Division of Plant Sciences, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602, Japan.
Mol Plant Microbe Interact. 2011 May;24(5):519-32. doi: 10.1094/MPMI-07-10-0172.
We previously detected infection-promoting activity in the supernatant of the conidial suspension (SCS) of the rice blast fungus. In the present study, a molecule carrying the activity was purified and identified as 2'-deoxyuridine (dU). The infection-promoting activity of dU was strictly dependent on its chemical structure and displayed characteristics consistent with those of the SCS. Notably, the activity of dU was exclusively detected during interactions between rice and virulent isolates of the fungus, the number of susceptible lesions in leaf blades was increased by dU, and nonhost resistance in rice plants was not affected by treatment with dU. In addition, the expression of pathogensis-related genes, accumulation of H(2)O(2), and production of phytoalexins in rice in response to inoculation with virulent fungal isolates was not suppressed by dU. The infection-promoting activity of dU was not accompanied by elevated levels of endogenous abscissic acid, which is known to modify plant-pathogen interactions, and was not detected in interactions between oat plants and a virulent oat blast fungus isolate. Taken together, these results demonstrate that dU is a novel infection-promoting factor that acts specifically during compatible interactions between rice plants and rice blast fungus in a mode distinct from that of toxins and suppressors.
我们之前在稻瘟病菌分生孢子悬浮液（SCS）的上清液中检测到了促进感染的活性。在本研究中，纯化并鉴定出一种具有该活性的分子，它是 2'-脱氧尿苷（dU）。dU 的促感染活性严格依赖于其化学结构，表现出与 SCS 一致的特征。值得注意的是，dU 的活性仅在水稻与强毒力真菌分离株的相互作用中被检测到，叶片上易感病斑的数量因 dU 而增加，而 dU 处理对水稻的非寄主抗性没有影响。此外，dU 不抑制稻瘟病菌强毒力分离株接种后与致病性相关基因的表达、H（2）O（2）的积累和植物抗毒素的产生。dU 的促感染活性不伴随已知能修饰植物-病原体相互作用的内源脱落酸水平的升高，也不在燕麦植株与燕麦稻瘟病菌强毒力分离株的相互作用中被检测到。综上所述，这些结果表明 dU 是一种新型的促感染因子，它在水稻与稻瘟病菌之间的亲和相互作用中特异性发挥作用，其作用模式不同于毒素和抑制剂。
