Transcriptome analysis of grape root to determine the regulatory network response to melatonin

Abstract

A root system, which serves as the cornerstone of a plant, is the organ system that initially perceives alterations in soil nutrient concentrations and water conditions. Plant hormones constitute highly significant determinants of root growth and development. To explore the response patterns of ‘Sapphire’, ‘Black Emperor’ and ‘Autumn Crisp’ grape (Vitis vinifera L.) roots to melatonin (MT), grape roots were treated with different concentrations of melatonin respectively. The results revealed that the effects of different MT concentrations were similar to those of different auxin concentrations within the range of 0.1, 0.3, and 0.5 mg·L−1 for IBA and IAA, which promoted root growth at low concentrations but inhibited root growth at high concentrations. Furthermore, compared with the control, 10 μmol·L−1 MT significantly promoted root growth and development by interacting with various endogenous hormones and signaling molecules and with phenols and anthocyanins in grape roots. RNA–seq analysis revealed that a total of 1,419 differentially expressed genes (DEGs) identified after MT treatment were enriched in 20 biological processes associated with secondary metabolism, including the biosynthesis of phenylpropanoids, nitrogen metabolism, plant hormone signal transduction, and galactose metabolism. In particular, 11 genes were significantly enriched in the resveratrol metabolic pathway, with 10 being upregulated from 2.93– to 9.19–fold compared with those in the control. Overall, these results suggested that MT promoted the growth and development of grape roots by regulating the levels of hormones and signaling molecules. Our findings revealed a novel role for MT in root growth and development, suggesting that several transcription-related metabolic pathways could be involved in hormone signaling. This study provided valuable information on root growth and development for the breeding of grape varieties.