A core collection of common bean from the Iberian peninsula

Characterization of crop germplasm from specific regions helps understand the patterns of genetic variation that facilitates further germplasm collection, characterization, management and their more efficient utilization in genetics, breeding and other studies. Common bean (Phaseolus vulgaris L.) is a traditional crop in the Iberian Peninsula (Spain and Portugal) where subsistence farmers have been growing and maintaining their own cultivars since their introductions from the Americas in the sixteenth century. Our objectives were to: (i) characterize diversity in the landraces collected from the Iberian Peninsula and (ii) form a core collection. Of 388 landraces from the major production regions characterized for 34 quantitative and 13 qualitative characters, including morphological, agronomic and biochemical traits, 74.7% had an Andean origin, 16.8% a Mesoamerican origin and 8.4% had seed mixtures or were recombinants between the two gene pools. Landraces of indeterminate climbing growth habit Type IV (47.2%) and bush determinate Type I (26.4%) with large (52.9%) and medium (27.4%) seeds of white (38.8%) and cream (25.9%) colour were predominant. Similarly, the 'T' phaseolin pattern and common bean race Nueva Granada were the most frequent (51%). Some exceptionally large-seeded landraces of Andean (e.g., PHA-0917 with 119 g 100-seed weight(-1)) and Mesoamerican (e.g., PHA-0399 with 66 g 100-seed weight(-1)) were found. These and other possible recombinants between the two gene pools merit further investigation. Fifty two landraces (13%) were chosen to form a core collection representing the genetic diversity in the Iberian Peninsula.