A new variant of antimetabolic protein, arcelin from an Indian bean, Lablab purpureus (Linn.) and its effect on the stored product pest, Callosobruchus maculatus.

The anti-metabolic or insecticidal gene, arcelin (Arl) was isolated, cloned and sequenced using sequence specific degenerate primers from the seeds of Lablab purpureus collected from the Western Ghats, Tamil Nadu, India. The L. purpureus arcelin nucleotide sequence was homologous to Arl-3 and Arl-4 alleles from Phaseolus spp. The protein it encodes has 70% amino acid identity with the amino acid sequences of Arl-3I, Arl-3III, Arl-4 precursor, Arl-4 and Arl-4I. The partially purified arcelin from the seeds of L. purpureus using an artificial diet confirmed the complete retardation of development of the stored product pest Callosobruchus maculatus at 0.2% w/w arcelin-incorporated artificial seeds.