|Wechter, William - Pat|
Submitted to: Journal of Horticultural Science and Biotechnology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/3/2006
Publication Date: 3/1/2006
Citation: Blenda, A., Wechter, W.P., Reighard, G., Baird, W., Abbott, A. 2006. Development and characterization of diagnostic AFLP markers in prunus persica for its response to peach tree short-life syndrome. Journal of Horticultural Science and Biotechnology. 81:291-288. Interpretive Summary: The disease complex called Peach Tree Short Life (PTSL) has been responsible for the loss of millions of peach trees and hundreds of million dollars in revenues for United States peach growers since the early 1980s. The loss of inexpensive and effective chemical control compounds from the market has left growers with limited, if any, control of this devastating disease. In an effort to provide alternative control strategies to the growers, we screened both susceptible and tolerant peach germplasm for genetic markers that can be used to track inheritance of PTSL tolerance, and thus useful in a PTSL-tolerance breeding program. Our work has allowed us to identify a number of putative genetic markers associated with tolerance and susceptibility to the disease. These markers should allow us to identify areas within the peach genome that are important in both tolerance and susceptibility. The use of such markers in a breeding program, marker assisted selection (MAS), would greatly decrease the amount of time necessary to develop tolerant rootstock material. Because it takes up to six years to test a single cross using standard breeding and disease observation methods, the use of MAS in a PTSL-tolerance program will be extremely important to rapidly address the peach growers’ needs.
Technical Abstract: Peach Tree Short Life (PTSL) is a complex disease syndrome caused by multiple factors, genetics of which is not known. Amplified fragment length polymorphism (AFLP) technology and bulked segregant analysis (BSA) were used to identify diagnostic markers for PTSL syndrome in peach rootstocks. Forty-four AFLPs were selected as potential PTSL-tolerance associated markers based on the combined results of BSA screening and screening 11 PTSL tolerant, 2 intermediately susceptible and 2 highly susceptible genotypes with the polymorphic EcoRI/MseI primer combinations. The use of EAC/MCCC primer combination in conjunction with bulked segregant analysis resulted in the identification of a single amplification product in the bulk of DNA from ten susceptible trees (died from PTSL), and its absence in the bulk of DNA from ten tolerant trees. The AFLP fragment also was detected in the intermediately susceptible rootstock Lovell and highly susceptible Nemared. In addition, the fragment was found in the susceptible parent Nemaguard but not the tolerant parents, in four controlled crosses segregating for response to PTSL. Testing of this AFLP primer combination on additional 111 trees that either died or survived on a severe PTSL site revealed the presence of the diagnostic fragment in 18 trees of which 17 were Lovell. PTSL death was observed in 61% of the trees with the fragment, which was significantly (P less than 0.05) higher in comparison with those that did not have the fragment. Furthermore, the PTSL rating of symptoms was significantly higher and the cumulative tree life was significantly shorter (P less than 0.05) for Lovell compared with the other 93 rootstocks lacking the AFLP fragment.