Genetics and mechanism of resistance to Meloidogyne arenaria in peanut germplasm

Segregation of resistance to Meloidogyne arenaria in six BC5F2 peanut breed ing populations was examined in greenhouse tests. Chi-square analysis indic ated that segregation of resistance was consistent with resistance being co nditioned by a single gene in three breeding populations (TP259-3, TP262-3, and TP271-2), whereas two resistance genes may be present in the breeding populations TP259-2, TP263-2, and TP268-3. Nematode development in clonally propagated lines of resistant individuals of TP262-3 and TP263-2 was compa red to that of the susceptible cultivar Florunner. Juvenile nematodes readi ly penetrated roots of all peanut genotypes, but rate of development was sl ower (P = 0.05) in the resistant genotypes than in Florunner. Host cell nec rosis indicative of a hypersensitive response was not consistently observed in resistant genotypes of either population. Three RFLP loci linked to res istance at distances of 4.2 to 11.0 centiMorgans were identified. Resistant and susceptible alleles for RFLP loci R2430E and R2545E were quite distinc t and are useful for identifying individuals homozygous for resistance in s egregating populations.