Development of somatic hybrids Solanum × michoacanum Bitter. (Rydb.) (+) S. tuberosum L. and autofused 4x S. × michoacanum plants as potential sources of late blight resistance for potato breeding

Key message

Phytophthora infestans resistant somatic hybrids of S. × michoacanum (+) S. tuberosum and autofused 4 x S. × michoacanum were obtained. Our material is promising to introgress resistance from S. × michoacanum into cultivated potato background.

Abstract

Solanum × michoacanum (Bitter.) Rydb. (mch) is a wild diploid (2n = 2x = 24) potato species derived from spontaneous cross of S. bulbocastanum and S. pinnatisectum. This hybrid is a 1 EBN (endosperm balance number) species and can cross effectively only with other 1 EBN species. Plants of mch are resistant to Phytophthora infestans (Mont) de Bary. To introgress late blight resistance genes from mch into S. tuberosum (tbr), genepool somatic hybridization between mch and susceptible diploid potato clones (2n = 2x = 24) or potato cultivar Rywal (2n = 4x = 48) was performed. In total 18,775 calli were obtained from postfusion products from which 1,482 formed shoots. The Simple Sequence Repeat (SSR), Cleaved Amplified Polymorphic Sequences (CAPS) and Random Amplified Polymorphic DNA (RAPD) analyses confirmed hybrid nature of 228 plants and 116 autofused 4x mch. After evaluation of morphological features, flowering, pollen stainability, tuberization and ploidy level, 118 somatic hybrids and 116 autofused 4x mch were tested for late blight resistance using the detached leaf assay. After two seasons of testing three somatic hybrids and 109 4x mch were resistant. Resistant forms have adequate pollen stainability for use in crossing programme and are a promising material useful for introgression resistance from mch into the cultivated potato background.     

Yield stability of hybrids versus lines in wheat,barley, and triticale

Key message

We present experimental data for wheat, barley, and triticale suggesting that hybrids manifest on average higher yield stability than inbred lines.

Abstract

Yield stability is assumed to be higher for hybrids than for inbred lines, but experimental data proving this hypothesis is scarce for autogamous cereals. We used multi-location grain yield trials and compared the yield stability of hybrids versus lines for wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), and triticale (×Triticosecale Wittmack). Our study comprised three phenotypic data sets of 1,749 wheat, 96 barley, and 130 triticale genotypes, which were evaluated for grain yield in up to five contrasting locations. Yield stability of the group of hybrids was compared with that of the group of inbred lines estimating the stability variance. For all three crops we observed a significantly (P < 0.05) higher yield stability of hybrids compared to lines. The enhanced yield stability of hybrids as compared to lines represents a major step forward, facilitating coping with the increasing abiotic stress expected from the predicted climate change.     

Comparative QTL analysis of root lesion nematode resistance in barley

Key message

This study demonstrates for the first time that resistance to different root lesion nematodes ( P. neglectus and P. penetrans ) is controlled by a common QTL. A major resistance QTL ( Rlnnp6H ) has been mapped to chromosome 6H using two independent barley populations.

Abstract

Root lesion nematodes (Pratylenchus spp.) are important pests in cereal production worldwide. We selected two doubled haploid populations of barley (Igri × Franka and Uschi × HHOR 3073) and infected them with Pratylenchus penetrans and Pratylenchus neglectus. Nematode multiplication rates were measured 7 or 10 weeks after infection. In both populations, continuous phenotypic variations for nematode multiplication rates were detected indicating a quantitative inheritance of resistance. In the Igri × Franka population, four P. penetrans resistance QTLs were mapped with 857 molecular markers on four linkage groups (2H, 5H, 6H and 7H). In the Uschi × HHOR 3073 population, eleven resistance QTLs (P. penetrans and P. neglectus) were mapped with 646 molecular markers on linkage groups 1H, 3H, 4H, 5H, 6H and 7H. A major resistance QTL named Rlnnp6H (LOD score 6.42–11.19) with a large phenotypic effect (27.5–36.6 %) for both pests was mapped in both populations to chromosome 6H. Another resistance QTL for both pests was mapped on linkage group 5H (Igri × Franka population). These data provide first evidence for common resistance mechanisms against different root lesion nematode species. The molecular markers are a powerful tool for the selection of resistant barley lines among segregating populations because resistance tests are time consuming and laborious.     

