Cytokinins Act Synergistically with Salicylic Acid to Activate Defense Gene Expression in Rice
Cytokinins Act Synergistically with Salicylic Acid to Activate Defense Gene Expression in Rice
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DOI：
10.1094/mpmi-06-12-0152-r
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发表时间：
2013-03-01
影响因子：
3.5
通讯作者：
Takatsuji, Hiroshi
中科院分区：
文献类型：
--
作者：
Jiang, Chang-Jie;Shimono, Masaki;Takatsuji, Hiroshi
激素串扰是植物病原体相互作用的关键。本文报道了稻瘟病菌侵染水稻幼苗后细胞分裂素（CK）的积累及其在稻瘟病菌中的潜在意义。相互作用。稻瘟病菌感染水稻幼苗后，叶片中N-6-（Delta（2）-isopentenyl）adenine（iP）、iP riboside（iPR）和iPR 5 '-phosphates（iPRP）的含量增加。与此相一致，CK信号在感染部位周围被激活，如由CK响应性OsRR 6启动子驱动的β-葡萄糖醛酸酶活性的组织化学染色所示。在稻瘟病菌的菌丝、分生孢子和培养物中也检测到不同的CK种类，表明M.该菌既能产生CK，也能分泌CK。CK和水杨酸（SA）共处理叶片，可显著诱导病程相关基因OsPR 1b和烯丙苯咪唑诱导蛋白1（PBZ 1）的表达。这些效应被水稻中SA信号通路的关键调节子OsNPR 1或WRKY 45的RNAi敲低所减弱，表明CK的效应依赖于这两个调节子。综上所述，我们的数据暗示了一个共同进化的水稻M。相互作用，其中M.水稻CK水平的提高可能是其自身的利益，如养分转运。而水稻则将SA作为侵染信号，通过与SA的协同作用激活防御反应。
Hormone crosstalk is pivotal in plant pathogen interactions. Here, we report on the accumulation of cytokinins (CK) in rice seedlings after infection of blast fungus Magnaporthe oryzae and its potential significance in rice-M. oryzae interaction. Blast infection to rice seedlings increased levels of N-6-(Delta(2)-isopentenyl) adenine (iP), iP riboside (iPR), and iPR 5'-phosphates (iPRP) in leaf blades. Consistent with this, CK signaling was activated around the infection sites, as shown by histochemical staining for beta-glucuronidase activity driven by a CK-responsive OsRR6 promoter. Diverse CK species were also detected in the hyphae (mycelium), conidia, and culture filtrates of blast fungus, indicating that M. oryzae is capable of production as well as hyphal secretion of CK. Co-treatment of leaf blades with CK and salicylic acid (SA), but not with either one alone, markedly induced pathogenesis-related genes OsPR1b and probenazole-induced protein 1 (PBZ1). These effects were diminished by RNAi-knockdown of OsNPR1 or WRKY45, the key regulators of the SA signaling pathway in rice, indicating that the effects of CK depend on these two regulators. Taken together, our data imply a coevolutionary rice M. oryzae interaction, wherein M. oryzae probably elevates rice CK levels for its own benefits such as nutrient translocation. Rice plants, on the other hand, sense it as an infection signal and activate defense reactions through the synergistic action with SA.