Phytoalexin Accumulation in the Interaction Between Rice and the Blast Fungus
Phytoalexin Accumulation in the Interaction Between Rice and the Blast Fungus
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DOI：
10.1094/mpmi-23-8-1000
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发表时间：
2010-08-01
影响因子：
3.5
通讯作者：
Ohashi, Yuko
中科院分区：
文献类型：
--
作者：
Hasegawa, Morifumi;Mitsuhara, Ichiro;Ohashi, Yuko
研究了稻瘟病菌诱导水稻主要二萜植物抗毒素（PA）、豆蔻内酯A和B以及植物卡桑烷A~E的合成和解毒作用。在抗性水稻中，所有PA在接种后2天（dpi）开始积累，此时过敏反应（HR）特异性小病变变得可见，并在4 dpi时增加500至1，000倍，而在易感水稻中，PA的积累被延迟并降低数倍。PA生物合成基因的表达仅在2 dpi时在抗性植物中被瞬时诱导，而在4 dpi时在两种植物中被高度诱导。真菌的生长受到严重抑制，在抗性植物的2 dpi，但在3至4 dpi的敏感植物显着增加。momilactone A治疗抑制真菌生长在植物和体外，和真菌解毒PA在体外。这些结果表明，HR相关的快速PA生物合成诱导真菌的严重限制，允许较高的PA积累在抗性水稻，而在敏感水稻，PA积累的失败，在早期感染阶段允许真菌生长。PA的降解可能是真菌入侵寄主的一种策略，而在HR上迅速诱导PA的生物合成可能是抗病水稻对稻瘟病菌的一种限制。
Blast fungus induced accumulations of major rice diterpene phytoalexins (PA), momilactones A and B, and phytocassanes A through E were studied, focusing on their biosynthesis and detoxification. In resistant rice, all PA started to accumulate at 2 days postinoculation (dpi), at which hypersensitive reaction (HR)-specific small lesions became visible and increased 500- to 1,000-fold at 4 dpi, while the accumulation was delayed and several times lower in susceptible rice. Expression of PA biosynthetic genes was transiently induced at 2 dpi only in resistant plants, while it was highly induced in both plants at 4 dpi. Fungal growth was severely suppressed in resistant plants by 2 dpi but considerably increased at 3 to 4 dpi in susceptible plants. Momilactone A treatment suppressed fungal growth in planta and in vitro, and the fungus detoxified the PA in vitro. These results indicate that HR-associated rapid PA biosynthesis induces severe restriction of fungus, allowing higher PA accumulation in resistant rice, while in susceptible rice, failure of PA accumulation at the early infection stage allows fungal growth. Detoxification of PA would be a tactic of fungus to invade the host plant, and prompt induction of PA biosynthesis upon HR would be a trait of resistant rice to restrict blast fungus.