Occurrence and segregation of a heterozygous narrow-leaf mutant in peanut

The heterozygous Narrow-Leaf mutant phenotype found in the U.S. runner-type peanut (Arachis hypogaea L. subsp. hypogaea var. hypogaea) cultivar ‘Tifguard’ segregated into three phenotypes: Normal-leaf plant, smaller Narrow-Leaf plant, and a very small seed sterile Dwarf-leaf plant. Upon selfing individual plants of the Normal phenotype only Normal plants were produced. However, selfing individual plants of the Narrow-Leaf resulted in a 1 Normal: 2 Narrow-Leaf: 1 Dwarf genetic ratio. No other plant types were found within the segregating plant phenotypes. Following bulk segregant analysis the homozygous Normal and Dwarf phenotypes were found to be genetically more similar than the heterozygous Narrow-Leaf mutant type. Since these three phenotypes (genotypes) were also found to breed true-to-type for tan testa color, root-knot nematode resistance, normal-oleic, and leaflet length/width ratio, the results support a rare single gene mutation rather than natural outcrossing origin for the Narrow-Leaf mutants found in the Tifguard peanut cultivar.