Abstract
AbstractSugar beet is hypothesized to have a narrowed genetic base due to its origin as White Silesian Beet and from numerous breeding selections and practices. High sugar quality, yield of recoverable sugar, cytoplasmic-male sterility system, monogermity, pests and disease resistance and bolting resistance constitute some of the adaptations that significantly influenced the existing genetic background of the crop. In this study we aimed to evaluate the extent of genetic diversity existing in wild beet representatives of Beta and Patellifolia and sugar beet cultivars, with a special focus on the complex Beta vulgaris. Another purpose was to determine the potential usefulness and conformity of selected molecular markers in different groups of materials in the context of rhizomania resistance. To reach these goals, molecular RAPD, ISSR techniques, literature-selected rhizomania resistance-segregating sequences as well as mitochondrial markers were used. The comparison of genetic diversity in wild and cultivated Beta forms shows that the population differentiation values and distance values are relatively high in cultivars. Moreover, the diversity component seemed to be compromised rather on the level of population (Hs) than in total (Ht) in cultivars. Our results shed a new light on the expected genetic bottlenecks existing in cultivars and revealed features specific for individual taxa (Patellifolia, Corollinae). Some degree of distinctiveness was suggested between genetic determinants of rhizomania resistance in modern cultivars in comparison with wild resistance sources. In addition, we document here an internal heterogeneity existing in selected wild/weedy accessions at the level of crucial sequences using high resolution melting.
Highlights
Sugar beet (Beta vulgaris L. ssp. vulgaris) is a crop with great economic importance, especially in temperate climate zones where it constitutes a valuable sucrose source
In this study we aimed to evaluate the extent of genetic diversity existing in wild beet representatives belonging to the genera Beta and Patellifolia as compared to sugar beet cultivars with a special emphasis on the complex Beta vulgaris using molecular RAPD, ISSR techniques and literature-selected putative rhizomania resistance-segregating markers as well as mitochondrial markers
The materials selected for the study comprise representatives of five wild beet species, i.e. B. vulgaris ssp. maritima (4 accessions: B.m.01, B.m.27—resistant, B.m.40 and B.m.72), B. macrorhiza (B.macr.21), B. corolliflora (B.c.20), P. procumbens (P.p.25) and P. patellaris (P.pat.22), one weed beet accession, and five sugar beet cultivars with contrasting phenotypes for rhizomania resistance (B.v.14, B.v.15 and B.v.16—diploid, tolerant, B.v.13 and B.v.17—triploid, susceptible)
Summary
Sugar beet (Beta vulgaris L. ssp. vulgaris) is a crop with great economic importance, especially in temperate climate zones where it constitutes a valuable sucrose source. Vulgaris) is a crop with great economic importance, especially in temperate climate zones where it constitutes a valuable sucrose source. It contributes about one fifth to the global sugar production, which for the 2007–2011 period reached approximately 157 million metric tons (Koo and Taylor 2012). Crop rotation is necessary in beet production due to disease problems (Koo and Taylor 2012), which may be effectively eliminated by resistance breeding approaches. Breeding contributed above all to the increase in sugar yield. ‘‘White Silesian’’, constituted the origin for all subsequently developed sugar beet varieties (Fischer 1989; Biancardi et al 2010). At the same time other breeding practices and directions, for example cytoplasmic male sterility and genetic monogermity systems, used throughout the history of the modern crop’s development, are supposed to impinge significantly on its genetic structure and, as a consequence, to result in genetic bottlenecks, reducing available diversity and hampering in a way the progress in genetic combinations for new cultivars’ releases (Biancardi et al 2010)
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