Carotenoids are involved in many essential physiological functions and are produced from geranylgeranyl pyrophosphate through synthase,desaturase,and cyclase activities.In the pea aphid(Acyrthosiphon pisum),the duplic...Carotenoids are involved in many essential physiological functions and are produced from geranylgeranyl pyrophosphate through synthase,desaturase,and cyclase activities.In the pea aphid(Acyrthosiphon pisum),the duplication of carotenoid biosynthetic genes,including carotenoid synthases/cyclases(ApCscA-C)and desaturases(ApCdeA-D),through horizontal gene transfer from fungi has been detected,and ApCdeB has known dehydrogenation functions.However,whether other genes contribute to aphid carotenoid biosynthesis,and its specific regulatory pathway,remains unclear.In the current study,functional analyses of seven genes were performed using heterologous complementation and RNA interference assays.The bifunctional enzymes ApCscA-C were responsible for the synthase of phytoene,and ApCscC may also have a cyclase activity.ApCdeA,ApCdeC,and ApCdeD had diverse dehydrogenation functions.ApCdeA catalyzed the enzymatic conversion of phytoene to neurosporene(three-step product),ApCdeC catalyzed the enzymatic conversion of phytoene to ζ-carotene(two-step product),and ApCdeD catalyzed the enzymatic conversion of phytoene to lycopene(four-step product).Silencing of ApCscs reduced the expression levels of ApCdes,and silencing these carotenoid biosynthetic genes reduced the α-,β-,and γ-carotene levels,as well as the total carotenoid level.The results suggest that these genes were activated and led to carotenoid biosynthesis in the pea aphid.展开更多
基金This study was supported by the National Natural Science Foundation of China(32001908 and 32020103010)the Natural Science Foundation of Chongqing,China(cstc2020jcyj-msxmX0338)the Foundation Project of Southwest University(SWU019033).
文摘Carotenoids are involved in many essential physiological functions and are produced from geranylgeranyl pyrophosphate through synthase,desaturase,and cyclase activities.In the pea aphid(Acyrthosiphon pisum),the duplication of carotenoid biosynthetic genes,including carotenoid synthases/cyclases(ApCscA-C)and desaturases(ApCdeA-D),through horizontal gene transfer from fungi has been detected,and ApCdeB has known dehydrogenation functions.However,whether other genes contribute to aphid carotenoid biosynthesis,and its specific regulatory pathway,remains unclear.In the current study,functional analyses of seven genes were performed using heterologous complementation and RNA interference assays.The bifunctional enzymes ApCscA-C were responsible for the synthase of phytoene,and ApCscC may also have a cyclase activity.ApCdeA,ApCdeC,and ApCdeD had diverse dehydrogenation functions.ApCdeA catalyzed the enzymatic conversion of phytoene to neurosporene(three-step product),ApCdeC catalyzed the enzymatic conversion of phytoene to ζ-carotene(two-step product),and ApCdeD catalyzed the enzymatic conversion of phytoene to lycopene(four-step product).Silencing of ApCscs reduced the expression levels of ApCdes,and silencing these carotenoid biosynthetic genes reduced the α-,β-,and γ-carotene levels,as well as the total carotenoid level.The results suggest that these genes were activated and led to carotenoid biosynthesis in the pea aphid.
