Ubiquitin Ligase Gene OsPUB57 Negatively Regulates Rice Blast Resistance

The ubiquitination and degradation of proteins are widely involved in plant biotic and abiotic stress responses. E3 ubiquitin ligases play an important role in the ubiquitination of specific proteins. In this study, we identified the function of a U-box E3 ubiquitin ligase gene <i>OsPUB57</i> in rice. Expression analyses revealed that <i>OsPUB57</i> was mainly expressed in the aboveground part of rice. Drought, salt, cold, JA (jasmonic acid), PAMPs (pathogen-associated molecular patterns) or <i>Magnaporthe</i><i>oryzae</i> treatment could significantly suppress the expression of <i>OsPUB57</i> in rice. Compared with wild-type plants, <i>OsPUB57</i>-overexpressing plants showed a decrease in resistance to <i>M. oryzae</i>, while the mutant plants exhibited an enhancement of <i>M. oryzae</i> resistance. The expression level detection indicated that <i>OsPUB57</i> negatively regulates rice blast resistance, probably by down-regulating the expression of the defense-related genes <i>OsPR1a</i> and <i>OsAOS2</i>. This study provides a candidate gene for the genetic improvement of rice blast resistance.