目的 揭示大齿牛果藤Nekemias grossedentata的抗旱生理响应机制。方法 以大齿牛果藤一年生植株为研究对象，采用盆栽控水实验，以正常浇水处理为对照，探究轻度、中度和重度干旱胁迫对其成熟叶光合特性、渗透调节物质与抗氧化酶活性的影响。结果 随干旱持续，叶相对含水量（relative water content，RWC）先升后降，干旱强度越大叶片失水越多。各处理光合参数随干旱程度加深而下降。净光合速率（net photosynthetic rate，Pn）、气孔导度（stomatal conductance，Gs）及蒸腾速率（transpiration rate，Tr）随干旱时间延长呈下降趋势，胞间CO₂（intercellular CO₂ concentration，Ci）呈先下降后上升趋势。叶绿素a（chlorophyll a，Chla）、叶绿素b（chlorophyll b，Chlb）及类胡萝卜素（carotenoids，Car）含量随干旱加剧及持续缓慢减少。叶片丙二醛（malondialdehyde，MDA）及渗透调节物质含量随干旱加剧而增加，随干旱持续呈先升高后降低趋势，14 d时达峰值。干旱诱导MDA积累，重度干旱下含量最高（16.18 nmol/g）；中、重度干旱脯氨酸（proline，Pro）含量较对照显著提高69.33%、79.37%；干旱14 d时轻中重度下可溶性蛋白（soluble protein，SP）含量较对照分别显著提高21.21%、34.51%、52.18%。抗氧化酶活性差异明显。超氧化物歧化酶（superoxide dismutase，SOD）活性随干旱持续呈现先升后降趋势，56 d时显著失活；过氧化物酶（peroxidase，POD）活性随干旱持续和加剧显著提升，56 d时分别升至22.73、23.06、24.30、25.05 U/(g·min)；过氧化氢酶（catalase，CAT）于胁迫中期表现活跃，前、后期活性较低。结论 大齿牛果藤在干旱胁迫下通过维持高的叶片RWC、调控Gs、Tr及Pn实现水分节约，同时积累MDA、Pro和SP，并协同上调SOD、POD、CAT活性以抵御氧化损伤。

Objective To reveal the drought resistance physiological response mechanism of the raw material plant for vine tea of Nekemias grossedentata. Methods Taking annual N. grossedentata plants as subjects, a pot-controlled water experiment wasconducted with normal watering as the control to investigate the effects of light, moderate, and severe drought stress on photosynthetic characteristics, osmotic adjustment substances, and antioxidant enzyme activity in mature leaves. Results With the aggravation of drought, the leaf relative water content (RWC) initially increased and then decreased, as higher drought intensity led to increased water loss from the leaves. The photosynthetic parameters of each treatment decreased as the drought deepened. The net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) decreased with the extension of drought time, but intercellular CO₂ decreased first and then increased. In addition, the contents of chlorophyll a (Chla), chlorophyll b (Chlb) and carotenoids (Car) decreased slowly with the increase of drought. The contents of Leaf malondialdehyde (MDA) and osmotic adjustment substances in leaves increased with the severity of drought, accumulated and reached the peak at 14 d, then decreased with the duration of drought. The content of MDA induced by drought was the highest under severe drought (16.18 nmol/g). Compared with the control group, the proline (Pro) content in moderate and severe drought was significantly improved by 69.33% and 79.37% respectively. Under 14 d of drought, the content of soluble protein (SP) was relatively enhanced by 21.21%, 34.51% and 52.18% respectively, compared with the control. Antioxidant enzyme activities varied: The activity of superoxide dismutase (SOD) first boosted and then weakened with the continuous drought, and was eventually inactivated at 56 d. But, the peroxidase (POD) activity boosted significantly with the continuous and intensified drought, reaching 22.73, 23.06, 24.30, and 25.05 U/(g·min) at 56 d, respectively. Catalase (CAT) was active mid-stress but low early/late. Conclusion Under drought stress, N. grossedentata achieved water conservation by maintaining high leaf RWC and regulating Gs, Tr, and Pn.. It also accumulates MDA, Pro, and SP, and synergistically upregulates SOD, POD, and CAT activities to resist oxidative damage.

R286.2

湖南省自然科学基金项目（2025JJ70626）