Transfer of resistance to race 2 of Plasmodiophora brassicae from Brassica napus to cabbage (B. oleracea var. capitata). II. Meiosis in the interspecific hybrids between B. napus and 2x and 4x cabbage

Summary Meiosis in 14 interspecific F₁ hybrids with three chromosomal levels (triploid, tetraploid, hexaploid; 2n=28, 37 and 55) between Brassica napus L. and 2x and 4x cabbage (B. oleracea var. capitata L.) was studied. The oleracea genome from B. napus maintained close homology with the c genome of cabbage while the campestris genome of B. napus showed partial homology with the c genome contained in the hybrids. Genotypic influence on chromosome pairing was indicated. Structural chromosome differences and spontaneous chromosome breakage and reunion were suggested as causes for the abnormalities which related to the unbalance of the genotypes. The divergence of the genomes of B. napus and B. oleracea and the need for the qualification of the term secondary association were discussed.Contribution No. J. 673, Research Station, Agriculture Canada, St. Jean, Québec.     

根肿病生防菌Zhihengliuella aestuarii B18定殖能力及防效分析

Zhihengliuella aestuarii B18是一株对十字花科根肿病菌Plasmodiophora brassicae具有抑制作用的优良生防菌株。为探明其生防潜能,本文通过抗生素抗性标记法、盆栽试验和田间小区试验研究了B18在不同土壤pH、土壤温度、土壤含水量、初始接种浓度、蔬菜作物以及不同土壤类型中的定殖动态。灭菌土试验结果表明:调节土壤pH 7.5～8.5,含水量10%～30%,放置于10～25℃,70 d后B18定殖菌量保持在105～107 cfu/g。盆栽试验结果表明:初始接种菌液浓度为109 cfu/mL时,45 d后根际土中定殖菌量可稳定在104～105cfu/g。将50 mL浓度为2×109 cfu/mL的生防菌菌液接种于田间不同类型土壤后,第30天定殖菌量分别为病田8.7×105cfu/g,病土1.02×105cfu/g,健田8.5×104cfu/g,健土2.6×104cfu/g,即定殖能力由强到弱依次为:病田＞病土＞健田＞健土。且病田中B18在根际土中可存活至45 d且菌量保持在104 cfu/g,根内可存活至31 d且菌量保持在104 cfu/g。田间调查结果显示B18在病田和病土中对榨菜根肿病的防效分别为42.01%和47.53%,增产率分别为37.24%和40.22%。     

油菜根肿病在湖北省的发生分布及其引起的油菜产量损失评估(英文)

[目的]明确油菜根肿病在湖北省的发生范围和病害引起的油菜产量损失。[方法]2009-2011年间取样调查了我省沙洋县、当阳市、枝江市、宜都市和长阳县的根肿病的发生情况,通过盆栽接种试验和PCR分子检测确定根肿病。测量病区油菜根肿病的发病率,产量组成因子和小区产量,与健康区比较,评估根肿病引起的油菜产量损失。[结果]在枝江市和当阳市发现并确诊了油菜根肿病,沙洋和宜都没有发现油菜根肿病,而长阳县的根肿病主要发生在十字花科蔬菜上。发生根肿病后,油菜植株的一次有效分枝数、单株有效角果数、每角粒数和千粒重显著下降,产量损失达56.4%。[结论]湖北省油菜根肿病主要分布于枝江市和当阳市。病害的发生对油菜生长和产量造成较大影响。     

Effects of temperature on infection and subsequent development of clubroot under controlled conditions

Controlled‐environment studies were conducted on two Brassica crops (canola, Brassica napus; and Shanghai pak choi, B. rapa subsp. chinensis var. communis) to examine the effects of temperature on infection and subsequent development of clubroot caused by Plasmodiophora brassicae. In the first experiment, canola seedlings were grown in infested soil for 3 weeks at 14–26°C to assess the impact on primary and secondary infection and transferred to 20°C for 3 weeks to assess symptom development under uniform conditions, or started at 20°C for 3 weeks and then placed at the treatment temperatures for the final 3 weeks to assess the impact of temperature on symptom development. A second experiment examined a wider range of temperatures (10–30°C). Similar experiments were also conducted on Shanghai pak choi. The studies demonstrated that clubroot severity was affected by temperature during both infection and vegetative development of the crop. Both early and late in crop development, little or no clubroot developed at temperatures at or below 17°C, and development was slower above 26°C than at 23–26°C for both crops throughout the study. In canola, the high levels of inoculum used in the study resulted in a high incidence of clubroot irrespective of temperature, but in pak choi incidence showed the same pattern as severity. This is the first study to demonstrate under controlled conditions that temperature during vegetative growth of the crop affects symptom development of clubroot.     

