Fig 1.
Diagram of metabolic pathways involved in this study.
Note: Acetyl-CoA: acetoacetyl-coenzyme A. BCH: β-carotene hydroxylase gene. CCS: chromoplast-specific lycopene β-cyclase gene. CRTISO: carotenoid isomerase gene. DXP: 1-deoxy-D-xylulose-5-phosphate. CmDXR: 1-deoxy-D-xylulose-5-phosphate reductoisomerase gene. DXS: 1-deoxy-D-xylulose-5-phosphate synthase gene. FPP: farnesyl pyrophosphate. GAP: D-glyceraldehyde-3-phosphate. GGPP: geranylgeranyl diphosphate. IAA: indole-3-acetic acid. IPP: isopentenyl pyrophosphate. JA: jasmonic acid. LCYb: lycopene β-cyclase gene. LCYe: lycopene ε-cyclase gene. Lipid: lipid (pathway). MVA: mevalonic acid (pathway). MEP: methylerythritol 4-phosphate (pathway). NSY: neoxanthin synthase gene. PDS: phytoene desaturase gene. PEP: phosphoenolpyruvate. PSY: phytoene synthase gene. SA: salicylic acid. ZDS: ζ-carotene desaturase gene. ZEP: zeaxanthin epoxidase gene. ZISO: 15-cis-ζ-carotene isomerase gene. The red and italic abbreviations denote genes investigated in this study. The green in the filled frames denote compounds detected in this study.
Fig 2.
Developmental stages of ‘Chuhong’ and ‘Feicui’ pummelo (Citrus maxima) fruits.
Note: DPA: days postanthesis. The white ruler shown here is 5 cm in total length.
Fig 3.
Carotenoid profiles in the tissues of two pummelo fruits during development (μg/g DW).
Note: Columns represent the means (μg/g DW, n = 3) of the profiles of each carotenoid in the flavedo (A), albedo (B), SMs (segment membranes; C) and JS (juice sacs; D) in ‘CH’ and ‘FC’. a, b, c, etc. above each column indicate significant differences in carotenoid contents at the P<0.05 level among 5 stages of two pummelo fruits. DPA: days postanthesis. DW: dry weight.
Fig 4.
Limonin and nomilin contents (mg/g DW) in two pummelo fruits during development (A) as well as phytohormone contents (ng/g DW) at 150 DPA in two pummelo fruits (B).
Note: A, the data shown are the means±standard deviations (SDs) (n = 3). * indicates a significance level of P<0.05 between two pummelo fruits. B, the data shown are the means±SEs (n = 3). ABA: abscisic acid. DPA: days postanthesis. IAA: indole-3-acetic acid; JA: jasmonic acid; SA: salicylic acid. a, b above the columns indicate significant differences at the P<0.05 level. SM: segment membrane. JS: juice sacs.
Fig 5.
Carotenogenesis gene expression profiles in four tissues of ‘Chuhong’ and ‘Feicui’ pummelo fruits during different developmental stages.
Note: The data shown are the means±standard deviations (SDs) (n = 3). a, b, c, etc. above each column indicate significant differences at the P<0.05 level. SM: segment membrane. JS: juice sacs.
Table 1.
Alleles of carotenogenesis genes in different tissues of ‘Chuhong’ and ‘Feicui’ pummelo (Citrus maxima) fruits.