Phytohormones And Abiotic Stresses Regulated FAD2

The modification of unsaturated fatty acid. levels had been found to accompany multiple abiotic stress acclimations in many plants. Arabidopsis delta 12 fatty acid desaturase (FAD2) encoded by gene At3g12120, is an ER-localized fatty acid fatty acid desaturase mediated conversion of oleic acid (18:1) to linoleic acid (18:2), which is essential for polyunsaturated lipid synthesis in plant cell. To better understand the relation of plant PUFA metabolism to stress adaptation, we examined the expression of FAD2 and fatty acid composition of Arabidopsis in response to abiotic stress and phytohormones.A 1423 bp promoter region upstream FAD2 had been isolated from Arabidopsis thaliana. The cis-regulatory DNA elements were analyzed using online PLACE tool. The DNA sequence of FAD2 promoter contain a lot of putative hormone or stress induced elements. To investigate the fine regulation of FAD2 in vivo, the promoter was fused to aβ-glucuronidase (GUS) reporter gene and the recombinant construct was introduced into Arabidopsis. Histochemical GUS staining results showed that the FAD2 promoter exhibited ubiquitous activities in Arabidopsis. In 2 week-old seedlings, Compared to the control, GUS activity driven by the FAD2 promote was suppressed with dark, 1μM ABA, 1μM 24-eBL and 10μM GA3 both in cotyledons and roots; whereas low temperature, 0.1 mM SA and 1μM IAA induced GUS activities in leaves but presented no detectable changes of GUS staining in roots. The FAD2 promoter was responsive to exogenous ABA, IAA, GA3,24-eBL and SA. However, the activities of FAD2 promoter could be modified with darkness, high or low-temperature, salt and sucrose.The GUS expression was reduced with increasing the concentration of SA; in contrast, lower concentration ABA (0.1μM to 2μM) or 24-eBL (0.01μM to 0.2μM) reduced GUS expression in root;whereas higher concentration ABA (10μM) or 24-eBL (1μM) treatment resulted an increasing in GUS expression in leaves and roots.Fatty acid composition analysis showed Arabidopsis plants accumulate increased linoleic acids content resulted from ABA, SA,24-eBL, NaCl, manitol and sucrose treatments. All these results indicated that FAD2 gene had a unique expression profile during growth and development in Arabidopsis and is influenced by multiple phytohormones and abiotic stresses, and was participated in abiotic stress responses.