SIMYB1 and SIMYB2, two new MYB genes from tomato, transcriptionally regulate cellulose biosynthesis in tobacco

摘要

cqvip:Cellulose,a major constituent of plant biomass,is synthesized by a cellulose synthase complex.It has been demonstrated that MYB genes transcriptionally regulate cellulose synthase in Arabidopsis.However,little is known about this process in tomato.Here,two MYB(SIMYB1/2) and three cellulose synthase(CESA)(SICESA4/5/6) genes were isolated.SIMYB1/2and SICESA4I5I6 accumulation was found to correspond to cellulose accumulation in different tissues of tomato.Dual luciferase assays indicated that these two MYSs were transcriptional activators that interact with promoters of SICESA4/5/6.Moreover,SIMYB2 could also activate promoters of SIMYB1/2,suggesting the possible underlying auto-activation mechanisms for MYB transcription factors.Transient over-expression of SIMYB1/2 in Nicotiana tabacum up-regulated tobacco endogenous NtCESA genes and increased cellulose accumulation.The function of SIMYB1/2 was further investigated using stable transformation and the results indicated that N.tabacum lines heterologous expressing SIMYB1/2 displayed a pleiotropic phenotype,long and narrow leaves,with NtCESA induced and significant increase of cellulose.In conclusion,our data suggest that tomato SIMYB1I2 have transcriptional regulatory roles in cellulose biosynthesis and SIMYB2 was more effective than SIMYB1,which may due to the transcriptional activation by SIMYB2 on SIMYB1 and itself.