Banana fruit VQ motif-containing protein5 represses cold-responsive transcription factor MaWRKY26 involved in the regulation of JA biosynthetic genes.

Yu-Jie Ye,Yun-Yi Xiao,Zhong-Qi Fan,Jian-Ye Chen,Prakash Lakshmanan,Qun-Gang Xu,Yan-Chao Han,Jian-Fei Kuang,Wei Shan,Wang-Jin Lu

doi:10.1038/srep23632

Yu-Jie Ye, Yun-Yi Xiao + Show 8 more

Open Access

https://doi.org/10.1038/srep23632

Copy DOI

Abstract

Most harvested fruits and vegetables are stored at low temperature but many of them are highly sensitive to chilling injury. Jasmonic acid (JA), a plant hormone associated with various stress responses, is known to reduce chilling injury in fruits. However, little is known about the transcriptional regulation of JA biosynthesis in relation to cold response of fruits. Here, we show the involvement of a Group I WRKY transcription factor (TF) from banana fruit, MaWRKY26, in regulating JA biosynthesis. MaWRKY26 was found to be nuclear-localized with transcriptional activation property. MaWRKY26 was induced by cold stress or by methyl jasmonate (MeJA), which enhances cold tolerance in banana fruit. More importantly, MaWRKY26 transactivated JA biosynthetic genes MaLOX2, MaAOS3 and MaOPR3 via binding to their promoters. Further, MaWRKY26 physically interacted with a VQ motif-containing protein MaVQ5, and the interaction attenuated MaWRKY26-induced transactivation of JA biosynthetic genes. These results strongly suggest that MaVQ5 might act as a repressor of MaWRKY26 in activating JA biosynthesis. Taken together, our findings provide new insights into the transcriptional regulation of JA biosynthesis in response to cold stress and a better understanding of the molecular aspects of chilling injury in banana fruit.

Highlights

Low temperature is a major environmental stress that disrupts cellular homeostasis, and severely impairs plant growth and development
Homology search showed that the gene shared the highest identity with AtWRKY26 (53%), one of the 72 WRKY transcription factor (TF) of Arabidopsis thaliana, so it was designated as MaWRKY26 (Musa acuminata WRKY26)
Similar to AtWRKY26 and AtWRKY33, MaWRKY26 has two WRKY domains that contain the highly conserved amino acid sequence WRKYGQK and two putative zinc-finger motif (C-X4-CX23–24-H-X1-H) (Fig. 1B). These results clearly demonstrate that MaWRKY26 encodes a WRKY protein belonging to Group I family

Summary

Introduction

Low temperature is a major environmental stress that disrupts cellular homeostasis, and severely impairs plant growth and development. Little information is available about WRKY TFs in non-model plants, especially in economically important fruit crops Phytohormones such as abscisic acid (ABA), gibberellic acid (GA), ethylene and jasmonate (JA) have been shown to modulate cold stress responses[8]. A pair of allelic genes OsWRKY45-1 and OsWRKY45-2 play opposite roles in rice-bacteria interactions as OsWRKY45-1 modulates SA and JA levels whereas OsWRKY45-2 affects only JA levels[31] These investigations demonstrate that transcriptional regulation is an important mechanism in controlling JA synthesis in response to biotic stress. It is unknown whether and how JA biosynthesis is transcriptionally modulated by WRKY TFs under abiotic stresses, such as cold. The findings presented here reveal new insights on the transcriptional regulation of JA biosynthesis in response to cold stress in banana fruit

Methods

Results

Conclusion