Isozyme variation and inheritance in blueberry

Abstract

Leaf tissue extracts from diploid, tetraploid, and hexaploid species of blueberry, Vaccinium section Cyanococcus, were electrophoretically analyzed for isozyme polymorphism in 12 enzyme systems. Aldolase, shikimate dehydrogenase, triose phosphate isomerase, glucose-6-phosphate dehydrogenase, phosphoglucomutase, aconitase, alcohol dehydrogenase, and aspartate aminotransferase showed activity, but banding was not clear. Four enzymes, malate dehydrogenase (MDH), phosphoglucose isomerase (PGI), 6-phosphogluconate dehydrogenase (6-PGD), and isocitrate dehydrogenase (IDH), exhibited interpretable banding patterns. Two loci were apparent for MDH, PGI, and 6-PGD and one for IDH. Polymorphism was detected at Mdh-2, Pgi-2, 6-Pgd-2, and Idh. Three allozymes were found at Mdh-2 and Idh and at least four at Pgi-2 and 6-Pgd-2. Allozyme segregation ratios observed in progeny of controlled diploid crosses supported single-gene Mendelian inheritance. Banding patterns of all allozymes indicated a dimeric structure for these four enzymes. It appears that all alleles at multiallelic loci are expressed in polyploids. Preliminary data suggest that allozyme analyses may be useful in taxonomic studies in blueberry.Key words: Vaccinium, allozymes, inheritance, electrophoresis.