Cloning And Expression Of Genes Related To Glycometabolism In Tea Plant (Camellia Sinensis(L,) O. Kuntze) Under Low Temperature

Many plant species were able to increase their low temperature tolerance by anacclimation to suboptimal temperature, the cold acclimation included accumulation of anabundant soluble sugar. Camellia sinensis（L.） O. Kuntze “Chanong98” cultivar, of whichthe tree type is between shrubbery and small arbors pattern, has bigger than intermediatedsize leaves. Trees are straight, branches are oblique. Leaves are prolate elliptic,lance-shaped and greenish-yellow. Camellia sinensis（L.） O. Kuntze “Yingshuang” cultivar,of which the tree type is small arbors pattern, has intermediated size leaves. Trees arelarger and straight, branches are moderately dense. Leaves are elliptic and greenish-yellow.In this study, we examined three key genes of glycometabolism at low temperature inthe two cultivars, i.e. sucrose-phosphate synthase （CsSPS）, trehalose-6-phosphatesynthase （CsTPS） and α-Glucosidase （Csα-Glucosidase）. In order to understand thephysiological and molecular mechanism of glycometabolism at low temperature, theexpression levels of genes in different organs, different stress-treated time at lowtemperature and different parts in Camellia sinensis（L.） O. Kuntze were measured byquantitative real-time PCR. The aim was to provide a new idea revealing thecold-resistant mechanism of tea plant. Meanwhile, in order to provide some theoreticalfoundation explaining the function of genes, the cDNA full-length of CsTPS andCsα-Glucosidase genes were firstly obtained by RACE technology, then the relations anddifferences of these two genes in tea plant and other species were found by bioinformaticsanalysis.Results indicated that differential expression of the three correlative glycometabolismgenes existed in different organs. The different parts of “Chanong98” and “Yingshunang”showed accordant changing trend when CsSPS and CsTPS were induced by lowtemperature. The expression level was higest when stressed for12h, but increasing time ofCsSPS was earlier than increasing time of CsTPS. The expression level ofCsα-Glucosidase was increasing in different parts of “Yingshuang”, however, theexpression level of Csα-Glucosidase was decreasing in different parts of “Chanong98”.The cDNA full-length of CsTPS was3125bp,and932animo acid were encoded. Theamino acid sequences of CsTPS consisted two conserved regions in TPS and TPP but nophosphatase boxes, so it belonged to classⅡTPS homologues. The cDNA full-length of Csα-Glucosidase was2915bp,and924animo acid were encoded. The amino acidsequences of Csα-Glucosidase consisted one conserved regions in Glyco_hydro₃1butonly sequence motif of Asp（224）, so it belonged to classⅡα-Glucosidase homologues.The two genes were both close to angiosperm, dicotyledon in homologus relation.These results of this study suggested that CsSPS and CsTPS were more sensitive tolow temperature than Csα-Glucosidase. The expression of level was relevant to the stresstime only. In addition, the three genes were related to accumulating soluble sugar, whichrespectively regulated the content of sucrose, trehalose and glucose. The expression levelof genes increased as the content of soluble sugar in plants increased. Accumulation ofsoluble sugar in plants is a key physiological index, so CsSPS, CsTPS andCsα-Glucosidase possibly played important roles in cold resistance for tea plants.