The role of sucrose metabolizing proteins in hyperosmotic stress tolerance in sweet sorghum (Sorghum bicolor L. Moench)

Abstract

Sugar accumulation is a common metabolic response under drought stress conditions. However, studies on the underlying molecular mechanisms of sugar accumulation under stress remain restricted. This study explores the role of sucrose metabolizing proteins in conferring tolerance to drought-induced hyperosmotic stress, and ultimately osmotic adjustment in sorghum. The effect of stress on sugar content, enzyme activity and gene expression was investigated. Sweet sorghum varieties (ICSV213 and ICSB338) differing in levels of drought tolerance were subjected to a 10-day water deficit period. Brix plant sap analysis indicated elevated total soluble sugar levels under water stress conditions in both varieties with ICSV213 demonstrating a higher brix content than ICSB338. HPLC analysis gave a decrease in sucrose levels and an increase in glucose and fructose concentrations in both varieties with ICSV213 demonstrating higher hexose levels. Enzyme activity levels of invertase, sucrose phosphate synthase and sucrose synthase were found to increase under stress in both varieties with ICSV213 invertase displaying the highest activity when compared to other sucrose metabolizing enzymes. Transcriptional expression of invertase and sucrose phosphate synthase (SPS) genes was significantly up regulated in ICSV213 under stressed conditions, whereas sucrose synthase (Susy) levels remained low in both varieties. Data obtained for sorghum variety ICSV213 points towards a relationship between hyperosmotic stress tolerance and the accumulation of solutes and sucrose metabolism proteins. Consequently variety ICSV213 may therefore be an excellent target for future development of hyperosmotic stress tolerant sweet sorghum.

Terminal drought effect on sugar partitioning and metabolism is modulated by leaf stay-green and panicle size in the stem of sweet sorghum (Sorghum bicolor L. Moench)

“…The highest concentrations of glucose and fructose were recorded in the accession G10. Similar trend of variations for sucrose and hexoses was observed for two sorghum varieties (ICSV213, ICSB338) subjected to a post-anthesis drought through a pot experiment (Njokweni et al 2016).…”

Physiological and transcriptome analyses for assessing the effects of exogenous uniconazole on drought tolerance in hemp (Cannabis sativa L.)

“…In the present study, five SPS genes were regulated by uniconazole under drought stress (Supplementary Table S5 ). Previous studies have shown that sucrose synthase genes are regulated by drought stress, improving hyperosmotic stress tolerance of plants in relation to the accumulation of starch and sucrose metabolism proteins 46 . The present study described that two SuSy genes were differentially expressed in drought stress induced by uniconazole (Fig.…”

Study of Thermoplastic Extrusion and Its Impact on the Chemical and Nutritional Characteristics and Two Sorghum Genotypes SC 319 and BRS 332

“…The accumulation of sugar in sorghum varieties is related to defensive mechanisms in stress situations, which guarantees the metabolic activities of plant and grain development. 75 In the present study, phenolic acids predominant in sorghum grains were detected, including three cinnamic acids, caffeic acid (m/z 179), ρ-coumaric acid (m/z 165) and ferulic acid (m/z 193), in addition to the chlorogenic acid, caffeoylquinic acid (m/z 353), and its 3,5-di-O-caffeoylquinicacidmethylester derivative (m/z 535), and a benzoic acid, protocatechic acid (m/z 153). 76 Cinnamic acids are found whole or combined with other molecules such as glucose, esters and other acids, the most common being chlorogenic acid, a combination of quinic and caffeic acid.…”