Hormonal cross talk between fruit and seed throughout development and ripening in peach

Field observations and few physiological studies pointed out that peach embryogenesis and fruit development are strictly related. In fact, attempts to stimulate partenocarpic fruit development by means of external tools failed. Moreover, physiological disturbances during the early embryo development lead to seed abortion and fruitlet abscission. Later on, the interactions between seed and fruit development become less stringent. Genetic and molecular information about seed and fruit development in peach is limited and coming exclusively from a microarray approach. The identification of genes differentially expressed in seed and fruit was done by means of a comparative analysis of the transcription profiles carried out in peach seed and mesocarp throughout development using the first peach microarray (µPEACH 1.0). It has been shown that the transcription factor families (TFs) more involved were the MADS-box, AUX/IAA and bZIP. Some members of these families showed a differential expression pattern according to the organ and developmental phase, being more expressed in embryo at early development and in mesocarp at ripening. Among the isolated TFs, a bZIP, homologous to Arabidopsis ATB2, which controls transcription in seed and fruit, and similar to bZIPs highly abundant in ripe fleshy fruit of several species. Other factors deeply involved in the regulation of seed and fruit development are the plant hormones. Genes responsible for the biosynthesis and action of auxin, ethylene, ABA and jasmonates showed a differential expression pattern in seed and fruit, pointing out a possible role in the crosstalk between the two organs.