The Aegilops ventricosa segment on chromosome 2AS of the wheat cultivar 'VPM1' carries the cereal cyst nematode resistance gene Cre5

Previous studies showed that the intermediate level of resistance in bread wheat line ‘VPM1’ to pathotype Ha12 of the cereal cyst nematode could be conferred by an Aegilops ventricosa‐derived gene, CreX, in chromosome arm 2AS, which also carries the rust resistance genes Yrl7, Lr37 and Sr38. Near isogenic lines (NILs) differing for the presence and absence of the Ae. ventricosa‐derived linked genes Yrl7/Lr37/Sr38 were tested with cereal cyst nematode. Lines carrying Yr17 produced significantly fewer nematode cysts than the controls. An infested soil experiment produced better differentiation among resistant and susceptible genotypes. Susceptibility of ‘Trident’ indicated that linkage between CreX and Yr17 is incomplete. Microsatellite markers did not differentiate between ‘Trident’ and CreX‐carrying genotypes. However, Xgwm636 (104) was associated with the presence of Yr17 in all six genetic backgrounds. Since none of the reported cereal cyst nematode resistance genes is located in chromosome 2AS, CreX was designated as Cre5.     

Investigations on resistance of oats to Heterodera avenae: Location of resistance genes

Summary By using 15 available mono/nullisomic lines of Sun II back ground, the Heterodera avenae resistance gene in Nelson (from Avena sativa CI 3444) and Panema (from A. sterilis I. 376) were located on monosome XV. Genes with smaller effects were located on monosomes VIII and X. The absence of these genes derived from Sun II would increase cyst production on plants lacking major resistance genes.     

Chromosome localisation of genes for resistance to Heterodera schachtii, Cercospora beticola and Polymyxa betae using sets of Beta procumbens and B. patellaris derived monosomic additions in B. vulgaris

Beet cyst nematodes (BCN, Heterodera schachtii), Cercospora beticola, and rhizomania, caused by the beet necrotic yellow vein virus (BNYVV) and vectored by the soil-borne fungus Polymyxa betae, are the most serious diseases of sugar beet ( Beta vulgaris subsp. vulgaris). The wild Beta species of section Procumbentes are known to be completely resistant to H. schachtii, C. beticola and P. betae. Alien monosomic additions (2n=19), plants of cultivated beet (2n=18) carrying different individual chromosomes of B. procumbens (2n=18) or B. patellaris (2n=36), were tested in greenhouse experiments for resistance to these pathogens. Gene(s) conferring full resistance to the beet cyst nematode in B. patellaris are located on chromosome 1.1, and the other tested chromosomes of B. patellaris are not involved in the expression of resistance. Artificial inoculation under greenhouse conditions, with in vitro produced inoculum of C. beticola and spot-percentage rating of the disease intensity, showed that the high level of resistance that was observed in the wild species B. procumbens and B. patellaris was not found in any of the monosomic additions tested. It was suggested that genes on various chromosomes of the wild species are needed to express full resistance, and that the chromosomes of group 7 of B. patellaris and chromosome 7 of B. procumbens have the largest effect. The greenhouse tests for resistance to P. betae in B. patellaris derived monosomic additions showed that the addition families of group 4.1 have a strong partial resistance, while the addition families of group 8.1 appeared to be completely resistant to the pathogen. Resistance to P. betae in the two wild species as well as in the two resistant addition types did not exclude infection with BNYVV, but resulted in a considerable reduction of the virus concentration. It was concluded that resistance to the vector would complement virus resistance, and may provide a more effective and durable control of rhizomania. This revised version was published online in July 2006 with corrections to the Cover Date.     

