Effect of Meiotic Polyploidisation on Selected Morphological and Anatomical Traits in Interspecific Hybrids of Brassica oleracea × B. napus

In Brassica, interspecific hybridisation plays an important role in the formation of allopolyploid cultivars. In this study, the ploidy of F1 and F2 generations resulting from interspecific hybridisation between B. oleracea inbred lines of head cabbage (B. oleracea L. var. capitata) (2n = 18) and kale (B. oleracea L. var. acephala) (2n = 18) with inbred lines of rapeseed (B. napus L.) (2n = 38) was examined by flow cytometry analysis and chromosome observation. Furthermore, the effect of meiotic polyploidisation on selected phenotypic and anatomical traits was assessed. The F1 hybrids of head cabbage × rapeseed (S3) and kale × rapeseed crosses (S20) were allotriploids with 2n = 28 chromosomes, and nuclear DNA amounts of 1.97 (S3) and 1.99 pg (S20). These values were intermediate between B. oleracea and B. napus. In interspecific hybrids of the F2 generation, which were derived after self-pollination of F1 hybrids (FS3, FS20) or by open crosses between F1 generation hybrids (FC320, FC230), the chromosome numbers were similar 2n = 56 or 2n = 55, whereas the genome sizes varied between 3.81 (FS20) and 3.95 pg 2C (FC230). Allohexaploid F2 hybrids had many superior agronomic traits compared to parental B. napus and B. oleracea lines and triploid F1 hybrids. In the generative stage, they were characterised by larger flowers and flower elements, such as anthers and lateral nectaries. F2 hybrids were male and female fertile. The pollen viability of F2 hybrids was comparable to parental genotypes and varied from 75.38% (FS3) to 88.24% (FC320), whereas in triploids of F1 hybrids only 6.76% (S3) and 13.46% (S20) of pollen grains were fertile. Interspecific hybrids of the F2 generation derived by open crosses between plants of the F1 generation (FC320, FC230) had a better ability to set seed than F2 hybrids generated from the self-pollination of F1 hybrids. In the vegetative stage, F2 plants had bigger and thicker leaves, larger stomata, and significantly thicker layers of palisade and spongy mesophyll than triploids of the F1 generation and parental lines of B. oleracea and B. napus. The allohexaploid F2 hybrids analysed in this study can be used as innovative germplasm resources for further breeding new vegetable Brassica crops at the hexaploid level.

Genetic mapping of metabolic traits in the blind Mexican cavefish reveals sex-dependent quantitative trait loci associated with cave adaptation

Background Despite a longstanding interest in understanding how animals adapt to environments with limited nutrients, we have incomplete knowledge of the genetic basis of metabolic evolution. The Mexican tetra, Astyanax mexicanus, is a species of fish that consists of two morphotypes; eyeless cavefish that have adapted to a low-nutrient cave environment, and ancestral river-dwelling surface fish with abundant access to nutrients. Cavefish have evolved altered blood sugar regulation, starvation tolerance, increased fat accumulation, and superior body condition. To investigate the genetic basis of cavefish metabolic evolution we carried out a quantitative trait loci (QTL) analysis in surface/cave F2 hybrids. We genetically mapped seven metabolism-associated traits in hybrids that were challenged with a nutrient restricted diet. Results We found that female F2 hybrids are bigger than males and have a longer hindgut, bigger liver, and heavier gonad, even after correcting for fish size. Although there is no difference between male and female blood sugar level, we found that high blood sugar is associated with weight gain in females and lower body weight and fat level in males. We identified a significant QTL associated with 24-h-fasting blood glucose level with the same effect in males and females. Differently, we identified sex-independent and sex-dependent QTL associated with fish length, body condition, liver size, hindgut length, and gonad weight. We found that some of the genes within the metabolism QTL display evidence of non-neutral evolution and are likely to be under selection. Furthermore, we report predicted nonsynonymous changes to the cavefish coding sequence of these genes. Conclusions Our study reveals previously unappreciated genomic regions associated with blood glucose regulation, body condition, gonad size, and internal organ morphology. In addition, we find an interaction between sex and metabolism-related traits in A. mexicanus. We reveal coding changes in genes that are likely under selection in the low-nutrient cave environment, leading to a better understanding of the genetic basis of metabolic evolution.

