Abstract
Jatropha (Jatropha curcas) is a promising oil-seed crop for biodiesel production. However, the species is highly sensitive to waterlogging, which can result in stunted growth and yield loss. To date, the molecular mechanisms underlying the responses to waterlogging in Jatropha remain elusive. Here, the transcriptome adjustment of Jatropha roots to waterlogging was examined by high-throughput RNA-sequencing (RNA-seq). The results indicated that 24 h of waterlogging caused significant changes in mRNA abundance of 1968 genes. Comprehensive gene ontology and functional enrichment analysis of root transcriptome revealed that waterlogging promoted responses to hypoxia and anaerobic respiration. On the other hand, the stress inhibited carbohydrate synthesis, cell wall biogenesis, and growth. The results also highlighted the roles of ethylene, nitrate, and nitric oxide in waterlogging acclimation. In addition, transcriptome profiling identified 85 waterlogging-induced transcription factors including members of AP2/ERF, MYB, and WRKY families implying that reprogramming of gene expression is a vital mechanism for waterlogging acclimation. Comparative analysis of differentially regulated transcripts in response to waterlogging among Arabidopsis, gray poplar, Jatropha, and rice further revealed not only conserved but species-specific regulation. Our findings unraveled the molecular responses to waterlogging in Jatropha and provided new perspectives for developing a waterlogging tolerant cultivar in the future.
Highlights
Waterlogging is an adverse abiotic stress that can heavily damage crop production worldwide
WATERLOGGING STRESS TRIGGERED TRANSCRIPTOME READJUSTMENT IN JATROPHA ROOTS In our observation, we found that long-term waterlogging in young Jatropha seedlings resulted in leaf chlorosis (Supplementary Figure S1A) and reduction of total root carbohydrate content (Supplementary Figure S1B)
We found waterlogging induced the expression of low oxygen responsive marker genes, alcohol dehydrogenases (ADHs) and pyruvate decarboxylase (PDC) in roots, but not in leaves (Supplementary Figure S2)
Summary
Waterlogging is an adverse abiotic stress that can heavily damage crop production worldwide. Due to the limited diffusion of gas under water, waterlogging creates low oxygen (hypoxia) environments in the root areas, causing a shortage of ATP from the inhibition of oxidative phosphorylation. Upon experiencing long-term waterlogging stress (WS), stomatal closure can lead to impaired root hydraulic conductivity, thereby reducing the photosynthetic rate and the nutrient and water uptake of the plant. A decrease in leaf photosynthetic rate and a decline in carbohydrate concentration in both leaves and roots were observed in waterlogged Jatropha (Gimeno et al, 2012). Despite these lines of evidence, the molecular mechanism underlying the waterlogging response in Jatropha remains unknown
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