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The annual goatgrass, Aegilops biuncialis is a rich source of genes with considerable agronomic value. This genetic potential can be exploited for wheat improvement through interspecific hybridization to increase stress resistance, grain quality and adaptability. However, the low throughput of cytogenetic selection hampers the development of alien introgressions. Using the sequence of flow-sorted chromosomes of diploid progenitors, the present study enabled the development of chromosome-specific markers. In total, 482 PCR markers were validated on wheat (Mv9kr1) and Ae. biuncialis (MvGB642) crossing partners, and 126 on wheat-Aegilops additions. Thirty-two markers specific for U- or M-chromosomes were used in combination with GISH and FISH for the screening of 44 Mv9kr1 × Ae. biuncialis BC3F3 genotypes. The predominance of chromosomes 4M and 5M, as well as the presence of chromosomal aberrations, may indicate that these chromosomes have a gametocidal effect. A new wheat-Ae. biuncialis disomic 4U addition, 4M(4D) and 5M(5D) substitutions, as well as several introgression lines were selected. Spike morphology and fertility indicated that the Aegilops 4M or 5M compensated well for the loss of 4D and 5D, respectively. The new cytogenetic stocks represent valuable genetic resources for the introgression of key genes alleles into wheat. [ABSTRACT FROM AUTHOR]

Leaf rust, caused by Puccinia hordei, is one of the most widespread and damaging foliar diseases affecting barley. The barley leaf rust resistance locus Rph7 has been shown to have unusually high sequence and haplotype divergence. In this study, we isolate the Rph7 gene using a fine mapping and RNA-Seq approach that is confirmed by mutational analysis and transgenic complementation. Rph7 is a pathogen-induced, non-canonical resistance gene encoding a protein that is distinct from other known plant disease resistance proteins in the Triticeae. Structural analysis using an AlphaFold2 protein model suggests that Rph7 encodes a putative NAC transcription factor with a zinc-finger BED domain with structural similarity to the N-terminal DNA-binding domain of the NAC transcription factor (ANAC019) from Arabidopsis. A global gene expression analysis suggests Rph7 mediates the activation and strength of the basal defence response. The isolation of Rph7 highlights the diversification of resistance mechanisms available for engineering disease control in crops. Rph7 is a previously mapped barley leaf rust resistance locus, but the causal resistance gene remains unclear. Here, combining a fine mapping approach with RNA-Seq based analysis, the authors clone Rph7 and show it encodes putative NAC transcription factor containing a C-terminal BED domain. [ABSTRACT FROM AUTHOR]

The character of pure or mixed forest canopies and their litterfalls contribute to different forest-floor properties. These organic layers and also subjacent topsoil were studied at three study sites covered by mixed treatments such as beech–spruce, beech–fir, spruce–fir and two monospecific beech and spruce treatments. The age of the forest stands ranged from 11 to 15 years when sampled. All study sites were used as meadows when afforested; therefore, the forest floors were new, and the A-horizon topsoil properties were not influenced by older humus inherited from previous forest generations. The mineral soil was likely affected by different levels of former fertilization, which resulted in differences among the study sites. The early-developed forest floors showed differences between the treatments with beech and the others. The topsoil below beech with spruce had more nitrogen, oxidizable carbon and cations of exchangeable hydrogen as well as pH showing more acidic conditions and lower contents and saturation of base cations. Pure beech had more phosphorus. The nutrient pools did not differ among the treatments; significantly more matter was found below the oldest stands on the first afforested site, which also increased nutrient pools. [ABSTRACT FROM AUTHOR]

Occurrence of Festuca apennina De Not. (4 × Fape), F. pratensis Huds. (2 × Fp) and the triploid, sterile hybrid F. apennina × F. pratensis (3 × Fape × Fp) was studied in 12 regions of the Swiss Alps. In total, 1908 plants were sampled in elevational strata scaled by 50 m between 850 and 2000 m a.s.l., and accompanying vegetation was assessed for each sampling point. The hybrid 3 × Fape × Fp was more frequent and more dominant than both parental species around 1400 m, and had a wider elevational distribution than 2 × Fp and 4 × Fape, which were confined to lower and higher elevation, respectively. As evidenced by their preferred accompanying species, 2 × Fp colonizes dryer, nutrient poorer environments than 4 × Fape which clearly prefers wet and nutrient rich environments. On the contrary, 3 × Fape × Fp thrives similarly well in both environments. The ability to reach an important biomass proportion in a sward, and the wide environmental adaptation of 3 × Fape × Fp is favored by its capacity to strongly expand by rhizomes. A single genotype of 3 × Fape × Fp was found to colonize an entire field of 2.3 ha with a maximum distance between clonal plants of 304 m. It is concluded that 3 × Fape × Fp is a potentially valuable pasture plant for use at higher altitudes, but it may reduce biodiversity via suppressing less competitive plant species. [ABSTRACT FROM AUTHOR]

