MUTANTS AND DUPLICATION IN CHROMOSOME-7 (SYN. 5H) IN THE BARLEY LINE HA21 - DUPLICATIONS MAY ENHANCE QTLS AND SERVE TO MAKE CONSTANT LINEARCIS-HETEROZYGOSITY

Cytological and linkage data indicate a duplication in the short arm o f chromosome 7 (syn. 5H) in the mutant line HA21 (barley, Hordeum vulg are, cv. 'Pirkka'). The associated mutant (ha21) shows a weighted aver age linkage of 22.1 cM with pld, hitherto an ignored anthocyaninless g ene, of cv. Pirkka. Some crosses produce F-2 segregants with an exagge rated ha21 phenotype which may represent position effect or increased dosage of the mutant gene through recombination. Compared with cv. Pir kka, HA21 has changes in grain chemistry (alpha- and beta-amylase, bet a-glucanase), which may be caused by changed QTL dosage or QTL positio n effect due to duplication. The use of duplication in creating consta nt +m/+m or m+/m+ linear cis-heterozygotes is suggested. Linear cis-he terozygotes may produce stable heterosis or attenuate the undesired ef fects of drastic mutants.