Comparison and verification of the genes involved in ethylene biosynthesis and signaling in apple, grape, peach, pear and strawberry

Ethylene, which plays important roles in regulating plants’ life cycles, is biologically active in trace amounts, and its effects are of great commercial importance. The large-scale identification and comparison of the genes, which are involved in ethylene biosynthesis and signaling in multiple plants has not been reported. In this study, some key enzymes that involved in ethylene biosynthesis and signaling pathway in two non-climacteric fruits and three climacteric fruits have been identified through the comparison of gene copy number and related ESTs. The total EST number of the ethylene biosynthesis and signaling pathway related genes in grape and apple was more than that in peach. However, the ratios of the EST number in fruit to those in all the other tissues of the related genes in peach were more than that in apple and grape. We verified 27 genes in pear, 18 genes in apple, 23 genes in strawberry, 16 genes in peach and 23 genes in grape. The result showed that the transcript amounts of different members in the same gene family will be different in the expression and function of fruit ripening process. The difference between non-climacteric fruits and climacteric fruits was that the former could produce significant levels of ethylene during the ripening of fruits. Ethylene was produced during the early stages of fruit developments, which may indicate that the mechanism of ethylene perception occurs in these fruits prior to ripening.