5-ALA诱导的黄酮醇积累参与调节苹果叶片气孔开度

以苹果离体叶片为材料，发现外源5-ALA处理可以诱导下表皮保卫细胞内黄酮醇含量显著上升。在5-ALA预处理抑制外源ABA诱导气孔关闭的同时，叶片保卫细胞ROS含量下降，而用外源槲皮素及山奈酚等黄酮醇预处理，也抑制了ABA诱导的苹果叶片气孔关闭，并且降低保卫细胞ROS含量。此外，槲皮素和山奈酚可以抑制外源H₂O₂诱导的苹果叶片气孔关闭。以上结果喻示，5-ALA诱导苹果叶片气孔开放与其上调保卫细胞中黄酮醇含量而后降低活性氧含量有关。

Flavonols Induced by 5-aminolevulinic Acid are Involved in Regulation of Stomatal Opening in Apple Leaves

Using diphenylboric acid 2-amino ethyl ester（DPBA），a flavonol fluorescent dye，and a laser scanning confocal microscope（LSCM），we found that an increase of flavonol fluorescence appeared in the guard cells of the abaxial epidermis of detached leaves of apple（Malus ´ domestica Korkh.‘Fuji’），especially around the nucleus，after 5-ALA pretreatment for 2–4 h. 5-ALA pretreatment also inhibited ABA-induced stomatal closure，which was inseparably related to the reduction of the reaction oxygen species（ROS）accumulation. Coincidently，pretreatment of quercetin or kaempferol，two kinds of natural flavonols，also inhibited stomatal closure induced by ABA，and meanwhile decreased ROS content in the guard cells of apple leaves. Furthermore，the exogenous flavonols eliminated the effect of H₂O₂ that induced stomatal closure in apple leaves. Together with these above，it can be deduced that 5-ALA-induced stomatal opening is associated with its up-regulation of flavonol levels in guard cells，which then eliminates ROS levels. Therefore，flavonols are involved in stomatal regulation induced by 5-ALA in apple leaves.