Cloning and Expression of Stearoyl-ACP Desaturase and Two Oleate Desaturases Genes from Ginkgo biloba L.

Ginkgo (Ginkgo biloba L.) exhibits high level of resistance to various abiotic stresses, yet has undergone only minor morphological changes through millions of years. The conversion of membrane lipid components may play an important role in the temperature acclimation of plants. Stearoyl-ACP desaturase, microsomal omega-6 (Delta 12) desaturase, and plastidial omega-6 (Delta 12) desaturase are important enzymes in the unsaturated fatty acid biosynthetic pathway. In this study, full-length cDNA sequences of GbSAD, GbFAD2, and GbFAD6 were isolated from fresh leaves of ginkgo by rapid amplification of cDNA ends and polymerase chain reaction (PCR). Sequence analysis demonstrated that the cDNAs and deduced proteins had high similarity to other reported corresponding cDNAs and proteins. Real-time PCR revealed that transcripts of GbSAD and GbFAD2 in leaves were induced by cold stress (4 A degrees C, 15 A degrees C), but inhibited by high temperature (35 A degrees C, 45 A degrees C), whereas GbFAD6 is expressed constitutively at different temperatures.