Cold stress and freezing tolerance negatively affect the fitness of Arabidopsis thaliana accessions under field and controlled conditions

Main conclusion Higher acclimated freezing tolerance improved winter survival, but reduced reproductive fitness of Arabidopsis thaliana accessions under field and controlled conditions. Abstract Low temperature is one of the most important abiotic factors influencing plant fitness and geographical distribution. In addition, cold stress is known to influence crop yield and is therefore of great economic importance. Increased freezing tolerance can be acquired by the process of cold acclimation, but this may be associated with a fitness cost. To assess the influence of cold stress on the fitness of plants, long-term field trials over 5 years were performed with six natural accessions of Arabidopsis thaliana ranging from very tolerant to very sensitive to freezing. Fitness parameters, as seed yield and 1000 seed mass, were measured and correlation analyses with temperature and freezing tolerance data performed. The results were compared with fitness parameters from controlled chamber experiments over 3 years with application of cold priming and triggering conditions. Winter survival and seed yield per plant were positively correlated with temperature in field experiments. In addition, winter survival and 1000 seed mass were correlated with the cold-acclimated freezing tolerance of the selected Arabidopsis accessions. The results provide strong evidence for a trade-off between higher freezing tolerance and reproductive fitness in A. thaliana, which might have ecological impacts in the context of global warming.

Linking functional diversity to ecological indicators: A tool to predict the anthropogenic effects on ecosystem functioning

Functional diversity is related to the maintenance of processes and functions in ecosystems. However, there is a lack of a conceptual framework that highlights the application of functional diversity as an ecological indicator. Therefore, we present a new initiative for motivating the development of ecological indicators based on functional diversity. We are interested in showing the challenges and solutions associated with these indicators. We integrated species assemblage theories and literature reviews. We considered plant traits related to ecosystem processes and functions (specific leaf area, leaf dry matter content, wood density, phenology, and seed mass) to show the application of a selection of functional diversity metrics that can be used as ecological indicators (i.e., Community Weighted-Mean, Functional Divergence, Functional Richness and Functional Evenness). We caution that functional diversity as an ecological indicator can be misinterpreted if species composition is unknown. Functional diversity values can be overrepresented by weed species (species established in disturbed sites) and do not maintain original processes and functions in ecosystems. Therefore, we searched for evidence to demonstrate that weed species are ecological indicators of functional diversity changes. We found support for two hypotheses that explain the effect of weed species on ecosystem function: functional homogenization and functional transformation. Likewise, we showed the application of some tools that can help study the anthropogenic effect on functional indicators. This review shows that the paradigm of addressing the effects of disturbances on ecosystem processes by using functional diversity as an ecological indicator can improve environmental evaluation, particularly in areas affected by human activities.

The manifestation of the main quantitative characteristics in the populations of second-generation beans and their parent forms

The aim of the research was to study the nature of variability of the main quantitative traits in hybrid populations of the second generation Phaseolus vulgaris L. within the framework of the task 13.00.01.28. F “To study the nature of the inheritance of quantitative traits in hybrids of create a starting material with improved flavoring properties.As a result of the studies carried out, it was found that regardless of the duration of the growing season of the parent components of the crossing, in the hybrid populations of the second generation, the limits of variability for this indicator went beyond the limits of the variability of the parent forms. The average values of the duration of the growing season in hybrids were intermediate between the indicators of the corresponding parent forms. The coefficients of variation in the parent forms were insignificant (1.1 – 1.4%); in hybrid populations they were low – from 4.9% (Line 744-14 / Ukrainka) to 9.2% (Line 741-14 / Suita).In terms of plant height, the limits of variability of hybrid offspring F2 went beyond the limits of variability of the parent components. The average values of the trait in hybrid populations significantly exceeded the corresponding indicators of the parent forms. The degree of variability in plant height of hybrid populations was significant in the combination Line 872-14 / Podolyanka-1 (the parent components differ in the type of plant growth) and was equal to 20.6% versus 3.5% and 4.9% for the corresponding parent forms. In other hybrid populations, the coefficient of variation was average (Ukrainka / Suita-16.5%; Line 741-14 / Suita – 13.5%; Line 744-14 / Ukrainka -10.1%) The degree of variability of the corresponding parental forms was in the range from 2.8% to 3.1%.The widest range of variability was observed according to the characteristics of the mass of seeds from the plant, the number of seeds from the plant, the number of beans from the plant. The degree of variability of the seed mass from the plant in hybrid populations ranged from 30.3% to 39.1% (in the parent forms from 9.1% to 21.7%); the number of seeds from the plant from 22.3% to 40.7% (in the parent forms from 9.8% to 20.1%); the number of beans from the plant from 28.1% to 38.3% (in the parent forms from 4.7% to 16.2%). The degree of variation of the studied traits in hybrid populations was 2–3 times higher than in the parent forms.By the weight of 100 seeds in the offspring of the second generation, the range of variation was much wider than this indicator in the parent forms. The degree of variability on this trait was average for hybrid populations (from 10.6% to 13.4%), and insignificant for parental forms (from 3.7% to 6.6%).It is possible that the most valuable in terms of breeding may be the hybrid combination Line 872-14/Podolyanka, from the widest range of variability in the studied traits in the second generation population.

