Comparative analysis of maize (Zea mays L.) lines based on morphological and molecular characteristics

Purpose. To determine the phylogenetic relationships between maize lines based on morphological description (DUS test) and SSR markers. Methods. Field studies (descriptive plant morphology), molecular techniques (PCR, capillary electrophoresis), and statistical analyses (correlation analysis, hierarchical clustering). Results. Based on field studies of 57 maize lines by morphological traits, the codes of qualitative and quantitative characteristics were determined, allowing the classification of the studied maize lines into three groups according to their similarity level: distinct, similar, and very similar. Pearson correlation coefficients were used to calculate phenotypic distances between the studied maize lines, resulting in five cluster groups and seven separate clusters formed by individual lines. The most similar maize lines according to the morphological character codes were those with a similarity coefficient of 0.997, which belong to the group of similar lines according to the results of the testing for distinctness, uniformity, and stability (DUS). The similarity coefficients among lines classified as very similar were sufficiently high, ranging from 0.890 to 0.990, although one pair of lines within this group had a similarity coefficient of 0.771. Based on Roger's molecular distances for nine SSR markers, the most similar lines had a similarity coefficient of 0.16, yet this pair was classified as distinct according to DUS testing. The most distinct pair of lines based on SSR markers had a similarity coefficient of 0.42. The correlation analysis between phenotypic and molecular distance matrices revealed a very weak inverse correlation (r = −0.1). Conclusions. It was found that the calculation of phenotypic and molecular distances reflects the level of similarity among the studied genotypes based on morphological traits and SSR markers. It was shown that the degree of similarity among the studied maize lines varies depending on the evaluation approach, as indicated by expert assessment based on DUS testing results.