Oxidation and reduction of sulfite contribute to susceptibility and detoxification of SO2 in Populus × canescens leaves

Key Message

The critical level for SO ₂ susceptibility of Populus × canescens is approximately 1.2 μL L ^?1 SO ₂ . Both sulfite oxidation and sulfite reduction and assimilation contribute to SO ₂ detoxification.

Abstract

In the present study, uptake, susceptibility and metabolism of SO₂ were analyzed in the deciduous tree species poplar (Populus × canescens). A particular focus was on the significance of sulfite oxidase (SO) for sulfite detoxification, as SO has been characterized as a safety valve for SO₂ detoxification in herbaceous plants. For this purpose, poplar plants were exposed to different levels of SO₂ (0.65, 0.8, 1.0, 1.2 μL L^?1) and were characterized by visible injuries and at the physiological level. Gas exchange parameters (stomatal conductance for water vapor, CO₂ assimilation, SO₂ uptake) of the shoots were compared with metabolite levels (sulfate, thiols) and enzyme activities [SO, adenosine 5′-phosphosulfate reductase (APR)] in expanding leaves (80–90 % expanded). The critical dosage of SO₂ that confers injury to the leaves was 1.2 μL L^?1 SO₂. The observed increase in sulfur containing compounds (sulfate and thiols) in the expanding leaves strongly correlated with total SO₂ uptake of the plant shoot, whereas SO₂ uptake rate was strongly correlated with stomatal conductance for water vapor. Furthermore, exposure to high concentration of SO₂ revealed channeling of sulfite through assimilatory sulfate reduction that contributes in addition to SO-mediated sulfite oxidation to sulfite detoxification in expanding leaves of this woody plant species.     

Genetic composition of interspecific potato somatic hybrids and autofused 4<Emphasis Type="Italic">x</Emphasis> plants evaluated by DArT and cytoplasmic DNA markers

Key message

Using DArT analysis, we demonstrated that all Solanum × michoacanum (+) S. tuberosum somatic hybrids contained all parental chromosomes. However, from 13.9 to 29.6 % of the markers from both parents were lost in the hybrids.

Abstract

Somatic hybrids are an interesting material for research of nucleus-cytoplasm interaction and sources of new nuclear and cytoplasmic combinations. Analyses of genomes of somatic hybrids are essential for studies on genome compatibility between species, its evolution and are important for their efficient exploitation. Diversity array technology (DArT) permits analysis of the composition of nuclear DNA of somatic hybrids. The nuclear genome compositions of 97 Solanum × michoacanum (+) S. tuberosum [mch (+) tbr] somatic hybrids from five fusion combinations and 11 autofused 4x mch were analyzed for the first time based on DArT markers. Out of 5358 DArT markers generated in a single assay, greater than 2000 markers were polymorphic between parents, of which more than 1500 have a known chromosomal location on potato genetic or physical map. DArT markers were distributed along the entire length of 12 chromosomes. We noticed elimination of markers of wild and tbr fusion components. The nuclear genome of individual somatic hybrids was diversified. Mch is a source of resistance to Phytophthora infestans. From 97 mch (+) tbr somatic hybrids, two hybrids and all 11 autofused 4x mch were resistant to P. infestans. The analysis of the structure of particular hybrids’ chromosomes indicated the presence of markers from both parental genomes as well as missing markers spread along the full length of the chromosome. Markers specific to chloroplast DNA and mitochondrial DNA were used for analysis of changes within the organellar genomes of somatic hybrids. Random and non-random segregations of organellar DNA were noted.

