IDENTIFYING RAPD MARKERS LINKED TO AN ERECT GLANDULAR HAIR TRAIT IN ALFALFA

Abstract

Selection for molecular markers tightly linked to an important trait may improve selection efficiency and genetic gain in hybridization. This study was conducted to identify DNA markers associated with erect glandular hairs in diploid alfalfa. One hundred and sixty nine plants of “KS94GH6”, a diploid (2n = 2x = 16) Medicago sativa var. viscosa (Rchb.) possessing erect glandular hairs, were crossed to cultivated alfalfa at the diploid level (CADL), a non glandular-haired alfalfa. Genotypic selection for this trait was practiced by quantifying erect glandular hair number in 10 progeny from every simple cross family. The number of erect glandular hairs was determined based on a 1 cm length of stem from the third fully elongated internode of the shoot apex from a subsample of three stems each containing 10 internodes. Two DNA pools were generated by bulking equal quantities of DNA from the original parent genotypes, whose progeny possessed the 10 highest or the 10 lowest numbers of erect glandular hairs. Both DNA pools were screened for RAPD-PCR with 100 random 10-mer oligonucleotide primers. One primer (UBC-055) gave one polymorphic DNA product of 1603 bp size between the DNA bulks. The polymorphic band, denoted UBC-055₁₆₀₃, was present in the low glandular hair number DNA bulk and absent in the high glandular hair number DNA bulk. Co-segregation of the RAPD marker with erect glandular hair phenotype was determined to be highly associated (P ≤ 0.01).