Overexpression of BplERD15 Enhances Drought Tolerance in Betula platyphylla Suk.

Kaiwen Lv,Jing Jiang,Hairong Wei

doi:10.3390/f11090978

Kaiwen Lv, Jing Jiang + Show 1 more

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https://doi.org/10.3390/f11090978

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Abstract

In this study, we report the cloning and functional characterization of an early responsive gene, BplERD15, from Betula platyphylla Suk to dehydration. BplERD15 is located in the same branch as Morus indica Linnaeus ERD15 and Arabidopsis Heynh ERD15 in the phylogenetic tree built with ERD family protein sequences. The tissue-specific expression patterns of BplERD15 were characterized using qRT-PCR and the results showed that the transcript levels of BplERD15 in six tissues were ranked from the highest to the lowest levels as the following: mature leaves (ML) > young leaves (YL) > roots (R) > buds (B) > young stems (YS) > mature stems (MS). Multiple drought experiments were simulated by adding various osmotica including polyethylene glycol, mannitol, and NaCl to the growth media to decrease their water potentials, and the results showed that the expression of BplERD15 could be induced to 12, 9, and 10 folds, respectively, within a 48 h period. However, the expression level of BplERD15 was inhibited by the plant hormone abscisic acid in the early response and then restored to the level of control. The BplERD15 overexpression (OE) transgenic birch lines were developed and they did not exhibit any phenotypic anomalies and growth deficiency under normal condition. Under drought condition, BplERD15-OE1, 3, and 4 all displayed some drought tolerant characteristics and survived from the drought while the wild type (WT) plants withered and then died. Analysis showed that all BplERD15-OE lines had significant lower electrolyte leakage levels as compared to WT. Our study suggests that BplERD15 is a drought-responsive gene that can reduce mortality under stress condition.

Highlights

Drought stress is a severe environmental condition where plants are subjected to dehydration, resulting in loss in plant biomass productivity [1]
We found that BplERD15, BpeERD15, and MiERD15 had the closest distance and were clustered together
Tissue-specific expression analysis indicates that it has the highest expression level in mature leaves and the second highest expression in young leaves

Summary

Introduction

Drought stress is a severe environmental condition where plants are subjected to dehydration, resulting in loss in plant biomass productivity [1]. Various cellular signals are perceived and conveyed through multiple pathways, for example, ionic and osmotic steady-state signaling pathways, damage control and repair response pathways, and growth regulation pathways [4] Through these pathways, a series of physiological and biochemical reactions are activated or enhanced to produce gene products and various metabolites that can repair or prevent damages of cellular apparatuses, resulting in the survival in drought condition. Forests 2020, 11, 978 enzymes [5]; (2) The other category comprises regulatory proteins, for example, transcription factors, protein kinases, protein phosphatases, enzymes involved in phospholipid metabolism, and other signaling molecules such as calmodulin-binding protein [5] These drought responsive genes in general contain ABRE (ABA-responsive element) and DRE (dehydration-responsive element)/CRT (C-RepeaT) [6,7]. Promoter analysis of the ERD1 gene revealed that there is an ABRE-like cis-acting element that shares similarity to ABRE motif but does not respond to ABA

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