Comparative Physiological, Biochemical and Transcript Response to Drought in Sorghum Genotypes

Abstract

Sorghum [Sorghum bicolor (L.) Moench] is considered as an important staple crop in the tropical regions. However, the productivity of this useful crop is hindered by drought which contributes to significant yield reduction. The present study aimed to decipher the effects of drought stress on physiological, biochemical and gene expression changes in sorghum genotypes and to ascertain the differences in their response to drought stress. To achieve these objectives, six sorghum genotypes were grown in pot culture in a greenhouse, in a randomized complete block design and exposed to water stress treatment for 10 days. From the study, drought stress caused a significant (P < .05) reduction in plant height, leaf water and chlorophyll contents while the proline, malondialdehyde (MDA), soluble sugar, electrolyte leakage (EL), hydrogen peroxide (H2O2) and antioxidant enzymes activity increased significantly (P < .05) and differentially in all sorghum genotypes. Among the genotypes investigated, PI 585456 showed enhanced performance and was considered as the most tolerant to drought in relation to plant growth and water relation, membrane status, photosynthetic activity, ROS and osmolytes accumulation and antioxidant enzymes activity. Furthermore, the transcript expression analyses of different categories of drought-responsive genes, viz; antioxidant-related, osmolytes biosynthesis-related, dehydrin-related, photosystem-related and transcription-related were differentially upregulated in sorghum genotypes investigated. The results revealed the differences in metabolic response to drought among the genotypes, which accentuated the physiological, biochemical and molecular mechanism related to a specific response that may play a vital role in drought tolerance in sorghum.

Sorghum in dryland: morphological, physiological, and molecular responses of sorghum under drought stress

“…The total chlorophyll content as well as chlorophyll a and b contents directly affect the plant capacity to absorb light for photosynthesis. Different studies have reported a significant reduction in chlorophyll content in sorghum grown under drought stress (Xu et al 2000 ; Reddy et al 2014 ; Fracasso et al 2016 ; Fadoul et al 2018 ; Amoah and Antwi-Berko 2020 ). For instance, there was 23% reduction in total chlorophyll content in a stay green genotypes and 75% reduction in senescent genotypes grown under drought stress conditions, compared to corresponding genotypes grown under control conditions (Xu et al 2000 ).…”

Recent advancements in the breeding of sorghum crop: current status and future strategies for marker-assisted breeding

“…The ability of the plant to absorb light for photosynthesis is directly influenced by the amount of total chlorophyll as well as chlorophyll a and b. Several investigations have found a considerable decrease in the amount of chlorophyll in sorghum cultivated under drought stress (Rama Reddy et al, 2014;Fracasso et al, 2016;Amoah and Antwi-Berko, 2020). When compared to equivalent genotypes grown under control conditions, the total chlorophyll content of stay-green genotypes underwent a 23% decline while senescent genotypes underwent a 75% reduction (Xu et al, 2000).…”

Drought Tolerance and Application of Marker-Assisted Selection in Sorghum

“…Drought stresses enhance the reaction of enzyme antioxidants; it has been reported that plants that produce more antioxidants have more chance of tolerating drought than those producing less antioxidants [ 67 ]. These findings indicate that activities of those enzymes increase in drought-stress-tolerant sorghum [ 68 ]. Such findings point out the need to further study the mechanism of antioxidant enzymes systems in relation to drought stress in sorghum.…”