Biochemical and transcriptomic analyses reveal different metabolite biosynthesis profiles among three color and developmental stages in ‘Anji Baicha’ (Camellia sinensis)

Abstract

BackgroundThe new shoots of the albino tea cultivar ‘Anji Baicha’ are yellow or white at low temperatures and turn green as the environmental temperatures increase during the early spring. ‘Anji Baicha’ metabolite profiles exhibit considerable variability over three color and developmental stages, especially regarding the carotenoid, chlorophyll, and theanine concentrations. Previous studies focused on physiological characteristics, gene expression differences, and variations in metabolite abundances in albino tea plant leaves at specific growth stages. However, the molecular mechanisms regulating metabolite biosynthesis in various color and developmental stages in albino tea leaves have not been fully characterized.ResultsWe used RNA-sequencing to analyze ‘Anji Baicha’ leaves at the yellow-green, albescent, and re-greening stages. The leaf transcriptomes differed considerably among the three stages. Functional classifications based on Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes enrichment analyses revealed that differentially expressed unigenes were mainly related to metabolic pathways, biosynthesis of secondary metabolites, phenylpropanoid biosynthesis, and carbon fixation in photosynthetic organisms. Chemical analyses revealed higher β-carotene and theanine levels, but lower chlorophyll a levels, in the albescent stage than in the green stage. Furthermore, unigenes involved in carotenoid, chlorophyll, and theanine biosyntheses were identified, and the expression patterns of the differentially expressed unigenes in these biosynthesis pathways were characterized. Through co-expression analyses, we identified the key genes in these pathways. These genes may be responsible for the metabolite biosynthesis differences among the different leaf color and developmental stages of ‘Anji Baicha’ tea plants.ConclusionsOur study presents the results of transcriptomic and biochemical analyses of ‘Anji Baicha’ tea plants at various stages. The distinct transcriptome profiles for each color and developmental stage enabled us to identify changes to biosynthesis pathways and revealed the contributions of such variations to the albino phenotype of tea plants. Furthermore, comparisons of the transcriptomes and related metabolites helped clarify the molecular regulatory mechanisms underlying the secondary metabolic pathways in different stages.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-016-0885-2) contains supplementary material, which is available to authorized users.

Biochemical and Comparative Transcriptome Analyses Reveal Key Genes Involved in Major Metabolic Regulation Related to Colored Leaf Formation in Osmanthus fragrans ‘Yinbi Shuanghui’ during Development

“…Under natural conditions, the chloroplast granum thylakoids of Camellia sinensis 'Anji Baicha' were poorly developed. The degradation of granum thylakoids, membrane structure, and lamellar structure hindered the biosynthesis of chlorophyll and carotenoids [12].…”

“…The mechanism underlying leaf color variation is complex and mainly related to chlorophyll, carotenoid, secondary metabolite synthesis, photosynthesis, and chloroplast development. Remarkably, the leaf color changes in the leaf mutant and senescence process are usually related to the chlorophyll metabolism pathway [11,12]. However, the change in leaf color during leaf senescence is later followed by leaf drop, and the leaf color in coloration mutants start with the initial stage of leaf color formation and would keep this color during leaf growth and development.…”

Genome-wide analysis of PYL-PP2C-SnRK2s family in Camellia sinensis

“…According to previous report, a total of three stages were defined in the development of new C. sinensis shoots, including the yellow-green (YG) stage, albescent (W) stage, and re-greening (G) stage [46]. The changes of leaf color involve a variety of metabolic pathways related to plant growth and development, which was affected by ABA signaling [1][2][3][4][5].…”

Lipidomics Analysis Reveals the Effect of Light Intensity on Lipid Metabolism and Leaf Color in Light-Sensitive Albino Tea Plant (Camellia Sinensis cv. Baijiguan)

“…She found that CLH, RCCR and SGR were signi cantly high expression in the golden bud, and their chlorophyll synthesis genes were inhibited, resulting in the insu cient chlorophyll content after 40 days of shading. The degradation of chlorophyll in Anji Baicha and Huabai 1 was accelerated and the leaves became white [14,15].…”