The Soybean GmNAC019 Transcription Factor Mediates Drought Tolerance in Arabidopsis in an Abscisic Acid-Dependent Manner

Abstract

Being master regulators of gene expression, transcription factors (TFs) play important roles in determining plant growth, development and reproduction. To date, many TFs have been shown to positively mediate plant responses to environmental stresses. In the current study, the biological functions of a stress-responsive NAC [NAM (No Apical Meristem), ATAF1/2 (Arabidopsis Transcription Activation Factor1/2), CUC2 (Cup-shaped Cotyledon2)]-TF encoding gene isolated from soybean (GmNAC019) in relation to plant drought tolerance and abscisic acid (ABA) responses were investigated. By using a heterologous transgenic system, we revealed that transgenic Arabidopsis plants constitutively expressing the GmNAC019 gene exhibited higher survival rates in a soil-drying assay, which was associated with lower water loss rate in detached leaves, lower cellular hydrogen peroxide content and stronger antioxidant defense under water-stressed conditions. Additionally, the exogenous treatment of transgenic plants with ABA showed their hypersensitivity to this phytohormone, exhibiting lower rates of seed germination and green cotyledons. Taken together, these findings demonstrated that GmNAC019 functions as a positive regulator of ABA-mediated plant response to drought, and thus, it has potential utility for improving plant tolerance through molecular biotechnology.

Heterologous Expression of a Soybean Gene RR34 Conferred Improved Drought Resistance of Transgenic Arabidopsis

“…In addition, our findings indicated that the ectopic expression of GmRR34 resulted in retarded growth in the transgenic plants under normal growth conditions ( Figure 1B-D). Previous studies also reported on similar phenotypic alteration in relation to improved drought tolerance/resistance when using constitutive 35S promoter to drive the expression of transgenes in various transgenic species, including Arabidopsis [40][41][42], tobacco [43,44], and tomato [45,46].…”

“…During drought events, in addition to the electron transport chain activities in the chloroplast, photorespiration which is caused by stomatal closure is another source for extensive ROS production, especially H 2 O 2 [66,67]. Therefore, endogenous H 2 O 2 levels and detoxification activities by enzymes are commonly measured as important parameters in drought tolerance studies [40,42]. As 14-day-drought duration used in the survival test would be too severe and thus cause difficulties in analyzing biochemical data due to protein degradation and plant death, we determined to use a shorter stress duration (i.e., 10 days) for these assays.…”

“…For checking transgene expression, well-watered samples of transgenic plants were used, along with WT as negative control. Total RNA isolation, cDNA synthesis and RT-qPCR were conducted following the methods previously described in Hoang et al (2020) [40]. Primers used in this experiment were obtained from previous studies ( Supplementary Table S1).…”

NAC Transcription Factors as Positive or Negative Regulators during Ongoing Battle between Pathogens and Our Food Crops

“…These genes had similar genomic organization and high sequence similarity, especially in the NAC domains, but exhibited different expression patterns during seed development [ 108 ]. Subsequently, more NAC proteins were identified in soybean [ 109 ], most of which are involved in development and abiotic stress, such as GmNAC30 [ 110 ], GmNAC81 [ 110 , 111 ], GmNAC109 [ 112 ] and GmNAC8 [ 113 ], while up to now only GmNAC42 is reported to be involved in plant disease resistance [ 114 , 115 , 116 ]. Soybean GmNAC42-1 is a homolog of the Arabidopsis ANAC042-1, which is an indole alkaloid plant antitoxin regulator.…”

Exogenous 1′,4′-trans-Diol-ABA Induces Stress Tolerance by Affecting the Level of Gene Expression in Tobacco (Nicotiana tabacum L.)

“…The promoter of ABA-responsive genes possesses ABA-responsive elements (ABRE), which can bind to ABRE-binding proteins (ABREBPs) and activate transcription under ABA stimulation [ 20 ]. In addition, several transcription factors (TFs) of the bZIP, MYB, MYC, NAC, ERF, WRKY, and DREB protein families regulate gene expression in an ABA-dependent manner [ 21 , 22 , 23 , 24 , 25 ]. Typically, ABA-induced genes primarily encode the proteins associated with dehydrins and the enzymes that detoxify reactive oxygen species, enzymes of compatible solute metabolism, a variety of transporters, protein kinases and phosphatases, and the enzymes involved in phospholipid signaling.…”