DRL1, Encoding A NAC Transcription Factor, Is Involved in Leaf Senescence in Grapevine.

Ziguo Zhu,Bo Li,Zhen Han,Guirong Li,Qingtian Zhang,Chaohui Yan,Li Liu

doi:10.3390/ijms20112678

Abstract

The NAC (for NAM, ATAF1,2, and CUC2) proteins family are plant-specific transcription factors, which play important roles in leaf development and response to environmental stresses. In this study, an NAC gene, DRL1, isolated from grapevine Vitis vinifera L. “Yatomi Rose”, was shown to be involved in leaf senescence. The quantity of DRL1 transcripts decreased with advancing leaf senescence in grapevine. Overexpressing the DRL1 gene in tobacco plants significantly delayed leaf senescence with respect to chlorophyll concentration, potential quantum efficiency of photosystem II (Fv/Fm), and ion leakage. Moreover, exogenous abscisic acid (ABA) markedly reduced the expression of DRL1, and the ABA and salicylic acid (SA) concentration was lower in the DRL1-overexpressing transgenic plants than in the wild-type plants. The DRL1 transgenic plants exhibited reduced sensitivity to ABA-induced senescence but no significant change in the sensitivity to jasmonic acid-, SA- or ethylene-induced senescence. Transcriptomic analysis and RNA expression studies also indicated that the transcript abundance of genes associated with ABA biosynthesis and regulation, including 9-cis-epoxycarotenoid dioxygenase (NCED1), NCED5, zeaxanthin epoxidase1 (ZEP1), ABA DEFICIENT2 (ABA2), ABA4, and ABA INSENSITIVE 2 (ABI2), was markedly reduced in the DRL1-overexpressing plants. These results suggested that DRL1 plays a role as a negative regulator of leaf senescence by regulating ABA synthesis.

Highlights

Aging is one of the most important physiological phenomena in biology, and in plants, the leaf is one of the organs most sensitive to senescence
Ethylene and jasmonic acid (JA) can promote plant senescence, and genes involved with the biosynthesis of ethylene (ET) and jasmonic acid (JA) were up-regulated following the exogenous application of the respective hormone [8,9]
These results show that the DRL1 gene may be involved in leaf senescence

Summary

Introduction

Aging is one of the most important physiological phenomena in biology, and in plants, the leaf is one of the organs most sensitive to senescence. Plant hormones play an important regulatory role in leaf senescence [1]. Abscisic acid (ABA) can promote plant senescence with exogenous ABA application inducing the expression of senescence-associated genes (SAGs) and ABA-synthesis genes such as NCED2, NCED3, AAO1, and AAO3 in Arabidopsis thaliana (L.) Heynh and can lead to premature leaf senescence [5,6,7]. Ethylene and jasmonic acid (JA) can promote plant senescence, and genes involved with the biosynthesis of ethylene (ET) and jasmonic acid (JA) were up-regulated following the exogenous application of the respective hormone [8,9]

Methods

Results

Discussion

Conclusion