Search and Access Archived Conference Presentations

2019 ASHS Annual Conference

Genome Wide Association Studies for Fruit and Leaf Resistance to Bacterial Spot [Xanthomonas Arboricola pv Pruni (Xap)] in Peach

Tuesday, July 23, 2019
Cohiba 5-11 (Tropicana Las Vegas)
Maxwell W. Vonkreuzhof, University of Arkansas, Fayetteville, AR
Margaret Worthington, Ph.D., University of Arkansas, Fayetteville, AR
Lacy D. Nelson, University of Arkansas, Fayetteville, AR
Terrence J. Frett, University of Arkansas, Fayetteville, AR
John R. Clark, University of Arkansas, Fayetteville, AR
Cassia Da Silva Linge, Clemson University, Clemson, SC
Wanfang Fu, Clemson University, Clemson, SC
Ksenija Gasic, Clemson University, Clemson, SC
Bacterial spot, caused by the bacterium Xanthomonas arboricola pv. pruni (Xap), causes premature defoliation, reduced vigor and productivity, and yield loss due to unmarketable fruit in peaches (Prunus persica (L.) Batsch) grown in humid regions around the world. The development of bacterial spot resistant peach cultivars could help to mitigate the environmental and health risks of bactericides applied for disease control while reducing input costs for growers. Because Xap pressure varies from year to year depending on environmental conditions and disease incidence is low in some important breeding sites, molecular markers associated with bacterial spot resistance can help breeders to develop resistant cultivars efficiently. Markers for fruit resistance to bacterial spot developed from quantitative trait loci (QTL) discovered on linkage groups (LG) 1 and 6 and in an ‘O’Henry’ x ‘Clayton’ F2 mapping population are currently used in the University of Arkansas System Division of Agriculture (UA) and Clemson University peach breeding programs as part of the RosBREED project. A genome wide association study (GWAS) was conducted over five years to find additional loci contributing to fruit and leaf Xap resistance in UA peach breeding germplasm. Seven breeding populations and their parents (n = 144) were genotyped with the 9K peach array and phenotyped for fruit and leaf Xap symptom severity at the UA Fruit Research Station (FRS) in Clarksville, AR from 2013-2015. One of the same populations (n = 47) and six new populations (n = 78), were genotyped with the 9+9K SNP array and evaluated for fruit and foliar resistance to natural inoculum in the field at FRS 2017 and 2018 and foliar resistance with detached leaf assays using two Xap isolates from North Carolina and Arkansas. GWAS was performed using a MLM model in Tassel and a Q+K model in FarmCPU. Foliar resistance was quantitatively inherited and controlled by several small-effect QTLs located on chromosomes 2, 3, 4, 7, and 8. Fruit resistance was also quantitatively inherited and controlled by multiple small-effect QTLs located on chromosomes 2, 3, and 6.
See more of: Fruit Breeding 1 (Poster)
See more of: Poster Sessions