Sugar beets homozygous for resistance to beet cyst nematode (Heterodera schachtii Schm.), developed from monosomic additions of Beta procumbens to B. vulgaris

Summary Monosomic additions of Beta vulgaris x B. procumbens with resistance to beet cyst nematode (Heterodera schachtii Schm.) were used for the production of resistant diploids through incorporation of the B. procumbens chromosome fragment bearing the resistance gene(s) into one of the sugar beet chromosomes. The heterozygotes obtained accordingly were selfed for producing homozygotes. These homozygotes differed morphologically from commercial sugar beet varieties, but produced reasonable amounts of pollen. Female transmission of resistance was 100%, whereas male transmission, apart from some exceptions, was more than 90%. The number of hypersensitivity reactions to penetrated larvae was related to the degree of susceptibility. Larval development was severely retarded in the resistant plants, preventing most of them to produce cysts. If cysts were formed, their content was considerably less as compared to those in the susceptible plants.     

Variation in resistance level of potato genotypes and virulence level of potato cyst nematode populations

Summary In two experiments, using different testing methods, the number of newly formed cysts was determined on nine potato genotypes with resistance from various sources. Ten potato cyst nematode (PCN) populations were used in these experiments. Rank correlation between numbers of cysts over potato genotype-PCN population combinations for both experiments was high (r_s = 0.90). Dendrograms for PCN populations and potato genotypes were constructed, based on a simultaneous hierarchical clustering procedure for potato genotype-PCN population interaction terms. Several virulence groups could be identified within Globodera rostochiensis as well as within G. pallida. Host genotypes, derived from the same sources of resistance, were clustered in different resistance groups.     

Utilisation of the Commonwealth Potato Collection in potato breeding

Summary The use of the Commonwealth Potato Collection in potato breeding is set in the context of the evolution of the crop and the need to widen its genetic base by introgression and base broadening. The introduction of the potato to Europe and its subsequent worldwide spread is described. An introduction is given to the world's major potato genebanks, and the current status of the Commonwealth Potato Collection is presented. Material from this genebank has been extensively used to improve the potato. Work on wild species as sources of resistance to late blight started before the genebank was initiated, and since then CPC accessions have provided major R-genes and durable resistance to breeders, greatly benefiting growers and consumers of the potato. Progress identifying and exploiting resistance to viruses and potato cyst nematodes is described. New sources of further pest and disease resistance genes are present in the germplasm in the collection, offering the potential to overcome current and future pests and diseases. Use of the cultivated species in the collection for base broadening is described and discussed. The collection also harbours a wide range of quality traits of use to breeders, including variation for cooking and crisping, anthocyanins, carotenoids, ascorbate metabolism and others. As breeding and genetics become more precise, and as both the knowledge of biochemical pathways and means of analysing chemical composition advance, new ways of accessing this variation become possible. Possible strategies to achieve these goals are discussed.     

大豆胞囊线虫病抗源筛选及应用研究进展

大豆胞囊线虫病是大豆的主要病害，近年来许多学者在抗源筛选、抗性遗传、抗性生理机制 及抗性分子标记等方面做了大量的研究工作，并取得了较大的进展。本文仅就抗源的筛选及其应 用作以简要概述。     

接种大豆孢囊线虫4号生理小种诱导GmHs1pro-1基因的表达分析

大豆孢囊线虫(Heterodera glycines,Soybean cyst nematode,SCN)是严重危害世界大豆生产的害虫,大豆对孢囊线虫的抗性由多个基因控制,发掘和利用抗病基因对于SCN抗病品种的有效选育至关重要。本研究以大豆(Glycine max)感病品种中黄13和抗病品系中品03-5373为研究材料,对包含线虫抗病基因相关结构域Hs1pro-1_N和Hs1pro-1_C的候选基因GmHs1pro-1的表达特征进行实时荧光定量PCR分析,以期明确该基因与SCN抗性之间的关系。研究发现接种SCN4号生理小种(SCN4)后1d该基因的相对表达量出现明显的上调,比对照样品高13.4倍,其后的各时间点其表达量仍然保持持续上调的趋势,在接种6d后其上调趋势有所减弱。方差分析表明,接种与未接种相对表达量之间的差异均达到显著(P<0.05)和极显著(P<0.01)水平,说明SCN4侵染条件下,GmHs1pro1基因被诱导表达,该基因对SCN4具有一定的抗性作用。     

真菌寄生大豆孢囊线虫的初步研究

从山东省高密县、胶州市及江苏省沛县5个采集点的大豆孢囊线虫中,共分离出110个真菌菌株。优势真菌是镰刀菌,其它为柱孢菌、弯孢霉菌和一种子囊菌。真菌的出现机率平均为44％。在洋菜平板上测定,菌株对该线虫卵,均有不同程度的重寄生能力,其中茄病镰刀菌高达49％。该菌和柱孢菌的分生孢子萌发后可直接穿透卵壁,卵的内含物完全被其粗短的菌丝体取代。     

湖北襄阳禾谷孢囊线虫(Heterodera avenae)生活世代及发生动态研究

调查了湖北省禾谷孢囊线虫(Heterodera avenae)病的分布。在襄阳市重病田采样观察了禾谷孢囊线虫不同龄期的形态,研究了不同龄期线虫的发生动态。结果表明,禾谷孢囊线虫在襄阳、天门、潜江、钟祥、汉川都有发生,以襄阳最多,平均每100 mL土样含有效孢囊12.5个。在小麦播种后20 d就有2龄幼虫侵入根部,播种后143 d根内幼虫数量达到顶峰。入侵的幼虫在根内定居取食为害,在播种后158 d发育成白雌虫而露出根外,在播种后174 d白雌虫数量达最高峰。