lepidium-like, a naturally occurring mutant of Capsella bursa-pastoris

Naturally occurring mutants whose phenotype recapitulates the changes that distinguish species in phylogenetically related groups are of especial interest from the evolutionary point of view. They can give a key about the genetic control of the changes accompanying speciation. The flowers of Brassicaceae generally reveal a very stable ground plan, only several deviations from this pattern are known, in particular in the genus Lepidium. In some species of this genus, the loss of petals and/or stamens occurs. Here we describe lepidium-like (lel), a naturally occurring apetalous variety of Capsella bursa-pastoris. The number and structure of other floral organs are not affected. Petals do initiate in the mutant, but late in flower development and soon cease their growth. The lel phenotype has a wide geographical distribution, being found near the northern border of the species range as well as in its central part. The genetic analysis of inheritance demonstrated that the lel phenotype is controlled by two independent loci with different types of inheritance: dominant and recessive, this suggests the opposite functions of these loci. The identification and characterization of the apetalous mutant is a basis for further research into the genetic base of morphological evolution.