Production And Characteristic Identification Of Sweetpotato(Ipomoea Batatas(L.)Lam.) Plants Overexpressing IbMIPS1 And IbMVD Genes

The function of IbMIPS1 and IbMVD genes isolated at our laboratory was characterized using the Agrobacterium tumefaciens-mediated transformation system and sweetpotato(Ipomoea batatas(L.)Lam.)cvs.Lizixiang and Xushu 18.1.Lizixiang and Xushu 18 transgenic plants overexpressing IbMIPS1 gene were developed with A.tumefaciens-mediated transformation.The transgenic plants exhibited significantly enhanced salt and drought tolerance and stem nematode resistance.Inositol,inositol-1,4,5-trisphosphate(IP3),phosphatidic acid(PA),Ca2+,abscisic acid(ABA),K+,proline and trehalose content and superoxide dismutase(SOD)and photosynthetic activities were significantly increased,whereas malonaldehyde(MDA),Na+ and H2O2 content were significantly decreased in the transgenic plants under salt and drought stresses.After stem nematode infection,the significant increase of inositol,IP3,PA,Ca2+,ABA,callose and lignin content and antioxidase activities and significant reduction of MDA content were found,a rapid increase of H2O2 levels was observed,peaked at 1 to 2 days and thereafter declined in the transgenic plants,and the number of cork cell was increased.Transcriptome and real-time quantitative PCR(qRT-PCR)analyses showed that overexpression of IbMIPS1 up-regulated the genes involved in inositol biosynthesis,phosphatidylinositol(PI)signalling pathway,ABA signalling pathway,stress responses,photosynthesis and ROS-scavenging system under salt,drought and stem nomatode stresses,which might lead to the enhanced resistance to salt,drought and stem nomatodes.2.The production of the IbMVD-overexpressing Lizixiang plants was achieved through A.tumefaciens-mediated transformation.Overexpression of IbMVD significantly increased carotenoids accumulation and enhanced tolerance to abiotic stresses and resistance to stem nematodes.ABA and proline content and SOD and photosynthetic activities were significantly increased,whereas MDA and H2O2 content were significantly decreased in the transgenic plants under abiotic stresses.After stem nematode infection,the significant increase of furano-sesquiterpenes,callose and lignin content and antioxidase activities and significant reduction of MDA content were found,a rapid increase of H2O2 levels was observed,peaked at 1 to 2 days and thereafter declined,and the number of cork cell was increased in the transgenic plants.Transcriptome and qRT-PCR analyses showed that overexpression of IbMVD significantly up-regulated the genes involved in mevalonate(MVA)pathway,carotenoids biosynthesis,ABA signalling pathway,stress responses,photosynthesis and ROS-scavenging system under abiotic stresses.After stem nematode infection,the genes involved in MVA pathway,sesquiterpenes biosynthesis,stress responses and antioxidative system were significantly up-regulated,which might lead to the increased content of carotenoids and the enhanced resistance to abiotic stresses and stem nomatodes.