外源脯氨酸对低温胁迫下西藏野生垂穗披碱草幼苗生长和抗氧化酶相关基因表达的影响

本试验以西藏野生垂穗披碱草（Elymus nutans Griseb.）为研究对象，采用盆栽试验，研究叶面喷施外源脯氨酸（10 mM）对低温胁迫（4℃）下垂穗披碱草幼苗生长及抗氧化酶活性及其基因表达的影响。结果表明：低温胁迫下脯氨酸处理能够显著提高垂穗披碱草幼苗的根长、地上和地下鲜重、地上和地下干重，与低温胁迫相比分别增加27.11%，48.80%，48.83%，51.74%，38.87%；外源脯氨酸增加了低温胁迫下内源脯氨酸和可溶性糖的积累，分别增加42.96%和22.98%（P<0.05）；而且脯氨酸处理提高了APX、CAT、ChICu/ZnSOD、CytCu/ZnSOD基因的表达水平以及过氧化物酶（Peroxidase，POD）、过氧化氢酶（Catalase，CAT）、超氧化物歧化酶（Superoxide dismutase，SOD）和抗坏血酸过氧化物酶（Ascorbate peroxidase，APX）活性，降低了丙二醛（Malondialdehyde，MDA）含量和相对电导率水平（P<0.05）。综上所述，脯氨酸能够增强低温胁迫下垂穗披碱草幼苗的渗透调节能力及抗氧化酶活性，维持细胞膜的稳定性，缓解其生长抑制，从而提高垂穗披碱草的抗寒性。

Effects of Exogenous Proline on Growth and Antioxidant Enzyme Related Gene Expression of Elymus nutans under Low Temperature Stress

The wild Elymus nutans in Tibet was used as a test material,and 10 mM proline was sprayed on the leaves of E. nutans to investigate the physiological responses and the expression of antioxidant enzyme-related genes of plants in response to cold stress (4℃). The results showed that proline treatment significantly increased the root length (27.11%),aboveground fresh (48.80%) and dry weight (48.83%),and underground fresh and dry weight (51.74% and 38.87%) of E. nutans under low temperature stress (4℃). Meanwhile,pretreatment with proline increased proline and soluble sugar contents by 42.96% and 22.98% (P<0.05),respectively;increased the relative expression level of APX,CAT,ChICu/ZnSOD, and CytCu/ZnSOD genes. Antioxidant enzymes activities of POD,CAT,SOD,and APX were also improved (P<0.05) by proline treatment. Proline treatment led to a decrease in MDA accumulation and relative conductivity by 47.84% and 20.87%,respectively (P<0.05). In summary,these findings suggest that proline regulates the stability of cell membrane structure through enhancing the ability of osmotic adjustment and antioxidant defense activities,thereby improves the cold tolerance of E. nutans.