Divergência genética em genótipos de cana-deaçúcar (Saccharum spp.) através de caracteres morfoagronômicos e por marcadores moleculares

Abstract

This study had as objective to estimate the genetic divergence among sugarcane genotypes by means of morphoagronomical characters and molecular markers, and to verify the relation between these procedures. An experiment was conducted in Rio Largo, AL, using a randomized block design with four repetitions. The multivariated analysis of Principal Components, the genetic divergence based on the Mahalanobis 2 ii' D Generalized Distance, and the Average Euclidean Distance Standardized were used for the analysis of the quantitative characters. Based on these distances, a grouping analysis was performed by the More Distant Neighbor method and the UPGMA method, besides Tocher for 2 ii' D . Jaccard coefficient and UPGMA grouping were used in the evaluation of the genetic divergence by molecular markers and morphologic characters. The inconsistency as to formation of different groups between the Standardized Average Euclidean Distance and 2 ii' D of Mahalanobis characterize these two estimates as measures of different dissimilarity. In the same way, the grouping techniques by the More Distant Neighbor method and by UPGMA show graphical dispersions that are not coincident, with differences in relation to the number of groups and in the grouping pattern, while the grouping by UPGMA and obtained by Tocher showed the same agreements. The 2 ii' D Distance of Mahalanobis corresponded to the Principal Components technique, by showing the same groups made by Tocher and UPGMA, obtained from 2 ii' D . However, these techniques did not indicate agreement with the Standardized Average Euclidean Distance. The correlation between the genetic divergence through morphologic characters and estimated by molecular markers was significant, however, from average magnitude (r = 0,47), indicating to be complementary measurements. There was not significant correlation for the divergence obtained through quantitative characteristics with the morphologic characters and molecular markers obtained by the different estimators, as well as between Standardized Average Euclidean Distance and the Mahalanobis 2 ii' D , which indicates clearly that there is no relation between these estimates.