FRUIT MATURATION AND QUALITY

Fruit quality depends on both appearance and organoleptic aspects, although this idea has been simplified from the commercial point of view to just fruit size. Fruit size and shape are achieved during fruit development, while color and organoleptic aspects depend on fruit maturation.

The general objective of our group is to use the Functional Genomics techniques to obtain and analyze new information about the physiological processes controlling fruit external and internal maturation and determining citrus fruit quality. The knowledge of the genes involved in fruit maturation and their expression control will allow the identification of the physiological processes capable of exogenous manipulation in order to improve fruit quality. In addition, these genes will offer valuable tools for future biotechnology approaches.

As a complement to the Functional Genomics studies, we are also applying conventional Molecular Biology techniques to study the expression of specific genes which are known to be directly involved in these processes: the genes involved in the color change (mainly those encoding chlorophyll and carotenoid metabolism enzymes) and the genes encoding sugar and water carriers and the enzymes involved in citric acid metabolism.

We pursue the following objectives:

1. Construction of cDNA libraries from different parts of clemenules fruits at different stages of maturation and development.

2. Preparation of an EST collection from the cDNA libraries and printing macro- and microarrays.

3. Identification of genes associated with external maturation by macro- and microarray analysis and study of their hormonal regulation.

4. Identification of genes associated with internal maturation by macro- and microarray analysis.

5. Expression analysis of the genes involved in peel color change (chlorophyllase, chlorophyll synthase, phytoene synthase and licopene b-cyclase) during external maturation and study of hormonal regulation.

6. Expression analysis of the genes involved in citric acid metabolism (citrate synthase and aconitase) and sugar and water carriers during internal maturation.