Comparative analysis of surface wax in mature fruits between Satsuma mandarin (Citrus unshiu) and ‘Newhall’ navel orange (Citrus sinensis) from the perspective of crystal morphology, chemical composition and key gene expression

• Published in: Food chemistry 2014-06, Vol.153, p.177-185
• Main Authors: Wang, Jinqiu, Hao, Haohao, Liu, Runsheng, Ma, Qiaoli, Xu, Juan, Chen, Feng, Cheng, Yunjiang, Deng, Xiuxin
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Citrus; Citrus fruits; Citrus sinensis; Citrus sinensis - chemistry; Citrus sinensis - genetics; Citrus sinensis - growth & development; Citrus sinensis - metabolism; Food toxicology; Fruit - genetics; Fruit - growth & development; Fruit - metabolism; GC–MS; Gene expression; Gene Expression Regulation, Plant; Medical sciences; Plant Proteins - genetics; Plant Proteins - metabolism; Toxicology; Wax; Waxes - chemistry; Waxes - metabolism
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2013.12.021

•More aldehydes and larger wax platelets were found in mature fruits of Newhall than Satsuma.•Lupeol and lupenone were identified for the first time in citrus fruit wax.•Epicuticular wax constitutes about 80% of total wax in Newhall.•CER3, CER6, CER1–3, MYB96 are key genes associated with the formation of wax in citrus fruit. Surface wax of mature Satsuma mandarin (Citrus unshiu) and ‘Newhall’ navel orange (Citrus sinensis) was analysed by crystal morphology, chemical composition, and gene expression levels. The epicuticular and total waxes of both citrus cultivars were mostly composed of aldehydes, alkanes, fatty acids and primary alcohols. The epicuticular wax accounted for 80% of the total wax in the Newhall fruits and was higher than that in the Satsuma fruits. Scanning electron microscopy showed that larger and more wax platelets were deposited on the surface of Newhall fruits than on the Satsuma fruits. Moreover, the expression levels of genes involved in the wax formation were consistent with the biochemical and crystal morphological analyses. These diversities of fruit wax between the two cultivars may contribute to the differences of fruit postharvest storage properties, which can provide important information for the production of synthetic wax for citrus fruits.