Expression pattern of genes involved in ethylene signalling in Melting-Flesh and Non-Melting Flesh peaches

Ethylene plays a pivotal rule in the control of several developmental process in plants, among which of main importance is the ripening process of climacteric fruits. The climacteric peach fruits are classified by different flesh texture and firmness, which affects fruit shelf-life, as well as by ethylene evolution, finally determining the organoleptic quality of the ripe fruit. Concerning texture, peach fruits can be classified as melting flesh (MF), non-melting flesh (NMF) and stony hard. The former two phenotypes are characterized, other by different texture and firmness, also by a different ethylene evolution which is often higher in non-melting fruits. Increased expression of an ethylene-stimulated endo-PG gene and synthesis of the corresponding protein accompany the extreme peach fruit softening in MF phenotypes. This apparently paradoxical behaviour suggests possible genotype-related differences in ethylene signal perception and transduction. For this reason, we have investigated, by Northern analysis and real-time PCR, the changes, at different ripening and softening stages of two selected MF (‘Bolero’) and NMF (‘Oro A’) peach cultivars, in the expression of genes encoding several components of the ethylene signalling chain trying to relate these changes to the pattern of expression of genes involved in ripening-related cell wall disassembly.