Abiotic stress such as drought seriously endangers maize growth and production. Glycine betaine (GB) accumulation in transgenic crops following heterologous overexpression of the BADH gene has been shown to dramatically improve the tolerance to salt, cold, and oxidative stresses, but it is unclear if GB accumulation leads to improved drought tolerance of maize. In this study, we analyzed the drought tolerance of high-generation BADH transgenic maize inbred lines at different growth stages using the hyperosmotic solution and water-withholding methods. Molecular detection revealed that exogenous BADH was successfully introduced into the maize plant genome and overexpressed in three transgenic maize inbred lines. Under osmotic stress, transgenic maize held better germination ability than the unmodified Dan988 (WT) line. In addition, transgenic maize contained higher levels of antioxidant enzymes and osmotic regulatory substances compared with WT, and thus accumulated less harmful substances and this alleviated the negative effects of drought. We used the membership function method to quantify the drought tolerance and found that Dan988-BADH-4 showed the best tolerance, followed by Dan988-BADH-2 and Dan988-BADH-1 while WT ranked lowest. This was consistent with the statistical analysis of the experiments. From the indoor and field survey, we observed that the agronomic traits of transgenic maize were not affected by the overexpression of BADH. In conclusion, BADH overexpression in maize is beneficial for drought tolerance and the three transgenic maize lines can be used for further breeding experiments.

中文翻译：

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过表达甜菜碱醛脱氢酶基因的高代转基因玉米自交系的耐旱性

干旱等非生物胁迫严重危及玉米的生长和生产。BADH 基因异源过表达后转基因作物中甘氨酸甜菜碱 (GB) 的积累已被证明可显着提高对盐、冷和氧化胁迫的耐受性，但尚不清楚 GB 积累是否会导致玉米的耐旱性提高。在这项研究中，我们使用高渗溶液和截水方法分析了高代 BADH 转基因玉米自交系在不同生长阶段的耐旱性。分子检测表明，外源 BADH 成功导入玉米植物基因组，并在三个转基因玉米自交系中过表达。在渗透胁迫下，转基因玉米比未修饰的 Dan988 (WT) 系具有更好的发芽能力。此外，与WT相比，转基因玉米含有更高水平的抗氧化酶和渗透调节物质，因此积累的有害物质更少，这减轻了干旱的负面影响。我们使用隶属函数方法对耐旱性进行量化，发现 Dan988-BADH-4 表现出最好的耐旱性，其次是 Dan988-BADH-2 和 Dan988-BADH-1，而 WT 排名最低。这与实验的统计分析一致。从室内和田间调查中，我们观察到转基因玉米的农艺性状不受BADH过表达的影响。综上所述，BADH在玉米中的过表达有利于耐旱性，三个转基因玉米品系可用于进一步的育种试验。