Drought tolerance in apple seedlings through abscisic acid (ABA) regulation

本文研究了阿坝8 ′-羟化酶（AHI）抑制剂对苹果幼苗耐旱性的影响。干旱条件下，阿坝代谢，气孔开度，水势，自由基清除活性的叶片进行了研究。结果表明，AHI处理后，幼苗叶片气孔开度明显降低，但浇水后，气孔开度又恢复到原来的水平。此外，在AHI处理的叶片水势仍然高于未处理的叶片在暴露于干旱。干旱条件下增加阿坝浓度，AHI处理的植物和未处理的植物标本。干旱条件下，AHI处理叶片中阿坝含量显著高于未处理叶片。虽然9-顺式环氧类胡萝卜素二氧合酶（MdNCED）基因的表达量随干旱胁迫天数的增加而增加，但在AHI处理的叶片中，这些基因的表达量显著低于未处理的对照样品，这些结果表明，植物在相对较长的干旱条件下存活可能需要通过阿坝8 '-羟化酶的调节来迅速关闭气孔。

In this study, we examined the effect of an inhibitor of ABA 8'-hydroxylase (AHI) on drought tolerance in apple seedlings (Malus domestica Borkh.). ABA metabolism, stomatal aperture, water potential, and radical scavenging activity in leaves were all investigated under drought conditions. The result of our observation had shown that the AHI application to seedlings greatly decreased the stomatal aperture in the leaves as in contrast to untreated control samples.However, watering of AHI treated plants re-increased it to the original level. In addition, water potential in AHI-treated leaves remained higher than the one measured in untreated-leaves during the exposure to drought. Drought conditions increased ABA concentrations in both, AHI treated-plants and untreated-plant specimens. Notably, ABA concentrations in AHI-treated leaves were higher than those in untreated-leaves under drought conditions. Although the expression of 9-cis-epoxycarotenoid dioxigenase (MdNCED) genes increased with days of drought stress treatment, in AHI-treated leaves the expression of those genes was significantly lower than in untreated control samples.These results suggest that the prompt stomatal closure through the regulation of ABA 8'-hydroxylase may be required for the plants to survive under relatively long drought conditions.