RÉSUMÉ
Objective To explore the effect of γ-aminobutyric acid(GABA)on the growth and related physiological metabolism of plantlets of Tetrastigma hemsleyanum Diels et Gilg from Huaiyu Mountain under low temperature stress,which provides a basis for its application of anti-freezing and cold resistance in the wild-imitation cultivation of T.hemsleyanum Diels et Gilg from Huaiyu mountain.Methods Plantlets of T.hemsleyanum Diels et Gilg from Huaiyu Mountain,which were treated with GABA under low temperature stress,were selected as research objects.The growth indicators,physiological indexes,the relative expression levels of chalcone synthase and flavonol synthase genes were measured using plant tissue culture,physiological and biochemical methods and qRT-PCR,respectively.Results Compared with the control group without GABA,the proliferation coefficient,plant height,fresh weight,dry weight,and tissue water content of the two cultivated plantlets of T.hemsleyanum Diels et Gilg from Huaiyu Mountain("Huaiyu 1"and"Huaiyu 2")reach their maximum value when 0.5 g·L-1 GABA was added to the culture medium.Moreover,content of soluble protein(SP),soluble sugar(SS),proline(Pro),reduced glutathione(GSH),ascorbic acid(AsA),indole acetic acid(IAA),zeatin nucleoside(ZR),gibberellin(GA3),jasmonic acid(JA),the activity of superoxide dismutase(SOD),peroxidase(POD),ascorbic acid peroxidase(APX)and glutathione reductase(GR),and the relative expression level(RQ value)of chalcone synthase(CHS)gene were significantly increased.Moreover,relative conductivity,content of abscisic acid(ABA),hydrogen peroxide(H2O2),malondialdehyde(MDA),rate of O2·-production,and relative expression levels(RQ value)of flavonol synthase(FLS)gene were obviously decreased.The growth of plantlets of T.hemsleyanum Diels et Gilg from Huaiyu Mountain,which were treated with GABA under low temperature stress,was positively correlated with the contents of IAA,ZR,GA3,JA,SS,AsA,GSH,and the expression of CHS genes.Conclusion Appropriate concentration of GABA can regulate the contents of endogenous plant hormones and osmoregulation substances,antioxidant substances,and the expression of key genes in secondary metabolites,so as to promote the growth of plantlets of T.hemsleyanum Diels et Gilg from Huaiyu Mountain under low temperature stress.