Metabolomics and transcriptomics analysis of vitro growth in pitaya plantlets with different LED Light spectra treatment

Dragon fruit or pitaya has important practical and economic value that is cultivated widely in the world. In order to meet the market demand for pitaya seedlings, vitro (tissue) culture is the most widely and practical technique, which cultivated in greenhouses and the intensity and quality of light is also important factor for plant photosynthesis. However, little information was obtained about the molecular and metabolite basis on the different light spectra (quality) cultivation conditions in pitaya seedlings. Therefore, metabolomics and transcriptomics analyses were conducted in this study, to explore the effects of different light quality and wavelength ratios on the growth of pitaya plantlets. The results have shown that different light spectra can significantly change the growth, physiological and morphological in pitaya plants. Red light significantly inhibited biomass, stem diameter, and cross-sectional area (CSA) of pitaya plantlets, while blue light can alleviate this inhibition, and 1 Red+ 2 Blue mixture light (1R2B) had the best effect on pitaya plants. Red light also promoted plant height, while blue light inhibited this phenomenon. In addition, the results also showed that the red light significantly influences primary metabolic processes in pitaya plantlets, including glucose metabolism and photosynthesis. And the expression of genes and accumulation of metabolites in these pathways were reduced by red light treatment, while blue light can change this negative pattern. Furthermore, the accumulation of sucrose, glucose, fructose, fructose-6-phosphate, fatty acid, and flavonoids were found to significantly increased in 1R2B treatment group of pitaya plantlets, which further regulation the tricarboxylic acid cycle (TCA cycle) pathway in the energy metabolism process. Therefore, the results suggested that the mixture light quality (1R2B) may be the best condition for the high-quality cultivation of pitaya seedlings in the present study.