Identification of a Beta maritima Source of Resistance to Root‐Knot Nematode for Sugarbeet

Abstract

Root‐knot nematodes (Meloidogyne spp.) are economically important plant pests that cause root gall symptoms and limit sugarbeet (Beta vulgaris L.) production. With the increasingly restrictive use of nematicides, the development of resistant sugarbeet cultivars becomes urgent. This study was conducted to identify the source of root‐knot nematode resistance and to evaluate transmission of resistance in sugarbeet hybrid progeny. One hundred‐ninety B. vulgaris and 113 sea beet (B. maritima L.) germplasm lines and accessions were evaluated for nematode resistance, via 1000 second‐stage juveniles (J2) per‐plant inoculations, under greenhouse and growth chamber conditions from 1993 to 1994. Beet seedlings developed better root systems in conetainers and pulp pots than in growth pouches for host reaction to the nematode infection assay. From non‐cultivated sea beet, an accession (PI 546387) was identified that segregated for plants free from root gall formation and from reproduction of M. incognita Race 1. Resistance was transmitted to approximately 23% of the F1 progeny when resistant B. martima phenotypes were crossed to sugarbeet. Development of sugarbeet root‐knot nematode resistant cultivars should be facilitated by this identification of a resistance source and the close phylogenetic relationship of the two Beta taxa.