Meiotic recombination is a critical process for plant breeding, as it creates novel allele combinations that can be exploited for crop improvement. In wheat, a complex allohexaploid that has a diploid-like behaviour, meiotic recombination between homoeologous or alien chromosomes is suppressed through the action of several loci. Here, we report positional cloning of Pairing homoeologous 2 (Ph2) and functional validation of the wheat DNA mismatch repair protein MSH7-3D as a key inhibitor of homoeologous recombination, thus solving a half-century-old question. Similar to ph2 mutant phenotype, we show that mutating MSH7-3D induces a substantial increase in homoeologous recombination (up to 5.5 fold) in wheat-wild relative hybrids, which is also associated with a reduction in homologous recombination. These data reveal a role for MSH7-3D in meiotic stabilisation of allopolyploidy and provides an opportunity to improve wheat's genetic diversity through alien gene introgression, a major bottleneck facing crop improvement. In the allohexaploid genome of wheat, meiotic recombination between homoeologues is suppressed through the action of several loci. Here, the authors report the cloning of the long sought-after gene Ph2 and show its function in reduction of homoeologous recombination. [ABSTRACT FROM AUTHOR]

The occurrence of triploid hybrids in nature is scarce due to the so-called triploid block representing formation of nonviable progeny after mating diploid with tetraploid. Here we describe frequent presence of triploids originating from hybridization of diploid Festuca pratensis with tetraploid F. apennina in the Swiss Alps. F. pratensis is a forage grass grown in lowlands and up to 1800 m a.s.l., while F. apennina is a mountain grass found in elevations from 1100 to 2000 m a.s.l. In the overlapping zone these species often grow sympatrically and triploid hybrids have been observed. We show that elevation is the main factor in the distribution of plants with various ploidy levels. Diploids occupy lower elevations, while triploids predominate in the mid-elevation zones and tetraploids are the most frequent in higher elevations. Other factors, such as topography and soil composition probably have only marginal effects on the distribution of the plants with different ploidy levels. Triploids seem to be frequently formed in the Swiss Alps and crosses in both directions are involved in the formation of triploid hybrids. As shown by chloroplast DNA analysis, F. apennina more frequently serves as female. Our analysis suggests that in the mid-elevation zones, triploids have a higher level of competitiveness than both parents. Triploids can overgrow microhabitats to a much higher extent than tetraploids. Such frequent occurrence and local dominance of triploids can at least be partially explained by asexual reproduction. Using DNA markers, we show that triploids can disperse ramets of a single clone over a distance of at least 14.4 m. [ABSTRACT FROM AUTHOR]

Key message: Different blue-aleurone wheats display major differences in chromosome composition, ranging from disomic chromosome additions, substitutions, single chromosome arm introgressions and chromosome translocation of Thinopyrum ponticum. Abstract: Anthocyanins are of great importance for human health due to their antioxidant, anti-inflammatory, anti-microbial and anti-cancerogenic potential. In common wheat ( Triticum aestivum L.) their content is low. However, elite lines with blue aleurone exhibit significantly increased levels of anthocyanins. These lines carry introgressed chromatin from wild relatives of wheat such as Thinopyrum ponticum and Triticum monococcum. The aim of our study was to characterize genomic constitutions of wheat lines with blue aleurone using genomic and fluorescence in situ hybridization. We used total genomic DNA of Th. ponticum and two repetitive DNA sequences (GAA repeat and the Afa family) as probes to identify individual chromosomes. This enabled precise localization of introgressed Th. ponticum chromatin. Our results revealed large variation in chromosome constitutions of the blue-aleurone wheats. Of 26 analyzed lines, 17 carried an introgression from Th. ponticum; the remaining nine lines presumably carry T. monococcum chromatin undetectable by the methods employed. Of the Th. ponticum introgressions, six different types were present, ranging from a ditelosomic addition (cv. Blue Norco) to a disomic substitution (cv. Blue Baart), substitution of complete (homologous) chromosome arms (line UC66049) and various translocations of distal parts of a chromosome arm(s). Different types of introgressions present support a hypothesis that the introgressions activate the blue aleurone trait present, but inactivated, in common wheat germplasm. [ABSTRACT FROM AUTHOR]