Congruence between morphological and molecular markers inferred from the analysis of the intra-morphotype genetic diversity and the spatial structure of Oxalis tuberosa Mol.

Abstract

Oxalis tuberosa is an important crop cultivated in the highest Andean zones. A germplasm collection is maintained ex situ by CIP, which has developed a morphological markers system to classify the accessions into morphotypes, i.e. groups of morphologically identical accessions. However, their genetic uniformity is currently unknown. The ISSR technique was used in two experiments to determine the relationships between both morphological and molecular markers systems. The intra-morphotype genetic diversity, the spatial structures of the diversity and the congruence between both markers systems were determined. In the first experience, 44 accessions representing five morphotypes, clearly distinct from each other, were analyzed. At the molecular level, the accessions exactly clustered according to their morphotypes. However, a genetic variability was observed inside each morphotype. In the second experiment, 34 accessions gradually differing from each other on morphological base were analyzed. The morphological clustering showed no geographical structure. On the opposite, the molecular analysis showed that the genetic structure was slightly related to the collection site. The correlation between both markers systems was weak but significant. The lack of perfect congruence between morphological and molecular data suggests that the morphological system may be useful for the morphotypes management but is not appropriate to study the genetic structure of the oca. The spatial structure of the genetic diversity can be related to the evolution of the species and the discordance between the morphological and molecular structures may result from similar selection pressures at different places leading to similar forms with a different genetic background.

Genetic diversity of feral alfalfa (Medicago sativa L.) populations occurring in Manitoba, Canada and comparison with alfalfa cultivars: an analysis using SSR markers and phenotypic traits

“…Whereas, the population differences we observed for phenotypic traits could have been the result of environmental selection, as shown by Rieseberg et al (2002). A lack of strong correlation between phenotypic and molecular markers has been reported by other authors (e.g., Pissard et al 2008). Some studies have indicated the distinct phenotypic separation of wild or 'Mielga' alfalfa populations from alfalfa cultivars (Crochemore et al 1998;Jenczewski et al 1998;Julier et al 1995) but similar reports do not exist for feral alfalfa populations.…”

Diversity of 21 taro (Colocasia esculenta (L.) Schott) accessions of Andaman Islands

“…The similar morphotypes can be result of different genotypes under a set of genotype 9 environment interactions and vice versa. The spatial structure of the genetic diversity can be related to evolution of species and the discordance between the morphological and molecular structures may result from similar selection pressure at different places leads to similar forms with different genetic background (Pissard et al 2007). …”

Set up of simple sequence repeat markers and first investigation of the genetic diversity of West-African watermelon (Citrullus lanatus ssp. vulgaris oleaginous type)

“…In the case of Oxalis tuberosa Mol. for example, it is known that the correlation between morphological markers and molecular markers systems is weak but significant (Pissard et al 2008).…”