DEVELOPMENT OF ROOT -KNOT NEMATODE­ RESISTANT SUGARBEET

Sugarbeet, Beta vulgaris L , is a favored host of Meloidogyne spp. Host-plant resistance to multiple species of root-knot nematodes was not found in the cultivated sugarbeet but was identified from wild maritima beets. The resistance has been introgressed into sugarbeet genotypes. Several breeding populations were planted in heavily infested field plots Preliminary evaluations indicated that about 77% of plants in resistant families and 44% in backcrossed populations. produced healthy roots while the rest were with gall symptoms. In comparison, none of the susceptible control plants were free from galling; one­ third of them died Positive results were demonstrated by the improved taproot conformation and root weights A phosphoglucomutase (PGM) isozyme marker for Mi-1 Beta and a cleaved amplified polymorphic sequence (CAPS) marker for M66 Beta were recently identified The use of marker-assisted selections may facilitate sugarbeet root-knot nematode resistance breeding Additional improvements on the breeding materials are needed to develop an elite sugarbeet cultivar