Proceedings of the XLVI Italian Society of Agricultural Genetics - SIGA Annual Congress
Giardini Naxos, Italy - 18/21 September, 2002
Characterisation of catalase genomic structure by PCR analysIs in Prunus and Populus species
Santucci S., Caparrini S., Turchi A., De Blasi P., Racchi M.L.
Dip. Biotecnologie Agrarie Laboratorio di Genetica Università degli Studi di Firenze, P.le delle Cascine 24, 50144 Firenze, Italia
catalase, intron, Prunus, Populus, PCR
Catalase, which is an ubiquitous peroxisomal matrix enzyme, dismutates H2O2 into water and oxygen. Together with superoxide dismutase and hydroperoxidase, catalase is part of a defence system for scavenging superoxide radicals and hydroperoxides and protecting cells from oxidative stress. Plant catalases are encoded by a small gene family, usually three or at most four isoenzyme genes in one species. Each catalase isoenzymes shows a distinct spatial and temporal pattern of expression through the entire life cycle of the plants, which may account for the diverse roles played by plant catalases. Catalase activity is a determining factor for the protection of cells against oxidative stress induced during abiotic stress conditions such as chilling, drought, salt and ozone. Nevertheless catalase may play an important role in the signal transduction of the defence response in the plants leading to the development of SAR. Therefore, the interest in plant catalase has increased considerably in recent years.
In particular, in order to understand the molecular evolution of catalase genes, studies about genomic structures are performed comparing the exon-intron structures of known genomic sequences. Comparison of position and numbers of introns sequences indicates that intron positions are conserved, and suggests the existence of an ancestral catalase gene which contained seven introns. During evolution in plant species, the duplication of the primordial gene followed by the differential loss and gain of introns occurred to form three or four different isozyme genes.
Biochemical and molecular aspects of catalase multiplicity have been thoroughly studied in herbaceous plants. However, on woody plants biochemical aspects of catalase have been studied in gymnosperms and more recently in horse chestnut and oak, but few molecular data on genes coding for these enzymes are available on woody plants.
In this study, we compared the exon-intron structures of catalase genes of Prunus and Populus species, using the polymerase chain reaction (PCR). We analysed differences in the position, size and sequence of the introns, to characterise genotypes of species or cultivar. In particular, we compared Populus nigra with P. deltoides and Prunus persica with P. armeniaca, P. avium, P. domestica. To obtain detailed informations about the structures of introns of these plants, we cloned and sequenced the PCR products. The results obtained show that the position of introns of primordial catalase gene is conserved among the species analysed, but with some interesting differences in the number and sequence of introns.