Assessing Quantitative Resistance against Leptosphaeria maculans (Phoma Stem Canker) in Brassica napus (Oilseed Rape) in Young Plants
Assessing Quantitative Resistance against Leptosphaeria maculans (Phoma Stem Canker) in Brassica napus (Oilseed Rape) in Young Plants
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DOI：
10.1371/journal.pone.0084924
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发表时间：
2014-01-15
期刊：
影响因子：
3.7
通讯作者：
Fitt, Bruce D. L.
中科院分区：
文献类型：
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作者：
Huang, Yong-Ju;Qi, Aiming;Fitt, Bruce D. L.
由于从叶片出现病变到茎上出现溃烂症状的长时间无症状生长，因此很难在幼株中评估甘蓝型油菜对黄斑细螺旋体的定量抗性。利用双单倍体（DH）系A30（易感系）和C119（数量抗性系），在控制环境下，分两个阶段评估了幼植株对黄斑乳杆菌的数量抗性：第一阶段，通过叶面接种，病原菌沿叶脉/叶柄向茎部生长；第二阶段，茎组织生长，通过叶柄接种产生茎溃烂症状。采用两种类型的接种物（子囊孢子；分生孢子）和三种评估方法（可见坏死程度；使用GFP报告基因可视化无症状病原体生长；用PCR定量病原体DNA数量）。在第1阶段评估中，A30和C119在叶片病变面积、叶脉/叶柄生长距离（通过可见坏死或观察绿色荧光蛋白来评估）和叶柄中黄斑杆菌DNA的数量上观察到显著差异。在2期评估中，A30和C119在茎溃疡病的严重程度和茎组织中黄斑乳杆菌DNA的数量上观察到显著差异。gfp标记的黄斑菌在A30中从茎皮质向茎髓的扩散速度比在C119中快。用子囊孢子接种比用分生孢子接种能更快地产生茎溃烂症状。这些结果表明，在控制条件下，可以对甘蓝型油菜幼苗进行定量抗性评价。研究控制环境下幼株对植物病原菌的数量抗性表型，将有助于确定稳定的数量抗性，从而控制作物病害。
Quantitative resistance against Leptosphaeria maculans in Brassica napus is difficult to assess in young plants due to the long period of symptomless growth of the pathogen from the appearance of leaf lesions to the appearance of canker symptoms on the stem. By using doubled haploid (DH) lines A30 (susceptible) and C119 (with quantitative resistance), quantitative resistance against L. maculans was assessed in young plants in controlled environments at two stages: stage 1, growth of the pathogen along leaf veins/petioles towards the stem by leaf lamina inoculation; stage 2, growth in stem tissues to produce stem canker symptoms by leaf petiole inoculation. Two types of inoculum (ascospores; conidia) and three assessment methods (extent of visible necrosis; symptomless pathogen growth visualised using the GFP reporter gene; amount of pathogen DNA quantified by PCR) were used. In stage 1 assessments, significant differences were observed between lines A30 and C119 in area of leaf lesions, distance grown along veins/petioles assessed by visible necrosis or by viewing GFP and amount of L. maculans DNA in leaf petioles. In stage 2 assessments, significant differences were observed between lines A30 and C119 in severity of stem canker and amount of L. maculans DNA in stem tissues. GFP-labelled L. maculans spread more quickly from the stem cortex to the stem pith in A30 than in C119. Stem canker symptoms were produced more rapidly by using ascospore inoculum than by using conidial inoculum. These results suggest that quantitative resistance against L. maculans in B. napus can be assessed in young plants in controlled conditions. Development of methods to phenotype quantitative resistance against plant pathogens in young plants in controlled environments will help identification of stable quantitative resistance for control of crop diseases.