Cloning and Characterization of Two FLOWERING LOCUS T-like Genes from Rubber Tree (Hevea brasiliensis)

Abstract

Two Flower locus T-like genes were isolated and characterized in rubber tree. Both of them were found to have conserved genomic characteristics of the phosphatidylethanolamine-binding protein family and their encoding proteins possess conserved key amino acid residues of FT. RT-qPCR results showed that HbFT1 was restricted in mature leaves, male and female flowers whereas HbFT2 showed the main expression in reproductive organs. Both of them can be induced by short-day conditions but with different expression patterns and regulated by temperature. Transgenic wild-type Arabidopsis can reduce the flowering time and change plant morphogenesis, with fewer rosette leaves and terminal inflorescence to some degrees, as well as the phenotype of ft-10 can also be successfully rescued by ectopic expressing each of them, respectively, suggesting that both of them can exert the function of AtFT. However, they displayed different seasonal-change expression patterns, with HbFT1 mainly accumulating in September for adult trees and in October for juvenile trees and HbFT2 transcript accumulating in March, which was the main floral initiation period, even though both of them showed higher transcript levels in adult trees than 2-year-old trees, implying their different biological functions during growth and development as well as flowering transition in rubber tree.