The development of Raparadish (x Brassicoraphanus, 2n=38), a new crop in agriculture

Summary Raparadish, x Brassicoraphanus, the amphidiploid hybrid between Brassica rapa (syn. B.campestris) and Raphanus sativus (fodder radish) was made by Dolstra (1982). Primary hybrid plants grew vigorously, suggesting that the amphidiploid AARR might be useful as a fodder crop. Three populations of this new material were studied, with special attention to improvement of fertility and resistance to beet cyst nematode (Heterodera schachtii), whilst preserving genetic variability. For lack of progress one of the populations was abandoned after the fourth generation. The other two populations were observed through nine or ten generations. Apart from the last two generations mass selection for seed set was carried out on the basis of single plants. This led to a considerable increase in average seed production, without losing a wide variation for this trait. Thus more progress is being expected. Five cycles of mass selection for resistance to beet cyst nematodes led to a considerable increase of the level of resistance of both populations. The prospects of this new agricultural crop are discussed.     

Nematode Resistance and Meiotic Abnormality in Diploid Sugar Beet Selected from Interspecific Beta vulgaris×B. procumbens Hybrids*

Two nematode-resistant trisomic lines which were derived from interspecific Beta, vulgaris × B. procumbens hybrids were intercrossed or backcrossed with susceptible diploid sugar beer and their progenies were screened for nematode resistance. The transmission rate of resistance varied from 1.5 % to 47.6 % with an average of 20.4 % in the progenies of individual insomics derived from the two trisomic lines. Eleven resistant diploads were selected with a frequency of 0.2 %. These resistant diploids were classified into two groups, i.e., one group showed relatively high transmission rates of resistance with an average of 25.4 % and the other extremely low with an average of 1.2 % in their backcrossed and s el fed progenies., Meiotic chromosome behavior in a resistant diploid group with high transmission rates was considerably normal as compared to that in a resistant diploid group with low transmission rates. Chromatid bridges and acertric fragments were detected in 93 % of resistant diploids and in 46 % of susceptible diploids. Two different sized fragments occurred in resistant diploids, while only a smaller fragment was present in susceptible diploids. A frequency of sporocytes with bridges-fragments was 17.4% at anaphase I and 13.9 % at anaphase II in resistant diploids, while in susceptible diploids a frequency was 2.9 % and 5.3 % at the respective stages. These results suggest that at least two paracentric inversions are present in resistant diploids, one of which is linked to nernatode resistance and may be responsible for the low transmission rate of resistance.     

大豆孢囊线虫4号生理小种侵染大豆根系诱导表达的cDNA分析

大豆孢囊线虫(Heterodera glycines Ichinohe；Soybean Cyst Nematode，SCN)是一种土传的专性内寄生线虫。SCN的二龄幼虫侵入到大豆幼嫩的根组织中，导致大豆根内的细胞变形并与之形成“合胞体”。合胞体在形态上和生理上的变化是SCN直接诱导大豆基因表达的结果。本研究以高抗SCN的灰布支黑豆为材料，用大豆孢囊线虫二龄幼虫直接接种大豆的根系，应用DDRT—PCR技术及RDB(Reversedot—blotting)杂交鉴定，获得6个阳性cDNA克隆，分别是SCN侵染后5天的A32克隆(GenBank登录号为B1173978)；侵染后10天的B12克隆(GenBank登录号为B1173979)、B71克隆(GenBank登录号为B1173980)；侵染后15天的Cll克隆(GenBank登录号为B1173981)、CPl2(GenBank登录号为B1173982)克隆和CP32克隆(GenBank登录号为B1173983)。序列的同源比较表明，6个cDNA均与Shoemaker构建的大豆基因表达库中的cDNA序列有非常高的同源性，证明这些cDNA是大豆基因表达的产物。其中A32克隆的序列与控制拟南芥下胚轴生长的MYB转录因子、营养元素缺失诱导的番茄根的表达文库中的一个cDNA及番茄抗假单胞杆菌表达文库中的一个cDNA有较高的同源性。     

Sampling Survey and Identification of Races of Soybean Cyst Nematode (Heterodera glycines Ichinohe) in Huang-Huai Valleys

