Crosstalk between diurnal rhythm and water stress reveals an altered primary carbon flux into soluble sugars in drought-treated rice leaves

Abstract

Plants retain rhythmic physiological responses when adapting to environmental challenges. However, possible integrations between drought conditions and those responses have not received much focus, especially regarding crop plants, and the relationship between abiotic stress and the diurnal cycle is generally not considered. Therefore, we conducted a genome-wide analysis to identify genes showing both diurnal regulation and water-deficiency response in rice (Oryza sativa). Among the 712 drought-responsive genes primary identified, 56.6% are diurnally expressed while 47.6% of the 761 that are down-regulated by drought are also diurnal. Using the β-glucuronidase reporter system and qRT-PCR analyses, we validated expression patterns of two candidate genes, thereby supporting the reliability of our transcriptome data. MapMan analysis indicated that diurnal genes up-regulated by drought are closely associated with the starch-sucrose pathway while those that are down-regulated are involved in photosynthesis. We then confirmed that starch-sucrose contents and chlorophyll fluorescence are altered in a diurnal manner under drought stress, suggesting these metabolic diurnal alterations as a novel indicator to evaluate the drought response in rice leaves. We constructed a functional gene network associated with the starch-sucrose KEGG metabolic pathway for further functional studies, and also developed a regulatory pathway model that includes OsbZIP23 transcription factor.

Regulation of Agronomic Traits, Nutrient Uptake, Osmolytes and Antioxidants of Maize as Influenced by Exogenous Potassium Silicate under Deficit Irrigation and Semiarid Conditions

“…Soluble sugars are the second compatible osmolytes that were determined in this investigation. The accumulation of soluble sugars during water deficit irrigation could be due to the up-regulation of genes involved in the starch-sucrose pathway [52,53]. All of the above-mentioned responses may explain the dramatic accumulation of proline and soluble…”

Crop abiotic stresses and nutrition of harvested food crops: A Review of impacts, interventions and their effectiveness

“…Similar results have also been obtained (Mostajeran and Rahimi-Eichi, 2009). To the contrary, starch levels remained comparatively low at the end of the day, hinting at a possibility that changes in sugar and starch levels may playa roleas important indicators for drought response associated with diurnal rhythms in rice (Kim et al, 2017). The decrease in starch might have resulted from the starch degradation pathway that was elicited by water stress as also observed from transcriptomic analysis in tomatoes by Egea et al (Egea et al, 2018).…”

“…Moreover, after re-watering, both TSS and fructose concentration decreased, corroborating the suggestion. Recently, another study (Kim et al, 2017) has reported diurnal changes in starch and soluble sugars including sucrose, with soluble sugar contents tending to increase while starch decreased in response to drought stress, peaking during daytime. Similar results have also been obtained (Mostajeran and Rahimi-Eichi, 2009).…”

Systematic Analysis of Cold Stress Response and Diurnal Rhythm Using Transcriptome Data in Rice Reveals the Molecular Networks Related to Various Biological Processes

“…To understand the crosstalk between cold stress and circadian clock regulation, we used two different meta-expression datasets: Affymetrix array gene expression dataset for abiotic stresses (E-MEXP-2401, GSE16108, GSE18930, GSE21651, GSE24048, GSE25176, GSE26280, GSE33204, GSE37940, GSE38023, and GSE6901) and a diurnal dataset comprising Agilent 44K array gene expression data from 202 leaf samples collected from nine developmental stages (GSE36040). As previously described [ 111 , 112 ], public transcriptome data were downloaded from the GEO database [ 113 ]. After collecting the expression datasets, data were normalized with the Affy and Limma packages using the R programming language [ 114 , 115 ].…”