|Lang, Gregory - MICHIGAN STATE UNIV|
Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 4, 2002
Publication Date: August 15, 2003
Citation: Beckman, T.G., Lang, G.A. 2003. Rootstock breeding for stone fruits. Acta Horticulturae. 622:531-551. Interpretive Summary: This review summarizes changes in stone fruit rootstock breeding priorities over the last 10-15 years. Areas of significant progress, e.g., in waterlogging tolerance and root-knot nematode resistance are noted. Those areas where development of commercially usable materials now appears to be feasible are identified. These opportunities include vigor control and resistance to crown gall, bacterial canker, Armillaria and Phytophthora root rots, and boring insects. Germplasm collection (both foreign and domestic) and preservation needs further effort. Many native and naturalized stone fruit populations have been severely reduced and some are on the verge of being lost. The trend towards the use of complex interspecific hybrids has resulted in the release of functionally sterile materials that are essentially genetic `dead-ends'. This in conjunction with the need to protect intellectual property rights threatens to sharply curtail sharing of germplasm. Many new rootstocks were developed specifically to address pathology or adaptation issues yet most large scale cooperative testing programs address only horticultural characteristics which leaves a large information void. Opportunities also exist for more sophisticated analyses of the data already being collected. Progress has been made in the development of more efficient screening procedures, which in turn leads to the identification of useful variability, both of which by necessity precede the development of commercially useful materials. Modern genetic engineering technology is starting to realize much of its promise in the identification of markers that will reduce reliance on tedious, expensive, long-term field trials and thus accelerate progress.
Technical Abstract: Over the last 20 years stone fruit rootstock development has begun shifting from seedling to clonal types, many of interspecific origin. Publicly funded breeding programs have produced most of these rootstocks due to the time, cost, and risk associated with their development; however, private industry is emerging as a significant contributor of many of the newer rootstocks. Particularly noteworthy among recent releases have been the incorporation of resistance to soilborne diseases, nematodes, waterlogging and vigor control, and the last most notably in recent cherry rootstocks. Nevertheless, despite the remarkable progress in the development of clonal stocks, seedling rootstocks still dominate most stone fruit industries around the world, if only because of their relatively low cost, ease of propagation, and proven utility. Many opportunities and challenges remain to be addressed in the areas of disease and insect resistance, adaptation to biotic and abiotic stresses, graft compatibility, and rootstock influence on scion performance and fruit quality. Biotechnology is beginning to show potential in accelerating rootstock development. With the development of markers to assist selection for difficult to evaluate traits, new rootstocks with resistance to multiple diseases are feasible. Future prospects for breeding are presented.