Integrated Transcriptome and Metabolome Analyses Provided Insight into the Variation in Quality of Green Bamboo (Bambusa oldhamii) Shoots at Different Growth Stages

Green bamboo (Bambusa oldhamii) shoots are not only delicious but also highly nutritious. However, their palatability and quality changed significantly upon being unearthed, making them unsuitable for commercial sale and subsequently diminishing their market value. To clarify the mechanisms that regulate the quality of green bamboo shoots at different growth stages, we conducted a comprehensive analysis of the metabolome and transcriptome at the unearthed height of 0 cm (H0), 5 cm (H5), and 10 cm (H10). Metabolome analysis identified 149 differentially accumulated metabolites (DAMs) among H0, H5, and H10, primarily comprising phenolic acids, lipids and flavonoids. Metabolic pathways enriched by these DAMs included phenylpropanoid biosynthesis, phenylalanine metabolism, flavonoid biosynthesis, linoleic acid metabolism and alpha-linolenic acid metabolism. Further transcriptome analysis identified 2976 differentially expressed genes (DEGs) among H0, H5, and H10. Additionally, KEGG analysis indicated that these DEGs mainly enriched pathways associated with metabolic pathways, biosynthesis of secondary metabolites, and phenylalanine metabolism. We screened out 10 DEGs and 16 intermediate metabolites of these pathways. Furthermore, we identified six DEGs with expression patterns highly correlated with the content of lignin and the total flavonoids from H0 to H5 and H10. Finally, RT-qPCR analysis of six genes validated the transcriptome sequencing data. Our findings indicate significant quality variations in green bamboo shoots from H0 to H5 and H10. These variations are closely related to key genes involved in the synthesis of lignin and flavonoids, which result in the flavor and quality changes of green bamboo shoots from the belowground stage to unearthed stage.