Intergeneric Hybridization between Phalaenopsis 2166 and Vanda ‘saint valentine’: Characterization of Parents Using ndhE cpDNA Partial Sequence

An intergeneric cross between Phalaenopsis 2166 and Vanda ‘saint valentine’ has successfully produced protocorms that will be grown further to form seedlings. The present study aims to genetically characterize both parents by using ndhE partial gene as its sequence is shown polymorphic among five orchid genera of the subtribe Oncidiinae. The results reveal that the ndhE partial sequences of Phalaenopsis 2166 and Vanda ‘saint valentine’ are considerably homologous with those of Oncidium. However, alignment of ndhE partial sequences between both parents shows only 58% similarity, leading to the conclusion that a relatively high genetic difference between them may occur.

Capturing Multiple Disease Resistance in Wheat through Intergeneric Hybridization

Derivatives from 4 species from the secondary gene pool of wheat—1 diploid (T. monococcum), 2 tetraploid (T. carthlicum; T. timopheevi), and 1 hexaploid (T. miguschovae)—were screened for resistance to Fusarium head blight, leaf rust, stem rust, and stripe rust. Where screening, genetic studies, and mapping were completed it was shown that all species carried resistance to multiple plant diseases. Some derived lines carried resistance to up to four different diseases. Where mapping was completed, it was shown that different diseases mapped to different chromosomes within any one accession.

Hybridization in Selected Species and Genera of Diaptomid Copepods in China

To better understand the fauna of freshwater calanoid copepods of China, including the occurrence of intra- and intergeneric hybridization, we studied five species, distributed across the whole of China or in South China. We sequenced a mitochondrial (COI) and the nuclear ribosome 18S operon (ITS) to reconstruct the phylogenetic trees by using a Bayesian and maximum likelihood (ML) approach with 161 individuals. The phylogeny tree revealed five clades and two geographically separated subclades in both S. ferus and P. tunguidus. We found, for the first time, that the hybrid specimens occurred in Diaptomidae, but low hybridization suggested effective barriers to hybridization and introgression. One hypothesis, that hybridization is recent and was initiated by invasions via canals built between the Yangtze and Pearl rivers c. 2000 years ago, is not supported by K2P genetic distances of the order of 20%. Furthermore, COI analysis of different populations of S. ferus and P. tunguidus revealed two geographical clades in each species, with genetic distances commensurate with cryptic speciation. Both clades occupy subranges maintained without visible barriers to mixis.

An Analysis of Pollen Parameters, Fruit Set and Fruit Development During Attempts on Intergeneric Hybridization of Papaya (Carica papaya L.)

Research was conducted at the University Orchard, Horticultural College and Research Institute, to investigate the extent of pollen production, pollen fertility, fruit set, fruit growth and seed set as well as seedling vigour when two wild relatives of papaya (Vasconcellea cauliflora and Vasconcellea candamarcensis) are involved in the hybridization programme as male parents with three papaya cultivars (CO 7, TNAU Papaya CO 8 and Pusa Nanha) as female parents. Among the two wild relatives, V. candamarcensis was more polleniferous but with significantly lesser pollen viability and germination than V. cauliflora. Among the six intergeneric crosses, although the fruit set ranged from 60.00% to 93.33% the fruit retention till harvest was only 30.77 per cent to 35.71 per cent. The study also revealed metaxenic influence of wild parent on the growth of the fruits derived after crossing. Seed set was observed only with CO 7 as female parent but the seed size and weight, germination and seedling vigour recorded by intergeneric crosses of CO 7 with Vasconcellea were found to be low. The implications of the observations are discussed in relevance to employing the wild relatives for improvement of papaya.

Molecular Evolution and Organization of Ribosomal DNA in the Hawkweed Tribe Hieraciinae (Cichorieae, Asteraceae)

Molecular evolution of ribosomal DNA can be highly dynamic. Hundreds to thousands of copies in the genome are subject to concerted evolution, which homogenizes sequence variants to different degrees. If well homogenized, sequences are suitable for phylogeny reconstruction; if not, sequence polymorphism has to be handled appropriately. Here we investigate non-coding rDNA sequences (ITS/ETS, 5S-NTS) along with the chromosomal organization of their respective loci (45S and 5S rDNA) in diploids of the Hieraciinae. The subtribe consists of genera Hieracium, Pilosella, Andryala, and Hispidella and has a complex evolutionary history characterized by ancient intergeneric hybridization, allele sharing among species, and incomplete lineage sorting. Direct or cloned Sanger sequences and phased alleles derived from Illumina genome sequencing were subjected to phylogenetic analyses. Patterns of homogenization and tree topologies based on the three regions were compared. In contrast to most other plant groups, 5S-NTS sequences were generally better homogenized than ITS and ETS sequences. A novel case of ancient intergeneric hybridization between Hispidella and Hieracium was inferred, and some further incongruences between the trees were found, suggesting independent evolution of these regions. In some species, homogenization of ITS/ETS and 5S-NTS sequences proceeded in different directions although the 5S rDNA locus always occurred on the same chromosome with one 45S rDNA locus. The ancestral rDNA organization in the Hieraciinae comprised 4 loci of 45S rDNA in terminal positions and 2 loci of 5S rDNA in interstitial positions per diploid genome. In Hieracium, some deviations from this general pattern were found (3, 6, or 7 loci of 45S rDNA; three loci of 5S rDNA). Some of these deviations concerned intraspecific variation, and most of them occurred at the tips of the tree or independently in different lineages. This indicates that the organization of rDNA loci is more dynamic than the evolution of sequences contained in them and that locus number is therefore largely unsuitable to inform about species relationships in Hieracium. No consistent differences in the degree of sequence homogenization and the number of 45S rDNA loci were found, suggesting interlocus concerted evolution.

