relatives. To further broaden the genetic base of resistance to these pests, 914 fixed lines of synthetic hexaploid wheat (SHW) commonly designated as primary synthetic wheat were evaluated for resistance to Hessian fly, RWA and Sunn pest. The initial screenings for RWA and Sunn pest were carried out in the field at Tel Hadya, Aleppo, Syria, and for Hessian fly in the greenhouse at Tel Hadya during the 2009 and 2010 seasons. Promising accessions from the initial screening for Hessian fly, RWA and Sunn pest were evaluated for confirmation in replicated trials in the greenhouse and field. Fifteen SHWs showed high levels of resistance to Hessian fly and four showed moderate resistance. A wheat line derived from the cross (Triticum turgidum/T. dicoccoides) also showed a high level of resistance to Hessian fly. The level of resistance to RWA in SHW was considerably lower; only one SHW and one durum wheat ‘Altar 84’ exhibited a high level of resistance, while four SHW were moderately resistant. There were 21 SHW genotypes and one durum wheat ‘Langdon’ found resistant to Sunn pest feeding at the vegetative stage. Crosses between these potentially novel resistance sources and elite bread wheat were initiated. Genetic and genomic studies using these accessions are ongoing to identify and characterize the resistance genes and reveal potentially new resistance genes, which will be useful in breeding programs to develop wheat germplasm with multiple resistances to these pests.