부산대학교 도서관

SUMMARY: The rice immune receptor XA21 confers resistance to Xanthomonas oryzae pv. oryzae (Xoo), and upon recognition of the RaxX21‐sY peptide produced by Xoo, XA21 activates the plant immune response. Here we screened 21 000 mutant plants expressing XA21 to identify components involved in this response, and reported here the identification of a rice mutant, sxi4, which is susceptible to Xoo. The sxi4 mutant carries a 32‐kb translocation from chromosome 3 onto chromosome 7 and displays an elevated level of DCL2a transcript, encoding a Dicer‐like protein. Silencing of DCL2a in the sxi4 genetic background restores resistance to Xoo. RaxX21‐sY peptide‐treated leaves of sxi4 retain the hallmarks of XA21‐mediated immune response. However, WRKY45‐1, a known negative regulator of rice resistance to Xoo, is induced in the sxi4 mutant in response to RaxX21‐sY peptide treatment. A CRISPR knockout of a short interfering RNA (TE‐siRNA815) in the intron of WRKY45‐1 restores the resistance phenotype in sxi4. These results suggest a model where DCL2a accumulation negatively regulates XA21‐mediated immunity by altering the processing of TE‐siRNA815. Significance Statement: XA21 was identified in the wild rice, and was shown to confer broad‐spectrum resistance to Xoo and has been utilized in numerous breeding programs. But the understanding of the entire signaling networks is far from complete. Here, we conducted a forward genetic screen for rice mutants that suppress XA21‐mediated immunity, and characterized one of the mutants, named sxi4, that is susceptible to Xoo. [ABSTRACT FROM AUTHOR]