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Identification and functional characterization of three type III polyketide synthases from Aquilaria sinensis calli

Wang, Xiaohui, Zhang, Zhongxiu, Dong, Xianjuan, Feng, Yingying, Liu, Xiao, Gao, Bowen, Wang, Jinling, Zhang, Le, Wang, Juan, Shi, Shepo, Tu, Pengfei
Biochemical and biophysical research communications 2017
Aquilaria sinensis, Nicotiana benthamiana, abscisic acid, biosynthesis, cadmium chloride, callus, cell walls, cytoplasm, enzyme activity, genes, gibberellins, mannitol, methyl jasmonate, phylogeny, plant adaptation, polyketide synthases, polyketides, salicylic acid, salt stress, secondary metabolites, signal transduction
Type III polyketide synthases (PKSs) play an important role in biosynthesis of various plant secondary metabolites and plant adaptation to environmental stresses. Aquilaria sinensis is the main plant species for production of agarwood, little is known about the PKS family. In this study, AsCHS1 and two new type III PKSs, AsPKS1 and AsPKS2, were isolated and characterized in Aquilaria sinensis calli. The comparative sequence and phylogenetic analysis indicated that AsPKS1 and AsPKS2 belong to non-CHS group different from AsCHS1. The recombinant AsPKS1 and AsPKS2 produced the lactone-type products, suggesting different enzyme activities with AsCHS1. Three PKS genes had a tissues-specific pattern in A. sinensis. Moreover, we examined the expression profiles of three PKS genes in calli under different abiotic stresses and hormone treatments. AsCHS1 transcript was significantly induced by salt stress, AsPKS1 abundance was most remarkably enhanced by CdCl2 treatment, while AsPKS2 expression was most significantly induced by mannitol treatment. Furthermore, AsCHS1, AsPKS1 and AsPKS2 transcript were enhanced upon gibberellins (GA3), methyl jasmonate (MeJA), salicylic acid (SA) treatments, while three PKS genes displayed low transcript levels at the early stage under abscisic acid (ABA) treatment. In addition, three GFP:PKSs fusion proteins were localized in the cytoplasm and cell wall in Nicotiana benthamiana cells. These results indicated the multifunctional role of three type III PKSs in polyketide biosynthesis, plant resistance in abiotic stresses and signal transduction.