Isolation Of OsFAD6 And FAD Family Functions Under Low Temperature And Others Abiotic Stresses In Oryza Sativa L.

Unsaturated fatty acids are synthesized by fatty acid desaturase in plant, which play an important role in plant development and defense to abiotic stresses. The key enzyme, for the conversion of oleic into linoleic acid, was isolated from rice (Oryza sativa L.) and was named OsFAD6. The ORF length of OsFAD6 was 1365 bp, and it was predicted that OsFAD6 protein has 454 amino acids with an estimated molecular mass of 44.35 kDa and an isoelectric point of 9.24. The predicted OsFAD6 protein possessed a putative N-terminal plastidial signal peptide. There are three his-boxes in the protein, which were peculiar to membrane integrated fatty acid desaturase by Clustalx analysis. Mega 3.1 analysis showed that OsFAD6 were more homology to FAD6 of other species. RT-PCR analysis showed that OsFAD6 were expressed in all tissues in Oryza sativa L. seedlings, with maximum transcript accumulation in leaves. The mRNA abundance of OsFAD2 and OsFAD6 in leaves did not change under cold stress, however, the mRNA abundance of OsFAD7 and OsFAD8 increased in the same condition. It was also found that the expression of FAD family members had diurnal rhythm phenomena. Following experiments suggested that diurnal rhythm expression of OsFAD6 and OsFAD7 was related to changes of NADPH abundance. Plant protect themselves from cold by increasing their unsaturated fatty acids in cell membrane, therefore; FAD family member were transferred in rice (kasalath) with three promoters-OsFAD8-promoter and AtCor15a-promoter which were induced by cold and CaMV35-promoter which were constitutive expression to breed the cold-resistant rice variety. There are T2 seeds of some transgene lines now.