     

Prodrugs of fumarate esters for the treatment of psoriasis and multiple sclerosis—a computational approach

Density functional theory (DFT) calculations at B3LYP/6-31 G (d,p) and B3LYP/6-311?+?G(d,p) levels for the substituted pyridine-catalyzed isomerization of monomethyl maleate revealed that isomerization proceeds via four steps, with the rate-limiting step being proton transfer from the substituted pyridinium ion to the C=C double bond in INT1. In addition, it was found that the isomerization rate (maleate to fumarate) is solvent dependent. Polar solvents, such as water, tend to accelerate the isomerization rate, whereas apolar solvents, such as chloroform, act to slow down the reaction. A linear correlation was obtained between the isomerization activation energy and the dielectric constant of the solvent. Furthermore, linearity was achieved when the activation energy was plotted against the pK _a value of the catalyst. Substituted-pyridine derivatives with high pK _a values were able to catalyze isomerization more efficiently than those with low pK _a values. The calculated relative rates for prodrugs 1–6 were: 1 (406.7), 2 (7.6?×?10⁶), 3 (1.0), 4 (20.7), 5 (13.5) and 6 (2.2?×?10³). This result indicates that isomerizations of prodrugs 1 and 3–5 are expected to be slow and that of prodrugs 2 and 6 are expected to be relatively fast. Hence, prodrugs 2 and 3–5 have the potential to be utilized as prodrugs for the slow release of monomethylfumarate in the treatment of psoriasis and multiple sclerosis.

Unreduced gamete formation in wheat × <Emphasis Type="Italic">Aegilops</Emphasis> spp. hybrids is genotype specific and prevented by shared homologous subgenomes

Key message

The presence of homologous subgenomes inhibited unreduced gamete formation in wheat × Aegilops interspecific hybrids. Unreduced gamete rates were under the control of the wheat nuclear genome.

Abstract

Production of unreduced gametes is common among interspecific hybrids, and may be affected by parental genotypes and genomic similarity. In the present study, five cultivars of Triticum aestivum and two tetraploid Aegilops species (i.e. Ae. triuncialis and Ae. cylindrica) were reciprocally crossed to produce 20 interspecific hybrid combinations. These hybrids comprised two different types: T. aestivum × Aegilops triuncialis; 2n = ABDU^tC^t (which lack a common subgenome) and T. aestivum × Ae. cylindrica; 2n = ABDD^cC^c (which share a common subgenome). The frequency of unreduced gametes in F₁ hybrids was estimated in sporads from the frequency of dyads, and the frequency of viable pollen, germinated pollen and seed set were recorded. Different meiotic abnormalities recorded in the hybrids included precocious chromosome migration to the poles at metaphase I and II, laggards in anaphase I and II, micronuclei and chromosome stickiness, failure in cell wall formation, premature cytokinesis and microspore fusion. The mean frequency of restitution meiosis was 10.1 %, and the mean frequency of unreduced viable pollen was 4.84 % in T. aestivum × Ae. triuncialis hybrids. By contrast, in T. aestivum × Ae. cylindrica hybrids no meiotic restitution was observed, and a low rate of viable gametes (0.3 %) was recorded. This study present evidence that high levels of homologous pairing between the D and D^c subgenomes may interfere with meiotic restitution and the formation of unreduced gametes. Variation in unreduced gamete production was also observed between T. aestivum × Ae. triuncialis hybrid plants, suggesting genetic control of this trait.

     

QTL mapping for salt tolerance and domestication-related traits in Vigna marina subsp. oblonga,a halophytic species

Key message

QTL mapping in F ₂ population [ V. luteola × V. marina subsp. oblonga ] revealed that the salt tolerance in V. marina subsp. oblonga is controlled by a single major QTL.

