HbMADS4, a MADS-box Transcription Factor from , Negatively Regulates .

In plants MADS-box transcription factors (TFs) play important roles in growth and development. However, no plant MADS-box gene has been identified to have a function related to secondary metabolites regulation. Here, a MADS-box TF gene, designated as , was isolated from by the yeast one-hybrid experiment to screen the latex cDNA library using the promoter of the gene encoding small rubber particle protein (HbSRPP) as bait. was 984-bp containing 633-bp open reading frame encoding a deduced protein of 230 amino acid residues with a typical conserved MADS-box motif at the N terminus. was preferentially expressed in the latex, but little expression was detected in the leaves, flowers, and roots. Its expression was inducible by methyl jasmonate and ethylene. Furthermore, transient over-expression and over-expression of HbMADS4 in transgenic tobacco plants significantly suppressed the activity of the promoter. Altogether, it is proposed that HbMADS4 is a negative regulator of which participates in the biosynthesis of natural rubber.