Physiological and transcriptional evaluation of sweet sorghum seedlings in response to single and combined drought and salinity stress

Experiments were conducted to evaluate the physiological, biochemical and transcriptomic effects of single and combined drought and salinity stress on sweet sorghum seedlings in order to reveal the regulatory mechanism in sweet sorghum to abiotic stresses. This study was carried out under controlled conditions in a completely random design with factorial arrangements. Treatments included 4 levels (Control, Drought, Salt, Drought + Salt). Results indicated that the growth and photosynthesis of sweet sorghum seedlings were inhibited under the three examined stresses, especially the combined treatment had the strongest inhibitory effect. Large number of differently expressed genes (DEGs) involved in photosynthesis, hormone signaling regulation, trehalose metabolism, proline metabolism and the antioxidant system were identified by GO and KEGG enrichment analysis. These results suggested that sweet sorghum does not inconsistently respond to drought, salinity and combined treatment at physiological and transcriptional level. Sweet sorghum resists three stresses together by down-regulating photosynthesis, increasing antioxidant enzyme activity and increasing proline content, adapts to drought stress through trehalose biosynthesis and resists salinity and combined treatment by regulating phytohormone signaling. This research provides more insights into the regulatory mechanism in sweet sorghum to abiotic stresses. (c) 2021 SAAB. Published by Elsevier B.V. All rights reserved.