Characterisation of sugar beet (Beta vulgaris L. ssp. vulgaris) varieties using microsatellite markers

<p>Abstract</p> <p>Background</p> <p>Sugar beet is an obligate outcrossing species. Varieties consist of mixtures of plants from various parental combinations. As the number of informative morphological characteristics is limited, this leads to some problems in variety registration research.</p> <p>Results</p> <p>We have developed 25 new microsatellite markers for sugar beet. A selection of 12 markers with high quality patterns was used to characterise 40 diploid and triploid varieties. For each variety 30 individual plants were genotyped. The markers amplified 3-21 different alleles. Varieties had up to 7 different alleles at one marker locus. All varieties could be distinguished. For the diploid varieties, the expected heterozygosity ranged from 0.458 to 0.744. The average inbreeding coefficient F_iswas 0.282 ± 0.124, but it varied widely among marker loci, from F_is= +0.876 (heterozygote deficiency) to F_is= -0.350 (excess of heterozygotes). The genetic differentiation among diploid varieties was relatively constant among markers (F_st= 0.232 ± 0.027). Among triploid varieties the genetic differentiation was much lower (F_st= 0.100 ± 0.010). The overall genetic differentiation between diploid and triploid varieties was F_st= 0.133 across all loci. Part of this differentiation may coincide with the differentiation among breeders' gene pools, which was F_st= 0.063.</p> <p>Conclusions</p> <p>Based on a combination of scores for individual plants all varieties can be distinguished using the 12 markers developed here. The markers may also be used for mapping and in molecular breeding. In addition, they may be employed in studying gene flow from crop to wild populations.</p

Screening for genetic elements involved in the non-host response of sugar beet to the plasmodiophorid cereal root parasite Polymyxa graminis by representational difference analysis

Representational difference analysis (RDA) was used to select and clone cDNA fragments of genes whose steady state transcription was upregulated in sugar beet challenged with the nonhost parasite Polymyxa graminis. In silico analysis revealed that sequences with similarities to plant defence genes as well as genes of unknown function were represented amongst the cloned cDNAs. The utility of RDA was verified when, in material from the nonhost interaction, semiquantitative RT-PCR confirmed transcriptional upregulation of at least 10 of 17 genes randomly selected from the RDA library. Time-course transcriptional analysis of two plant defence gene-like sequences demonstrated that, in sugar beet, both were upregulated within 1 h in response to P. graminis but not to P. betae. This work comprises the first report of an active response by sugar beet to P. graminisPeer reviewe