Abstract
To elucidate the transcriptomic regulation mechanisms that underlie the response of Ginkgo biloba to dehydration and rehydration, we used ginkgo saplings exposed to osmotically driven water stress and subsequent rewatering. When compared with a control group, 137, 1453, 1148, and 679 genes were differentially expressed in ginkgo leaves responding to 2, 6, 12, and 24 h of water deficit, and 796 and 1530 genes were differentially expressed responding to 24 and 48 h of rewatering. Upregulated genes participated in the biosynthesis of abscisic acid, eliminating reactive oxygen species (ROS), and biosynthesis of flavonoids and bilobalide, and downregulated genes were involved in water transport and cell wall enlargement in water stress-treated ginkgo leaves. Under rehydration conditions, the genes associated with water transport and cell wall enlargement were upregulated, and the genes that participated in eliminating ROS and the biosynthesis of flavonoids and bilobalide were downregulated in the leaves of G. biloba. Furthermore, the weighted gene coexpression networks were established and correlated with distinct water stress and rewatering time-point samples. Hub genes that act as key players in the networks were identified. Overall, these results indicate that the gene coexpression networks play essential roles in the transcriptional reconfiguration of ginkgo leaves in response to water stress and rewatering.
Highlights
Drought is one of the most critical environmental constraints that limit trees’ growth and productivity [1]
The Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis revealed that flavonoid biosynthesis and monolignol biosynthesis pathways were enriched in D2, D3, D4, R1, and R2 (Figure S2). These results indicated that flavonoid biosynthesis plays a pivotal role in the respo5nsoef t1o9 water stress and rehydration in ginkgo leaves
We found that Xyloglucan endotransglucosylase/hydrolase 9 (XTH9), Endoxyloglucan transferase A4 (EXGT-A4), expansin A1 (EXPA1)/13, and EXLA1 involved in turgor-driven cell wall enlargement [74,75] were down-expressed in the leaves of G. biloba when exposed to water deficit
Summary
Drought is one of the most critical environmental constraints that limit trees’ growth and productivity [1]. The impact of drought on molecular processes has been well studied in herbaceous plants and model woody species such as poplar [4,5]. Response to water deficit begins with signal perception, in which histidine kinase 1 (HK1) can function as a drought sensor in Arabidopsis [6]. Several genes encoding HSPs, LEAs, and enzymes involved in eliminating ROS are upregulated by dehydration in various plants [5,10]. Endogenous ABA rapidly accumulates upon dehydration, stimulating a signaling cascade that leads to downstream responses such as stomatal closure [12]. ABA-induced stomatal closure is efficient in reducing water loss and plant growth because of a reduction in transpiration and inhibition of CO2 uptake for photosynthesis [13]
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