An isozyme marker for resistance to root-knot nematode in sugarbeet

Root-knot nematode (Meloidogyne spp.) is a destructive pest of sugarbeet (B eta vulgaris L.) that reduces production in infested areas and is difficult to manage. Identification of nematode-resistant plants is a time-consuming process that is subject to genotype-environment interaction. Development o f resistant cultivars/hybrids is the most effective control. This study was conducted to establish a rapid and effective screening technique to detect a large number of sugarbeet genotypes with resistance to Meloidogyne spp. A nematode-resistant sugarbeet germplasm line, Mi-1 Beta, was previously de veloped using J2 inoculation and screening procedures. Leaf and cotyledon e xtractions were used in diagnosis. Phosphoglucomutase (PGM) was found to be a potentially useful isozyme marker of resistance in Mi-1 Beta and derived lines in starch gel electrophoresis. Seven banding patterns (four resistan t and three susceptible) were produced. All susceptible plants shared the b anding pattern of the resistant strains, except for a single PGM band. If d emonstrated to be tightly linked to nematode resistance, this novel PGM iso zyme marker will accelerate breeding sugarbeet with resistance to root-knot nematode.