Analysis of bruchid resistance in the wild common bean accession G02771: no evidence for insecticidal activity of arcelin 5

Arcelins are abundant seed storage proteins thought to be implicated in the resistance of wild Phaseolus vulgaris (L.) genotypes against Zabrotes subf asciatus (Boheman), an important storage insect pest of common bean. Here, the insecticidal activity of the arcelin-5 variant that is present in the h ighly resistant P. vulgaris accession G02771 was investigated. No correlati on could be established between the presence of arcelin 5 and the insectici dal effects observed in G02771 seeds. Insect feeding assays with artificial seeds into which purified arcelin-5 protein was incorporated and with tran sgenic P, acutifolius (A, Gray) seeds in which the arcelin-5 genes were exp ressed, showed that the presence of arcelin-5 proteins, even at elevated le vels, was not sufficient to achieve adequate resistance against Z. subfasci atus, The same might apply to other arcelin variants. Nevertheless, as resi stance is clearly closely linked to the presence of the arcelin-1 or arceli n-5 locus, arcelins remain useful markers in breeding programmes aimed at i ntrogressing high levels of resistance to Z. subfasciatus in P. vulgaris cu ltivars.