Heredity of leaf apparatus features in F2 of soft winter wheat

The aim of the research was to study the heredity nature of flag (first top) and sub-flag (second top) leaves of F2 hybrid populations obtained from the crossbred varieties and lines of soft winter wheat of different morphophysiological types. The research was conducted in the experimental field of KhNAU named after V.V. Dokuchaiev in 2015 – 2016. The vegetation period of 2015 – 2016 turned out to be abnormally warm with a lot of precipitation. The amount of precipitation during the wheat vegetation period in 2015 – 2016 was 597,8 mm, which was significantly higher than the long-term average (456,0 mm). Such weather conditions affected the course of vernalization and wintering of plants, contributed to the development of diseases and pests, complicated and stretched the harvest period, its quantity and quality. 14 F2 hybrid populations, obtained by crossbreeding 16 varieties and lines were used as a starting material. The selection of the parent pairs was performed on a set of the morphological and anatomical productivity features. Based on cluster analysis (K-average method), the set of the studied genotypes of soft winter wheat was divided into four clusters. The genotypes of the first cluster had a high level of ear productivity and the maximum level of development of the anatomical structure features of the stem and ear. The genotypes of the second and third clusters are two “opposite” types of variability of the productivity features, leaf apparatus and anatomical structure of the stem and ear. Thus, the genotypes of the second cluster are characterized by a relatively high level of development of the features of ear productivity, but minimal – the features of anatomical structure, and for the third vice versa. The genotypes of the third cluster can be a donor of the anatomical structure features, and the second – ear productivity. The genotypes of the fourth cluster had the maximum level of development of the group of the features of the leaf apparatus, productivity and a fairly high level of the development of the anatomical structure features. The varieties from the first cluster were used for crossing: Smuhlianka, Izolda, Prestizh, Kharkivska 105; from the second one: Odeska 267, Venera, Ebi, Statna, Dobirna, KIU line – 7; from the third one: KIU lines – 40, L 80 – III / 7, Patriot variety; from the fourth one: Pereiaslavka, Lehenda, line L 89 – I/2. The hybrids were sown in a block with the parental forms, the area of the plot for the parental forms made up 1 m2, the area of the hybrid populations plots depended on the number of seeds and was equal to 1 – 2 m2. The level of heredity according to the characteristics of the leaf apparatus of F2 hybrids of soft winter wheat was determined, namely the frequency (Tf) and the degree of transgressions (Td) and the heredity coefficient in the “broad sense”. The frequency of transgressions of the hybrids on the basis of the area of the flag leaf varied from 3,00% to 40,00%, and the degree of transgressions varied from 3,30% to 52,90%, but in three combinations the transgression was zero. The heredity coefficient in the “broad sense” ranged from 0,07 to 0,99. According to the total area of the two upper leaves (flag and sub-flag), the frequency of transgressions varied from 6,70% to 50,00%, and the degree of transgressions – from 3,60% to 45,20%. In two combinations, the transgression was zero. High and medium heredity coefficients, exceeding 0,50, and a high manifestation of transgressions were observed in the combinations: KIU-7 / Smuhlianka (Tf – 33,3 and Td – 45,2%), Kharkivska 105 / Smuhlianka (Tf – 30,00 and Td – 45,23%) Izolda / Prestige (Tf – 30,00 and Td– 12,60%), Ebi / L 89 – I / 2 (Tf – 23,30 and Td – 31,50%). These combinations can predict the effective plant selection, starting with F2 and F3. Key words: soft winter wheat, F2 hybrids, heredity coefficient in the “broad sense”, frequency and degree of transgression.

New Genetic Insights About Hybridization and Population Structure of Hawksbill and Loggerhead Turtles From Brazil

An extremely high incidence of hybridization among sea turtles is found along the Brazilian coast. This atypical phenomenon and its impact on sea turtle conservation can be elucidated through research focused on the evolutionary history of sea turtles. We assessed high-quality multilocus haplotypes of 143 samples of the 5 species of sea turtles that occur along the Brazilian coast to investigate the hybridization process and the population structure of hawksbill (Eretmochelys imbricata) and loggerhead turtles (Caretta caretta). The multilocus data were initially used to characterize interspecific hybrids. Introgression (F2 hybrids) was only confirmed in hatchlings of F1 hybrid females (hawksbill × loggerhead), indicating that introgression was either previously overestimated and F2 hybrids may not survive to adulthood, or the first-generation hybrid females nesting in Brazil were born as recent as few decades ago. Phylogenetic analyses using nuclear markers recovered the mtDNA-based Indo-Pacific and Atlantic lineages for hawksbill turtles, demonstrating a deep genetic divergence dating from the early Pliocene. In addition, loggerhead turtles that share a common feeding area and belong to distinct Indo-Pacific and Atlantic mtDNA clades present no clear genetic differentiation at the nuclear level. Finally, our results indicate that hawksbill and loggerhead rookeries along the Brazilian coast are likely connected by male-mediated gene flow.

New genetic insights about hybridization and population structure of hawksbill and loggerhead turtles from Brazil

An extremely high incidence of hybridization among sea turtles is found along the Brazilian coast. To understand this atypical phenomenon and its impact on sea turtle conservation, research focused in the evolutionary history of sea turtles is fundamental. We assessed high quality multilocus haplotypes of 143 samples of the five species of sea turtles that occur along the Brazilian coast to investigate the hybridization process and the population structure of hawksbill (Eretmochelys imbricata) and loggerhead turtles (Caretta caretta). The multilocus data were initially used to characterize interspecific hybrids. Introgression (F2 hybrids) was only confirmed in hatchlings of F1 hybrid females (hawksbill × loggerhead), indicating that introgression was either previously overestimated and F2 hybrids may not survive to adulthood, or the first-generation hybrid females nesting in Brazil were born as recent as few decades ago. Phylogenetic analyses using nuclear markers recovered the mtDNA-based Indo-Pacific and Atlantic lineages for hawksbill turtles, demonstrating a deep genetic divergence dating from the early Pliocene. In addition, loggerhead turtles that share a common feeding area and belong to distinct Indo-Pacific and Atlantic mtDNA clades present no clear genetic differentiation at the nuclear level. Finally, our results indicate that hawksbill and loggerhead rookeries along the Brazilian coast are likely connected by male-mediated gene flow.

