Abstract |
- Inheritance of eight enzyme systems, alanine aminopeptidase (AAP), aspartate
aminotransferase (AAT), aconitase (ACON), glucose phosphate isomerase (GPI),
malate dehydrogenase (MDH), 6-phosphogluconate dehydrogenase (6-PGD),
phosphoglucomutase (PGM), and shikimate dehydrogenase (SDH) was studied in
hazelnut (Corylus avellana L.) by either polyacrylamide gel electrophoresis
(PAGE) or starch gel electrophoresis. Three isozymes were detected for AAP and
all were polymorphic, monomeric, and controlled by three, two, and five alleles,
respectively. One zone of activity was observed for AAT and it was polymorphic;
segregation data indicated that the active form of the enzyme is a dimer and is
controlled by a single locus with two alleles. Two isozymes were identified for
ACON. Both were polymorphic, monomeric, and controlled by two loci with
three alleles each. Two variable and one monomorphic regions of activity were
observed for GPI; Gpi-2 behaved as a dimer and was controlled by a single locus
with two alleles; Gpi-3 was also controlled by a single locus with two alleles but
was active as a monomer. Three MDH isozymes were identified and one zone was
polymorphic; Mdh-1 was active as a dimer and was controlled by a single locus
with two alleles, although a deficiency of aa phenotypes was detected. Two zones
of activity were observed for 6-PGD, one of which was polymorphic, active as a
dimer, and controlled by a single locus with three alleles. Two zones of activity
were identified for PGM; both were polymorphic, monomeric, and controlled by
two separate loci with three and four alleles, respectively. Two isozymes were
observed for SDH, one of which was polymorphic, monomeric, and controlled by
a single locus with four alleles. Rare alleles were detected at Aat, Aco-1, Gpi-2,
Mdh-1, and Sdh-2.
Of the 17 isozyme loci studied, 13 were polymorphic. The most useful
enzyme systems for hazelnut cultivar identification were AAP, PGM, ACON, and
GPI. 54 of 56 cultivars studied could be distinguished by a combination of the
isozymes examined. Thus, isozyme analysis is a very powerful tool for identifying
hazelnut cultivars. 'Tombul' and 'Extra Ghiaghli' appear to be the same cultivar
based on both isozyme analysis and morphological characteristics.
Three linkage groups were detected. 6-Pgd-2 was tightly linked to the leaf
anthocyanin gene (0+.0.06) in three crosses. Gpi-2 and Mdh-1 were linked with a
recombination frequency of 6.86±2.55 in two progenies. A loose linkage was
found among Aco-1, Pgm-2, and Pgm-1.
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