Integrated transcriptome and metabolome analysis reveals the physiological and molecular mechanisms of grape seedlings in response to red, green, blue, and white LED light qualities

Grape (Vitis vinifera L.) is an important fruit for which light quality plays a significant role in plant growth and development. However, the regulatory mechanisms between light quality and plant growth at the physiological and molecular levels are poorly understood. Therefore, in the present study, we performed multivariate sequencing analysis to investigate the effects of four light qualities: blue (B), red (R), green (G), and white (W, used as a control group) to investigate grapevine morphology at the molecular level, which revealed the possible networking pathway controlling grapevine growth. Our results showed that morphological and physiological parameters, such as plant height, stem diameter, leaf area, and the contents of total chlorophyll, chlorophyll a and b, and carotenoid, were significantly improved under blue and red light compared to those under white light. Photosynthetic measurements showed that the total conductance to water vapor, total conductance to water CO2, maximum quantum yield of photosystem (PS)II, apparent electron transfer chain, and net photosynthetic rate were elevated by blue and red light compared to white light. However, there were notable reductions in the intercellular CO2 concentration, transpiration rate, and non-photochemical quenching coefficient under blue light, which showed an irreversible trend compared to other light qualities. The contents of minerals, such as nitrogen, phosphorous, potassium, magnesium, iron, and zinc, were also improved by blue and red light compared to white light. Multivariate sequencing analysis revealed a total of 1065 metabolites, of which 747 were positive and 318 were negative. Gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses showed that many differentially expressed genes (DEGs) were associated with the biosynthesis of secondary metabolites, including flavones, flavonols, and alkaloids, and metabolic and phenylpropanoid pathways. Further, numerous transcription factors, including MYB (37 DEGs), bHLH (32 DEGs), NAC (31 DEGs), and WRKY (29 DEGs), were reported. Photosynthesis-related genes (PsaD, PsaO, PsbB, PetC, PetE, PetF, PetH, PetJ, and Lhca) played pivotal roles in the photosynthetic pathways. In addition, using weighed gene correlation network analysis, 7 module relationships (MEblack, MEgreenyellow, MEred, MEturquoise, MEgreen, MEyellow, and MEmagneta), 4 metabolites, 14 structural genes, and 36 transcription factor-related genes were found. Conclusively, the present research provides new insights for viticulture in response to light quality and offers new strategies for agriculture.