02576naa a2200217 a 450000100080000000500110000800800410001910000170006024500640007726000090014152019720015065300220212270000150214470000180215970000200217770000170219770000150221470000260222970000190225577300840227416518322004-04-05       1998    bl uuuu     u00u1 u    #d1 aALLEM, A. C.  aThe primary genepool of cassava (Manihot esculenta Crantz).  c1998  aAbstract: A crop genepool comprises three distinct categories of gene supliers, primary, secondary, and tertiary genepools. The primary genepool (GP1) is composed of gene reservoirs that cross easily with the domesticate and the crosses regularly produce fertile offspring. The secondary (GP2) and tertiary (GP3) genepools of a crop comprise wild gene sources that cross with a certain degree of dificulty with the crop species or may not cross at all, the picture implying in less close genetic distances. The GP1 is further subdivided into cultivated and wild genepools. The cultivated genepool comprises all comercial stocks of the crop besides all indigenous landraces and folk varieties of the domesticate. The wild primary genepool of a crop comprises putative ancestors and closely related species that show a fair degree of fertile relationships with the domesticated varieties. In this context, we suggest the two South American wild subspecies of cassava (M. flabellifolia and M. peruviana) as the original wild stocks which cassava descends from. Another Brazilian species (M. pruinosa) is so close morphologically to the two wild subspecies of cassava that we think the species may become a natural member of the wild GP1 of the indigen. The GP2 of cassava is more difficult to  delimit as few species have been tested for fertility relationships. Biosystematic crosses carried out between the crop and the Brazilian wild species M glaziovii and M dichotoma suggest that both are among the estabilished species of the GP2. Based on field experience, we guess that three untested Brazilian species are prospective candidates for the GP2 of cassava: M pilosa, M triphylla, and M brachvloba.  'Me inclusion of Mexican species in the GP1 or GP2 of cassava will have to wait for specific trials since our knowledge of the fertile relationships between these species and the indigen lags well behind the information available for their South American relatives.  aCassava - species1 aROA, A. C.1 aMENDES, R. A.1 aSALOMÃO, A. N.1 aBURLE, M. L.1 aSECOND, G.1 aCARVALHO, P. C. L. de1 aCAVALCANTI, J.  tRevista Brasileira de Mandioca, Salvadorgv. 17 , p. 11, nov, 1998, Suplemento.