Pre- and Postzygotic Barriers Associated with Intergeneric Hybridization between Aronia melanocarpa (Michx.) Elliott x Pyrus communis L. and ×Sorbaronia dippelii (Zabel) CK Schneid. x Pyrus communis

Intergeneric hybridization between Aronia and Pyrus may provide a pathway for developing novel fruit types with larger, sweeter fruits, while maintaining the high levels of biologically health-promoting compounds present in Aronia fruits. Here we describe a deleterious genetic incompatibility, known as hybrid necrosis or hybrid lethality, that occurs in intergeneric F1 hybrids of Aronia melanocarpa x Pyrus communis and ×Sorbaronia dippelii x Pyrus communis. Pollination experiments revealed that maternal A. melanocarpa and ×S. dippelii pistils are compatible with pollen from P. communis. Controlled pollinations using different mating combinations resulted in varying levels of fruit and seed set. Because every combination produced at least some viable seeds, prezygotic incompatibility does not appear to be present. We attempted to recover putative intergeneric progeny via either in vitro germination or in vitro shoot organogenesis from cotyledons. Progeny of putative hybrids from A. melanocarpa x P. communis only survived for a maximum of 14 days before succumbing to hybrid lethality. Regeneration of ×S. dippelii x P. communis was successful for two seedlings that have been maintained for an extended time in tissue culture. These two seedlings have leaf morphologies intermediate between the two parental genotypes. We also confirmed their hybrid status by using AFLPs and flow cytometry. Putative intergeneric hybrids were grown out ex vitro before showing symptoms of hybrid necrosis and dying after 3 months. Eventually micrografts failed, ultimately showing the same symptoms of hybrid necrosis. These results show that intergeneric hybridization is possible between Aronia and related genera in the Rosaceae, but there are postzygotic barriers to hybridity that can prevent the normal growth and development of the progeny.

Reproductive compatibility of Sorbocotoneaster with mountain ash species and varieties that are promising for breeding in Siberia

In Russia, in the Republic of Yakutia, there is the only point in the world where natural intergeneric hybridization of species of the genera Sorbus and Cotoneaster is observed, resulting in the formation of a new hybridogenic genus ×Sorbocotoneaster with a rich polymorphism of parental genera traits. For the selection of mountain ash in Siberia, it is promising to involve Sorbocotoneaster genotypes in artificial hybridization as sources of a complex of economically valuable traits, including winter hardiness, short stature, and self-fertility. Artificial hybridization of the tetraploid selective form Sorbocotoneaster with selected forms and varieties of Sorbus sibirica, S. aucuparia, S. sambucifolia and their hybrids allows obtaining viable hybrid offspring in combinations where Sorbocotoneaster is used as a pollen donor.

Regular Intergeneric Hybridization of Leuciscine Cyprinids (Cyprinidae, Leuciscinae) in the Dnipro Affluant

The large-scale hybridization of fishes of the subfamily Leuciscinae in the subordinate systems of the Dnipro River basin is presented by the data on two pairs of species, roach Rutilus rutilus × bream Abramis brama, and bleak Alburnus alburnus × rudd Scardinius erythrophthalmus. The hybridization and occurrence of F1 hybrids are confirmed with allozyme spectra and morphological characters on series of samples. A complete morphometric analysis of the characteristics of bleak and rudd hybrids was performed. The paper discusses the intergeneric hybridization in nature, which is a unique phenomenon characteristic only of some groups of cyprinids. The most likely reason is the overestimation of the taxonomic status of European cyprinids, which is confirmed by the insignificant level of intergeneric genetic divergence.

Intergeneric hybrids of Phalaenopsis 2166 x Vanda ‘Saint Valentine’ showing maternal inheritance: Genetic analysis based on ndhE partial gene

Dwiati M, Susanto AH, Prayoga L. 2020. Intergeneric hybrids of Phalaenopsis 2166 x Vanda ‘Saint Valentine’ showing maternal inheritance: Genetic analysis based on ndhE partial gene. Biodiversitas 21: 5138-5145. Genetic characterization in the intergeneric hybridization of orchids employing a particular molecular marker, such as ndhE gene, is needed to avoid phenotypic plasticity. The hybridization between Phalaenopsis 2166 as a female parent and Vanda ‘Saint Valentine'as a male parent has been successfully made to produce various leaf shapes and colors of the hybrid seedlings, which tend to resemble those of the female parent. This study aims to assess whether the maternally phenotypic traits of the hybrids of Phalaenopsis 2166 x Vanda ‘Saint Valentine’ are congruent with the inheritance pattern of ndhE partial sequences. The result reveals that the ndhE partial sequences of the hybrids are seemingly similar to that of Phalaenopsis 2166 as the female parent rather than to that of Vanda ‘Saint Valentine’. It is also found that three hybrids, i.e. F1.9, F1.11, and F1.14 show slightly different ndhE partial sequences from those of the other hybrids in that some base substitutions are observed. In general, the ndhE partial sequences of the hybrids are maternally inherited. This finding provides a fact that maternally phenotypic traits of the hybrids of Phalaenopsis 2166 x Vanda ‘Saint Valentine’ have strong genetic background rather than environmental involvement.