Identification of AFLP co-segregating with creeping rootedness in lucerne (Medicago sativa L.).

Creeping-rootedness (CR) is a form of vegetative propagation in lucerne (Medicago sativa L. complex) consisting of the development of new plants from adventitious shoots arising from roots with horizontal growth habit. Introgression of the CR character into cultivated lucerne may contribute to better stand persistence and greater grazing tolerance. Phenotypic selection of this trait is difficult owing to intrinsic features of the species such as autotetraploidy, allogamy and propagation by seed in addition to the polygenic control, low espressivity and variable penetrance of the trait. With the aim of developing a molecular marker-based system for the genotypic selection of the CR phenotype in lucerne, two segregating populations for this trait were screened with amplified fragment length polymorphisms (AFLPs), in order to identify CR-linked markers. Two AFLP amplicons were selected as segregating in a non-independent manner from the CR phenotype in both populations. The use of AFLP closer to the CR allows the conditional probability for CR selection to be nearly doubled. A PCR-based marker was developed for this AFLP and used to screen a collection of genotypes displaying either the CR or non-CR phenotype. The related primers were able to amplify the diagnostic amplicon in most of the CR genotypes and in approximately half of the non-CR individuals. Results are discussed in relation to the use of this marker in marker-assisted selection of the CR phenotype in lucerne.