02280nam a2200301 a 450000100080000000500110000800800410001902000180006010000170007824500650009526001710016030000130033152013960034465000120174065000180175265000130177065000130178365000220179665000140181865300170183270000150184970000180186470000190188270000170190170000150191870000260193370000190195911340742016-05-05       2000    bl uuuu     u00u1 u    #d  a85-87697-05-61 aALLEM, A. C.  aThe primary gene pool of cassava (Manihot esculenta Crantz).  aIn: INTERNATIONAL SCIENTIFIC MEETING CASSAVA BIOTECHNOLOGY NETWORK, 4., 1998, Salvador. Cassava biotechnology: proceedings. Brasília, DF: EMBRAPA-CENARGEN: CBNc2000  aP. 3-14.  aA crop gene pool comprises three distinct categories of gene suppliers, primary, secondary, and tertiary gene pools. The primary gene pool (GP-1) is composed of gene reservoirs that cross easily with the domesticate and the crosses produce fertile offspring regularly. The secondary (GP-2) and tertiary (GP-3) gene pools comprise gene sources that cross with variable degrees of diffilculty with the crop species, this implies less close genetic distances. The GP-1 is further subdivided in cultivated and wild gene pools. The cultivated gene pool englobes commercial stocks of the crop besides indigenous landraces and folk varieties of the domesticate. The wild GP-1 of a crop comprises putative ancestors and closely related species that show a fair degree of fertile relationships with the domesticate. Two Douth American wild subspecies of cassava (M. flabellifolia and M. peruviana) are natural members of the wild GP-1 of the species. Another Brazilian species (M. pruinosa) is so close morphologically to the two wild subspecies of cassava that it may turn out another member of the wild GP-1 of the indigen. The GP-2 of cassava is more difficult to delimit as few species have been tested for genetic compatibility. Biosystematic crosses carried out between the crop and a number of wild species suggest a dozen of them as components of the GP-2, the majority are Brazilian species.  aCassava  aBiotecnologia  aEspécie  aMandioca  aManihot Esculenta  aTaxonomia  aBiotecnology1 aROA, A. C.1 aMENDES, R. A.1 aSALOMAO, A. N.1 aBURLE, M. L.1 aSECOND, G.1 aCARVALHO, P. C. L. de1 aCAVALCANTI, J.