Submitted to: North American Strawberry Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 1/16/2001
Publication Date: N/A
Technical Abstract: Studies were conducted to determine whether increased resistance to Colletotrichum acutatum (anthracnose) could be detected in shoots regenerated from leaf explants derived from several strawberry cultivars. Shoots were generated (without a callus phase) from explants on MS medium containing either 1 or 10 uM thidiazuron and 0.49 uM indole-3-butyric acid (IBA), propagated on medium containing MS salts, 4.4 uM 6-benzyladenine and 5.7 uM IBA, and then four weeks prior to screening, were transferred to propagation medium without growth regulators. Regenerants and cultivars were screened in vitro by soaking leaves from 4-week-old cultures in a spore suspension of C. acutatum isolate Goff for 24 hr, subculturing leaves onto 0.5 water agar, and then scoring leaves for percentage infection after 7 days. Somaclonal variants exhibited 3.5-, 1.7-, 1.7-, 2.1-, 1.4- and 3.9-fold increases in levels of resistance compared to cultivars Chandler, Delmarvel, Honeyoye, Latestar, Pelican and Sweet Charlie, respectively. Maximum levels of resistance to C. acutatum were exhibited by somaclonal variants CS-1 and CS-10 (from 'Chandler'), and SS-3 and SS-9 (from 'Sweet Charlie'). CS-1, CS-10, SS-3 and SS-9 exhibited 17.5, 17.7, 11.7 and 13.9 per cent leaf infection, respectively, compared to 62.4 and 45.1 per cent for 'Chandler' and 'Sweet Charlie', respectively. These studies suggest that screening for somaclonal variation may be a feasible approach to generating strawberry cultivars with increased levels of anthracnose resistance.