Studies On The Mechanism Of Disease Resistance Mediated By Rice Ubiquitin Ligase OsPUB57

Ubiquitin-proteasome system is widely involved in the regulation of cell cycle progression, signal transduction, transcriptional regulation, receptor degradation, endocytosis, immune response, development, programmed cell death. Ubiquitin ligases (E3) play a specific role to recognize the targets for degradation via the ubiquitin-proteasome system. Studies have shown that rice (Oryza Sativa L.) ubiquitin ligases are involved in hormone signaling, growth, development and regulation of biotic and abiotic stresses.In the previous work, we isolated the U-box ubiquitin ligase gene OsPUB57based on rice genomic information. In vitro ubiquitination and protoplast cell death experiments showed that OsPUB57may be involved in the programmed cell death pathway. In addition, we obtained overexpression and RNA silencing OsPUB57transgenic lines. In this study, I have tested these transgenic lines, performed disease resistance evaluations, and screened for OsPUB57-interacting proteins to understand the OsPUB57-mediated resistance mechanism. The results are summarized as follows:(1) Six overexpression and seven RNA silencing OsPUB57T3-transgenic lines with single-copy insertion were identified by genotyping analysis.(2) When inoculated with rice blast(Magnaporthe oryzae), compared to the control Nipponbare, the RNA silencing lines showed more resistance, and the overexpression lines displayed more susceptibility, suggesting that OsPUB57may act as a negative regulator of resistance against rice blast. When inoculated with the bacterial blight pathogen(Xanthomonas oryzae pv. Oryzae, or Xoo), compared to the control Nipponbare, the RNA silencing lines showed more resistance, and the overexpression lines were unstable and need further confirmation in the future.(3) The vector pDBLeu-OsPUB57was constructed for screening OsPUB57-interaction proteins via the yeast two-hybrid system.214OsPUB57interacting proteins were obtained and22of the interacting genes were picked up for functional analysis. Moreover, constructs of overexpression, RNAi or cellular localization were made for12interacting genes and were transformed into the Nipponbare cali via the Agrobacterium-mediated transformation method. Characterization of the transgenic lines is m progress.