Submitted to: Plant Disease Management Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/25/2008
Publication Date: 7/21/2008
Citation: Strausbaugh, C.A., Eujayl, I.A., Foote, P. 2008. Transgenic sugar beet cultivars evaluated for resistance to bacterial root rot in Idaho, 2007. Plant Disease Management Reports. 2:FC108. Interpretive Summary: Bacterial root rot is an important problem in sugar beets because of issues it causes in the field, storage, and factories. Bacterial rot in sugar beets has normally been attributed to Erwinia carotovora subsp. betavasculorum, but recent field observations and isolations indicate this situation may be changing. In the Intermountain West, a previously undescribed bacterial-like root rot complex was found to be occurring in sugar beets. The primary bacteria responsible for the rot is Leuconostoc mesenteroides subsp. dextranicum. In effort to manage this rot problem, sugar beet cultivars with glypohosate resistance were screened for resistance to L. mesenteroides. These cultivars ranged from susceptible to resistant indicating that selecting and improving resistance to bacterial rot may be possible.
Technical Abstract: Bacterial root rot caused by Leuconostoc mesenteroides subsp. dextranicum is an important problem in sugar beets because of issues it causes in the field, storage, and factories. Thirty-three transgenic (roundup ready) sugar beet cultivars were grown in a commercial irrigated field. Four roots from each cultivar were hand harvested and topped on 1 Oct 07 and stored at 3°C till assayed on 3 Feb 08. Roots were surface sterilized and cross sectioned. The slice from the middle of the root was inoculated with a tooth pick that had been dipped in a 48 hr old culture of L. mesenteroides. The inoculated slices were placed in a Petri dish, arranged in a randomized complete block design and incubated at 30°C. The rot diameter was recorded at 72 and 96 hr. After 96 hr, rot ranged from a high of 27 mm with cultivar C10 to a low of 9 mm with cultivar C4. This range of responses in the cultivars for bacterial rot indicates it may be possible to improve resistance to L. mesenteroides in sugar beet cultivars through breeding efforts.