Soybean cyst nematode (SCN Heterodera glycines Ichinohe) is one of the most important nationwide soybean diseases in China. A total of 38 soil specimens or locations in the area was sampled and tested for SCN races during 2001-2003 for the inspection of race distribution in Huang-Huai Valleys. A map of race distribution was constructed according to the data from both the present study and the published reports cited. Three areas, namely, the area of southeast to Jinan in Shangdong Province; the area of northern Henan Province and its border region to south of Hebei Province; and the area of Luohe, Zhoukou of Henan Province and Fuyang of Anhui Province mainly infested with Race 1 were identified. Race 4 was predominant in Shanxi Province, Beijing and the adjacent area of Henan, Shandong, and Anhui provinces, and the delta of Huanghe River in Shandong Province. Race 2 was mainly found in Liaocheng, Dezhou of Shangdong Province and Shijiazhuang of Hebei Province, and Jiaozuo and Huojia of Henan Province. Race 7 was distributed in the west part of Jiaodong Peninsula of Shandong Province and Kaifeng, Huaxian, Wenxian of Henan Province. Race 5 was found and scattered in Hebei and Henan Province. Race 9 was found in Shangqiu of Henan Province, which was reported for the first time in China. It can be seen that Race 1 and Race 4 were the two predominant races in Huang-Huai Valleys, and that research should focus on developing resistant cultivars of these races. There might exist other races in an area with some predominant races. The race substitution in the past decade was not obviously found, therefore, the results should be meaningful to future breeding for resistance to SCN in Huang-Huai Valleys.     

小麦孢囊线虫病的研究：Ⅱ.病原燕麦孢囊线虫的孵化

用湖北天门小麦病田土壤中分离的燕麦孢囊线虫接种，并种植小麦，待小麦收割后，于不同时间内分离孢囊，在不同条件下进行孵化试验。结果表明，在室温下，旬平均９－１２℃ｘ孵出的幼虫总数多。在１５±１℃恒温下，孢囊孵出的幼虫显高于２０℃，１０℃，５℃的处理。黄棕壤土浸液，小麦根汁５倍液有抑制孢囊孵化的作用，小麦根叶汁１０倍液对孢囊孵化无显影响，小麦根汁２０倍液对孢囊孵化有利。室外自然条件下，６－１０月线虫     

旱稻孢囊线虫的快速分子检测

根据旱稻孢囊线虫(Heterodera elachista)和常见孢囊线虫的ITS序列比对分析,设计1对旱稻孢囊线虫特异性引物He–F/He–R,特异性片段长度为281 bp。运用该特异性引物及建立的DNA提取方法和PCR体系,可特异性检测旱稻孢囊线虫单条2龄幼虫,可以从混合有1条旱稻孢囊线虫的0.1 g水稻根组织中特异性检测出目的DNA片段。特异性引物He–F/He–R与通用引物D2A/D3B结合,运用一步双重PCR检测方法可快速鉴定单孢囊,也可从初始分离的田间土壤总线虫样品中直接检测出旱稻孢囊线虫。     

胶州市小麦禾谷孢囊线虫群体动态的年度间差异

为明确山东胶州市禾谷孢囊线虫(Heterodera avenae,CCN)的田间发生状况及其年度间的差异,于2011-2012和2012-2013年两个小麦生长季在该地区麦田进行定点定期取样、土壤中线虫分离和根组织内线虫染色后镜检,以确定各虫态的季节和年度间群体动态变化。结果表明,与2011-2012年相比,2012-2013年春季CCN 2龄幼虫(J2)孵出较早,但对根系侵入较晚;土壤中J2群体密度较高,根组织中反而较低;根内幼虫发育不良,表现为3龄和4龄幼虫发生较晚且持续时间较短,没有明显发生高峰,群体密度持续低下;小麦收获后土壤中孢囊密度减少85.9%。2012-2013年J2侵入期推后和侵入率下降与3-4月份土壤干旱有关,而根内幼虫发育不良与4-5月份气温偏低有关。因此CCN侵染和发育关键期的干旱和低温可能是造成孢囊密度下降的主要原因。