Aldehyde dehydrogenase superfamily of three <i>Cymbidium</i> orchids: genome-wide identification and response models to drought and salt stress

Aldehydes serve as intermediates in various metabolic processes, and their excessive accumulation can disrupt normal plant metabolic activities. Environmental stressors, including drought and salinity, can trigger the generation of reactive oxygen species (ROS), which results in elevated levels of aldehydes within plant cells. Aldehyde dehydrogenases (ALDHs) are recognized as key enzymes that act as 'aldehyde scavengers' capable of detoxifying the harmful aldehydes produced during oxidative stress conditions. Orchids constitute one of the largest families within angiosperms and possess significant economic value. However, genetic data for these non-model plants are limited, and the molecular mechanisms underlying orchid responses to abiotic stress remain poorly understood. In this study, we identified 17, 14, and 21 <italic>ALDH</italic> family members in three <italic>Cymbidium</italic> orchids: <italic>C. sinense</italic>, <italic>C. ensifolium</italic>, and <italic>C. goeringii</italic>, respectively. We conducted comprehensive analyses of their conserved domains, promoter elements, and collinearity relationships and predicted the interaction networks of ALDH proteins and microRNA binding sites in these three orchid species. Furthermore, we subjected <italic>C. sinense</italic> to drought and high salt-stress treatments and examined its expression patterns under these conditions using quantitative real-time PCR (qRT-PCR). Subcellular localization experiments were also performed on genes that exhibited significant responses to stress. Our findings provide valuable insights into the molecular mechanisms of stress resistance in orchids and contribute to a deeper understanding of their potential applications as ornamental plants.