Overexpression of ScALDH21 gene in cotton improves drought tolerance and growth in greenhouse and field conditions

Aldehyde dehydrogenase (ALDH) is essential for scavenging redundant aldehydes when plants are exposed to stress. The aim of the present study was to validate the ectopic expression of the ScALDH21 gene, which is isolated from Syntrichia caninervis, an extremely drought-tolerant moss, to improve drought tolerance in cotton (Gossypium hirsutum L.). In our study, the ScALDH21-transformed cotton was identified via PCR, RT-PCR, and DNA gel blotting, and the growth and physiological characteristics related to drought tolerance were compared between the transgenic cotton (TC) and non-transgenic cotton (NT) grown in a greenhouse and in field conditions. The results indicated that TC accumulated approximately 11.8-304 % more proline than did NT under drought stress, and produced a lower concentration of lipid peroxidation-derived reactive aldehydes and had a higher peroxidase activity under oxidative stress. Moreover, TC showed reduced loss of the net photosynthetic rate compared with NT. Under field conditions, TC showed greater plant height, larger bolls, and greater cotton fiber yield than NT, but no significant difference in fiber quality between TC and NT following different water-withholding treatments. These results suggest that overexpression of ScALDH21 can greatly improve the drought tolerance of cotton without reduction in yield and fiber quality.