酸黄瓜对南方根结线虫抗性的光合响应

摘要

[目的]酸黄瓜对南方根结线虫具有高度抗性,明确其抗性的光合响应特性,为进一步抗性基因的分离及功能鉴定提供理论依据.[方法]采用温室盆栽苗期人工接种技术,研究线虫侵染对抗、感黄瓜叶片光合作用、叶绿素荧光参数及相关生理指标的影响.[结果]线虫侵染使抗病材料酸黄瓜叶绿素(Ch1)含量降低幅度显著小于感病材料北京截头,酸黄瓜Ch1随氮素含量降低较北京截头平缓；抗、感材料净光合速率(Pn)、气孔导度(Gs)下降,酸黄瓜胞间C02浓度(Ci)下降,而北京截头Ci上升,酸黄瓜Gs对叶片相对含水量(RWC)持续下降的反应较北京截头敏感；实际光化学效率(φrsⅡ)、光化学猝灭系数(qP)降低幅度酸黄瓜小于北京截头,非光化学猝灭系数(qN)升高幅度酸黄瓜显著高于北京截头；酸黄瓜Pn/Ci初始斜率变化不大,而北京截头Pn/Ci急剧降低.[结论]酸黄瓜叶绿素含量下降较小,从而保持了较高的净光合速率,使线虫侵染对酸黄瓜植株生长造成的影响不大.%[Objective] Sour cucumber shows a high resistance to the root-knot nematode Meloidogyne incognita. To make clear on the photosynthetic responsive characteristics of its resistance will provide a theoretical basis for isolation and functional identification of resistance gene. [Method] The effects of nematode infection on photosynthesis, chlorophyll fluorescence parameters and physiological indices related of cucumber leaves resistant and susceptible to M. incognita were investigated by using seedling inoculation in greenhouse. [Result] Nematode infection induced a significantly lower decrease of cucumber leaf chlorophyll (Chl) content in resistant Sour cucumber than in susceptible Beijingjietou. Decreased extents of Chi content with nitrogen content reduction in Sour cucumber leaves were less than in Beijingjietou. Net photosynthetic rate(Pn), stomatal conductance (Gs) decreased in two varieties leaves after nematode infection, intercellular CO2 concentration (Ci) of leaves decreased in Sour cucumber, while its value have a sharp rise in Beijingjietou. Gs reduction in response to relative water content (RWC) declining in Sour cucumber leaves was more sensitive than Beijingjietou. Nematode infection led to a lower reduction of actual photochemical efficiency (Opsn) and photochemical quenching (qP), while induced a significantly higher increase of non-photochemical quenching (qN) in Sour cucumber than in Beijingjietou. Nematode infection has little effect on the initial slope of Pn/Ci in Sour cucumber, leaving a sharp decrease in Beijingjietou. [Conclusion] The results indicated that there is a lower decrease of chlorophyll content in Sour cucumber, so as to maintain a higher net photosynthetic rate in resistant compared with susceptible ones. All these did not cause significant effect on the plant growth of Sour cucumber.