Genetc variability of Brazilian wheat germplasm obtained by high-density SNP genotyping 399 Crop Breeding and Applied Biotechnology - 18: 399-408, 2018 Genetc variability of Brazilian wheat germplasm obtained by high-density SNP genotyping Adriana Scherlosky 1 , Volmir Sérgio Marchioro 2 , Francisco de Assis Franco 3 , Alessandro Lucca Braccini 1 and Ivan Schuster 4 Abstract: The aim of this study was to evaluate the genetc diversity of the wheat germplasm using high-density genotyping with SNP markers. A set of 211 wheat varietes genotyped with 35,142 SNP markers were used in the experiment. Genetc distances ranged from 0.013 to 0.471, with the highest frequency of distances varying between 0.31 and 0.40. In the cluster analysis by the UPGMA method, 81% of the varietes were clustered in three groups. Genetc variability in the Brazilian wheat germplasm has remained constant for over 70 years. Mean genetc distances among the varietes developed in each decade ranged from 0.33 to 0.34. A trend of genetc distance between genotypes from diferent eras has been observed over tme as a result of breeding. Results described in this study can help Brazilian wheat breeders to manage more adequately genetc variability in the Brazilian wheat germplasm. Keywords: Tritcum aestvum (L.), genetc variability, genotypes from diferent eras, breeding. Crop Breeding and Applied Biotechnology 18: 399-408, 2018 Brazilian Society of Plant Breeding. Printed in Brazil htp://dx.doi.org/10.1590/1984- 70332018v18n4a59 ARTICLE *Corresponding author: E-mail: ivanschuster.ivan@gmail.com Received: 21 February 2018 Accepted: 13 September 2018 1 Universidade Estadual de Maringá, Departa- mento de Agronomia, 87.020-900, Maringá, PR, Brazil 2 Universidade Federal de Santa Maria, 98.400-000, Frederico Westphalen, RS, Brazil 3 Coodetec, 85.813-450, Cascavel, PR, Brazil 4 Longping High-Tech, 14.140-000, Cravinhos, SP, Brazil INTRODUCTION One of the features of plant breeding in Brazil is the possibility of using commercial varietes in crosses regardless of the intellectual property associated with them (Riede et al. 2001). This is the so-called breeder’s right, provided for by the Plant Variety Protecton (PVP) Law in Brazil (Law 9456, from 1997). This possibility allows the sharing of genetc variability between the various breeding programs. Varietes developed by a breeding program can be used as germplasm source by other breeding programs. Genetc variability is the foundaton of breeding. Breeding programs are aimed at exploitng the genetc variability of species to obtain genetc combinatons of adapted, high yielding, disease-resistant, and higher-quality varietes, in additon to other characteristcs. Although genetc variability can be increased through the introducton of exotc germplasm, only a fracton of this variability is useful in breeding. The most part of the exotc genome is not adapted and must be eliminated afer being introduced as a source of variability, through successive breeding cycles. For this reason, in most cases, breeding programs use exclusively germplasm already improved for the generaton of breeding populatons and variability. Because the genetc variability used in breeding programs is only a fracton of the variability present in the species, knowing the existng variability in the