Maturation in fruits of clementine: biochemical and molecular analysis

Peel color is one of the main factors in quality of fresh citrus fruit. Clementine is a widespread citrus species with several mutants showing a delay in pigmentation and harvesting. In this work we analyzed some aspects of peel color evolution of two clementine clones, ‘Comune’ and one of its natural mutations, ‘Tardivo’, which differ by a delayed color-break and extended harvest period. Physical, chemical and molecular analyses were carried out on fruits of both genotypes during the maturation process.Previous study showed that the late ripening mutant did not modify the ripening characteristics as juice acidity and total soluble solid (TSS). However, biochemical and molecular analysis revealed marked differences in the flavedo regarding carotenogenesis and in the expression of genes involved in ethylene biosynthesis and perception. Also, carotenoid showed quantitative differences at biochemical and molecular level. In this study, further analyses were performed on the two genotypes. We observed that exogenous application of ethylene triggered a different response of the two clones to this hormone. Moreover, modifications at the level of the transcriptome were investigated by cDNA-AFLP analysis to search for differentially expressed genes in the flavedo of the two genotypes. The analysis added new information to better understand the complex ripening process in citrus.