He Qin, McLellan Hazel, Boevink Petra C, Sadanandom Ari, Xie Conghua, Birch Paul R J, Tian Zhendong
Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, Hubei, 430070, China and the National Centre for Vegetable Improvement (Central China), Huazhong Agricultural University, Wuhan, Hubei, 430070, China; Division of Plant Sciences, University of Dundee, James Hutton Institute (JHI), Errol Road, Invergowrie, Dundee DD2 5DA, UK Dundee Effector Consortium, James Hutton Institute, Errol Road, Invergowrie, Dundee DD2 5DA, UK.
Division of Plant Sciences, University of Dundee, James Hutton Institute (JHI), Errol Road, Invergowrie, Dundee DD2 5DA, UK Dundee Effector Consortium, James Hutton Institute, Errol Road, Invergowrie, Dundee DD2 5DA, UK.
J Exp Bot. 2015 Jun;66(11):3189-99. doi: 10.1093/jxb/erv128. Epub 2015 Apr 6.
Ubiquitination regulates many processes in plants, including immunity. The E3 ubiquitin ligase PUB17 is a positive regulator of programmed cell death (PCD) triggered by resistance proteins CF4/9 in tomato. Its role in immunity to the potato late blight pathogen, Phytophthora infestans, was investigated here. Silencing StPUB17 in potato by RNAi and NbPUB17 in Nicotiana benthamiana by virus-induced gene silencing (VIGS) each enhanced P. infestans leaf colonization. PAMP-triggered immunity (PTI) transcriptional responses activated by flg22, and CF4/Avr4-mediated PCD were attenuated by silencing PUB17. However, silencing PUB17 did not compromise PCD triggered by P. infestans PAMP INF1, or co-expression of R3a/AVR3a, demonstrating that not all PTI- and PCD-associated responses require PUB17. PUB17 localizes to the plant nucleus and especially in the nucleolus. Transient over-expression of a dominant-negative StPUB17(V314I,V316I) mutant, which retained nucleolar localization, suppressed CF4-mediated cell death and enhanced P. infestans colonization. Exclusion of the StPUB17(V314I,V316I) mutant from the nucleus abolished its dominant-negative activity, demonstrating that StPUB17 functions in the nucleus. PUB17 is a positive regulator of immunity to late blight that acts in the nucleus to promote specific PTI and PCD pathways.
泛素化调控植物中的许多过程，包括免疫。E3泛素连接酶PUB17是番茄中由抗性蛋白CF4/9触发的程序性细胞死亡（PCD）的正向调节因子。本文研究了它在对马铃薯晚疫病病原菌致病疫霉的免疫中的作用。通过RNA干扰使马铃薯中的StPUB17沉默，以及通过病毒诱导的基因沉默（VIGS）使本氏烟草中的NbPUB17沉默，均增强了致病疫霉在叶片上的定殖。由flg22激活的PAMP触发的免疫（PTI）转录反应以及CF4/Avr4介导的PCD因PUB17沉默而减弱。然而，PUB17沉默并未损害由致病疫霉PAMP INF1触发的PCD，或R3a/AVR3a的共表达，这表明并非所有与PTI和PCD相关的反应都需要PUB17。PUB17定位于植物细胞核，尤其是核仁。保留核仁定位的显性负性StPUB17(V314I,V316I)突变体的瞬时过表达抑制了CF4介导的细胞死亡并增强了致病疫霉的定殖。将StPUB17(V314I,V316I)突变体排除在细胞核外消除了其显性负性活性，表明StPUB17在细胞核中发挥作用。PUB17是对晚疫病免疫的正向调节因子，在细胞核中发挥作用以促进特定的PTI和PCD途径。