Evidencias moleculares de hibridación entre Serinus canaria domestica (L., 1758) y Spinus barbatus (Molina, 1782) (Aves: Fringillidae)

Resumen En este estudio se muestran evidencias moleculares de éxito en la hibridación entre Serinus canaria domestica (linnaeus, 1758) y Spinus barbatus (molina, 1782). Como parte de una secuencia de retrocruzamiento, se logró reproducir híbridos F2 a partir de hembras híbridas fértiles viables F1 x S. c. domestica. La F1 fue la descendencia entre P0 = Serinus c. domestica x Spinus barbatus. Las secuencias de nucleótidos de dos segmentos de ADN, citocromo b mitocondrial (Cyt b) y el receptor de tirosina quinasa muscular (MuSK) del ADN nuclear se obtuvieron de tres especímenes híbridos F2. Tanto las secuencias de Cyt b como de MuSK señalaron fuerte soporte filogenético a la condición genética híbrida de los tres embriones F2. De esta manera la evidencia molecular refleja el éxito en el cruce interespecífico entre S. barbatus con S. c. domestica y que es posible obtener híbridos fértiles viables F1 (en este caso hembras) y F2 entre estos dos linajes en poblaciones naturales. Abstract In this study we show molecular evidences of success in hybridization between Serinus canaria domestica and Spinus barbatus. As part of a sequence of backcrossing we have achieved to reproduce F2 hybrids of fertile hybrid females F1 with parental S. c. domestica. F1 was the offspring between, P0 = S. c. domestica x S. barbatus. In this study the space where the observations and the breeding success are carried out between these species, they are described: is a room with the following measures; 4,45 m (lenghty) x 1,60 m (width) x 2,30 m (high), located in an urban building; specifically, glassed-balcony at a height of 10,60 m above ground level, facing some ornamental and exuberant canopy trees of Platanus orientalis (L., 1753) and with direct entrance of natural sunlight, in urban city of Santiago, Chile, where his perceptual world develops. We took care to keep the biotic and abiotic factors under control; specifically, incoming natural light, ambient vegetation and temperature. On the other hand, we fed the individuals appropriately and provided them with plenty of clean water to drink and get clean, where there were no predators. In sum, the individuals were kept in a healthy environment. The backcrossing between the male S. c. domestica (generation 0) bred with two viable hybrid F1 offspring females, it gave as resulted in a total of three independent generations of F2 hybrids (n = 12). All the individuals came out healthy, and none of them died, despite being inbred lineages. Three embryos representative of the F2 hybrids were sacrificed and deposited in 99% alcohol. Nucleotide sequences of two DNA segments, mitochondrial cytochrome b (Cyt b) and muscle-specific receptor tyrosine kinase (MuSK) gene of the nuclear DNA were obtained from three F2 hybrid specimens. The model of molecular evolution with the greatest adjustment to the data obtained by jModeltest was GTR + I + G (I = 0,1450, G = 0,0930), according to the phylogenetic analysis of mitochondrial DNA (Fig. 1a), the female progenitor P0 is S.c.domestica. This conclusion is based on the evi- dence that mitochondrial DNA in birds, as well as in most animal groups, is exclusively inherited through the maternal ways. The same analysis carried out with the nuclear MuSK gene shows that the parental male P0 of the embryos analyzed is very much related to S. barbatus (Fig. 1b). The Cyt b and MuSK region show strongly support to hybrids genetic condition of the three F2 embryos. Intergeneric hybrids are usually sterile, but it is worth noting that genera of Fringillidae are very closely related (the Family as a whole is only 12 million years old, and most genera in the terminal canary-siskin group are <5 million years old). This is simply a case of poor classification with oversplitting or maybe the nature of these lineages are fractals, since in most of the Passeriformes, family-level taxa are more than 20 million years old, and in other groups of Aves families and genera are even older. Then hybridization takes place more easily in captivity. Many authors considered that hybridization in birds is not important because hybrids are formed in proportion 1/50,000 specimens. Despite this, many bird hybrids have been created in captivity. In addition, hybrids produced ex situ under controlled conditions would play an important role for reproductive success and subsequent interspecific viability. The main conclusions derived from this study are as follows: 1) The present report strongly indicates that hybridizations have occurred among S. c. canary x S. barbatus. 2) In this way the molecular evidence reflects and justifies the success in interspecific reproduction between S. barbatus with S. c. domestica and that it is possible to obtain viable fertile hybrids F1 (in this case females) and F2 between these two lineages, 3) And consequently the close genetic affinity between these two genera and the formation of hybrids in natural populations should not discard.