冬春季节低温伤害是影响茶树(Camellia sinensis)生产的重要因素。以茶树盆栽苗为试验材料, 通过喷施不同浓度的γ-氨基丁酸(GABA)、绿藻粉和竹醋液溶液, 研究低温胁迫下3种外源物质对茶树耐寒能力的影响, 并对蔗糖代谢关键基因SPS、SUS4、INV4和INV5表达量及耐寒相关生理指标进行分析, 解析外源物质影响茶树耐寒性的生理与分子机制。结果表明, 低温胁迫下, 用不同浓度GABA、绿藻粉和竹醋液喷施处理茶树盆栽苗叶片, 其冻害指数和相对电导率显著低于对照; 可溶性糖含量显著高于对照, 以10 mmol·L ^-1GABA、0.22 mg·mL ^-1绿藻粉及2.5 mg·mL ^-1竹醋液处理效果最佳。低温胁迫下, 与清水处理相比, 分别用10 mmol·L ^-1GABA、0.22 mg·mL ^-1绿藻粉或2.5 mg·mL ^-1竹醋液处理茶树盆栽苗后, 茶树苗丙二醛含量显著降低, 抗氧化酶活性显著提高; 叶片叶绿素、可溶性糖和脯氨酸含量显著增加, 蔗糖含量在处理72小时后分别增加了15.24%、11.39%和5.97%; SPS、SUS4、INV4和INV5基因的表达量显著升高。实验结果表明, GABA、绿藻粉和竹醋液能显著增强茶树的耐寒性。研究结果可为茶树抗寒剂的筛选提供理论依据。

In recent years, low temperature damage in winter and spring has become an important factor affecting tea production. We used tea tree (Camellia sinensis) potted seedlings to test the effect of GABA, chlorella powder and bamboo vinegar on sucrose-related gene expression (SPS, SUS4, INV4, INV5) and cold-tolerant related physiological indexes. Different concentrations of the three kinds of exogenous substances were sprayed on seedlings under cold stress. We analyzed the expression of SPS, SUS4, INV4 and INV5 of the key sucrose-coding genes as well as the physiological indexes related to cold tolerance to determine the possible physiological and molecular mechanisms of the effect of exogenous substance spraying on cold tolerance of tea trees. The frost index and relative conductivity were significantly lower after application of GABA, chlorella powder or bamboo vinegar than control values and the soluble sugar content was increased. The optimal application concentration for GABA, chlorella powder and bamboo vinegar was 10 mmol·L ^-1, 0.22 mg·mL ^-1 and 2.5 mg·mL ^-1, respectively. Malondialdehyde content was significantly decreased and antioxidant enzyme activity was increased; chlorophyll, soluble sugar and proline content was also increased. Sucrose content was increased by 15.24%, 11.39% and 5.97%, respectively, after 72 h treatment. The expression of SPS, SUS4, INV4 and INV5 in leaves was significantly increased with 10 mmol·L ^-1 GABA, 0.22 mg·mL ^-1 chlorella powder and 2.5 mg·mL ^-1 bamboo vinegar. Thus, GABA, chlorophyll powder and bamboo vinegar can significantly improve the cold tolerance of tea plants. We provide a theoretical basis for the cryoprotectant selection for tea plants.