2017 ASHS Annual Conference

Our working hypothesis is that Rosaceae fruit quality and flavor could be improved if the fruits remain on the tree longer, allowing accumulation of desired sugars, antioxidants, and bioactive compounds without excessive softening. Thus, if the climacteric response of the ethylene-induced ripening process can be controlled while fruits are on the tree, ripening-softening can be optimized to increase fruit consumer quality. Also, keeping fruit longer on the tree will reduce fruit pickings, saving labor costs and potentially adapting the cultivar to mechanical harvesting. Our group has recently described the ripening pattern of six Japanese plum bud sports derived from ‘Santa Rosa’, a commercial plum cultivar that depicts the typical climacteric pattern. ‘Santa Rosa’ bud sports series, that contain variations on ripening from climacteric, suppressed ripening, through non-climacteric, provides an interesting model to study the role of ethylene and the key mechanisms governing fruit ripening, softening, and senescence. The aim of our study was to understand the different fruit softening patterns using this series of plum, with special reference to known genes involved in ethylene biosynthesis at the genomic level. Leaf samples of six cultivars of Japanese plum, Santa Rosa, July Santa Rosa, Late Santa Rosa, Sweet Miriam, Roysum, and Casselman, were used for isolation of genomic DNA. Paired-end standard Illumina libraries for each of these six cultivars were constructed, sequenced and aligned to the Prunus persica reference genome assembly and used to compare differences among key ethylene gene families. We detected several frameshift mutations in genes involved in sugar transport and ethylene biosynthesis on chromosomes 7 and 8. Gene copy number variation and a comprehensive mutation profile implications in ripening differences will be presented.