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Research Project: Breeding Stone Fruit Adapted to the Production Environment of the Southeastern United States

Location: Fruit and Tree Nut Research

Title: Genetic variability among populations of Fusicladium species from different host trees and geographic locations in the USA

Author
item Chen, Chunxian
item Bock, Clive
item Brannen, Phillip - University Of Georgia
item Adaskaveg, James - University Of California
item Hotchkiss, Michael - Mike
item Brewer, Marlin - University Of Georgia
item Wood, Bruce

Submitted to: Mycological Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/29/2014
Publication Date: 8/30/2014
Publication URL: http://link.springer.com/article/10.1007%2Fs11557-014-1006-y
Citation: Chen, C., Bock, C.H., Brannen, P.M., Adaskaveg, J.E., Hotchkiss, M.W., Brewer, M.T., Wood, B.W. 2014. Genetic variability among populations of Fusicladium species from different host trees and geographic locations in the USA. Mycological Progress. 13(4):1179–1190.

Interpretive Summary: Peach, almond, pecan are important fruit/nut crops in many regions worldwide. The scab diseases in the three crops cause substantial yield loss, downgrading of fruit, defoliation and subsequent decline of the orchard. Peach and almond scab is caused by Fusicladium carpophilum and pecan scab is caused by F. effusum. Many isolates of these pathogens have been collected from major production areas in the United States but their genetic variability and diversity have not been compared, including 18 peach F. carpophilum isolates and 21 pecan F. effusum isolates from several southeastern states, and 12 almond F. carpophilum isolates from California. This study is to compare the genetic diversity and divergence of the 51 isolates using 10 RAPD and 5 UP-PCR markers. Knowledge of the genetic diversity of the isolates can provide useful insight into the reproductive strategies of the fungi and the threat posed to host resistance by the ability of the pathogen to adapt.

Technical Abstract: Peach and almond scab (caused by Fusicladium carpophilum) and pecan scab (caused by F. effusum) cause yield loss, downgrading of fruit, defoliation and subsequent decline of the orchard. To understand the levels of genetic diversity and divergence of the pathogens from different hosts and locations, 51 isolates were genotyped and analyzed using 10 RAPD and 5 UP-PCR markers, including 18 isolates of F. carpophilum from peach in the southeastern United States, 12 isolates of F. carpophilum from almond in California, and 21 isolates of F. effusum (a related species) from pecan in the southeastern United States. The combined marker results showed a low incidence of polymorphisms among the peach isolates (4.2% of markers), but a higher incidence of polymorphisms among the almond isolates (42.0%) and the pecan isolates (61.0%). The Dice coefficient of similarity ranged from 0.932 to 1.000 for the peach F. carpophilum isolates, 0.214 to 0.976 for the almond F. carpophilum isolates, and 0.528 to 0.920 for the pecan F. effusum isolates. UPGMA bootstrap values indicated that UP-PCR data were slightly more robust, and based on the combined data, the UPGMA bootstrap analysis (1000 runs) gave a high node value (100%) differentiating all the isolates of F. carpophilum from F. effusum, and a moderate node value differentiating the peach and almond isolates of F. carpophilum (68%). The results suggest some divergence between the F. carpophilum populations from almond in California and from peach in the southeastern United States, and different levels of genetic diversity within the two populations.