2019 ASHS Annual Conference

M. sieversii represents a source of genetic diversity for economically-important apple traits, including stress and disease resistance, as well as unique fruit quality attributes. USDA-sponsored expeditions to Central Asia have resulted in a large collection of M. sieversii accessions that are maintained at the USDA Plant Genetics Resources Unit (PGRU) in Geneva, NY. M. sieversii - PI 613981, is one of the elite lines that was originally selected for collection in Kazakhstan as budwood for its potential drought tolerance and disease resistance. The identification of genes responsible for these and other traits, in M. sieversii, however, have not been explored. The characterization of functional genes in wild apple and the establishment of independent overexpressing lines in Arabidopsis that could be used for high-throughput screening would represent a valuable resource for studying apple traits. Thus far, large-scale, high-throughput screening for stress tolerance genes in apple has not been conducted. In the present project, the FOX (Full-length cDNA Over-eXpressing) gene hunting system, which represents an alternative gain-of-function gene hunting technique, has been used to generate 10 - 12,000 gain-of-function mutant lines in Arabidopsis carrying independent apple cDNAs derived from a cDNA library of M. sieversii – PI613981 constructed from mid-winter bark tissues. The high-throughput screening effort will focus on identifying genes related to freezing tolerance, salt tolerance, drought tolerance, and morphological traits (dwarfing, early-flowering, branching, root architecture, etc.). Initial characterization of the system, a sampling of inserted apple genes, and examples of morphological mutants will be presented.