MOLECULAR-GENETIC MAPPING OF DWARFING GENES IN OAT

Restriction fragment length polymorphism (RFLP) analysis provides a va luable tool for characterizing and understanding relationships among g enes for useful traits in crop species, particularly in ones with comp lex genomes such as the hexaploid cultivated oat Avena sativa L. (2n = 6x = 42). Using Bulked Segregant Analysis (BSA) and Fz RFLP linkage d ata, we mapped three dominant oat dwarfing loci to different regions o f the oat genome. Dw6, in oat line OT207, is 3.3 +/- 1.3 cM from the X umn145B locus, which has not been placed on the hexaploid oat linkage map. Dw7, in line NC2469-3, is 4.3 +/- 2.3 cM from Xcdo1437B and 33 +/ - 4.1 cM from Xcdo708B. This places Dw7 to linkage group 22. Dw8, in t he Japanese lines AV17/3/10 and AV18/2/4, mapped 4.9 +/- 2.2 cM from X cdo1319A in an AV17/3/10 x 'Kanota' F-2 population and 6.6 +/- 2.6 cM from it in an AV18/2/4 x 'Kanota' population. This places' Dw8 to link age group 3. Aneuploid analysis of markers linked to the dwarfing gene s located Dw6 on the smallest oat chromosome (chromosome 18) and Dw7 o n the longest satellited chromosome (chromosome 19). The RFLP markers closely linked to the three dwarfing genes identify distinct regions o f the oat genome that contribute to plant height and they should be us eful in characterizing new genetic sources of dwarfness in oat.