Rice glutaredoxin GRXS15 confers broad-spectrum resistance to Xanthomonas oryzae pv. oryzae and Fusarium fujikuroi.

Rice is a particularly widely consumed food crop globally, but its yield is seriously damaged by bacterial blight due to Xanthomonas oryzae pv. oryzae (Xoo) and bakanae disease due to Fusarium fujikuroi (F. fujikuroi). However, broad-spectrum resistance (BSR) to both Xoo and F. fujikuroi remains largely elusive. In this study, we showed that rice monothiol glutaredoxin GRXS15 localizes in mitochondria and the nucleus, and its transcription is induced by Xoo. Transgenic rice lines constitutively expressing OsGRXS15 showed enhanced disease resistance to Xoo and F. fujikuroi, while CRISPR/Cas9-based knockout mutants showed reduced resistance compared with the wild-type plants. The transcription of pathogenesis-related (PR) genes was significantly induced in OsGRXS15-expressing plants. The rice transcription factor OsWRKY65 was identified as a binding partner, and it directly interacted with OsGRXS15 in the nucleus. Moreover, we revealed that the interaction of OsGRXS15 and OsWRKY65 results in the upregulation of OsPR1. These results suggested that OsGRXS15 interacts with transcription factors, and it confers BSR through regulating the expression of genes related to pathogen response. This is the first report on the nuclear function associated with the monothiol glutaredoxin GRXS15.