Rubisco Content and Specific Activity in Barley (Hordeum vulgare L.): I. GENETIC VARIABILITY

Seven barley varieties, differing widely in their geographicorigin, were analysed at the seedling stage under controlledconditions for the following traits: (A) Soluble leaf proteincontent, (B) Rubisco content, (C) Total carboxylase activity,as well as for combinations of these basic characteristics:relative Rubisco concentration, relative carboxylase activity,and specific carboxylase activity of the enzyme. A very large genotypic variability was detected in all traits,especially for the total activity of Rubisco, with strong genotypiccorrelations between these traits, whereas environmental correlationswere almost non-existent. There were also relatively good correlationswith the gross assimilation rate (Pg) among the same range ofvarieties, measured in the adult stage in a previous investigation.For two out of five crosses analysed in the F₁ generation, significantdifferences were found between reciprocal hybrids. These results are discussed in terms of heredity patterns ofthe characteristics concerned, namely the double genetic determinismof Rubisco: a large subunit controlled by maternally inheritedchloroplast DNA and a small subunit controlled by nuclear DNA. Key words: Rubisco, barley, genetic variability, maternal inheritance