BIOCHEMICAL EVIDENCE SUPPORTING THE EXISTENCE OF A WEEDY FORM IN TEPARY BEAN (PHASEOLUS ACUTIFOLIUS A. GRAY)

摘要

Four forms of Phaseolus acutifolius A. Gray are known: three wild varieties and a domesticated form (Freytag and Debouck, 2002). However, until now an intermediate form between the wild and cultivated forms has not been identified (Pratt and Nabhan, 1988). The aconitase isozyme (ACO-2 allozyme) has been an informative evolutionary marker in teparies beans as to know the origin of its domestication. The slow ACO-2 allozyme was present in domesticated tepary, whereas the fast ACO-2 allozyme was presentin wild tepary (Garvin and Weeden, 1994). Additionally, the seed storage proteins patterns (globulins) serve to separate wild from the domesticated form, 25 globulins types were found only in wild P. acutifolius, while in the domesticated accessions there were only two patterns, not having counterpart in the wild materials (Schinkel and Gepts, 1988; Florez, 1996). Both biochemical markers may therefore serve as an evolutionary marker to help identify wild and domesticated teparies, and by extension, inorder to help identify a putative intermediate form. We analyzed a complex (wild-weedy-crop) from a wild population of teparies beans, from a biochemical (globulins and ACO-2 allozyme) and morphological viewpoint to find evidence that suggests the existence of a true intermediate form in tepary bean.