Estimation of selfing rate in a natural population of Scrophularia nodosa L. using Allozymes

The genetics of 4 polymorphic enzyme systems PO, 6PGDH, PGM1 and PGM2, is investigated in a seed population derived from a natural population of Scrophularia nodosa. No linkage was detected between any of the four loci. Two of the loci are used to estimate outcrossing rates in a natural population by single-locus as well as multilocus methods. The absence of selfing is in contradiction with the expectations. Testing the fitness of alien pollen against self pollen by performing artificial crosses with different pollen mixtures with PO as a genetic marker revealed no differences between alien and own pollen. Therefore the mechanism preventing self-pollination in this natural population of S. nodosa remains unresolved. The ecological significance of the observed mating system is discussed.