弱光对不同生态型黄瓜幼苗光合速率及蔗糖代谢相关酶活性的影响

摘要

采用弱光敏感型S404和耐弱光S1两种不同生态型黄瓜自交系,在人工气候室内,研究了弱光对黄瓜幼苗糖代谢相关酶活性的影响,以期了解黄瓜苗期弱光响应的生理机制.结果表明,弱光处理可使黄瓜幼苗叶片净光合速率(Pn)、多糖含量、酸性转化酶(SAI)、中性转化酶(NI)、蔗糖磷酸合成酶(SPS)和蔗糖合成酶(SS)活性下降.随着弱光处理时间的延长,不同酶活性反应不一.其中,SAI和NI活性逐渐上升,而Pn和SPS活性则呈继续下降趋势.弱光下,S1叶片Pn和SPS活性降幅明显低于S404.总之,SAI和SPS是弱光响应的关键酶;SAI活性的恢复性上升,可能与黄瓜弱光适应性有一定关系,SPS活性的持续下降,与净光合速率的持续下降有关;在弱光下耐弱光品种叶片中蔗糖合成代谢相对较强,而弱光敏感型品种蔗糖裂解代谢相对较强.%Using two genotypes of cucumbers low light-sensitive S404 line and low light-tolerant S1 line as materials,we investigated their differences in the net photosynthetic rate(Pn) and sugar metabolism related enzymes activities under low light condition. The result showed that Pn,polysaccharide content,acid invertase(SAI) activities, neutral invertase (NI) activities, sucrose phosphate synthase (SPS) activities, and sucrose synthase (SS) activities of cucumber seedlings decreased. With the prolonging of low light treatment, different enzymes had differential reaction to low light,SAI and NI activities rose gradually,Pn and SPS activities dropped persistently. S1 leaves Pn and SPS activities obviously decreased less than S404. In eonclusion,SAI and SPS were key enzymes of low light response. The recovering rise of SAI activities may be related to low light adaptability of cucumber. The sustained decline of SPS activities was involved with that of Pn. Sucrose synthase metabolism in low light-tolerant cucumber lines was higher than that of low light-sensitive cucumber lines,while the latter had higher sucrose degradation metabolism than the former under low light condition.