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Durham University

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Publication details for Professor Ari Sadanandom

He, Q., McLellan, H., Boevink, P.C., Sadanandom, A., Xie, C., Birch, P.R. & Tian, Z. (2015). U-box E3 ubiquitin ligase PUB17 acts in the nucleus to promote specific immune pathways triggered by Phytophthora infestans. Journal of Experimental Botany 66(11): 3189-3199.

Author(s) from Durham

Abstract

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 StPUB17V314I,V316I mutant, which retained nucleolar localization, suppressed CF4-mediated cell death and enhanced P. infestans colonization. Exclusion of the StPUB17V314I,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.