1a.Objectives (from AD-416)
The objective of this cooperative research project is to develop strategies for breeding new and improved woody ornamental germplasm adapted to the southeastern United State that exhibit host-plant resistance to diseases, insects, and other pests.
1b.Approach (from AD-416)
1)Elucidate the genetic/genomic bases of host-plant resistance to microbes, insects and/or nematodes in woody ornamentals, especially those characteristic of the southeastern United States; and. 2)Apply the knowledge gained through the preceding research to developing effective genetic enhancement and/or improvement strategies for host-plant resistant woody ornamentals adapted to the southeastern United States utilizing molecular and conventional breding techniques.
Evaluations of one hundred and thirty-six cultivars of rose with industry resistance claims were completed for black spot and cercospora leaf spot at two locations in Tennessee and in south Mississippi. Resistance claims were compared to rating data and most claims were not confirmed. Previous evaluations of hydrangea cultivars suggested that there is genetic resistance to cercospora leaf spot but also that increased shading reduced severity of leaf spot in hydrangea. Leaf spot evaluations continue on hydrangea cultivars in sun tolerance trials, which include replicated plantings of 29 cultivars grown in full sun. Research describing how powdery mildew infects hydrangea leaf tissue and possible mechanisms for resistance was published. Genetic diversity data was analyzed for native dogwood populations across the United States and assembled for publication. Results indicate that massive mortality and reduced population sizes due to anthracnose disease has not significantly reduced genetic diversity among wild populations, which are an important source of genetic diversity for dogwood breeding programs. In addition to continued breeding for superior dogwood cultivars with improved anthracnose tolerance, a genetic linkage map of flowering dogwood was published and subsequent studies have identified at least three genetic markers closely associated with flower color. The first genetic linkage map of flowering dogwood and the new molecular markers that have been added are fundamental tools for new gene identification and marker-assisted selection in our flowering dogwood breeding program. Improved methods for dogwood breeding using bee pollinators were also published. The ADODR or his representative meets regularly with the cooperating scientist, and these meetings include site visits.