MORPHOLOGICAL AND ISOZYME CHARACTERIZATION OF ARACHIS-PINTOI KRAP ET GREG NOM NUD GERMPLASM

Arachis pintoi, a wild perennial relative of the peanut, originated in Brazil, is of increasing importance to pasture improvement in the tro pics. Its available genetic base, however, is very narrow, and intensi ve collection is being carried out. This study aimed to characterise t he existing eight accessions in the CIAT germplasm collection in order to describe the existing variation, identify plant types, and discove r possible duplicates. Morphological characterisation, based on 60 mor phological descriptors, demonstrated that variation exists. Numerical taxonomic techniques were used to rank the importance of these descrip tors. Cluster analysis, conducted on those pre-selected morphological characters, grouped the accessions into two major plant types: one hom ogenous, and the other falling into four distinct subgroups. Polyacryl amide gel electrophoresis (PAGE) was applied to root-tip tissue. Isozy me characterisation by PAGE showed polymorphisms in the isozymes a-EST , ACP, GOT, and DIA. When analysed together, the four isozymes could u niquely distinguish every accession of A. pintoi held in the CIAT germ plasm collection. Correspondence and cluster analyses of these isozyme patterns showed the morphologically homogenous plant type to be heter ogenous, and the heterogenous morphotype to have similar banding patte rns. The lack of continuous patterns of variation in both morphology a nd isozymes manifests the need for further germplasm collection of A. pintoi.