Genome-Wide Analysis of OPR Family Genes in Cotton Identified a Role for GhOPR9 in Verticillium dahliae Resistance.

Shichao Liu,Zili Feng,Yalin Zhang,Lihong Zhao,Hongjie Feng,Feng Wei,Xiaojian Zhang,Longfu Zhu,Heqin Zhu,Ruibin Sun

doi:10.3390/genes11101134

Abstract

The 12-oxo-phytodienoic acid reductases (OPRs) have been proven to play a major role in plant development and growth. Although the classification and functions of OPRs have been well understood in Arabidopsis, tomato, rice, maize, and wheat, the information of OPR genes in cotton genome and their responses to biotic and abiotic stresses have not been reported. In this study, we found 10 and 9 OPR genes in Gossypium hirsutum and Gossypium barbadense, respectively. They were classified into three groups, based on the similar gene structure and conserved protein motifs. These OPR genes just located on chromosome 01, chromosome 05, and chromosome 06. In addition, the whole genome duplication (WGD) or segmental duplication events contributed to the evolution of the OPR gene family. The analyses of cis-acting regulatory elements of GhOPRs showed that the functions of OPR genes in cotton might be related to growth, development, hormone, and stresses. Expression patterns showed that GhOPRs were upregulated under salt treatment and repressed by polyethylene glycol 6000 (PEG6000). The expression patterns of GhOPRs were different in leaf, root, and stem under V. dahliae infection. GhOPR9 showed a higher expression level than other OPR genes in cotton root. The virus-induced gene silencing (VIGS) analysis suggested that knockdown of GhOPR9 could increase the susceptibility of cotton to V. dahliae infection. Furthermore, GhOPR9 also modulated the expressions of jasmonic acid (JA) pathway-regulated genes under the V. dahliae infection. Overall, our results provided the evolution and potential functions of the OPR genes in cotton. These findings suggested that GhOPR9 might play an important role in cotton resistance to V. dahliae.

Highlights

In plants, jasmonic acid (JA) is a lipid-derived signaling phytohormone and activates defense against various stresses, such as insects, pathogen, salt, temperature, and wounding [1,2]
The different species oxo-phytodienoic acid reductases (OPRs) named were displayed in Supplemental Table S3
A total of 19 OPR genes were identified in G. hirsutum and G. barbadense, which were classified into three groups

Summary

Introduction

Jasmonic acid (JA) is a lipid-derived signaling phytohormone and activates defense against various stresses, such as insects, pathogen, salt, temperature, and wounding [1,2]. Jasmonic acid biosynthesis is originated from α-linolenic, followed by the function of lipoxygenase (LOX), allene oxide synthase (AOS), and allene oxide cyclase (AOC) to form 12-oxophytodienoic acid (OPDA) via the octadecanoic pathway [8,9,10]. OPRs are the key enzyme to catalyze the conversion from OPDA to 12-oxo-phytodienoic acid (OPC-8:0), a reaction that is a key process of JA biosynthesis [11,12]. OPR genes belong to the old yellow enzyme (OYE) family. They are categorized as flavin mononucleotide (FMN)-dependent oxidoreductases. The OPR was first purified from cell cultures of Corydalis sempervirens, and the first OPR homologous gene in a plant was cloned from Arabidopsis thaliana [13]. There were three OPR genes in A. thaliana: AtOPR1, AtOPR2, and AtOPR3

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Results

Discussion

Conclusion