Transcriptional Regulation of the Acer truncatum B. Response to Drought and the Contribution of AtruNAC36 to Drought Tolerance

Abstract

Drought stress is one of the major environmental factors severely restricting plant development and productivity. Acer truncatum B, which is an economically important tree species, is highly tolerant to drought conditions, but the underlying molecular regulatory mechanisms remain relatively unknown. In this study, A. truncatum seedlings underwent a drought treatment (water withheld for 0, 3, 7, and 12 days), after which they were re-watered for 5 days. Physiological indices were measured and a transcriptome sequencing analysis was performed to reveal drought response-related regulatory mechanisms. In comparison to the control, the drought treatment caused a significant increase in antioxidant enzyme activities, with levels rising up to seven times, and relative electrical conductivity from 14.5% to 78.4%, but the relative water content decreased from 88.3% to 23.4%; these indices recovered somewhat after the 5-day re-watering period. The RNA sequencing analysis identified 9126 differentially expressed genes (DEGs), which were primarily involved with abscisic acid responses, and mitogen-activated protein kinase signaling. These DEGs included 483 (5.29%) transcription factor genes from 53 families, including ERF, MYB, and NAC. A co-expression network analysis was conducted and three important modules were analyzed to identify hub genes, one of which (AtruNAC36) was examined to clarify its function. The AtruNAC36 protein was localized to the nucleus and had a C-terminal transactivation domain. Moreover, it bounded specifically to the NACRS element. The overexpression of AtruNAC36 in Arabidopsis thaliana resulted in increased drought tolerance by enhancing antioxidant enzyme activities. These findings provide important insights into the transcriptional regulation mediating the A. truncatum response to drought. Furthermore, AtruNAC36 may be relevant for breeding forest trees resistant to drought stress.

Picea wilsonii NAC31 and DREB2A Cooperatively Activate ERD1 to Modulate Drought Resistance in Transgenic Arabidopsis

“…Previous studies reported that the functions of a large number of NAC TFs in different plant species were involved in various processes, including growth [6] and development processes [7] and abiotic stress responses, such as salt and drought resistance [8][9][10]. For example, the overexpression of RcNAC72 [11], ThNAC4 [12], FtNAC31 [10] and AtruNAC36 [13] could enhance drought tolerance in Arabidopsis, and GmNAC12 in Glycine max positively regulated plant tolerance to drought stress [14]. Plant survival rates were significantly improved in ANAC019-, ANAC055and ANAC072-overexpressing Arabidopsis lines compared to the wild type [15].…”