Avaliação da diversidade genética de populações de fáfia (Pfaffia glomerata (Spreng.) Pedersen) por RAPD, caracteres morfológicos e teor de beta-ecdisona / Genetic diversity of pfaffia populations (Pfaffia glomerata (Spreng.) Pedersen) by RAPD, morphological characters and ß-ecdisone contents

Takeshi Kamada

Pfaffia (Pfaffia glomerata (Spreng.) Pedersen) is a native species of South America with widespread occurrence in the States of Paraná, Mato Grosso do Sul and Goiás. Its economic value is mainly due to the similarity of their phytochemical characteristics to the Korean-ginseng (Panax ginseng). Research institutions are carrying out continual germplasm collections, once the risks of losing variability are increased by the extracting and commercialization of roots to pharmaceutical companies. The objective of the present study was to evaluate the genetic diversity of four populations collected in the region of the Paraná river, and maintained in the germplasm collection of medicinal plants at Embrapa/Cenargen, through the evaluation of phenotypic characters and RAPD markers. Fourteen continuous and eight multicategorical phenotypic characters were used. RAPD markers were obtained by screening 67 primers, with the amplification 267 polymorphic patterns. Data were initially analyzed for the dissimilarity measures using the Mahalanobis D2-statistics (continuous characters), dissimilarity index of binary data (multicategorical) and arithmetic complement of Nei and Lis coefficient (RAPD). Dissimilarity matrices were used for grouping individuals and populations by the Tocher optimization method and UPGMA. The relative importance of the characters towards diversity was analyzed by the SINGH methodology. The correlations between the types of characters were tested by the Z statistics (Mantel test) for the dissimilarity matrix of genetic distances. The dissimilarity measurements of the populations presented similar results regarding molecular and multicategorical characters, with the populations of larger dissimilarity coinciding. The results indicated lower dissimilarity levels among individuals and higher among populations suggesting that new populations can be obtained to increase diversity in the germplasm collection. In all the analyses, the population collected in the municipality of Northern Querência, PR, stood out as the largest established dissimilarity among populations, besides their individuals present high ß-ecdisone contents, becoming fundamental to prioritize the preservation of this population, which is also located in an area of intense extractivism. The correlations between the genetic distance matrices were significant by the Z test (p <0,01), however those values were low. The largest correlation was found between the diversity obtained with the multicategorical characters and the RAPD marker (0,2815). The results led to the conclusion that it is not recommended to use just one type of characteristic, either phenotypic or molecular, to evaluate the genetic diversity in the qualitative aspect, once the correlations between the genetic distances of each characteristic were small (<0,30). The exclusive use of RAPD markers can be a suitable choice in some aspects, mainly when there is no time and resources for periodic visits to the site for evaluation of the populations. However, when the species is already in advanced stages of improvement, the evaluation of the phenotypic characters will be essential.

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