Morphological and chemical characteristics of doubled haploids of flue-cured tobacco combining resistance to Thielaviopsis basicola and TSWV

Thielaviopsis basicola and Tomato spotted wilt virus (TSWV) are the most important problems in a moderate climate zone. Previously obtained doubled haploids (DH) of F₁ hybrids of the flue-cured line WGL3 resistant to Th. basicola and the dark-cured line PW-834 carrying RTSW-al gene provided the research material. Biological tests and SCAR markers linked with TSWV were applied to confirm resistance of DH. Lines combining resistance to TSWV and Th. basicola were evaluated for morphological and chemical characteristics. Most of DH were significantly shorter than parents but two lines, 31/A/2 and 31/B/3, were close to the flue-cured WGL3. Usually DH possessed fewer leaves while one of them 31/B/3, exceeded parental forms. The doubled haploids flowered later than their parents. The most negative effect was reduced area of mid-position leaves of DH. It might be explained by a recombination during microsporogenesis in F₁, however the influence of ‘Polalta’-derived RTSW-al gene cannot be excluded. Extensive line to line variation for nicotine and sugars content was not associated with the genes for TSWV and Th. basicola resistance. Biological tests and field performance of DH revealed potential to overcome the negative effect of coupling between the RSTV-al gene and genes responsible for the morphological deformations.     

Phosphorus forms in forest soil colloids as revealed by liquid‐state 31P‐NMR

Nanoparticles and colloids affect the storage and hence the availability of P in forest ecosystems. We investigated the fine colloids present in forest soils and their association with inorganic and organic P. To differentiate between the different P forms, we performed liquid‐state ³¹P‐nucelar magnetic resonance (³¹P‐NMR) measurements on forest bulk soil extracts, on colloid extracts and on the electrolyte phase of their soil suspensions. The ³¹P‐NMR spectra indicated that soil nanoparticles and colloids were more enriched with organic than with inorganic P forms compared to the electrolyte phase. The P concentration was enriched in the colloidal fraction in comparison to the bulk soil and the phosphate diesters were more dominant in the colloidal fraction when compared to the bulk soil. The colloidal P‐diester to P‐monoester ratios were 2 to 3 times higher in the colloidal fraction than in the bulk soil. In contrast, relatively large percentages of inorganic P were found in the electrolyte phase. Supplementary (not shown) Data are available at the JuSER Server (juser.fz‐juelich.de, reference number: FZJ‐2016‐01739) https://juser.fz‐juelich.de/record/283057 .     

Changes in the activity and abundance of the soil microbial community in response to the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP)

Purpose

The application of organic and inorganic fertilizers to soil can result in increased gaseous emissions, such as NH₃, N₂O, CO₂, and CH₄, as well as nitrate leaching, contributing to climate warming and ground and surface water pollution, particularly in regions with hot climates, where high temperatures and high soil nitrification rates often occur. The use of nitrification inhibitors (NIs) has been shown to effectively decrease nitrogen (N) losses from the soil-plant system.

Materials and methods

Non-disruptive laboratory incubation experiments were conducted to assess the extent to which temperature (20 and 30 °C) and nutrient source (mineral and organic fertilizers) influence the rate of carbon (C)- and N-related microbial processes in soil in response to the NI 3,4-dimethylpyrazole phosphate (DMPP). Furthermore, short-term changes in the ability of microbes to degrade C substrates were evaluated in disruptive soil microcosms using microbial community-level physiological profiling and the abundance of the bacterial 16S rRNA gene as a measure of total bacterial population size.

Results and discussion

DMPP reduced net nitrification after 2 and 4 weeks of incubation at 30 and 20 °C by an average of 78.3 and 84.5 %, respectively, and with similar dynamics for mineral or organic fertilization. The addition of labile organic matter with cattle effluent led to a rapid increase in C mineralization that was significantly reduced by DMPP at both temperatures, whereas no changes could be detected after the addition of mineral fertilizer. The culturable heterotrophic microorganisms showed metabolic diversification in the oxidation of C sources, with organic fertilizer playing a major role in the substrate utilization patterns during the first week of incubation and the DMPP effects prevailing from day 14 until day 28. Furthermore, the copy number of the bacterial 16S rRNA gene was reduced by the application of DMPP and organic fertilizer after 28 days.

