Silencing of DS2 aminoacylase-like genes confirms basal resistance to Phytophthora infestans in Nicotiana benthamiana
Silencing of DS2 aminoacylase-like genes confirms basal resistance to Phytophthora infestans in Nicotiana benthamiana
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DOI：
10.4161/psb.28004
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发表时间：
2014-01-01
影响因子：
2.9
通讯作者：
Kiba, Akinori
中科院分区：
文献类型：
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作者：
Nakano, Masahito;Nishihara, Masahiro;Kiba, Akinori
benthamiana是几种植物病原体的潜在寄主，其未成熟叶片对疫霉（Phytophthora infestans）敏感。相比之下，拟南芥成熟叶片对病原菌的敏感性较弱，对病原菌表现出基础抗性。我们筛选了一株对病原菌具有高抗性的基因沉默成熟植株，命名为DS2 （Disease suppression 2）。推导出的DS2的cDNA氨基酸序列编码了一个推测的氨基酰化酶。病原菌在DS2植株中的生长下降。台盼蓝染色显示，在DS2植株中，侵染部位的死亡细胞数量增加，菌丝生长受到抑制。与病原菌的生长抑制一致，与对照植物相比，DS2植株的防御反应，如活性氧的产生和水杨酸依赖性PR-1a的表达显著增加。在NahG植物中，DS2表型受损，表明DS2表型依赖于水杨酸信号通路。在DS2植物中观察到INF1诱导素和NbMEK2（DD）引起的加速防御反应，NbMEK2是NbMEK2的组成活性形式，并作为INF1感知的下游调节剂。另一方面，过表达ds2的转基因烟草可阻止INF1-和NbMEK2（DD）诱导的防御反应。这些结果表明，DS2通过NbMEK2和sa依赖的信号通路负向调节benthamiana对病原菌的防御反应。
Nicotiana benthamiana is a potential host to several plant pathogens, and immature leaves of N. benthamiana are susceptible to Phytophthora infestans. In contrast, mature leaves of N. benthamiana are weakly susceptible and show basal resistance to P. infestans. We screened a gene-silenced mature plant showing high resistance to P. infestans, designated as DS2 (Disease suppression 2). The deduced amino acid sequence of cDNA responsible for DS2 encoded a putative aminoacylase. Growth of P. infestans decreased in DS2 plants. Trypan blue staining revealed inhibited hyphae growth of P. infestans with an increased number of dead cells under the penetration site in DS2 plants. Consistent with growth inhibition of P. infestans, defense responses such as reactive oxygen generation and expression of a salicylic acid-dependent PR-1a increased markedly in DS2 plants compared with that of control plants. DS2 phenotype was compromised in NahG plants, suggesting DS2 phenotype depends on the salicylic acid signaling pathway. Accelerated defense response was observed in DS2 plants elicited by INF1 elicitin as well as by NbMEK2(DD), which is the constitutive active form of NbMEK2, and act as a downstream regulator of INF1 perception. On the other hand, INF1- and NbMEK2(DD)-induced defense responses were prevented by DS2-overexpressing transgenic tobacco. These results suggest that DS2 negatively regulates plant defense responses against P. infestans via NbMEK2 and SA-dependent signaling pathway in N. benthamiana.