Transcriptional Profiling of Rice Early Response to Magnaporthe oryzae Identified OsWRKYs as Important Regulators in Rice Blast Resistance

Tong Wei,Dongshu Guo,Zhangliang Chen,Yang Zhao,Youyong Zhu,Chengyun Li,Bin Ou,Li-Jia Qu,Genji Qin,Hongya Gu,Jinbin Li,Mingliang Xu

doi:10.1371/journal.pone.0059720

Abstract

Rice blast disease is a major threat to rice production worldwide, but the mechanisms underlying rice resistance to the causal agent Magnaporthe oryzae remain elusive. Therefore, we carried out a transcriptome study on rice early defense response to M. oryzae. We found that the transcriptional profiles of rice compatible and incompatible interactions with M. oryzae were mostly similar, with genes regulated more prominently in the incompatible interactions. The functional analysis showed that the genes involved in signaling and secondary metabolism were extensively up-regulated. In particular, WRKY transcription factor genes were significantly enriched among the up-regulated genes. Overexpressing one of these WRKY genes, OsWRKY47, in transgenic rice plants conferred enhanced resistance against rice blast fungus. Our results revealed the sophisticated transcriptional reprogramming of signaling and metabolic pathways during rice early response to M. oryzae and demonstrated the critical roles of WRKY transcription factors in rice blast resistance.

Highlights

Plants are frequently challenged by various kinds of pathogens in their living environments
We found that the up-regulated genes greatly outnumbered the down-regulated ones in either rice–M. oryzae interaction, demonstrating that the majority of genes involved in rice early response to M. oryzae were positively regulated (Figure 2B)
After decades of study of rice–M. oryzae interactions, a number of blast resistance genes have been mapped and identified, and many have been successfully applied in the field

Summary

Introduction

Plants are frequently challenged by various kinds of pathogens in their living environments. PTI is mediated by pattern recognition receptors (PRRs) that recognize PAMPs, whereas ETI is mediated by resistance (R) proteins that recognize pathogen effectors. If fungal effectors are recognized by cognate rice R proteins, ETI is triggered and culminates in hypersensitive response (HR) that halt fungal growth within 48 hours. If fungal effectors are not recognized, a limited PTI response occurs upon the recognition of fungal PAMPs, such as chitin [9,10], and fungal hyphae continue to spread through plant tissues, leading to disease symptoms after days [5,11,12,13]. The early defense response immediately after M. oryzae invasion is critical to the final outcome of rice blast resistance

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Results

Conclusion