Common bean (Phaseolus vulgaris L.) lines devoid of major lectin proteins

In common bean, the most abundant proteins of the lectin family (arcelin, phytohaemagglutinin and α-amylase inhibitor – APA proteins) are major antinutritional factors of the seeds. Reduced protein digestibility and high toxicity at the intestinal level are the causes of their antinutritional effect. Bean lines producing seeds without the lectins mentioned above were developed to improve nutritional characteristics of bean seeds used for human consumption and, potentially, for animal feeding. The genetic trait was transferred from a wild bean accession into a number of bean cultivars. The 1 : 3 'lectin-free/lectin-containing seeds' segregation ratio hypothesis was confirmed by chi-square analysis in the F2 progenies. Four lectin-free stable lines, P500, P501, 938 and 586/8 (white seeded), and 44 climbing breeding lines, have been developed. The 'white seed coat' trait, correlated with a reduced amount of tannins and polyphenols in bean seeds, has been introduced in our lectin-free materials to further improve their nutritional characteristics. The field performance of P501, 938 and 586/8 and that of their lectin-containing parents, was evaluated on 2007 in two locations. Dry seed yield, seed emergence, plant height, plant growth duration, average weight and germination capacity of the produced seeds were surveyed and statistically analysed. At the location of Battipaglia (Salerno), the dry seed yield value of the lectin-free line 938 (3.74 t/ha) and that of one of its parent, the CIAT line BAT 881 (3.65 t/ha), were significantly higher than those of all other lines tested. Germination percentage of lectin-free lines, recorded 3 days after sowing, was significantly higher than that of controls.