Biochemical and expression profiling of sorghum [Sorghum bicolor (L.) Moench] under salt stress
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Date
2021-04
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CCSHAU, Hisar
Abstract
Salinity induces complex metabolic processes that involve ion toxicity, osmotic stress, biochemical and physiological perturbations. Sorghum is a gluten-free cereal crop, well adapted to semi-arid tropics, highly biomass productive, and water-efficient. Therefore, the present study aimed to assess sorghum genotypes' tolerance behavior under different salinity levels (6, 8, 10, and 12 dSm-1) concerning the performance of physiological, biochemical, and molecular responses. Amongst 23 screened sorghum genotypes, SSG59-3 was identified as salt-tolerant and PC-5 as salt susceptible genotype based on germination studies. The results revealed that at 35 and 95 DAS, morpho-physiological parameters (RWC, OP, CF, CSI, total chlorophyll content) and growth traits (plant height, fresh and dry weight, root and shoot length) decreased with increasing salt concentration. The maximum decrease was observed in PC-5 as compared to SSG 59-3 at 10 dSm-1. PC-5 accumulated higher Na+and K+ content in roots while the exclusion potential of SSG 59-3 was more in roots, so it had minimum Na+ and K+ content. The quality traits viz. HCN, CP, IVDMD, CPY, DDM, and cell wall components (except HC, which decreased with plant maturity) also followed a similar pattern. SSG 59-3 maintained the higher GFY, DMY, and yield components at 10 dSm-1 (at physiological maturity). The imposition of salinity induces the activities of ROS scavenging enzymes viz. SOD, CAT, POX, APX, GPX, GR, MDHAR, and DHAR and the content of ROS scavenging metabolites viz. ascorbate, glutathione, and carotenoids which were maximum in SSG 59-3 while lower in PC-5 at 10 dSm-1. The oxidative stress as judged by accumulation of MDA and H2O2 content was maximum in PC-5 and minimum in SSG 59-3. A significant increase was observed in compatible osmolytes viz. proline, glycine betaine, and total carbohydrates, which was more pronounced in SSG 59-3 than PC-5 at 10 dSm-1. Analysis of the LFQ results using MASCOT software revealed more than 100 differentially expressed proteins, out of which 40 proteins were upregulated, 29 proteins were down regulated and the majority was involved in catalytic activity, binding proteins, metabolic inter-conversion enzymes and ion transporters. The relative expression of CIPK24, LEA3, BADH1 was highly upregulated at 10 dS m-1while NCED3, SNAC1, GPX, H+-PPase, and P5CS1 were up-regulated at 12 dS m-1. The fold change was maximum in SSG 59-3 while the expression level of transcripts was less in PC-5. Hence, SSG 59-3 seems physiologically and biochemically promising and may be exploited in plant breeding programs aimed at developing salt-tolerant sorghum genotypes.