Figure 9 - uploaded by Thomas Molnar
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Overview of the Rutgers University Woody Ornamentals Breeding Program along with a description of recent efforts to develop dogwoods that are resistant to powdery mildew.
Citations
... Over the course of his career, Dr. Orton released 14 dogwood cultivars (Molnar and Capik, 2013). Today, the program under the direction of Dr. Tom Molnar is focused on breeding powdery mildew (PM) resistant C. florida and unique dark pink-bracted C. kousa (Molnar, 2018). To support the program, we are using advanced genetic tools to better understand the genetic makeup, pedigrees, and relationships of our breeding selections and cultivars in the industry. ...
... One selection in the Rutgers University dogwood breeding program, H4AR15P25, shows excellent resistance to PM (Molnar, 2018). We are using a technique called QTL mapping to find the regions of DNA where resistance genes may be located. ...
At Rutgers University, we are continuing a tradition of innovation as we adopt advanced genetic tools and analyses in our dogwood breeding program. In this paper, we present preliminary results of two studies. The first is a genetic diversity study of 181 Cornus florida, C. kousa, and interspeific hybrids using the ddRADseq technique. We found that the pink-bracted C. florida formed a distinct clade separate from white-bracted trees and were more genetically similar than expected. For C. kousa, the accessions separated clearly into two different subspecies groups based on country of origin: ssp. chinensis from China and ssp. kousa from Korea and Japan. We verified eight previously described ssp. chinensis cultivars and found 13 additional cultivars that were previously unknown to be ssp. chinensis. We also found 17 cultivars that were genetically intermediate between the two subspecies, indicating they are subspecies hybrids. For both C. kousa and C. florida, there were also several cases of cultivars that are phenotypically and genetically indistinguishable, representing potential mix-ups in the nursery trade. Our data suggests these cultivars are clones that have been sold under different names in the industry. The largest group of such cultivars contains C. kousa 'Satomi', 'Rosabella', 'Schmred' Heart Throb®, 'Hanros' Radiant Rose®, and ‘Grist Mill Pink’. The second study is a Quantitative Trait Loci (QTL) mapping study of C. florida to identify regions of the genome associated with powdery mildew (PM) resistance and tolerance that could be used in breeding. Based on 196 full-sibling seedlings of Rutgers H4AR15P25 (PM resistant) x Rutgers H4AR15P28 (PM susceptible), we discovered a QTL on Chromosome 3. This QTL was found to be statistically significant, but explains only 7.8% of the variation in the seedling population.