Abstract

The habitats of beach cowpea (Vigna marina) are sandy beaches in tropical and subtropical regions. As a species that grows closest to the sea, it has potential to be a gene source for breeding salt-tolerant crops. We reported here for the first time, quantitative trait loci (QTLs) mapping for salt tolerance in V. marina. A genetic linkage map was constructed from an F₂ population of 120 plants derived from an interspecific cross between V. luteola and V. marina subsp. oblonga. The map comprised 150 SSR markers. The markers were clustered into 11 linkage groups spanning 777.6 cM in length with a mean distance between the adjacent markers of 5.59 cM. The F_2:3 population was evaluated for salt tolerance under hydroponic conditions at the seedling and developmental stages. Segregation analysis indicated that salt tolerance in V. marina is controlled by a few genes. Multiple interval mapping consistently identified one major QTL which can explain about 50 % of phenotypic variance. The flanking markers may facilitate transfer of the salt tolerance allele from V. marina subsp. oblonga into related Vigna crops. The QTL for domestication-related traits from V. marina are also discussed.     

Synthesis of modified fragments of fibrinogen and their effect on the activity of proteolytic enzymes

New analogues of the Gly-Pro-Arg and Arg-Gly-Asp fragments of fibrinogen were synthesized: Gly-Pro-Arg-Pro (I), Gly-Pro-Arg-Pro-Met-OMe (II), Gly-Pro-Arg-Pro-Phe (III), Gly-Pro-Arg-Pro-Asp (IV), Gly-Pro-Arg-Pro-Glu (V), and Arg-Asn-Trp-Asp (VI). Their effect on the activity of proteases of various types was studied with the method of lysis of fibrin plates. All the peptides were found to inhibit plasmin activity (by 60–85%) and the γ-subunit of nerve growth factor (by 55–93%). Tetrapeptide (VI) proved to be an effective inhibitor of tissue activator of plasminogen and the γ-subunit of nerve growth factor (by 96 and 93%, respectively). The peptides exerted practically no effect on the activity of urokinase and moderately inhibited the activity of streptokinase [(III), IV), and (VI)], papain [(I), (II), IV), and (VI)], subtilisin [(V) and (VI)], α-chymotrypsin [(III), (V), and VI)], and Bacillus subtilis metalloprotease (VI). They inhibit trypsin [except for (I) and (III)] when applied on fibrin plates at a concentration of 1 × 10^?2 M, while, at the concentration of 1 × 10^?3 M, (I) and (II) induced an increase in proteolytic activity by 35 and 47%, respectively.     

Fertile introgression products generated via somatic hybridization between wheat and Thinopyrum intermedium

Key message

Fertile hybrids were produced with genetic material transferred from Th. intermedium into a wheat background and supply a source of genetic variation to wheat improvement.

Abstract

Both symmetric and asymmetric somatic hybrids have been obtained from the combination of wheatgrass (Thinopyrum intermedium) and bread wheat (Triticum aestivum). Two wheat protoplast populations, one derived from embryogenic calli and the other from a non-regenerable, rapidly dividing cell line, were fused with Th. intermedium protoplasts which had been (or not been) pre-irradiated with UV. Among the 124 regenerated calli, 64 could be categorized as being of hybrid origin on the basis of plant morphology, peroxidase isozyme, RAPD DNA profiling and karyological analysis. Numerous green plantlets were regenerated from 13 calli recovered from either the symmetric hybrid (no UV pre-treatment) or the asymmetric one (30 s UV irradiation). One of these hybrid plants proved to be vigorous and self-fertile. The regenerants were all closer in phenotype to wheat than to Th. intermedium. Genomic in situ hybridization analysis showed that the chromosomes in the hybrids were largely intact wheat ones, although a few Th. intermedium chromosome fragments had been incorporated within them.     

Separation and purification of bioactive botrallin and TMC-264 by a combination of HSCCC and semi-preparative HPLC from endophytic fungus Hyalodendriella sp. Ponipodef12

Two dibenzo-α-pyrones, botrallin (1) and TMC-264 (2) were preparatively separated from crude ethyl acetate extract of the endophytic fungus Hyalodendriella sp. Ponipodef12, which was isolated from the hybrid ‘Neva’ of Populus deltoides Marsh × P. nigra L. using a combination of high-speed counter-current chromatography (HSCCC) and semi-preparative HPLC. Botrallin (1) with 74.73 % of purity and TMC-264 (2) with 82.29 % of purity were obtained through HSCCC by employing a solvent system containing n-hexane–ethyl acetate–methanol–water at a volume ratio of 1.2:1.0:0.9:1.0. It was the first time for TMC-264 (2) to be isolated from this fungus. TMC-264 (2) showed strong antimicrobial and antinematodal activity, and botrallin (1) exhibited moderate inhibitory activity on acetylcholinesterase.     

