Structural variants (SVs) affect plant phenotypes, but they are a largely unexplored feature of plant genomes. Little is known about the type and size of SVs, their distribution among individuals or their evolutionary dynamics. Here we identify SVs and study their evolutionary dynamics in clonally propagated grapevine cultivars and their outcrossing wild relatives. To catalog SVs, we assembled the highly heterozygous Chardonnay genome, for which one in seven genes is hemizygous. Using genomic inference as the standard, we extended SV detection to population samples. We found that negative selection acts against SVs, but particularly against inversion and translocation events. SVs nonetheless accrue as recessive heterozygotes in clonal lineages. They also define outlier regions of genomic divergence between wild and cultivated grapevines, suggesting roles in domestication. Outlier regions include the sex determination region and the berry color locus, where independent large, complex inversions drive convergent phenotypic evolution..

No abstract

No abstract

Hexaploid wheat (Triticum aestivum L., genomes AABBDD) originated in South Caucasus by allopolyploidization of the cultivated Emmer wheat T. dicoccum (genomes AABB) with the Caucasian Ae. tauschii ssp strangulata (genomes DD). Genetic variation of Ae. tauschii is an important natural resource, that is why it is of particular importance to investigate how this variation was formed during Ae. tauschii evolutionary history and how it is presented through the species area. The D genome is also found in tetraploid Ae. cylindrica Host (2n = 28, CCDD). The plasmon diversity that exists in Triticum and Aegilops species is of great significance for understanding the evolution of these genera. In the present investigation the complete nucleotide sequence of plasmon D (chloroplast DNA) of nine accessions of Ae. tauschii and two accessions of Ae. cylindrica are presented. Twenty-eight SNPs are characteristic for both TauL1 and TauL2 accessions of Ae. tauschii using TauL3 as a reference. Four SNPs are additionally observed for TauL2 lineage. The longest (27 bp) indel is located in the intergenic spacer Rps15-ndhF of SSC. This indel can be used for simple determination of TauL3 lineage among Ae. tauschii accessions. In the case of Ae. cylindrica additionally 7 SNPs were observed. The phylogeny tree shows that chloroplast DNA of TauL1 and TauL2 diverged from the TauL3 lineage. TauL1 lineage is relatively older then TauL2. The position of Ae. cylindrica accessions on Ae. tauschii phylogeny tree constructed on chloroplast DNA variation data is intermediate between TauL1 and TauL2. The complete nucleotide sequence of chloroplast DNA of Ae. tauschii and Ae. cylindrica allows to refine the origin and evolution of D plasmon of genus Aegilops.

<p style="text-align: justify;"><strong>Aims</strong>: The chloroplast DNA sequence of eight Georgian grape cultivars (Rkatsiteli, Saperavi, Meskhuri Mtsvane, Chkhaveri, Aladasturi, Krakhuna, Tsitska, Tsolikouri) and three French cultivars (Chardonnay, Gouais Blanc, Chasselas), belonging to four different haplogroups (AAA, ATT, ATA, GTA), was determined by Illumina resequencing of genomic DNA. The chloroplast DNA sequence of the Maxxa cultivar was used as reference.</p><p style="text-align: justify;"><strong>Methods and results</strong>: The comparison of sequenced chloroplast DNA gave 100 % identity to Chardonnay and Gouais Blanc, differing from Meskhuri Mtsvane by two insertions/deletions (indels) (all ATA haplogroup). The difference between Chasselas and Saperavi was a single insertion (both ATT haplogroup), while Maxxa, Chkhaveri, Aladasturi, Krakhuna, Tsitska and Tsolikouri were all identical (all members of the GTA haplogroup). Forty-seven identical single nucleotide polymorphisms (SNPs) were detected in the AAA, ATA and ATT haplogroups in comparison to the reference DNA. Additionally, 18 SNPs were detected for the ATT haplogroup, 4 for AAA, 6 for ATA and 11 for both AAA and ATA. The phylogenetic results show that the ATT, AAA and ATA haplogroups are more closely related to each other than to the GTA haplogroup.</p><p style="text-align: justify;"><strong>Conclusion</strong>: In the sequencing data of grape genomic DNA at the coverage (read depth) of chromosomal DNA 30-40, the coverage of chloroplast DNA reaches several thousand reads per bp due to the high number of chloroplast DNA copies in genomic DNA, much higher than necessary for resequencing. Based on these data, a new methodology of simultaneous resequencing of large number of chloroplast DNA was developed without preliminary chloroplast isolation or chloroplast enrichment.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: This method has great potential for expanding both phylogenetic and population genetic information on the evolution of domesticated crops.</p>