USING FUNCTIONAL AND APPLIED GENOMICS TO IMPROVE STRESS AND DISEASE RESISTANCE IN FRUIT TREES
Location: Appalachian Fruit Research Laboratory: Innovative Fruit Production, Improvement and Protection
Title: Identification of QTLs for resistance to fire blight (Erwinia amylovora) in Malus sieversii
Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: December 15, 2010
Publication Date: January 16, 2011
Citation: Norelli, J.L., Wisniewski, M.E., Lalli, D., Malnoy, M., Pindo, G., Homer, M., Forsline, P.L., Aldwinckle, H.S., Gardiner, S.E. 2011. Identification of QTLs for resistance to fire blight (Erwinia amylovora) in Malus sieversii [abstract]. Plant and Animal Genome Conference. p. 468.
Malus sieversii (Ms) is the progenitor of the domestic apple. Ms PI613981 is elite scion material collected at a xerophytic site in Kazakhstan from a tree free of disease and insect damage. The F1 family GMAL4593 (‘Royal Gala’ X PI631981) is segregating for resistance to both apple scab and fire blight. In order to identify genomic regions associated with these and other important traits in Ms, we have undertaken the construction of a genetic framework map for GMAL4593 using a combination of SSR and SNP markers. Over 725 molecular markers were screened in the entire population (194 individuals) or in a population subset (96 select individuals). Although 56 % of the markers were polymorphic in the population, only 22% were polymorphic in Ms and used for the construction of the Ms PI613981 framework map. Replicate plants of the GMAL4593 mapping progeny were grafted to seedling rootstock and phenotyped for fire blight resistance in the greenhouse (2008) and the field (2010). Vigorously growing shoot tips of the grafted plants were scissor-inoculated with Erwinia amylovora Ea273 and the percent of the current season’s shoot length that became necrotic recorded. Kruskal-Wallis analysis (MapQTL® 6.0, Kyazma) found significant association between fire blight resistance determined in the greenhouse and markers on linkage group 8, whereas the association with resistance determined in the field was associated with markers on linkage group 10. To better define these putative QTLs, additional markers are being added to the map and resistance will be evaluated in 2011.