Experimental Sugar Beet Cultivars Evaluated for Resistance to Bacterial Root Rot in Idaho, 2008

Strausbaugh, C.A. and Eujayl, Imad A. and Foote, P. (2010) Experimental Sugar Beet Cultivars Evaluated for Resistance to Bacterial Root Rot in Idaho, 2008. Plant Disease Management Reports. 4:FC011.

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Abstract

Thirty-six experimental sugar beet cultivars were grown in a commercial sprinkler-irrigated sugar beet field near
American Falls, ID where potatoes were grown in 2007. The plots were planted on 21 Apr 08 and managed according to
standard cultural practices. Plants were free of foliar and root disease symptoms. Four roots representative of each cultivar
were hand topped and harvested on 1 Oct. The roots were then placed in a cold room at 3°C and 90% relative humidity until
they were assayed on 7 Jan 09. The roots were washed, dipped in 0.6% sodium hypochlorite solution for 1 min, rinsed in
sterile reverse osmosis water, and then air dried in a laminar hood. A cross section of the root 8-10 mm thick and 45-70 mm
in diameter was cut just below the widest portion of root and placed in a Petri dish on sterile filter paper moistened with sterile
tap water. A 2-mm diameter and 3-mm deep hole was created with a sterile tooth pick in the center of the root slice. A sterile
tooth pick was then dipped in a 48-hr old culture of Leuconostoc mesenteroides subsp. dextranicum B322 grown on MRS
media at 30°C and placed in the hole along with a drop of sterile tap water. Four additional root slices served as the non-
inoculated check (no bacteria inoculated). The root slice/Petri dish combination was placed in a plastic bag and incubated at
30°C. The experiment was a randomized complete block design with four replications (1 root slice = 1 replication for each
cultivar). The diameter of rotted root area was recorded after 72, 96, and 120 hr. Bacteria from the lesions in each replication
were re-isolated by streaking onto MRS to prove only L. mesenteroides was present. Data were analyzed using the general
linear models procedure (Proc GLM-SAS), and Fisher’s protected least significant difference was used for mean comparisons.

The plants from which the roots were collected were healthy in appearance (no signs or symptoms for any disease
problem). The root slices in the non-inoculated check treatment developed no rot. On the inoculated slices, only L.
mesenteroides was isolated from the bacterial rot lesions. After 120 hr, bacterial rot ranged from a high of 18.3 mm on
cultivar HM080011 to a low of 2.8 mm on cultivar B-40. These data should provide a starting point in the search to identify
resistance to L. mesenteroides in sugar beet. Given the range of responses, improving sugar beet cultivars for resistance to
bacterial rot should be possible.

Item Type:	Article
NWISRL Publication Number:	1356
Subjects:	Irrigated crops > Sugarbeet
Depositing User:	Users 6 not found.
Date Deposited:	26 May 2010 02:24
Last Modified:	13 Oct 2016 20:30
Item ID:	1380
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/1380