Suppression of a Phospholipase D Gene,OsPLDβ1, Activates Defense Responses and Increases Disease Resistance in Rice

Takeshi Yamaguchi,Tomonori Shinya,Leona Kurimoto,Masaharu Kuroda,Hiromoto Yamakawa,Taketo Ashizawa,Kazuyuki Hirayae,Naoto Shibuya

doi:10.1104/pp.108.131979

Takeshi Yamaguchi, Tomonori Shinya + Show 6 more

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https://doi.org/10.1104/pp.108.131979

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Journal: Plant Physiology	Publication Date: Mar 13, 2009
Citations: 80	License type: CC BY 4.0

Affiliation: Meiji University

Abstract

Phospholipase D (PLD) plays an important role in plants, including responses to abiotic as well as biotic stresses. A survey of the rice (Oryza sativa) genome database indicated the presence of 17 PLD genes in the genome, among which OsPLDalpha1, OsPLDalpha5, and OsPLDbeta1 were highly expressed in most tissues studied. To examine the physiological function of PLD in rice, we made knockdown plants for each PLD isoform by introducing gene-specific RNA interference constructs. One of them, OsPLDbeta1-knockdown plants, showed the accumulation of reactive oxygen species in the absence of pathogen infection. Reverse transcription-polymerase chain reaction and DNA microarray analyses revealed that the knockdown of OsPLDbeta1 resulted in the up-/down-regulation of more than 1,400 genes, including the induction of defense-related genes such as pathogenesis-related protein genes and WRKY/ERF family transcription factor genes. Hypersensitive response-like cell death and phytoalexin production were also observed at a later phase of growth in the OsPLDbeta1-knockdown plants. These results indicated that the OsPLDbeta1-knockdown plants spontaneously activated the defense responses in the absence of pathogen infection. Furthermore, the OsPLDbeta1-knockdown plants exhibited increased resistance to the infection of major pathogens of rice, Pyricularia grisea and Xanthomonas oryzae pv oryzae. These results suggested that OsPLDbeta1 functions as a negative regulator of defense responses and disease resistance in rice.

Highlights

Phospholipase D (PLD) plays an important role in plants, including responses to abiotic as well as biotic stresses
We show that the knockdown of a rice PLD gene, OsPLDb1, resulted in the activation of defense responses and increased disease resistance in rice
We establish the knockdown plants for eight PLD genes in rice, OsPLDa1, -a3, -a4, -a5, -«, -b1, -b2, and -d2, which were listed in the database when we started this work, using RNA interference (RNAi)

Summary

Introduction

Phospholipase D (PLD) plays an important role in plants, including responses to abiotic as well as biotic stresses. The OsPLDb1-knockdown plants exhibited increased resistance to the infection of major pathogens of rice, Pyricularia grisea and Xanthomonas oryzae pv oryzae These results suggested that OsPLDb1 functions as a negative regulator of defense responses and disease resistance in rice. 1-butanol, which inhibits the generation of PA by PLD, suppressed the elicitor-induced ROS generation and phytoalexin production in rice cells (Yamaguchi et al, 2005) Based on these findings, it has been expected that PLD positively regulates defense responses in plants. On the contrary, Bargmann et al (2006) reported that xylanase elicitor-induced ROS generation was increased in PLDb-suppressed tomato cells These findings indicate that plant PLDs play important roles in defense signaling, most evidence remains circumstantial and the potential role of each PLD isoform is still obscure. There is no evidence for the involvement of PLDs in the disease resistance against pathogens

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