Conclusions

Our results show the marked efficiency of DMPP as an NI at elevated temperatures of incubation and when associated with both mineral and organic fertilization, providing support for its use as a tool to mitigate N losses in Mediterranean ecosystems. However, we also observed impaired C respiration rates and bacterial abundances, as well as shifts in community-level physiological profiles in soil, possibly indicating a short-term effect of DMPP and organic fertilizers on non-target C-related processes and microorganisms.

     

Acclimation of apple spur leaf nutrient concentrations and gas exchange to summer-pruning

Foliar concentrations of nitrogen, phosphorus, potassium, calcium, magnesium, and chlorophyll were measured in shade-adapted and sun-adapted spur leaves of apple cvs ”︁Golden Delicious” and ”︁Granny Smith” as well as in shade-adapted leaves after summer-pruning. The shade-to-sun transition of summer-pruned leaves resulted in concentration changes towards the level of sun-adapted leaves, which were accompanied by significant increases in net photosynthesis and transpiration rates as well as maximum photosynthesis rates. Gas exchange parameters of fully expanded spur leaves after the shade-to-sun transition did not differ from those of sun adapted leaves. This indicates the capacity of fully expanded apple spur leaves to adapt to a new light environment and supports the hypothesis that nutrients are distributed to leaves growing under the highest light intensity in order to maximize their photosynthesis.     

Role of EphA4 and EphrinB3 in local neuronal circuits that control walking

Local circuits in the spinal cord that generate locomotion are termed central pattern generators (CPGs). These provide coordinated bilateral control over the normal limb alternation that underlies walking. The molecules that organize the mammalian CPG are unknown. Isolated spinal cords from mice lacking either the EphA4 receptor or its ligand ephrinB3 have lost left-right limb alternation and instead exhibit synchrony. We identified EphA4-positive neurons as an excitatory component of the locomotor CPG. Our study shows that dramatic locomotor changes can occur as a consequence of local genetic rewiring and identifies genes required for the development of normal locomotor behavior.     

Myxomycetes in soil

The myxomycetes are a group of protists that form a monophyletic taxon in the phylum Amoebozoa. Evidence of their evolutionary success is the fact that they account for more species (ca. 900 are currently recognized) than the combined total for the rest of the Amoebozoa. Moreover, myxomycetes are present in every terrestrial environment investigated to date and also, as amoebae or flagellated cells, in aquatic environments where they cannot form fruiting bodies. Even if culture-based methods tend to underestimate their occurrence in soil, myxomycetes probably account for ∼50% of soil amoebae. The emergence of molecular-based methods has revolutionized our concepts of biodiversity, but myxomycetes are conspicuously absent from all environmental surveys. Herein we show that this is due to their highly diverging SSU rRNA gene sequences, which contain numerous Group I introns.Further proof comes from a recent study that used a massive sequencing approach without primer bias to amplify RNAs. The results obtained show that the mycetozoans (myxomycetes along with dictyostelids and protostelids) are indeed a dominant group of soil protozoans.     

On the origin of artichoke and cardoon from the <Emphasis Type="Italic">Cynara</Emphasis> gene pool as revealed by rDNA sequence variation

The evolutionary history of artichoke and cultivated cardoon and their relationships to wild allies of the genus Cynara are not fully understood yet. To try resolve the evolutionary patterns leading to the domestication of these two crops, a study of molecular evolution was undertaken. The species C. cardunculus, including artichoke, cultivated and wild cardoon, together with four wild Cynara species were taken into consideration. Internal (ITS) and external (ETS) rDNA transcribed spacers were used as markers of nuclear genome, the psbA-trnH spacer as a marker of chloroplast genome. Sequences were analysed using phylogenetic analysis packages. Molecular data indicate that the whole genus is quite recent and that the domestication of artichoke and cultivated cardoon, crops diverging for reproduction system and use, are independent events which diverge in time and space. As for wild Cynara species, an evolutionary pattern consistent with their present geographical distribution was hypothesized in relation to the climatic changes occurring in the Mediterranean during the last 20 millennia: C. humilis and C. cornigera appeared to have differentiated first, C. syriaca and C. baetica were differentiated in a second period, while C. cardunculus showed to be the most recent and plastic species. The high plasticity of C. cardunculus has not only allowed its nowadays wide distribution, but has also given the potential for domestication. Dedicated to the memory of Richard Neville Lester (1937–2006) who greatly contributed to the understanding of the evolution, domestication, and genetic resources of eggplants as well as to the biosystematics and taxonomy of allied species. IGV Publication N. 78 of the Institute of Plant Genetics, CNR