Population Structure and Genetic Diversity in Sweet Cassava Cultivars from Paraná, Brazil

Abstract

The objectives of the present study were to assess the population structure and genetic diversity in traditional sweet cassava cultivars collected in Bbackyard^cultivations in the municipalities of Maringá, Cianorte, and Toledo, State of Paraná, Southern Brazil, using 13 SSR molecular markers. All the loci analyzed were considered polymorphic with a mean of 3.15 alleles per locus; the mean polymorphism information content (PIC) value found was 0.4598, indicating that the primers were reasonably informative and the heterozygosity amplitude observed ranged from 0.0270 (GA134) to 0.8718 (SSRY45), with a mean of 0.4762, while the mean genetic diversity obtained was 0.5407, ranging from 0.3138 (GA21) to 0.6502 (GA140). The most divergent combinations were BGM434T-BGM20M, BGM35C-BGM20M, BGM430T-BGM232M, BGM430T-BGM164M, BGM430T-BGM322M, and BGM35C-BGM164M. The analysis of population structure distributed the traditional cultivars assessed in four different groups. The analysis of molecular variance (AMOVA) estimated that 11, 15, and 74 % of the variance were between groups, between individuals within groups, and between individuals within the population as a whole, respectively. The F is (0.170) and F it (0.259) values indicated a number of heterozygotes present in the population under study lower than that necessary to reach the Hardy-Weinberg equilibrium. The genetic variability found among the traditional sweet cassava cultivars assessed was considered wide, and the groups that were most distant were mostly cultivars from Toledo and Maringá.

Genetic diversity and population structure of traditional sweet cassava accessions from Southern of Minas Gerais State, Brazil, using microsatellite markers

“…Our results show the presence of 17 rare alleles with frequency values ranging from 0.0096 to 0.0306, corroborating with previously published data Peroni et al, 2007;Rocha et al, 2008;Siqueira et al, 2009;Asare et al, 2011;Turyiagienda et al, 2012;Costa et al, 2013;Ferreira et al, 2015;Ortiz et al, 2016).…”

“…The mean PIC value found was low compared to others studies related to cassava reported in the literature (Xia et al, 2005;Asare et al, 2011;Turyagyenda et al, 2012). On the other hand, studies developed by Costa et al (2013) and Ortiz et al (2016) with traditional sweet cassava cultivars from Paraná State, Brazil, showed PIC values such as 0.4040 and 0.4598. This fact can be explained because smaller and more homogeneous populations tend to present lower values of informative content per locus.…”

“…This kind of subsistence farming has been extinguished in the past years due to the migration from rural to urban areas, and also to the expansion of large-scale farmers that now dominate areas previously occupied by smallholders, consequently leading to a drastic reduction of genetic diversity (Cleveland et al, 1994). Therefore, the characterization of the available germplasm, elucidation of genetic identity and population structure of sweet cassava accesses is very important (Costa et al, 2013;Ortiz et al, 2016). Genetic diversity can be assessed by using biochemical and morphological markers (Elias at al., 2001;Ortiz et al, 2016), but molecular markers are highly recommended because they provide more detailed information about polymorphism, independently of physiological state of the plant and environmental conditions (Agarwal et al, 2008;Raji et al, 2009).…”

“…Therefore, the characterization of the available germplasm, elucidation of genetic identity and population structure of sweet cassava accesses is very important (Costa et al, 2013;Ortiz et al, 2016). Genetic diversity can be assessed by using biochemical and morphological markers (Elias at al., 2001;Ortiz et al, 2016), but molecular markers are highly recommended because they provide more detailed information about polymorphism, independently of physiological state of the plant and environmental conditions (Agarwal et al, 2008;Raji et al, 2009). Molecular marker techniques, such as microsatellites (Raji et al, 2009;Monteiro-Rojas et al, 2011;Asare et al, 2011;Turyagyenda et al, 2012;Costa et al, 2013;Mezette et al, 2013;Kawuki et al, 2013;Ndung'u et al, 2014;Fu et al, 2014;Ortiz et al, 2016) have showed satisfactory results for evaluating the genetic diversity and population structure in sweet cassava.…”

“…Genetic diversity can be assessed by using biochemical and morphological markers (Elias at al., 2001;Ortiz et al, 2016), but molecular markers are highly recommended because they provide more detailed information about polymorphism, independently of physiological state of the plant and environmental conditions (Agarwal et al, 2008;Raji et al, 2009). Molecular marker techniques, such as microsatellites (Raji et al, 2009;Monteiro-Rojas et al, 2011;Asare et al, 2011;Turyagyenda et al, 2012;Costa et al, 2013;Mezette et al, 2013;Kawuki et al, 2013;Ndung'u et al, 2014;Fu et al, 2014;Ortiz et al, 2016) have showed satisfactory results for evaluating the genetic diversity and population structure in sweet cassava. Furthermore, microsatellite markers, also known as simple sequence repeats (SSR), are informative due to their multi-allelic nature, codominant inheritance and wide distribution through the genome (Varshney et al, 2005;Raji et al, 2009).…”