Molecular evidence of outcrossing rate variability in Brassica napus

A leafy crop of Brassica napus L. called nabicol has been grown by farmers in northwestern Spain for many years, being an important horticultural product during the winter season. A collection of landraces of a Brassica napus leafy crop called nabicol is kept at ‘Misión Biológica de Galicia’ (CSIC-Spain) which can be used to search for desirable characteristics or to produce new commercial varieties to release in the market. The assessment of the mating system of nabicol landraces is particularly important to carry on adequate breeding and genetic conservation programs. The objective of this work is to estimate the outcrossing rate in nabicol under controlled pollinator conditions using SSRs. Pairs of flowering plants taken from nabicol landrace MBG-BRS0039 were placed in separated isolation cages and bumble bees ( Bombus sp.) were released for facilitating the crosses between plants. A seed sample from each plant in the cross was analyzed by SSRs that were polymorphic in the parental population. We found that the crop is partially allogamous and that there is genetic variation for the outcrossing rate among individuals. Several consequences for the maintenance and genetic improvement of the crop are discussed. The existence of genetic variability for this trait is a valuable tool that will allow us to study the genetic mechanisms underlying the mating system of this crop.