Molecular cloning and expression of a novel MYB transcription factor gene in rubber tree.

MYB family proteins regulate a variety of cellular processes in plants. Tapping panel dryness (TPD) in rubber tree (Hevea brasiliensis Muell. Arg.) affects latex biosynthesis and causes serious losses to rubber producers. In this study, a novel SANT/MYB transcription factor gene down-regulated in TPD rubber tree, named as HbSM1, was isolated from rubber tree. The complete HbSM1 open reading frame (ORF) was 948 bp in length. The deduced HbSM1 protein is 315 amino acids. HbSM1 belonged to 1RMYB subfamily with a single SANT domain. Sequence alignment revealed that HbSM1 had high homology with MYB members from Ricinus communis and Manihot esculenta, with 72 and 78 % identity, respectively. Moreover, HbSM1 shared 56 % identity with Glycine max GmMYB176. Phylogenetic analysis revealed that HbSM1, GmMYB176, rice OsMYBS2, and OsMYBS3 fell into the same cluster with 93 % bootstrap support value. Comparing expression among different tissues demonstrated that HbSM1 was ubiquitously expressed in all tissues, but it appeared to be preferentially expressed in leaf and latex. Furthermore, HbSM1 transcripts were significantly induced by various phytohormones (including gibberellic acid, ethephon, methyl jasmonate, salicylic acid, and abscisic acid) and wounding treatments. These results suggested that HbSM1 might play multiple roles in plant development via different phytohormones signaling pathways.