ANALYSIS OF GENES-CONTROLLING PHOTOPERIOD SENSITIVITY IN COMMON BEAN USING DNA MARKERS

The genetic basis of the photoperiod response in common bean (Phaseolu s vulgaris L.) was investigated using DNA markers and recombinant inbr ed populations. Two loci affecting photoperiod response were resolved, the previously defined primary locus (Ppd), at which the dominant all ele confers sensitivity to photoperiod, and a second locus (herein def ined as Hr), which influences the degree to which a plant responds to photoperiod. The DNA marker P5(1600) cosegregated with the recessive a llele, ppd, displaying a recombination frequency with the photoperiod locus of about 3%. A second marker, B303(600), was linked to the reces sive allele at Hr and mapped approximately 13 cM from this locus. The markers demonstrated that in crosses involving Redkloud and several ph otoperiod sensitive lines, insensitivity to photoperiod is primarily c ontrolled by ppd and that Hr does not significantly affect flowering t ime in ppd/ppd plants under the environmental conditions used.