Summary The present study aims to examine fruit cell wall‐associated fruit softening in Lycium barbarum L. by the microstructure of the fruit cells and the changes in the contents of cell wall components, molecular weights of cell wall polysaccharides and the activities of related cell wall degrading enzymes at different development stages of L. barbarum L. fruit. Fruit firmness significantly declined during ripening, with the greatest reduction between the 28 and 35 days stages. The decrease in firmness correlated with an extensively deformed microstructure in the parenchyma tissues and positively correlated with reductions in the contents of fruit cell wall materials and molecular weight in cell wall polysaccharide. Cellulase, α‐galactosidase, polygalactosidase and pectin methylesterase showed higher activities during 28 days; whereas, the activities of β‐galactosidase were higher during 35 days. These results indicate that cell wall‐related processes are a key feature of early softening in L. barbarum L.

The isobaric tag for relative and absolute quantification (iTRAQ)-based proteomic approach was used to identify the key enzymes involved in the carotenoids accumulation from flowering to maturity stage of Lycium barbarum L. A total of 1,799 differentially expressed proteins were identified, and 190 were related to carotenoids metabolism. Six enzymes, including phytoene synthase, phytoene desaturase, zeta-carotene desaturase, P450 carotenoid beta-ring hydroxylase (LUT5), neoflavin synthase and nine-cis-epoxycarotenoid dioxygenase were found to be associated with the carotenoid accumulation during L. barbarum ripening by the proteomic analysis and qRT-PCR. The changes in the chromaticity and carotenoid contents during fruit ripening were also studied. The contents of carotenoid, except violaxanthin were strongly correlated with the expression levels of the key enzymes, and the colours were strongly correlated with the contents of carotenoid. This study may contribute to further investigations of the accumulation mechanism of carotenoids in L. barbarum.

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