Transcriptional Modulation of Resistance against <i>Xanthomonas oryzae</i> pv. <i>oryzae</i> Korean Race K2 in <i>japonica</i> Rice

• Main Authors: Marjohn C. Niño, Yong-Gu Cho
• Format: Article
• Language: English
• Published: MDPI AG 2020-07-01
• Series: Agronomy
• Subjects: bacterial blight; differentially expressed genes; microarray; Xanthomonas oryzae pv. oryzae; rice
• Online Access: https://www.mdpi.com/2073-4395/10/7/960

Bacterial blight is a common disease found in the rice-growing regions in the Korean peninsula. Identification of the gene network involved against <i>Xanthomonas oryzae</i> pv. <i>oryzae</i> Korean race K2 in popular japonica cultivars is essential in underpinning the molecular mechanism of resistance. A microarray of two popular Korean <i>japonica</i> rice cultivars, a bacterial blight susceptible Dongjin and resistant Jinbaek, was performed to investigate the transcripts of inducible genes at 48 h post-inoculation. A total of 771 differentially expressed genes were identified in Jinbaek, whereas 298 were found in Dongjin. The resistance observed in Jinbaek is likely participated by genes with predicted functions in transmembrane perception, intracellular signal transduction, and transcription activity. Moreover, the remarkable involvement of numerous WRKY proteins signifies orchestration of defense signals via robust cellular reprogramming, which leads to resistance. To discover genes essential to bacterial blight resistance in Jinbaek, 13 highly expressed genes encoding different protein classes were cloned and overexpressed in rice. Although none of the overexpression plants exhibited resistance comparable to Jinbaek, four candidate genes, including one twin-arginine translocation pathway signal (LOC_Os01g45640.1), one cytochrome p450 (LOC_Os09g10340.1), and two uncharacterized expressed protein (LOC_Os08g26230.4, LOC_Os09g04310.1) conferred partial resistance. However, of these four genes, only p450s have been reported to play an important role in the synthesis of plant defense compounds. These findings revealed the complexity of key immune signaling conduits critical to mounting a full defense against <i>Xanthomonas. oryzae</i> pv. <i>oryzae</i> race K2 in japonica rice.