Ishiga Yasuhiro, Ishiga Takako, Ikeda Yoko, Matsuura Takakazu, Mysore Kirankumar S
Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan; Plant Biology, The Samuel Roberts Noble Foundation, Ardmore, OK, USA.
Plant Biology, The Samuel Roberts Noble Foundation , Ardmore, OK , USA.
PeerJ. 2016 Apr 26;4:e1938. doi: 10.7717/peerj.1938. eCollection 2016.
Chloroplasts are cytoplasmic organelles for photosynthesis in eukaryotic cells. In addition, recent studies have shown that chloroplasts have a critical role in plant innate immunity against invading pathogens. Hydrogen peroxide is a toxic by-product from photosynthesis, which also functions as a signaling compound in plant innate immunity. Therefore, it is important to regulate the level of hydrogen peroxide in response to pathogens. Chloroplasts maintain components of the redox detoxification system including enzymes such as 2-Cys peroxiredoxins (2-Cys Prxs), and NADPH-dependent thioredoxin reductase C (NTRC). However, the significance of 2-Cys Prxs and NTRC in the molecular basis of nonhost disease resistance is largely unknown. We evaluated the roles of Prxs and NTRC using knock-out mutants of Arabidopsis in response to nonhost Pseudomonas syringae pathogens. Plants lacking functional NTRC showed localized cell death (LCD) accompanied by the elevated accumulation of hydrogen peroxide in response to nonhost pathogens. Interestingly, the Arabidopsis ntrc mutant showed enhanced bacterial growth and disease susceptibility of nonhost pathogens. Furthermore, the expression profiles of the salicylic acid (SA) and jasmonic acid (JA)-mediated signaling pathways and phytohormone analyses including SA and JA revealed that the Arabidopsis ntrc mutant shows elevated JA-mediated signaling pathways in response to nonhost pathogen. These results suggest the critical role of NTRC in plant innate immunity against nonhost P. syringae pathogens.
叶绿体是真核细胞中进行光合作用的细胞质细胞器。此外，最近的研究表明，叶绿体在植物对入侵病原体的先天免疫中起着关键作用。过氧化氢是光合作用产生的一种有毒副产物，它在植物先天免疫中也作为信号化合物发挥作用。因此，响应病原体来调节过氧化氢水平很重要。叶绿体维持氧化还原解毒系统的组分，包括诸如2-半胱氨酸过氧化物酶（2-Cys Prxs）和NADPH依赖性硫氧还蛋白还原酶C（NTRC）等酶。然而，2-Cys Prxs和NTRC在非寄主抗病性分子基础中的重要性很大程度上未知。我们利用拟南芥敲除突变体评估了Prxs和NTRC对非寄主丁香假单胞菌病原体的响应作用。缺乏功能性NTRC的植物在响应非寄主病原体时表现出局部细胞死亡（LCD），同时伴随着过氧化氢积累增加。有趣的是，拟南芥ntrc突变体对非寄主病原体表现出细菌生长增强和疾病易感性增加。此外，水杨酸（SA）和茉莉酸（JA）介导的信号通路的表达谱以及包括SA和JA在内的植物激素分析表明，拟南芥ntrc突变体在响应非寄主病原体时JA介导的信号通路增强。这些结果表明NTRC在植物对非寄主丁香假单胞菌病原体的先天免疫中起关键作用。