Silencing Agrobacterium oncogenes in transgenic grapevine results in strain-specific crown gall resistance

Key message

Grapevine rootstock transformed with an Agrobacterium oncogene-silencing transgene was resistant to certain Agrobacterium strains but sensitive to others. Thus, genetic diversity of Agrobacterium oncogenes may limit engineering crown gall resistance.

Abstract

Crown gall disease of grapevine induced by Agrobacterium vitis or Agrobacterium tumefaciens causes serious economic losses in viticulture. To establish crown gall-resistant lines, somatic proembryos of Vitis berlandieri × V. rupestris cv. ‘Richter 110’ rootstock were transformed with an oncogene-silencing transgene based on iaaM and ipt oncogene sequences from octopine-type, tumor-inducing (Ti) plasmid pTiA6. Twenty-one transgenic lines were selected, and their transgenic nature was confirmed by polymerase chain reaction (PCR). These lines were inoculated with two A. tumefaciens and three A. vitis strains. Eight lines showed resistance to octopine-type A. tumefaciens A348. Resistance correlated with the expression of the silencing genes. However, oncogene silencing was mostly sequence specific because these lines did not abolish tumorigenesis by A. vitis strains or nopaline-type A. tumefaciens C58.     

New taxa and nomenclatural changes in arceuthobium (viscaceae)

The following new taxa are recognized inArceuthobium: subgeneraArceuthobium andVaginata; sectionsVaginata, Campylopoda, andMinuta; seriesCampylopoda,Rubra, andStricta; speciesA. apachecum,A. californicum,A. guatemalense,A. hondurense, andA. pini; new formae spécialesA. abietinum f. sp.concoloris,A. abietinum f. sp.magnificae. New combinations:A. abietinum (Engelm.) Hawksworth & Wiens, andA. microcarpum (Engelm.) Hawksworth & Wiens.     

Mapping and identification of a Cicer arietinum NSP2 gene involved in nodulation pathway

Key message

For the first time the putative NSP2 gene in chickpea has been identified using pairs of NILs differing for the Rn1 / rn1 nodulation gene that was located in LG5 of chickpea genetic map.

Abstract

An intraspecific cross between the mutant non-nodulating genotype PM233, carrying the recessive gene rn1, and the wild-type CA2139 was used to develop two pairs of near-isogenic lines (NILs) for nodulation in chickpea. These pairs of NILs were characterized using sequence tagged microsatellite site (STMS) markers distributed across different linkage groups (LGs) of the chickpea genetic map leading to the detection of polymorphic markers located in LG5. Using this information, together with the genome annotation in Medicago truncatula, a candidate gene (NSP2) known to be involved in nodulation pathway was selected for mapping in chickpea. The full length sequence obtained in chickpea wild-type (CaNSP2) was 1,503 bp. Linkage analysis in an F₃ population of 118 plants derived from the cross between the pair of NILS NIL7-2A (nod) × NIL7-2B (non-nod) revealed a co-localization between CaNSP2 and Rn1 gene. These data implicate the CaNSP2 gene as a candidate for identity to Rn1, and suggest that it could act in the nodulation signaling transduction pathway similarly to that in other legumes species.     

New combinations and one new variety among the genera Indigofera,Robinia, and Tephrosia (Leguminosae)

This report includes: a new variety,Indigofera miniata var.florida, and five new combinations.I. mucronata var.keyensis, Robinia hispida var.kelseyi, Tephrosia angustissima var.corallicola, T. angustissima var.curtissii, andT. × floridana.