Poliformismo isoenzimático de seis poblaciones naturales de Raigrás inglés de Galicia

Abstract

Six vvild populations of Lolium perenne representing two agronomic «pools» were scored for isozvme variants in seven enzyme systems: PGI, GOT, ACP, PGM, 6-PGD, SHDH and EST. From the individual banding pattern a genetic interpretation of the variation was formulated and population studies of the resulting seven polymorphic enzyme loci were performed. Genetic differentiation between and within populations was estimated using several methods: Nei's genetic distances, Wright's fixation índices, average number of alíeles and" average heterozygosity. Perennial ryegrass populations were variable genetically; the average number of alíeles per locus was 3.16, the average heterozygosity was 0.395 and average Nei's distance was 0.057. Chi-squared test and Fixation Índices showed a deficiency of heterozygotes relative to Hardy-Weinberg expectations for three populations, likely because either the neighbourhood size was smaller than the «sampling» área size there was a preferential crossing among related individuáis. Agronomic typology does not show genetic relationships, with which the better strategy for conserving genetic variability is to multiply independently several representative populations of each agronomic «pool».