Genetic identity and seed production in heterogeneous common bean landraces (Phaseolus vulgaris L.) of “new “commercial interest 2003.

Basilicata region (Southern Italy) is rich of highly variable common bean (Phaseolus vulgaris L.) landraces that are the subject of increasing economic interests as typical food productions. The request of larger scale seed production poses a serious risk of genetic erosion and criteria to monitor and certify the genetic “identity” in heterogeneous landraces is needed. Two common bean landraces Marrozzo (indeterminate growth habit) and Verdolino (determinate growth habit), mixtures of 39 and 22 accessions, respectively, collected in a large area of Basilicata were grown in two environmentally distinct locations to observe the effect of growing environment on their genetic structure. 19 morpho-agronomical traits (9 qualitative and 10 quantitative) and 16 microsatellites loci were scored. On the basis of morpho-agronomical traits, “Marrozzo”, widely distributed, did not show significantly different response to different growing environments while Verdolino, for most traits, did show significant differences. The 16 pairs of SSRs primers detected 75 alleles in Marrozzo and 58 alleles in Verdolino with a polymorphic degree of 100% in Marrozzo and 81.2% in Verdolino. The heterozigosity average observed value (Ho) is 0.011 in Marrozzo and 0.005 in Verdolino. 7 “unique” alleles were detected in Marrozzo and 4 in Verdolino with frequency higher of 40%. Genetic identity of each common bean landrace can be easily assessed on the basis of the presence and the frequency of unique alleles. To avoid genetic erosion the genetic structure of landraces during seed production needs to be monitored.