Genética molecular y evolutiva de los cromosomas B de Prospero autumnale

Résumé

Prospero autumnale (Asparagaceae) is a perennial bulbous herbaceous plant distributed throughout the circum-Mediterranean region. It constitutes a complex of cryptic species with different chromosomal numbers and genomic DNA content. In addition to this canonical genomic variability, B chromosomes have been described in three of their four diploid cytotypes. These chromosomes are supernumerary, dispensable, and do not recombine with the standard (A) chromosomes. Therefore, they follow their own evolutionary pathway, showing drive mechanisms in the germline of the individuals containing them. At Cuesta de la Palma (Granada, Spain), Ruiz-Rejón et al. found in the 80s of the last century a natural population of P. autumnale harbouring B chromosomes that affected the expression of an esterase enzyme. However, many aspects of this B chromosome system yet remained to be known. We have performed a series of analyses in this population to address some fundamental topics of B chromosome research (e.g., frequency evolution and transmission). Taking advantage of the development of new DNA sequencing technologies, we have also analyzed the DNA content of these B chromosomes.