Molecular cloning and characterization of three novel subtilisin-like serine protease genes from Hevea brasiliensis

Subtilisin-like serine proteases play important roles in a variety of biological functions. In this study, three novel subtilisin-like serine protease genes (HbSPA, HbSPB, and HbSPC) were isolated from Hevea brasiliensis leaves treated with salicylic acid using RT-PCR followed by RACE. HbSPA, HbSPB and HbSPC genes encode polypeptides consisting of 766, 748, and 748 amino acids, respectively, which belong to members of the subtilisin-like serine protease family from plants. Semi-qRT-PCR revealed that HbSPA was expressed in Hevea leaf, stem, hypocotyl, and root, whereas HbSPB and HbSPC were also expressed in the latex. qRT-PCR demonstrated that the expression of HbSPA was significantly induced during P. palmivora infection and slightly induced by wounding, while the expression of HbSPB or HbSPC was notably suppressed during P. palmivora infection and highly induced by salicylic acid treatment. Our results implied that HbSPA might be involved in rubber tree defense mechanisms against P. palmivora.