Department of Biochemistry and Molecular Biology, Shahjalal University of Science and Technology, Sylhet, 3114, Bangladesh.
Plant Breeding and Biotechnology Laboratory, Department of Botany, University of Dhaka, Dhaka, 1000, Bangladesh.
BMC Plant Biol. 2022 Jul 4;22(1):316. doi: 10.1186/s12870-022-03708-4.
Aldehyde dehydrogenases (ALDHs) are a family of NAD(P) dependent enzymes that detoxify aldehydes by promoting their oxidation to respective carboxylic acids. The role of ALDH enzymes in various plant species has been extensively studied, revealing their critical role in salinity, drought, heat, and heavy metal stress tolerance. Despite their physiological significance, ALDH genes in Sorghum bicolor have yet to be studied thoroughly.
In this study, a total of 19 ALDH genes have been identified that have been grouped into ten families based on the criteria of the ALDH gene nomenclature committee. Segmental duplication assisted more in the enhancement of SbALDH gene family members than tandem duplication. All the identified SbALDH members made a cluster with monocot rice and maize in the phylogenetic tree rather than dicot species, suggesting the pre-eudicot-monocot separation of the ALDH superfamily members. The gene structure and protein domain were found to be mostly conserved in separate phylogenetic classes, indicating that each family played an important role in evolution. Expression analysis revealed that several SbALDHs were expressed in various tissues, developmental stages, and in response to abiotic stresses, indicating that they can play roles in plant growth, development, or stress adaptation. Interestingly, the majority of the SbALDH genes were found to be highly responsive to drought stress, and the SbALDH18B1 transcript showed maximum enhancement in all the stress conditions. The presence of cis-acting elements (mainly ABRE and MBS) in the promoter region of these genes might have a significant role in drought tolerance.
Our findings add to the current understanding, evolutionary history, and contribution of SbALDHs in stress tolerance, and smooth the path of further functional validation of these genes.
醛脱氢酶（ALDHs）是一组依赖 NAD（P）的酶，通过促进醛氧化为相应的羧酸来解毒醛。已经广泛研究了 ALDH 酶在各种植物物种中的作用，揭示了它们在盐度、干旱、热和重金属胁迫耐受中的关键作用。尽管它们具有生理意义，但高粱中的 ALDH 基因尚未得到充分研究。
在这项研究中，共鉴定出 19 个 ALDH 基因，根据 ALDH 基因命名委员会的标准将它们分为十个家族。片段复制比串联复制更有助于增强 SbALDH 基因家族成员。在系统发育树中，所有鉴定出的 SbALDH 成员都与单子叶水稻和玉米聚类，而不是双子叶物种，这表明 ALDH 超家族成员在真双子叶植物-单子叶植物分离之前就已经存在。基因结构和蛋白质结构域在不同的系统发育类群中被发现大多是保守的，这表明每个家族在进化中都起着重要作用。表达分析表明，几个 SbALDH 在各种组织、发育阶段以及对非生物胁迫的反应中表达，表明它们可以在植物生长、发育或胁迫适应中发挥作用。有趣的是，大多数 SbALDH 基因对干旱胁迫高度敏感，并且在所有胁迫条件下 SbALDH18B1 转录本的增强幅度最大。这些基因启动子区域中顺式作用元件（主要是 ABRE 和 MBS）的存在可能在耐旱性中起重要作用。
我们的研究结果增加了对 SbALDH 在胁迫耐受中的当前理解、进化历史和贡献，并为这些基因的进一步功能验证铺平了道路。
