Identification and characterization of the MADS-box genes highly expressed in the laticifer cells of Hevea brasiliensis

Abstract

MADS-box transcription factors possess many functions in plant reproduction and development. However, few MADS-box genes related to secondary metabolites regulation have been identified. In H evea brasiliensis , natural rubber is a representative cis -polyisoprenoids in secondary metabolism which occurs in the rubber laticifer cells, the molecular regulation basis of natural rubber biosynthesis is not clear. Here, a total of 24 MADS-box genes including 4 type I MADS-box genes and 20 type II MADS-box genes were identified in the transcriptome of rubber tree latex. The phylogenetic analysis was performed to clarify the evolutionary relationships of all the 24 rubber tree MADS-box proteins with MADS-box transcription factors from Arabidopsis thaliana and Oryza sativa . Four type I MADS-box genes were subdivided into Mα (3 genes) and Mβ (1 gene). Twenty type II MADS-box genes were subclassified into MIKC* (8 genes) and MIKC c (12 genes). Eight MADS-box genes ( HblMADS3 , 5 , 6 , 7 , 9 , 13 , 23 , 24 ) were predominant expression in laticifers. ABA up-regulated the expression of HblMADS9 , and the expression of HblMADS3 , HblMADS5 , HblMADS24 were up-regulated by MeJA. The function of HblMADS24 was elucidated. HblMADS24 bound HbFPS1 promoter in yeast and HblMADS24 activated HbFPS1 promoter in tobacco plants. Moreover, we proposed that HblMADS24 is a transcription activator of HbFPS1 which taking part in natural rubber biosynthesis.

Genome-Wide Identification of MADS-Box Genes in Taraxacum kok-saghyz and Taraxacum mongolicum: Evolutionary Mechanisms, Conserved Functions and New Functions Related to Natural Rubber Yield Formation

“…A recent study also indicated that MADS-box genes were involved in the regulation of natural rubber (NR) biosynthesis. Rubber tree HblMADS24 binds to the promoter of HbFPS1 , a key enzyme-encoding gene involved in NR biosynthesis, and transcriptionally activates the HbFPS1 promoter, suggesting that HblMADS24 is a transcriptional activator of HbFPS1 [ 26 ]. HbMADS4 binds with the promoter of HbSRPP , and transient overexpression of HbMADS4 in tobacco was shown to repress the activity of the HbSRPP promoter significantly [ 27 ].…”