Detached-leaf bioassay for evaluating taro resistance to Phytophthora colocasiae
Detached-leaf bioassay for evaluating taro resistance to Phytophthora colocasiae
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DOI：
10.1094/pdis-92-1-0126
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发表时间：
2008-01-01
期刊：
影响因子：
4.5
通讯作者：
Brooks, F. E.
中科院分区：
文献类型：
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作者：
Brooks, F. E.
由芋疫霉（Phytophthoracolocasiae）引起的芋叶枯病是世界范围内芋生产的主要限制因子。芋疫霉是一种气传病原体，类似于马铃薯晚疫病的致病菌致病疫霉，但发生在温暖的气候中。在太平洋岛屿的全年自给种植制度中，抗病品种是必不可少的。采用离体叶片生物测定和田间试验，在美属萨摩亚测试了来自东南亚和大洋洲的育种品系对芋头叶枯病的抗性。从生物测定的平均病变直径高度相关的健康叶片的数量，每株植物和产量（球茎重量）的字段估计。然而，生物测定法没有充分评估感染效率。另外的实验表明，附着的叶子比在封闭容器中孵育的离体叶子具有更小的病变直径，但两者都非常高度相关。芋头抗性随树龄增加而增加，第二老叶比第三老叶抗性更强。该方法是一种快速、节省空间、有效的芋头抗刺后锈性筛选方法。它还提供了一种在受控条件下评价宿主-病原体相互作用的简单标准化方法。
Taro leaf blight disease, caused by Phytophthora colocasiae, is a major limiting factor in taro production worldwide. P colocasiae is an aerial pathogen similar to P. infestans, causal agent of potato late blight disease, but occurs in warmer climates. In the year-round subsistence cropping systems of the Pacific Islands, resistant cultivars are essential. Breeding lines from Southeast Asia and Oceania were tested in American Samoa for resistance to taro leaf blight using a detached-leaf bioassay and field trials. Mean lesion diameters from bioassays were highly correlated with field estimates of the number of healthy leaves per plant and yield (corm weight). However, the bioassay did not adequately assess infection efficiency. Additional experiments revealed that attached leaves had smaller lesion diameters than detached leaves incubated in closed containers, but both were very highly correlated. Taro resistance increased with plant age and the second-oldest leaf was more resistant than the third-oldest leaf. The bioassay was a fast, space-saving, effective method of screening taro lines for post-penetration resistance to R colocasiae. It also provided an easily standardized method of evaluating host-pathogen interactions under controlled conditions.