| The trichomes of majority terrestrial plants are multicellular structures,which play important roles in resistance to biotic and biotic stresses.As sources of a large array of secondary metabolites,multicellular trichomes also have considerable economic value to many plants.In previous study,wo gene have been reported that are important for the trichome initiation.Wov is one of wo allele with two point mutations.Ectopic expression of Wov induce the expression of SlCycB2 and the increase of trichome density and branches in tomato and tobacco.Thus,Wov was considered through indirectly promote the expression of SlCycB2 to regulate the type ? trichome formation in tomato.However,in a recently paper,it was found that overexpression of SlCycB2 caused a non-trichome(include type ?)phenotype in the wild type of tomato.These contradicting results leave important questions unanswered--what is the function of SlCycB2 in trichome formation?What is the relationshipes between SlCycB2 and wo or Wov?In this study,we used Nicotiana benthamiana as a model,and demonstrated that NbCycB2 was positively regulated by Nbwo or NbWov through the binding target of the L1-like box in the NbCycB2 promoter.In addition,Nbwo and NbWov also regulate itself expression by binding at itself genomic DNA sequences.In contrast,NbCycB2 was suggested through repressing the transactivation activity of Nbwo and indirectly reduce the expression of Nbwo by competitive binding to its leucine zipper domain to repress trichome formation.While the mutations of Nbwo woolly motif can block the interaction and remove the repression of NbCycB2,which result in the notable increase of endogenous expression of Nbwo and the trichome density.In this study,Nbwo was aslo found to affect the development of cuticle by directly regulating the expression of NbMIXTA2 and NbMIXTA3.This result proved the relationship between multicellular trichomes and drought resistance in N.benthamina. |
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