The Role Of Trehalose Synthesis Pathway In Resisting Drought In Caragana Korshinskii Kom

Trehalose is a kind of non-reducing disaccharide,which can be used as a protectant for proteins and membranes under stress conditions.Accumulated trehalose enhance the tolerance of plants to various abiotic stresses and plays a special role in preserving biological vitality.Trehalose-6-phosphate synthase(TPS)and Trehalose-6-phosphate phosphatase(TPP)are the key enzymes in trehalose biosynthesis pathway,therefore the expression abundance of TPS and TPP genes directly affect the synthesis of trehalose and stress tolerance of plants.Caragana korshinskii.Kom is mainly distributed in the western region of Inner Mongolia,and plays an important role in sand-fixing and soil and water conservation,which has wide adaptability and strong resistance,ans is excellent fodder shrub in the desert and desert steppe zone.Therefore,it is very important to study the expression mechanism of CkTPS and CkTPP,and their function in response to abiotic stress.In this study,the expression feature and function of the CkTPS and CkTPP wereanalyzed using the sequences of CkTPS and CkTPPcloned in previous research.The results of real-time fluorescence quantitative PCR showed that the CkTPS and CkTPP were expressed in roots,stems and leaves of C.korshinskii with the higher expression in root than in stem and leave,and its expression was induced by PEG-simulated drought stress.The CkTPS promoter sequence was cloned by genomic walking,and sequence analysis revealed that the promoter region contains some cis-elements responding to plant hormones including methyl jasmonic acid,gibberellin and abscisic acid,as well as photoinducible elements.Heterologous expression of GUS reporter gene driven by CkTPS promoter in Arabidopsis thaliana showed that Pro.CkTPS:: GUS expressed in leaf of transgenic plants,its expression activity was induced by methyl jasmonic acid,gibberellin,abscisic acid and mannitol-simulated drought stress.RT-PCR analysis confirmed that these two foreign genes were stably expressed in transgenic lines,respectively.The drought resistance analysis showed that the transgenic A.thaliana plants overexpressing CkTPS and CkTPP showed preferable growth status than those of wild type,which have higher activities of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)and contents of proline and chlorophyll and lower content of malondialdehyde(MDA)under drought stress conditions,indicating overexpression of CkTPS and CkTPP increased drought tolerance of transgenic plants.The transcriptome analysis of C.korshinskii under PEG-simulated drought stress conditions showed that the different expression genes were mainly annotated in the pathways of photosynthesis,oxidative phosphorylation,carbon metabolism,a min o acid metabolism,lipid transport and metabolism,plant-pathogen interactions and phytohormone signal transduction including trehalose biosynthesis.The expression levels of CkTPS and CkTPP genes were significantly up-regulated under the drought stress conditions,which was consistent with the results of real-time PCR detection for CkTPS and CkTPP expression,indicating that the trehalose synthesis pathway plays an important role in resisting drought in C.korshinskii.These results provided theoretical and experimental basis for further studying expression regulation mechanism of the CkTPS and CkTPP,as well as in application of drought tolerant related genes of C.korshinskii to genetic improvement of plants in the future.