Profiling of ACC synthase gene (ACS11) expression in Arabidopsis induced by abiotic stresses

Abiotic stress induce the production of 1-aminocyclopropane-1-carboxylate (ACC), the precursor of ethylene by activating the enzyme ACC synthase. There are twelve ACC synthase genes reported in the genome of Arabidopsis, and the ACC synthase 11 (ACS11) gene encodes a polypeptide that is functional; however, its involvement in ethylene biosynthesis in response to abiotic stresses remains unclear. We evaluated the effects of higher ACC accumulation on A. thaliana seedlings in response to abiotic stressors such as flooding, salinity, cold, and drought. Transgenic plants were generated with ACS11 (ACS11-OX), and they demonstrated that overexpression of ACS11 reduces both root and shoot length observed in seedlings. RT-PCR analysis revealed that abiotic stressors induce the expression of the wild type ACS11 gene. Histochemical staining revealed that GUS activity followed the same time course as induction of wild type ACS11 gene expression, increased ACC levels, and production of stress hormone, ethylene. One finding showed that although induction of wild type ACS11 gene occurs under drought stress, GUS activity was highest at 6 h of drought stress and decreased to levels similar to control seedlings at 12 and 24 h. Thus, Wild type ACS11 expression is involved in ACC production, and abiotic stressors induce the expression of ACS11 gene. Moreover, ACC increases in response to abiotic stress lead to the production of ethylene. All of the data presented here suggest that the overexpression of ACS11 paves the way for the production of stress hormone, ethylene, which adversely affected the growth and development of the plant.