Minghuai 1 (MH1) is a yam (Dioscorea alata) cultivar with high tolerance to flooding but sensitivity to chilling. MH1 responded differently to chilling and flooding according to various physiological parameters and antioxidant enzymes. Flooding led to an increase in ascorbate peroxidase (APX) activity in both roots and leaves, while chilling did not affect APX activity. The full length DaAPX ORF sequence from MH1 (750 bp) was then cloned. Phylogenetic analysis showed that plant cytosolic APXs into four major clusters and DaAPX was closely related to Oncidium. The DaAPX gene driven by a 35S promoter was transferred into Arabidopsis. The gene expression and enzyme activity of APX in the DaAPX transgenic lines 1-3 were significantly higher than in wild type (WT) plants. Compared to WT plants, seedling growth characteristics were significantly better in all transgenic lines under chilling, flooding, and oxidative stresses, indicating that the overexpression of DaAPX in Arabidopsis enhanced tolerance to several abiotic stresses. MH1 plants supplied with H2O2 presented an increase in the activity of APX leading to enhanced tolerance to chilling. Functional characterization of the APX gene should improve our understanding of the chilling- and flood-response mechanism in the yam.

中文翻译：

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从山药（Dioscorea alata）中抗坏血酸过氧化物酶基因的克隆和过表达增强了转基因拟南芥的耐寒性和耐洪性。

Minghuai 1（MH1）是一种山药（Dioscorea alata）品种，对洪水具有较高的耐受性，但对寒冷敏感。MH1根据各种生理参数和抗氧化酶对寒潮和洪水的反应不同。淹没导致根和叶中抗坏血酸过氧化物酶（APX）活性增加，而低温并不影响APX活性。然后克隆了MH1的全长DaAPX ORF序列（750 bp）。系统发育分析表明，植物胞质APXs分为四个主要簇，DaAPX与Oncidium密切相关。由35S启动子驱动的DaAPX基因被转移到拟南芥中。DaAPX转基因株系1-3中APX的基因表达和酶活性显着高于野生型（WT）植物。与野生植物相比 在低温，水淹和氧化胁迫下，所有转基因品系的幼苗生长特征均明显好于其他植物，表明DaAPX在拟南芥中的过表达增强了对几种非生物胁迫的耐受性。供应有H2O2的MH1工厂增加了APX的活性，从而增强了其耐寒性。APX基因的功能表征应改善我们对山药冷潮反应机理的理解。