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  • Autor: Birgit Kersten x
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Abstract

Populus trichocarpa and P. deltoides are the only Populus species known to date to have a publicly available nuclear genome sequence that has been assembled to chromosomes and annotated (https://phytozome.jgi.doe.gov/). Here we focus on the clone INRA 717-1B4, a female P. tremula x P. alba (P. x canescens) interspecific hybrid that is universally used by scientists worldwide as a tree model in transgenic experiments. The already available INRA 717-1B4 nuclear genomic resource (v1.1 of sPta717 at http://aspendb.uga.edu/index.php/databases/spta-717-genome) presents only INRA 717-1B4 genomic regions with high similarity to the P. trichocarpa genomic reference sequences. We assembled draft genomic scaffolds by a combination of de novo assembly with reference-based assembly using 30x resequencing NGS data (Illumina MiSeq® and Ion Torrent Ion PGM™) of INRA 717-1B4. In total, 419,969 scaffolds of length larger than 500 bp were generated. The mean length of the scaffolds is 2,166 bp and the size of the largest scaffold 84,573 bp. The N50 contig length is 3,850 bp when considering contigs larger than 1,000 bp. Probably due to the high level of heterozygosity of this interspecific hybrid, the accumulated scaffold length is with 0.9 GB about twice the expected size of the haploid nuclear genome. DNA sequences of the genomic scaffolds of INRA 717-1B4 are publicly available for Blast analyses and download via the new INRA web portal at https://urgi.versailles.inra.fr/Species/Forest-trees/Populus/Clone-INRA-717-1B4/. This new genomic sequence resource will complement the already available INRA 717-1B4 resources and will facilitate the future optimization of genetic transformation experiments to discover gene function.

Abstract

We developed a new set of 25 nuclear (nc), 12 chloroplast (cp) and 7 mitochondrial (mt) SNPs and used it to genotype 371 Mongolian oak (Quercus mongolica Fisch. ex Ledeb.) trees from seven locations in a 200 km by 400 km area in the Russian Far East. One of the locations in an area of 15 km by 25 km east of the city Ussuriusk was analyzed more intensively with 188 collected trees. The genetic differentiation at the nuclear SNPs was small to moderate and for the plastid SNPs it was high when considering all trees from the seven locations. The gene pool distances between locations were for 19 out of 21 pairs statistically highly significant. There was no correlation of genetic and spatial distances. Only three different multilocus-haplotypes could be identified and 42 two-loci-combinations of plastid SNPs could be used to identify them. Conclusions for the practical application such as timber tracking and gene conservation are discussed.