Comparison of Pch313 (pTOM13 Homolog) RNA Accumulation during Fruit Softening and Wounding of Two Phenotypically Different Peach Cultivars.

Pch313 was isolated as a cDNA whose RNA accumulated during the softening period of peach (Prunus persica L. Batsch) fruit development. To better understand the role of the gene, we compared the amount of pch313-related RNA detected during fruit softening and tissue wounding between cultivars with different softening characteristics. The cultivar that softened faster, "Bailey," had a significantly higher amount of pch313-related RNA accumulate during softening than the slower-softening cultivar, "Suncrest." Pch313 was sequenced and found to be related to a tomato fruit cDNA clone, pTOM13, which has been shown to encode the ethylene-forming enzyme. The derived amino acid sequence of pch313 is 74 to 83% identical to the pTOM13-related sequences. A pch313-3' noncoding region probe was used to demonstrate that pch313 is related to both a wound-induced RNA transcript and the major fruit-softening transcript. The relationship of pch313 RNA accumulation and ethylene evolution was examined upon wounding and appeared to be both tissue and cultivar specific. When leaves were wounded, more pch313-related RNA was detected in Bailey and the rate of ethylene evolved was also higher in Bailey. When fruits were wounded, the levels of ethylene evolved were nearly identical but Suncrest accumulated more pch313-related RNA. Southern analysis of the DNA indicated a small number of related genes.