Transcriptome Analysis of Drought-Resistant and Drought-Sensitive Sorghum (Sorghum bicolor) Genotypes in Response to PEG-Induced Drought Stress

Abstract

Drought is a major limiting factor of crop yields. In response to drought, plants reprogram their gene expression, which ultimately regulates a multitude of biochemical and physiological processes. The timing of this reprogramming and the nature of the drought-regulated genes in different genotypes are thought to confer differential tolerance to drought stress. Sorghum is a highly drought-tolerant crop and has been increasingly used as a model cereal to identify genes that confer tolerance. Also, there is considerable natural variation in resistance to drought in different sorghum genotypes. Here, we evaluated drought resistance in four genotypes to polyethylene glycol (PEG)-induced drought stress at the seedling stage and performed transcriptome analysis in seedlings of sorghum genotypes that are either drought-resistant or drought-sensitive to identify drought-regulated changes in gene expression that are unique to drought-resistant genotypes of sorghum. Our analysis revealed that about 180 genes are differentially regulated in response to drought stress only in drought-resistant genotypes and most of these (over 70%) are up-regulated in response to drought. Among these, about 70 genes are novel with no known function and the remaining are transcription factors, signaling and stress-related proteins implicated in drought tolerance in other crops. This study revealed a set of drought-regulated genes, including many genes encoding uncharacterized proteins that are associated with drought tolerance at the seedling stage.

Distinct Preflowering Drought Tolerance Strategies of Sorghum bicolor Genotype RTx430 Revealed by Subcellular Protein Profiling

“…Similarly, the dehydrin protein Sb09G018420, thioredoxin protein Sb03G036980, and glucose-1-phosphate adenylyltransferase Sb09G029610 were significantly >2-fold more abundant in our experiments and elsewhere [ 25 ]. We also observed a significant >2-fold increase in the AAA domain-containing protein Sb03G001130, and ribosomal L16 protein Sb01G036330 in cytosolic-enriched RTx430 and BTx642 during drought stress, consistent with observations in Abdel-Ghany et al, 2020 [ 26 ]. A cross reference of our observations with literature findings can be found in Supplemental Table S1 .…”

Physiological and Differential Proteomic Analyses of Imitation Drought Stress Response in Sorghum bicolor Root at the Seedling Stage

“…This protein has been proposed to contribute to membrane and protein stability, metal scavenging, and suppression of ROS-induced damage that occurs in plants exposed to water deficit [32,[73][74][75]. These findings together indicate that the abovementioned enzymes play key roles in protecting root cells from drought-induced oxidative damage.…”

“…Considering the importance of sorghum stress resistance, its resistance molecular mechanism research is of broad interest. Recently, Abdel-Ghany et al (2020) performed a transcriptome analysis in seedlings of sorghum genotypes by Polyethylene Glycol (PEG)-induced drought stress to identify the changes in gene expression that are unique to drought-resistant genotypes of sorghum and revealed a set of drought-regulated genes, including many genes encoding uncharacterized proteins that are associated with drought tolerance at the seedling stage [32]. This study reflects the molecular characteristics of sorghum resistance/tolerance to drought stress and give us useful transcriptome study data of sorghum response to water deficit.…”

Genome-Wide Association Study for Biomass Related Traits in a Panel of Sorghum bicolor and S. bicolor × S. halepense Populations

“…The remaining two major effect SNPs on chromosome 9 are associated to plant maturity: the physical distance between Chr9_58527007 ( R 2 = 5.4%) and Chr9_58584246 ( R 2 = 5.9%) is 57 Kb, indicating that they might be associated to the same functional gene; this gene dense region includes 10 transcripts, several of which have a possible functional correlation with maturity and biomass-related traits ( Supplementary Table 1 ). For instance, Sobic.009G249900 is the putative ortholog of rice jasmonic acid-amido synthetase JAR1 , which modulates light and JA signaling in the photomorphogenesis of rice and is involved in plant response to several stresses ( Riemann et al, 2008 ; Wakuta et al, 2011 ; Svyatyna et al, 2014 ); Sobic.009G250000 is a putative transcription factor of the basic Helix–Loop–Helix (bHLH) family; Sobic.009G250100 and Sobic.009G250500 lack functional annotations, but for the former a probable zinc-ribbon domain is reported suggesting a possible role as transcription factor; Sobic.009G250200 encodes a putative transmembrane amino acid transporter whose expression is down-regulated in response to drought stress ( Abdel-Ghany et al, 2020 ); Sobic.009G250300 is homolog to rice OsPAP10c, a secreted purple acid phosphatase (PAP) that by scavenging organic phosphorus (P) in the rhizosphere enhances the plant utilization efficiency of external organic P ( Lu et al, 2016 ); the product of Sobic.009G250400 has sequence homology to SIG5, a nuclear encoded σ 70 subunit of plastidial RNA polymerase that drives chloroplast transcriptional response to light intensity and the circadian clock ( Belbin et al, 2017 ); Sobic.009G250600 encodes a F-box protein and its role might therefore be related to protein degradation via the ubiquitin -proteasome pathway, with a wide variety of possible cytological, physiological and developmental effects ( Zhang et al, 2019 ); Sobic.009G250700 corresponds to a pentatricopeptide repeat (PPR) protein, a large family typically involved in the modulation of organellar gene expression, organelle biogenesis and function, with considerable effects on photosynthesis, respiration, plant development and environmental responses ( Barkan and Small, 2014 ); finally, Sobic.009G250800, the gene closest to SNP Chr9_58584246 (55 bp distant), encodes for a putative pectin lyase reported to be up-regulated in response to heat stress ( Johnson et al, 2014 ).…”