Abstract
The most daunting issue of global climate change is the deleterious impact of extreme temperatures on tea productivity and quality, which has resulted in a quest among researchers and growers. The current study aims to unravel molecular programming underpinning thermotolerance by characterizing heat tolerance and sensitivity response in 20 tea cultivars. The significantly higher negative influence of heat stress was recorded in a sensitive cultivar with reduced water retention (47%), chlorophyll content (33.79%), oxidation potential (32.48%), and increase in membrane damage (76.4%). Transcriptional profiling of most tolerant and sensitive cultivars identified 78 differentially expressed unigenes with chaperon domains, including low and high molecular weight heat shock protein (HSP) and heat shock transcription factors (HSFs) involved in heat shock response (HSR). Further, predicted transcriptional interactome network revealed their key role in thermotolerance via well-co-ordinated transcriptional regulation of aquaporins, starch metabolism, chlorophyll biosynthesis, calcium, and ethylene mediated plant signaling system. The study identified the key role of HSPs (CsHSP90) in regulating HSR in tea, wherein, structure-based molecular docking revealed the inhibitory role of geldanamycin (GDA) on CsHSP90 by blocking ATP binding site at N-terminal domain of predicted structure. Subsequently, GDA mediated leaf disc inhibitor assay further affirmed enhanced HSR with higher expression of CsHSP17.6, CsHSP70, HSP101, and CsHSFA2 genes in tea. Through the current study, efforts were made to extrapolate a deeper understanding of chaperons mediated regulation of HSR attributing thermotolerance in tea.
Highlights
IntroductionConsidering the high global demand, tea production is a major source of revenue in South-east Asian and African countries[3]
The tolerance and sensitivity of the cultivars were determined based on the level of leaf scorching, wherein, a heat-tolerant cultivar exhibiting ≤10% scorching of tissue with prolific flushing and no dormant shoots; while heat-sensitive cultivar showing ≥76% scorching with severe leaf defoliation and completely dormant shoots
Cultivar TV17 was categorized as the most heat tolerant (HT), while, C6017 was the most heatsensitive (HS) cultivar used for downstream elucidation of physiological and molecular insights of heat stress response in tea
Summary
Considering the high global demand, tea production is a major source of revenue in South-east Asian and African countries[3]. Climate-driven abiotic and biotic factors resulted in a significant reduction in the quality and global production of tea[4,5,6]. According to the intergovernmental panel on climate change (IPCC), global warming triggered by the greenhouse effect is one of the major threats to most of the tea-growing regions[7]. Current projections indicate that constantly raising ambient temperature may restrict the spatial distribution of tea cultivation by inhibiting its growth, yield, and quality in various tea-growing regions[9,10]. A sustainable increase in tea production requires intensified efforts through multi-targeted approaches to develop climateresilient tea cultivars with improved yield and quality
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