Isoenzymes and polyploidy I. Qualitative and quantitative isoenzyme studies in the Triticinae

Abstract

Isoenzymes of alcohol (ADH), malate (MDH), glutamate (GDH) and isocitrate (IDH) dehydrogenases, and a fast migrating esterase (EST-1) were separated by disk electrophoresis from dry seed extracts of diploid, tetraploid, hexaploid and octaploid species or amphiploids belonging to the subtribe Triticinae. Only ADH and EST-1 isoenzymes showed inter-species variation; the other dehydrogenases, which show stringent substrate specificities ('critical' enzymes), revealed the same pattern in all diploid and polyploid species. The qualitative zymogram studies showed that (1) the number of variant enzyme bands increased with the level of ploidy, (2) the amphiploid isoenzyme pattern was additive of the parental species, (3) enhancement in the number of bands was due to the presence of not only parental bands, but also hybrid bands formed by association between heteromonomers. Quantitative data were obtained by densitometry of the enzyme bands as well as spectrophotometric measurements of enzyme activity in crude extracts. Increase in the level of enzyme activity was observed with ploidy level. In spite of the evidence that all duplicate/triplicate genes are expressed, increased enzyme activity observed in the polyploid species was not proportional to the level of ploidy or expected gene dosage. On the basis of ADH and EST-1 zymograms obtained in 2 x and 4 x wheat, probable zymograms for these enzymes in the B-genome donor to 4 x wheat were extrapolated. Neither Ae. speltoides nor Ae. bicornis showed the extrapolated ADH pattern. Amphiploids involving Ae. speltoides and Triticum monococcum or T. aegilopoides fully reproduced the EST-1 zymogram of 4x wheat, but not the ADH. Ae. bicornis x T. aegilopoides amphiploid showed an ADH zymogram similar to that of 4 x wheat, but the EST-1 bands were different.

Genetic studies on .ALPHA.-amylase isozymes in wheat. III. Intraspecific variation in Aegilops squarrosa and birthplace of hexaploid wheat.

“…Mitra and Bhatia (1971) showed greater variation in those enzymes like esterase which had broad substrate specificity and like alcohol dehydrogenase which was not essential for normal metabolic process, in contrast to those enzymes like malate dehydrogenase, glutamate dehydrogenase and isocitrate dehydrogenase which had definite substrate specificity. a-Amylase isozymes studied here were evidently more variable, with an exception for T, timopheevi, than esterase Nakai (1979a), and not so much as isozymes of peroxidase that is one of the most variable enzymes.…”

The genetic diversity of reed canarygrass (Phalaris arundinaceae L.) assessed by isozyme markers

“…The rye IDH is monomorphic (Mitra, Bhatia, 1971). Two loci (Idh1, comprising five alleles, and Idh2, comprising eight alleles) have been detected in the maize , while this enzyme of the sugar beet is controlled by three loci, including two polymorphic diallelic loci (Levites, 1986).…”

Changes in nitrogenous compounds in response to polyploidy in Narcissus tazetta L.

“…Impact of polyploidy on plant metabolites has been studied during the past by Bhatia (1968), Sing and Brewer (1969), Mitra et al (1970), Mitra and Bhatia (1971), Smith et al (1970), Murray and Williams (1973) etc. Their observations indicate that the response is diverse depending mainly on the nature of polyploidy.…”

“…Similar increase was also noticed by Bhatia (1968) in Triticinae, De Maggio and Lambrukos (1974) in Todea barbara and Levites and Novojilova (1977) in maize. The qualitative increase in isoperoxidases may be attributed to the activity of co dominant or duplicate genes brought together by polyploidy (Mitra and Bhatia 1971).…”