Abstract
BackgroundDrought-tolerance ensures a crop to maintain life activities and protect cell from damages under dehydration. It refers to diverse mechanisms temporally activated when the crop adapts to drought. However, knowledge about the temporal dynamics of rice transcriptome under drought is limited.ResultsHere, we investigated temporal transcriptomic dynamics in 12 rice genotypes, which varied in drought tolerance (DT), under a naturally occurred drought in fields. The tolerant genotypes possess less differentially expressed genes (DEGs) while they have higher proportions of upregulated DEGs. Tolerant and susceptible genotypes have great differences in temporally activated biological processes (BPs) during the drought period and at the recovery stage based on their DEGs. The DT-featured BPs, which are activated specially (e.g. raffinose, fucose, and trehalose metabolic processes, etc.) or earlier in the tolerant genotypes (e.g. protein and histone deacetylation, protein peptidyl-prolyl isomerization, transcriptional attenuation, ferric iron transport, etc.) shall contribute to DT. Meanwhile, the tolerant genotypes and the susceptible genotypes also present great differences in photosynthesis and cross-talks among phytohormones under drought. A certain transcriptomic tradeoff between DT and productivity is observed. Tolerant genotypes have a better balance between DT and productivity under drought by activating drought-responsive genes appropriately. Twenty hub genes in the gene coexpression network, which are correlated with DT but without potential penalties in productivity, are recommended as good candidates for DT.ConclusionsFindings of this study provide us informative cues about rice temporal transcriptomic dynamics under drought and strengthen our system-level understandings in rice DT.
Highlights
Drought-tolerance ensures a crop to maintain life activities and protect cell from damages under dehydration
The drought-tolerant index based on the relative biomass (DTIB) ranged from 0.261 to 1.058 (Table 1)
We could divide the twelve genotypes into two groups of contrasting drought tolerance (DT) based on their DTIBs
Summary
Drought-tolerance ensures a crop to maintain life activities and protect cell from damages under dehydration. Among various mechanisms of drought resistance, drought tolerance (DT) ensures a plant to maintain its normal life activities under drought and protect plant cell away from damages of dehydration [8] It is compromised by diverse mechanisms (e.g. stomata conductance, osmotic adjustment, and protective molecules), which are temporally activated when a plant adapts to a naturally-occurred drought [8, 29]. The plant represents various acclimation responses (e.g. closure of stomata, leaf rolling, decrease in photosynthesis, inhibitions of growth and development) to reduce water loss and consumption [6, 11, 30, 43] It needs to activate protective mechanisms, such as antioxidant enzymes and molecular chaperones, to protect cell from damages of dehydration at middle-later drought [31, 44]. Learning temporal transcriptomic dynamics of a plant adapting to a long-term drought can deepen our understanding in drought tolerance
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