烟草赤星病胁迫对不同抗性品种光合特性和渗透调节的影响

摘要

以抗烟草赤星病品种净叶黄（JYH）和感病品种长脖黄（CBH）为材料，在盆栽试验条件下，研究不同烟草赤星病胁迫程度（轻度胁迫、中度胁迫和重度胁迫）对光合特性和渗透调节的影响。结果显示：⑴烟草赤星病胁迫导致2个品种的叶绿素a、叶绿素b、总叶绿素和类胡萝卜素含量均呈下降趋势，且JYH 的降幅小于CBH。⑵ JYH、CBH 的净光合速率、气孔导度因烟草赤星病胁迫而降低。2个品种的胞间CO2浓度、气孔限制值变化具有明显差异，烟草赤星病胁迫导致CBH 的胞间CO2浓度上升，气孔限制值则明显下降，这与JYH 在重度胁迫下的变化趋势一致。而JYH 的胞间CO2浓度在轻度、中度胁迫降低，气孔限制值则呈上升趋势。⑶与CBH 相比，JYH 在烟草赤星病胁迫下具有较高的脯氨酸和可溶性总糖含量，较低的MDA 含量。研究结果表明，JYH 具有较强的光合作用和渗透物质调节能力，是对烟草赤星病胁迫具有较强抗性的生理基础。%Responses of photosynthetic characteristics and osmotic regulation were studied under three different stress levels of tobacco brown spot at pot experiment condition, and two tobacco cultivars with different resistance to tobacco brown spot including a resistant cultivar Jingyehuang (JYH) and sensitive one Changbohuang (CBH) were selected as experimental material. Results showed that tobacco brown spot stress decreased chlorophyll a, chlorophyll b, total chlorophyll and carotenoids in the two cultivars. In addition, the decreased range of photosynthetic pigments was less in JYH than that in CBH. Both the net photosynthetic rate and the stomatal conductance were inhibited under tobacco brown spot stress. However, the net photosynthetic rate of JYH increased under mild stress whereas there was a decrease under moderate and severe stress. In the two cultivars, changes in intercellular CO2 concentration and stomatal conductance were divergent. The intercellular CO2 concentration in CBH tended to rise under the three stress levels, whereas the stomatal limitation value showed a significant decrease. In JYH under severe stress, the photosynthetic parameters consisting of both intercellular CO2 concentration and stomatal conductance showed the same trend as in CBH. However, in contrast with the rising trend of intercellular CO2 concentration under severe stress, the stomatal limitation value of JYH decreased under both mild and moderate stress. Compared with CBH, JYH showed higher content of total soluble sugar and proline and lower content of MDA under three stress levels. These results indicate that, JYH featured higher photosynthetic performance and betterosmotic adjustment, which formed the physiological basis for strong resistance to tobacco brown spot stress.