ISOLATION OF A SET OF RIPENING-RELATED GENES FROM STRAWBERRY - THEIR IDENTIFICATION AND POSSIBLE RELATIONSHIP TO FRUIT-QUALITY TRAITS

The ripening of strawberry (Fragaria ananassa Duch.), a non-climacteri c fruit, is a complex developmental process that involves many changes in gene expression. To understand how these changes relate to the bio chemistry and composition of the fruit the specific genes involved hav e been examined. A high-quality cDNA library prepared from ripe strawb erry fruit was differentially screened for ripening-related clones usi ng cDNA from ripe and white fruits. From 112 up-regulated clones obtai ned in the primary screen, 66 differentially expressed clones were iso lated from the secondary screen. The partial sequences of these cDNAs were compared with database sequences and 26 families of non-redundant clones were identified. Northern analysis confirmed that all of these cDNAs were ripening-enhanced. The expression of many of their corresp onding genes was negatively regulated in auxin-treated fruit. These se quences, several of which are novel to fruits, encode proteins involve d in key metabolic events including anthocyanin biosynthesis, cell wal l degradation, sucrose and lipid metabolism, protein synthesis and deg radation, and respiration. These findings are discussed in relation to the role of these genes in determining fruit quality characteristics.