Genetic Analysis of Hexaploid Wheat (Triticum aestivum L.) Using the Complete Sequencing of Chloroplast DNA and Haplotype Analysis of the Wknox1 Gene.

The aim of the presented study is a genetic characterization of the hexaploid wheat Triticum aestivum L. Two approaches were used for the genealogical study of hexaploid wheats-the complete sequencing of chloroplast DNA and PCR-based haplotype analysis of the fourth intron of Wknox1d and of the fifth-to-sixth-exon region of Wknox1b. The complete chloroplast DNA sequences of 13 hexaploid wheat samples were determined: Free-threshing-T. aestivum subsp. aestivum, one sample; T. aestivum subsp. compactum, two samples; T. aestivum subsp. sphaerococcum, one sample; T. aestivum subsp. carthlicoides, four samples. Hulled-T. aestivum subsp. spelta, three samples; T. aestivum subsp. vavilovii jakubz., two samples. The comparative analysis of complete cpDNA sequences of 20 hexaploid wheat samples (13 samples in this article plus 7 samples sequenced in this laboratory in 2018) was carried out. PCR-based haplotype analysis of the fourth intron of Wknox1d and of the fifth-to-sixth exon region of Wknox1b of all 20 hexaploid wheat samples was carried out. The 20 hexaploid wheat samples (13 samples in this article plus 7 samples in 2018) can be divided into two groups-T. aestivum subsp. spelta, three samples and T. aestivum subsp. vavilovii collected in Armenia, and the remaining 16 samples, including T. aestivum subsp. vavilovii collected in Europe (Sweden). If we take the cpDNA of Chinese Spring as a reference, 25 SNPs can be identified. Furthermore, 13-14 SNPs can be identified in T. aestivum subsp. spelta and subsp. vavilovii (Vav1). In the other samples up to 11 SNPs were detected. 22 SNPs are found in the intergenic regions, 2 found in introns, and 10 SNPs were found in the genes, of which seven are synonymous. PCR-based haplotype analysis of the fourth intron of Wknox1d and the fifth-to-sixth-exon region of Wknox1b provides an opportunity to make an assumption that hexaploid wheats T. aestivum subsp. macha var. palaeocolchicum and var. letshckumicum differ from other macha samples by the absence of a 42 bp insertion in the fourth intron of Wknox1d. One possible explanation for this observation would be that two Aegilops tauschii Coss. (A) and (B) participated in the formation of hexaploids through the D genome: Ae. tauschii (A)-macha (1-5, 7, 8, 10-12), and Ae. tauschii (B)-macha M6, M9, T. aestivum subsp. aestivum cv. 'Chinese Spring' and cv. 'Red Doly'.

Dates and rates in grape's plastomes: evolution in slow motion.

The family Vitaceae includes the domesticated grapevine (Vitis vinifera), one of the most economically important crops in the world. Despite the importance of Vitaceae, there is still considerable controversy surrounding their phylogenetic relationships and evolutionary timescales. Moreover, variation in rates of molecular evolution among Vitaceae remains mostly unexplored. The present research aims to fill these knowledge gaps through the analysis of plastome sequences. Thirteen newly sequenced grape plastomes are presented and their phylogenetic relationships examined. Divergence times and absolute substitution rates are inferred under different molecular clocks by the analysis of 95 non-coding plastid regions and 43 representative accessions of the major lineages of Vitaceae. Furthermore, the phylogenetic informativeness of non-coding plastid regions is investigated. We find strong evidence in favor of the random local clock model and rate heterogeneity within Vitaceae. Substitution rates decelerate in Ampelocissus, Ampelopsis, Nekemias, Parthenocissus, Rhoicissus, and Vitis, with genus Vitis showing the lowest values up to a minimum of ~ 4.65 × 10-11 s/s/y. We suggest that liana-like species of Vitaceae evolve slower than erect growth habit plants and we invoke the "rate of mitosis hypothesis" to explain the observed pattern of the substitution rates. We identify a reduced set of 20 non-coding regions able to accurately reconstruct the phylogeny of Vitaceae and we provide a detailed description of all 152 non-coding regions identified in the plastomes of subg. Vitis. These polymorphic regions will find their applications in phylogenetics, phylogeography, and population genetics as well in grapes identification through DNA barcoding techniques.

The population genetics of structural variants in grapevine domestication.

