Overexpression of Sweet Potato Carotenoid Cleavage Dioxygenase 4 () Decreased Salt Tolerance in .

Salt stress has a serious impact on normal plant growth and yield. Carotenoid cleavage dioxygenase (CCD) degrades carotenoids to produce apocarotenoids, which are involved in plant responses to biotic and abiotic stresses. This study shows that the expression of sweet potato was significantly induced by salt and dehydration stress. The heterologous expression of in Arabidopsis was induced to confirm its salt tolerance. Under 200 mM NaCl treatment, compared to wild-type plants, the rosette leaves of -overexpressing showed increased anthocyanins and carotenoid contents, an increased expression of most genes in the carotenoid metabolic pathway, and increased malondialdehyde (MDA) levels. -overexpressing lines also showed a decreased expression of resistance-related genes and a lower activity of three antioxidant enzymes: peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT). These results indicate that reduced salt tolerance in , which contributes to the understanding of the role of IbCCD4 in salt stress.