|LYNN, NAFEESA - US Department Of Agriculture (USDA)|
|LESLIE, CHUCK - University Of California|
Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 6/15/2011
Publication Date: 8/15/2011
Publication URL: http://apsjournals.apsnet.org/doi/pdf/10.1094/PHYTO.2011.101.6.S1
Citation: Lynn, N., Leslie, C., Gonzalez, A., Sudarshana, M.R. 2011. Molecular screening of walnut backcross populations for a DNA marker linked to cherry leafroll virus resistance. Phytopathology. 101:S111.
Technical Abstract: Blackline disease, a graft union disorder caused by infection of English walnut (Juglans regia) trees by Cherry leafroll virus (CLRV) is a major problem for walnut production in Northern California where scions are grafted onto virus resistant black walnut (J. hindsii) or ‘Paradox’ (J. hindsii × J. regia) rootstocks. A breeding program is currently developing CLRV-resistant English walnut cultivars by recurrent backcrossing of ‘Paradox’ hybrid with English walnut cultivars. We have developed primers to detect a DNA marker specific to J. hindsii parent linked to hypersensitivity to CLRV for marker assisted selection. In PCR assays, these primers amplified a 535-bp DNA fragment from J. hindsii and ‘paradox’ rootstocks. Analysis of nucleic acid extracts from trees of a third generation backcross population by PCR indicated association of the marker with hypersensitivity to CLRV as determined by bark patch grafting inoculations. We then screened 1,174 fourth generation backcross seedlings for the presence of the DNA marker and found that 48% (563/1174) of these seedlings were positive for the marker. The molecular screening method used in this study was able to reduce time and resources that were otherwise required for screening by patch graft testing.