Structural variants (SVs) are a largely unexplored feature of plant genomes. Little is known about the type and size of SVs, their distribution among individuals and, especially, their population dynamics. Understanding these dynamics is critical for understanding both the contributions of SVs to phenotypes and the likelihood of identifying them as causal genetic variants in genome-wide associations. Here, we identify SVs and study their evolutionary genomics in clonally propagated grapevine cultivars and their outcrossing wild progenitors. To catalogue SVs, we assembled the highly heterozygous Chardonnay genome, for which one in seven genes is hemizygous based on SVs. Using an integrative comparison between Chardonnay and Cabernet Sauvignon genomes by whole-genome, long-read and short-read alignment, we extended SV detection to population samples. We found that strong purifying selection acts against SVs but particularly against inversion and translocation events. SVs nonetheless accrue as recessive heterozygotes in clonally propagated 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 colour locus, where independent large, complex inversions have driven convergent phenotypic evolution.

Georgian cattle, sheep, goats: are they of Near-Eastern origins?

The main aim of this research was to establish the nucleotide sequence of the highly variable region of the D loop of the mitochondrial DNA of some Georgian domestic animal species (cattle, goat, sheep) as well as their phylogenetic position among the worldwide set of domestic animals. In this study, a total of 5 haplogroups (T - 5; T3 - 7; T1 - 1; T2 - 2; T5 - 2) in 17 Georgian Mountain cattle (GMC), 4 haplogroups (A - 15; A2a1 - 3; A1a - 1; A6 - 3) in 22 Georgian goats and 3 haplogroups (A - 10; B - 16; C -15) in 41 Georgian sheeps (15 Imeretian and 26 Tushetian) were detected. This study represents the first attempt of Genetic study of native Georgian livestocks. The GMC, Georgian (Megrelian) goat, Georgian (Imeretian and Tushetian) sheep mitogenomes were grouped phylogenetically in the haplogroups indicating the closeness to the Near Eastern animals.

Whole genome comparative analysis of four Georgian grape cultivars.

Grapevine is the one of the most important fruit species in the world. Comparative genome sequencing of grape cultivars is very important for the interpretation of the grape genome and understanding its evolution. The genomes of four Georgian grape cultivars-Chkhaveri, Saperavi, Meskhetian green, and Rkatsiteli, belonging to different haplogroups, were resequenced. The shotgun genomic libraries of grape cultivars were sequenced on an Illumina HiSeq. Pinot Noir nuclear, mitochondrial, and chloroplast DNA were used as reference. Mitochondrial DNA of Chkhaveri closely matches that of the reference Pinot noir mitochondrial DNA, with the exception of 16 SNPs found in the Chkhaveri mitochondrial DNA. The number of SNPs in mitochondrial DNA from Saperavi, Meskhetian green, and Rkatsiteli was 764, 702, and 822, respectively. Nuclear DNA differs from the reference by 1,800,675 nt in Chkhaveri, 1,063,063 nt in Meskhetian green, 2,174,995 in Saperavi, and 5,011,513 in Rkatsiteli. Unlike mtDNA Pinot noir, chromosomal DNA is closer to the Meskhetian green than to other cultivars. Substantial differences in the number of SNPs in mitochondrial and nuclear DNA of Chkhaveri and Pinot noir cultivars are explained by backcrossing or introgression of their wild predecessors before or during the process of domestication. Annotation of chromosomal DNA of Georgian grape cultivars by MEGANTE, a web-based annotation system, shows 66,745 predicted genes (Chkhaveri-17,409; Saperavi-17,021; Meskhetian green-18,355; and Rkatsiteli-13,960). Among them, 106 predicted genes and 43 pseudogenes of terpene synthase genes were found in chromosomes 12, 18 random (18R), and 19. Four novel TPS genes not present in reference Pinot noir DNA were detected. Two of them-germacrene A synthase (Chromosome 18R) and (-) germacrene D synthase (Chromosome 19) can be identified as putatively full-length proteins. This work performs the first attempt of the comparative whole genome analysis of different haplogroups of Vitis vinifera cultivars. Based on complete nuclear and mitochondrial DNA sequence analysis, hypothetical phylogeny scheme of formation of grape cultivars is presented.

Complete chloroplast genomes of Aegilops tauschii Coss. and Ae. cylindrica Host sheds light on plasmon D evolution.

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.