The broad objectives of the CRIS project are the development of genetic solutions to major problems affecting temperate tree fruit production and consumer acceptance of tree fruits.  This work is being accomplished through a coordinated effort of scientists within our unit and through our cooperation with other research units at our facility, other USDA labs throughout the country, and university, private and governmental laboratories in the U.S. and abroad.  We are working on improving fruit quality through traditional breeding of novel genetic material, and also through the isolation and transgenic manipulation of key genes that control fruit development, stone formation, and ripening.  We are also investigating the possibility of creating marketable stoneless stone fruit varieties.  Stoneless/seedless peaches, cherries, plums, etc. could revolutionize the way we grow, market, and consume these fruits. We are developing solutions to some of the most important disease problems affecting stone fruits and pear in order to improve the sustainability of these crops and to reduce inputs of pesticides. The improvement of resistance to fire blight and psylla in pear is being approached through hybridization of existing resistant germplasm to germplasm with high fruit quality to develop new cultivars which combine these traits.  Gene transfer is being used to produce resistance to virus diseases in stone fruits and particularly Plum pox virus which is an invasive pathogen that is threatening the viability of our stone fruit industry. Basic research on the natural plant virus defense system is underway in order to find ways to increase resistance.  In order to make the best use of the land area devoted to fruit culture and to improve the profitability of small orchard operations we are developing improved tree forms for high-density production systems in peach.  This work is being done through traditional breeding using novel peach germplasm with desirable tree growth habits such as columnar and semi-columnar.  We are developing smaller pear trees through genetic transformation.  Since our program is committed to the application of molecular technologies along with traditional approaches for fruit tree genetic improvement we are also undertaking fundamental and applied work in genetic engineering and risk mitigation.  The utilization of our findings by the industry and the availability of improved fruits to consumers is critical to our program and we evaluate the improved material from our program in collaboration with the fruit industry and through them with consumers.  

Highlights of Ralph Scorza’s research program are described below.  For other aspects of the CRIS project research program please visit the sites of individual scientists in the CRIS – Drs. Richard Bell, Ann Callahan, Chris Dardick, Zongrang Liu, and Chinnathambe Srinivasan.