Unravelling hybridization in Phytophthora using phylogenomics and genome size estimation

The genus Phytophthora comprises many economically and ecologically important plant pathogens. Hybrid species have previously been identified in at least six of the 12 phylogenetic clades. These hybrids can potentially infect a wider host range and display enhanced vigour compared to their progenitors. Phytophthora hybrids therefore pose a serious threat to agriculture as well as to natural ecosystems. Early and correct identification of hybrids is therefore essential for adequate plant protection but this is hampered by the limitations of morphological and traditional molecular methods. Identification of hybrids is also important in evolutionary studies as the positioning of hybrids in a phylogenetic tree can lead to suboptimal topologies. To improve the identification of hybrids we have combined genotyping-by-sequencing (GBS) and genome size estimation on a genus-wide collection of 614 Phytophthora isolates. Analyses based on locus- and allele counts and especially on the combination of species-specific loci and genome size estimations allowed us to confirm and characterize 27 previously described hybrid species and discover 16 new hybrid species. Our method was also valuable for species identification at an unprecedented resolution and further allowed correct naming of misidentified isolates. We used both a concatenation- and a coalescent-based phylogenomic method to construct a reliable phylogeny using the GBS data of 140 non-hybrid Phytophthora isolates. Hybrid species were subsequently connected to their progenitors in this phylogenetic tree. In this study we demonstrate the application of two validated techniques (GBS and flow cytometry) for relatively low cost but high resolution identification of hybrids and their phylogenetic relations.info:eu-repo/semantics/publishedVersio

Transgenic resistance of Bulgarian potato cultivars to the Colorado potato beetle based on Bt technology

Colorado potato beetle, Leptinotarsa decemlineata Say, is the most destructive insect pest of potatoes. When the population of beetles is high, plants can be completely defoliated and commercial potato production is nearly impossible without control of the beetle. The beetles have shown a tremendous ability to develop resistance against insecticides. Previously, a biotechnology approach to control Colarado potato beetle based on the use of the synthetic Bt gene was developed. In this article, a transformation procedure for three commercial Bulgarian potato cultivars was developed and potentially commercial transgenic lines have been selected based on field resistance to Colorado potato beetles and yield. Plants were transformed with the Bacillus thuringiensis (Bt) cry3A gene using Agrobacterium-mediated transformation. 110 plants from the three cultivars were regenerated and tested by double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). The Cry3A protein accumulation varied across the transgenic lines, rating from very low to 71.5 $\mu$g/g fresh weight. 21 transgenic lines expressing the Cry3A protein at levels above 10 $\mu$g/g fresh weight were tested in two successive years in filed conditions at two different locations of the country. All transgenic lines compared with the controls, nontransgenic potatoes from the respective cultivar, were consistently protected from foliar damages from all developmental stages of the beetle. The comparison of all properties of the tested transgenic lines, including variety phenotypes and tuber yield, allowed the selection of the most promising 2–3 lines per cultivar. Selected lines produced tuber amounts 80–100% higher compared with the control, non-transgenic plants. Those lines were grown for mass propagation during the third year of field experiments. The presence of the transgene in these lines was confirmed with the use of primers specific to the transgene by polymerase chain reaction (PCR). Additionally, the results from the insect bioassay showed that these lines were highly resistant to insect feeding, leading to 100% of mortality of larval populations. In summary, we generated potentially commercial potato lines highly resistant to Colorado potato beetle using Bt technology that may have a profound impact on development of sustainable agriculture in Bulgaria. This is one of the several agriculture biotechnology products entirely developed and tested in Bulgaria

Data from: Unravelling hybridization in Phytophthora using phylogenomics and genome size estimation

The genus Phytophthora comprises many economically and ecologically important plant pathogens. Hybrid species have previously been identified in at least six of the 12 phylogenetic clades. These hybrids can potentially infect a wider host range and display enhanced vigour compared to their progenitors. Phytophthora hybrids therefore pose a serious threat to agriculture as well as to natural ecosystems. Early and correct identification of hybrids is therefore essential for adequate plant protection but this is hampered by the limitations of morphological and traditional molecular methods. Identification of hybrids is also important in evolutionary studies as the positioning of hybrids in a phylogenetic tree can lead to suboptimal topologies. To improve the identification of hybrids we have combined genotyping-by-sequencing (GBS) and genome size estimation on a genus-wide collection of 614 Phytophthora isolates. Analyses based on locus- and allele counts and especially on the combination of species-specific loci and genome size estimations allowed us to confirm and characterize 27 previously described hybrid species and discover 16 new hybrid species. Our method was also valuable for species identification at an unprecedented resolution and further allowed correct naming of misidentified isolates. We used both a concatenation- and a coalescent-based phylogenomic method to construct a reliable phylogeny using the GBS data of 140 non-hybrid Phytophthora isolates. Hybrid species were subsequently connected to their progenitors in this phylogenetic tree. In this study we demonstrate the application of two validated techniques (GBS and flow cytometry) for relatively low cost but high resolution identification of hybrids and their phylogenetic relations