GENETIC DIVERSITY CHARACTERIZATION OF CASSAVA CULTIVARS (MANIHOT-ESCULENTA CRANTZ) - I) RAPD MARKERS

RAPD markers were used to investigate the,genetic diversity of 31 Braz ilian cassava clones. The results were compared with the genetic diver sity revealed by botanical descriptors. Both sets of variates revealed identical relationships among the cultivars. Multivariate analysis of genetic similarities placed genotypes destinated for consumption ''in nature'' in one group, and cultivars useful for flour production in a nother. Brazil's abundance of landraces presents a broad dispersion an d is consequently an important resource of genetic variability. The bo tanical descriptors were not able to differentiate thirteen pairs of c ultivars compared two-by-two, while only one was not differentiated by RAPD markers. These results showed the power of RAPD markers over bot anical descriptors in studying genetic diversity, identifying duplicat es, as well as validating, or improving a core collection. The latter is particularly important in this vegetatively propagated crop.