Comprehensive germplasm evaluation and transcriptome analysis reveal ABA signal transduction responses to dehydration stress in Centella asiatica germplasms

Dehydration is one of the main environmental stresses affecting the growth and quality of Centella asiatica . In this study, nine C. asiatica germplasms (namely C1-C9) were evaluated for their dehydration resistance. Twelve morphological, physiological and biochemical indicators were systematically determined in both control and PEG-8000-induced dehydration groups. Among the twelve indicators, ABA showed the strongest correlation with dehydration resistance across C. asiatica germplasms. Based on principal component analysis, membership function evaluation and cluster analysis, nine C. asiatica germplasms were divided into strong dehydration-resistant (C1 and C2), medium dehydration-resistant (C3, C6 and C9), and weak dehydration-resistant types (C4, C5, C7 and C8). C2 and C7 germplasms with different resistance levels were selected for transcriptome analysis. 338 overlapping differentially expressed genes (DEGs) were identified. KEGG analysis revealed that the DEGs were primarily enriched in pathways including plant-pathogen interaction, plant hormone signal transduction, phenylpropanoid biosynthesis, biosynthesis of secondary metabolites, and alpha-Linolenic acid metabolism. GO classification annotation showed that the DEGs were significantly enriched in cellular process, metabolic process, cellular anatomical entity, binding and catalytic activity categories. DEGs related to ABA signal transduction contribute substantially to the difference in dehydration resistance between the C2 and C7 germplasms. The qRT-PCR results were consistent with the gene expression trends from transcriptome sequencing. This study provides valuable insights into the physiological and molecular responses to dehydration stress among C. asiatica germplasms and identifies ABA signal transduction pathways, which may aid future breeding efforts for improved dehydration resistance.