Specific polyclonal antibodies for the obligate plant parasite Polymyxa— a targeted recombinant DNA approach

Highly specific rabbit polyclonal antibodies for the obligate sugar-beet root parasite, Polymyxa betae , were produced using a novel recombinant DNA approach. Parasite cDNA was selectively isolated from infected roots, expressed in vitro , and the purified protein used to raise antibodies. This produced clean, precisely targeted antibodies, and allowed for rigorous screening of candidate genes and their products at the molecular level prior to animal immunization. This approach selects for genes whose products are highly expressed by the parasite in planta , and five such candidate genes from Polymyxa betae were identified and cloned. Polyclonal antiserum developed using the product of one such gene was found to react specifically with P. betae in sugar-beet roots and with the closely related Polymyxa graminis in barley roots, and to cross-react with Plasmodiophora brassicae in cabbage roots, without the need for further purification. No cross-reaction was detected with protein extracts from potato roots infected by the plasmodiophoromycete Spongospora subterranea . In all cases, there was no interaction with proteins from host plants, or from other microorganisms found in association with uninoculated sugar-beet, barley, cabbage and potato roots.     

江西省油菜根肿菌小种鉴定与油菜品种抗性分析

明确江西省油菜根肿病病菌类型及油菜品种对病害的抗性,对指导油菜生产及景区观光业的发展具有重要意义。为了探明油菜根肿病的分布及其病菌的致病性分化,于2011年至2016年持续对江西省油菜根肿病的地理分布进行调查,并对病区油菜根肿病株进行生理小种鉴定。结果表明,江西油菜根肿病主要分布在赣东北局部区域,致病菌为4号和9号生理小种,其中4号小种仅发现在赣东北区域分布。在4号和9号小种的病区分别设置田间病圃进行200余个油菜品种的抗性鉴定,结果表明,测试的全部油菜品种对9号小种表现抗病,而94.74%油菜品种对4号小种表现感病;萝卜籽花和59-013等12个品种对4号小种具中抗以上水平。本研究筛选到生理小种特异性的抗病资源或品种,可为油菜抗根肿病育种提供抗源。     

芸薹根肿菌侵染早期甘蓝型油菜转录组分析

根肿病是油菜最为严重的病害之一。为探索根肿病菌和油菜互作中的抗性分子机制,采用RNA-seq技术对根肿病早期侵染中抗病品系ZHE-226(R)和感病油菜10159(S)进行转录组分析。与感病材料S相比,在0、12、48和72h 4个接种时间点,抗性材料R中共有809个基因上调表达,1082个基因下调表达。模式识别受体、几丁质酶、R基因、WRKY、水杨酸和茉莉酸等抗性相关(PRR)基因在抗病材料R和感病材料S中诱导表达并表现出不同的表达模式。抗病材料R中PRR相关基因主要表现为下调表达,R基因上调表达,水杨酸表现为前期下调后期上调表达,茉莉酸、几丁质酶和WRKY因子在R和S中均诱导表达。结果表明PRR介导的PTI(病原相关分子模式触发的免疫反应)在感病材料S中显著诱导,在抗病材料R中作用不明显;R基因介导的ETI(效应蛋白触发的免疫反应)和水杨酸介导的抗病信号途径对根肿病抗性起重要作用。     

Clubroot resistance introgression in interspecific hybrids between Raphanus sativus and Brassica napus

Clubroot is a prevailing soil-borne disease affecting rapeseed production worldwide.However,few clubroot resistant rapeseed accessions were available for breeding.Identification and introgression of new clubroot resistant genes from closely related species by distant hybridization is an effective strategy.In the present study,9 radish(Raphanus sativus L.,2n=18,RR)lines resistant to Plasmodiophora brassicae pathotype 4 were used as donors to transfer clubroot resistance into a susceptible rapeseed(Brassica napus L.,2n=38,AACC)line by distant hybridization combined with embryo rescue.Nine intergeneric crosses were made but only 1(411×93039)produced F1 plants both from embryo rescue and natural seed-setting.Authenticity of triploid F1 hybrids(2n=28,ACR)were verified by flower color,cytological observation and molecular marker analysis,and 2 genuine F1 hybrids were identified.After chromosome doubling,these synthetic allohexaploid plants(2n=56,AACCRR)became partially fertile(pollen viability rate=35%)and were backcrossed with rapeseed parent to generate a BC1 population(2n=47,AACCR).Totally 178 BC1 plants were obtained,of which the majority(96.1%)were resistant to clubroot.These backcrossing progenies could be used for the breeding of new rapeseed varieties resistant to clubroot.     

芸薹根肿菌生理小种鉴别方法研究进展

本文综述了芸薹根肿菌生理小种鉴别方法和国际通用的根肿病生理小种鉴别系统及鉴别寄主,详细介绍了“Williams”和“ECD”根肿病鉴别系统的优缺点及适用范围,分析了分子生物学鉴定根肿病生理小种的技术,以期为抗病品种选育和持续控制根肿病提供准确的抗病鉴定方法。