ABSTRACT
Stylosanthes species are economically important tropical and subtropical forage legumes which are generally vulnerable to chilling and frost. Fine-stem stylo (S. guianensis var. intermedia) has the most superior cold tolerance among all stylo species. A REVEILLE (RVE) gene, SgRVE6, was cloned from fine-stem stylo. Bioinformatic analysis suggests that SgRVE6 encodes a transcription factor of 292 amino acid residues, which belongs to the LATE ELONGATED HYPOCOTYL/CIRCADIAN CLOCK ASSOCIATED 1-LIKE (LCL) subgroup of RVE family and contains a SHAQKYF-class MYB domain and a LCL domain. SgRVE6 is universally expressed in root, stem and leaf tissues of fine-stem stylo and is rapidly up-regulated in all tested tissues under cold stress. Over-expressing SgRVE6 affects expression of 21 circadian clock genes, up-regulates expression of 6 nucleotide binding domain leucine-rich repeats (NB-LRR) encoding genes associated with tobacco cold tolerance, improves physiological responses to low temperature, and endows the transgenic tobaccos with higher tolerance to cold stress. This is the first time a study investigates the biological function of RVE6 in cold responses of plant species.
ABSTRACT
A full-length cDNA of phytoene desaturase (PDS) gene from Andrographis paniculata was obtained through RACE-PCR. The cDNA sequence consists of 2 224 bp with an intact ORF of 1 752 bp (GeneBank: KP982892), encoding a ploypeptide of 584 amino acids. Homology analysis showed that the deduced protein has extensive sequence similarities to PDS from other plants, and contains a conserved NAD ( H) -binding domain of plant dehydrase cofactor binding-domain in N-terminal. Phylogenetic analysis demonstrated that ApPDS was more related to PDS of Sesamum indicum and Pogostemon cablin. The semi-quantitative RT-PCR analysis revealed that ApPDS expressed in whole aboveground tissues with the highest expression in leaves. Virus induced gene silencing (VIGS) was performed to characterize the functional of ApPDS in planta. Significant photobleaching was not observed in infiltrated leaves, while the PDS gene has been down-regulated significantly at the yellowish area. To the best of our knowledge, this represents the first report of PDS gene cloning and functional characterization from A. paniculata, which lays the foundation for further investigation of new genes, especially that correlative to andrographolide biosynthetic pathway.
