Delineation of Sclerotinia sclerotiorum pathotypes using differential resistance responses on Brassica napus and B. juncea genotypes enables identification of resistance to prevailing pathotypes
Delineation of Sclerotinia sclerotiorum pathotypes using differential resistance responses on Brassica napus and B. juncea genotypes enables identification of resistance to prevailing pathotypes
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DOI：
10.1016/j.fcr.2011.11.022
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发表时间：
2012-02-27
影响因子：
5.8
通讯作者：
Barbetti, Martin J.
中科院分区：
文献类型：
--
作者：
Ge, Xin Tian;Li, Yu Pin;Barbetti, Martin J.
油菜菌核病是由核盘菌引起的一种危害最大、最难防治的油菜和芥菜病害。鉴定具有有效抗性的油菜基因型为改善该病的管理提供了最好的长期前景。尽管早先的研究报道了油菜籽油菜与核盘菌分离物之间存在显著的互作，但大多数情况下都是用单一的病原菌分离物来鉴定抗性基因。本文报道了来自西澳大利亚北部和南部农业区的53个菌核菌分离物的研究结果，该地区的菌核病是油菜的一种严重病害。测定了分离物在马铃薯葡萄糖琼脂上的菌落特性，并进行了两个田间毒力(即病情严重程度)的研究。第一个田间试验包括14个甘蓝型油菜对3个菌核菌的抗性研究，第二个田间试验包括8个油菜型油菜对50个油菜菌核病的防治研究。只有生长在马铃薯葡萄糖琼脂上的菌株菌落直径与田间病斑长度呈正相关。在两个田间试验中，菌株和寄主基因型之间存在显著的互作效应，并且菌株和基因型之间存在显著的互作效应，这与茎病变长度有关。在第一次田间试验中，高抗甘蓝型油菜ZY006的平均茎病长度为1 cm，感病品种芥菜型油菜2号和甘蓝型油菜的平均茎病长度至少为9 cm。后者是最敏感的，平均茎病损长度为11.1。甘蓝型油菜ZY006的高水平抗性表达在很大程度上独立于核盘菌分离物。相反，甘蓝型油菜中优821、06-6-3792、RT108和Charlton的反应对菌株的依赖性较强。在第一个田间试验中，寄主基因型数量多于核盘菌分离物，分离物的变异率(VR=158.4)高于寄主基因型的变异率(VR=10.7)。在第二个田间试验中，当菌核菌分离物数量多于寄主时，寄主基因型的变异率(VR=458.9)高于分离物(VR=71)。增加分离物的数量极大地提高了在不同测试基因型之间区分抗性水平的能力。在本实验中，一些基因型表现出更一致的抗性反应(例如.甘蓝型油菜和甘蓝型油菜新优9号)，是油菜育种中利用这一抗性进行商业利用的理想目标。本试验结果表明，三种甘蓝型油菜和三种芥菜型油菜的标准化表型适合作为八种命名法鉴定核盘菌致病类型的通用差异。8个不同的核盘菌致病类型已被描述和鉴定，这6个寄主不同的基因型现可用于鉴定和监测核盘菌当前和未来的致病类型的发病率和分布。此外，通过提供一种可靠的手段来表征菌核病的致病类型，不仅首次能够鉴定对特定地区流行的菌核病的主要致病类型(S)的抗性(S)，而且现在还允许油菜育种计划将寄主对几种特定的菌核病病型的抗性结合到未来的品种中。(C)2011爱思唯尔B.V.保留所有权利。
Sclerotinia stem rot caused by the fungus Sclerotinia sclercitiorum is one of the most damaging and difficult-to-manage diseases of oilseed rape (Brassica no pus) and mustard (B. juncea). Identifying oilseed Brassica genotypes with effective resistance offers the best long-term prospect for improved management of the disease. Despite some significant interactions between oilseed Brassica genotypes and S. sclerotiorum isolates reported in earlier studies, mostly a single pathogen isolate has been used to identify resistant genotypes. This paper reports the results of studies involving 53 isolates of S. sclerotiorum from the northern and southern agricultural regions of Western Australia where Sclerotinia stem rot is a serious disease of oilseed rape. Colony characteristics of isolates on potato dextrose agar were determined, and two field virulence (i.e., levels of disease severity) studies conducted. The first field study included 14 Brassica genotypes against three S. sclerotinia isolates and the second had eight Brassica genotypes against 50 S. sclerotinia isolates. Only colony diameter of isolates growing on potato dextrose agar was correlated with stem lesion length in the field. In both field experiments, there were significant effects of isolates and host genotypes, as well as a significant interaction between isolates and genotypes in relation to stem lesion length. In the first field experiment, mean stem lesion length ranged from 1 cm in the highly resistant B. napus ZY006 to at least 9 cm for susceptible genotypes Brassica juncea #2 and B. juncea Montara. The latter genotype was the most susceptible with a mean stem lesion length of 11.1. Expression of high-level resistance in B. napus ZY006 was largely independent of S. sclerotiorum isolate. In contrast, responses in B. napus genotypes, Zhongyou 821,06-6-3792, RT108 and Charlton were much more isolate-dependent. In the first field experiment, with a greater number of host genotypes than S. sclerotiorum isolates, a higher variance ratio occurred for isolates (VR = 158.4) than for host genotypes (VR = 10.7). In the second field experiment, with a larger number of S. sclerotinia isolates than hosts, host genotypes had a higher variance ratio (VR = 458.9) compared to the isolates (VR = 71.2). Increasing the number of isolates greatly improved the capacity to differentiate levels of resistance among test genotypes. In this experiment, some genotypes showed more consistent resistant reactions (e.g.. B. napus Mystic and B. juncea Xinyou 9) across different isolates and these are ideal targets for commercial exploitation of this resistance in oilseed Brassica breeding programs. From this experiment, a standardized set of three B. napus and three B. juncea genotypes were shown to be suitable for use as universal differentials to characterize pathotypes of S. sclerotiorum using octal nomenclature. Eight distinct pathotypes of S. sclerotiorum were delineated and characterized and these six host differential genotypes can now be utilized to identify and monitor the incidence and distribution of current and future pathotypes of S. sclerotiorum. Further, by providing a reliable means to characterize pathotypes of S. sclerotiorum, for the first time not only allows identification of resistance(s) against the predominant pathotype(s) of S. sclerotiorum prevailing in a particular region, but also now allows oilseed rape breeding programs to combine host resistances against several specific pathotypes of S. sclerotiorum into future cultivars. (C) 2011 Elsevier B.V. All rights reserved.