Analysis of Fennel Breeding Populations Based on Distinctness, Uniformity, and Stability (DUS) Testing via Morphological Descriptors and DNA Molecular Markers

Abstract

A bred plant variety is a valuable tool for enhancing crop production and total yield. Recently, our breeding team developed three high seed yielding synthetic cultivars of bitter fennel. To characterize these newly breeding populations and differentiate them from each other and their parental populations, we conducted a Distinctness, Uniformity, and Stability (DUS) assessment using morphological traits evaluated over two consecutive years, as well as 20 Start Codon Targeted (SCoT) markers. The evaluation of morphological traits revealed that, five of qualitative traits exhibited monomorphism, while two other qualitative traits displayed polymorphism. Additionally, the investigation of eight quantitative traits showcased significant diversity. The Combined Over Years Distinctiveness analysis at a 1% significance level, based on eight quantitative characteristics, indicated distinctiveness for two breeding populations, namely Early and Medium Maturity Synthetic cultivars, compared to other populations. The Combined Over Years Uniformity analysis identified that all of the breeding populations and their parental populations were uniform in terms of the measured traits. The differences between Phenotypic Coefficients of Variation and Genotypic Coefficients of Variation were not particularly noticeable in the experimental material used currently. The majority of the measured traits showed high heritability, highlighting their stability over time. PCA utilized for quantitative morphological features, the first two principal components collectively accounted for more than 86.8% of the phenotypic variation. Subsequently, a dendrogram was constructed, which clustered breeding and parental populations into three distinct groups. The 15 SCoT markers produced a total of 164 extended fragments, with 139 (85%) of them showed polymorphic.The genetic similarity between the populations exhibited a range of 0.08–0.81, and cluster analysis utilizing Jaccard similarity coefficients and the Unweighted Pair Group Method with Arithmetic Mean (UPGMA) technique revealed clear distinctions among the three breeding populations and their parental populations. Altogether, the findings indicate that morphological DUS descriptors effectively distinguish some the populations, while others with overlapping expressions cannot be discriminated. Notably, SCoT markers demonstrate a fine ability to detect distinctions among fennel populations, suggesting the possibility of utilizing them as a complement to morphological traits in the DUS test. As a conclusion, these three newly breeding populations of fennel are distinct from each other and from their parental populations, and they can advance for registration and seed purity testing.