Impact of engineering properties of grass seeds in developing post-harvest operations and machineries

Engineering properties of grass seeds are most important for the development of post-harvest mechanization and operations. Therefore engineering properties of fluffy as well as true seeds were determined in view of its important in development of post-harvest mechanization. The mean values of length, width, thickness, arithmetic mean diameter, geometric mean diameter, sphericity, surface area, volume, thousands seed mass and bulk density of fluffy Deenanath grass seed were observed in the range of 5.23-7.17 mm, 2.10-3.44 mm, 1.17-2.49 mm, 3.07- 4.13 mm, 2.53- 3.69 mm, 41.01-60.13 %, 19.12-43.70 mm2, 3.70-18.24 mm3, 0.789-0.849 g and 7.41-7.89 kg/m3 respectively. However, for true seeds of Deenanath grass, the range of these values varied from 2.23-2.65 mm, 0.69-0.95 mm, 0.47-0.69 mm, 1.16-1.40 mm, 0.93-1.17 mm, 38.69-47.33 %, 2.67-4.31 mm2, 3.60-9.64 mm3, 0.468-0.488 g and 602.97-624.29 kg/m3 respectively moisture level of 9 % db. Determined properties of fluffy as well as true seeds of Deenanath would be utilized to develop threshing, cleaning, grading, seed storage and packaging operations and machineries.

The ecology and quantitative genetics of seed and seedling traits in upland and lowland ecotypes of a perennial grass

Plants have evolved diverse reproductive allocation strategies and seed traits to aid in dispersal, persistence in the seed bank, and establishment. In particular, seed size, dormancy, and early seedling vigor are thought to be key functional traits with important recruitment and fitness consequences across abiotic stress gradients. Selection for favored seed-trait combinations, or against maladaptive combinations, is likely an important driver shaping recruitment strategies. Here, we test for seed-trait plasticity and local adaptation in contrasting upland and lowland ecotypes of Panicum hallii with field experiments in native versus foreign habitats. Furthermore, we test whether seed traits have been under directional selection in P. hallii using the v-test (Fraser 2020) based on trait variance in a genetic cross. Finally, we evaluate the genetic architecture of ecotypic divergence for these traits with Quantitative Trait Locus (QTL) mapping. Field experiments reveal little plasticity but support a hypothesis of local adaptation among ecotypes based on recruitment. Patterns of segregation within recombinant hybrids provides strong support for directional selection driving ecotypic divergence in seeds traits. Genetic mapping revealed a polygenic architecture with evidence of genetic correlation between seed mass, dormancy, and seedling vigor. Our results suggest that the evolution of these traits may involve constraints that affect the direction of adaptive divergence. For example, seed size and germination percentage shared two colocalized QTL with antagonistic additive effects. This supports the hypothesis of a functional genetic relationship between these traits, resulting in either large seed/strong dormancy or small seed/weak dormancy trait combinations. Overall, our study provides insights into the factors facilitating and potentially constraining ecotypic differentiation in seed traits.

Linnemannia elongata (Mortierellaceae) stimulates Arabidopsis thaliana aerial growth and responses to auxin, ethylene, and reactive oxygen species

Harnessing the plant microbiome has the potential to improve agricultural yields and protect plants against pathogens and/or abiotic stresses, while also relieving economic and environmental costs of crop production. While previous studies have gained valuable insights into the underlying genetics facilitating plant-fungal interactions, these have largely been skewed towards certain fungal clades (e.g. arbuscular mycorrhizal fungi). Several different phyla of fungi have been shown to positively impact plant growth rates, including Mortierellaceae fungi. However, the extent of the plant growth promotion (PGP) phenotype(s), their underlying mechanism(s), and the impact of bacterial endosymbionts on fungal-plant interactions remain poorly understood for Mortierellaceae. In this study, we focused on the symbiosis between soil fungus Linnemannia elongata (Mortierellaceae) and Arabidopsis thaliana (Brassicaceae), as both organisms have high-quality reference genomes and transcriptomes available, and their lifestyles and growth requirements are conducive to research conditions. Further, L. elongata can host bacterial endosymbionts related to Mollicutes and Burkholderia . The role of these endobacteria on facilitating fungal-plant associations, including potentially further promoting plant growth, remains completely unexplored. We measured Arabidopsis aerial growth at early and late life stages, seed production, and used mRNA sequencing to characterize differentially expressed plant genes in response to fungal inoculation with and without bacterial endosymbionts. We found that L. elongata improved aerial plant growth, seed mass and altered the plant transcriptome, including the upregulation of genes involved in plant hormones and “response to oxidative stress”, “defense response to bacterium”, and “defense response to fungus”. Furthermore, the expression of genes in certain phytohormone biosynthetic pathways were found to be modified in plants treated with L. elongata . Notably, the presence of Mollicutes- or Burkholderia- related endosymbionts in Linnemannia did not impact the expression of genes in Arabidopsis or overall growth rates.

The Effect of Plant Density, Zinc Added to Phosphorus Fertilizer Sources and Location on Selected Yield Parameters of Soybean

Background: Soybean [Glycine max (L.) Merrill] is an annual herbaceous leguminous grain crop which is cultivated mainly for its oil and protein. The objective of the study was to determine the effects of plant density and zinc added to phosphorus fertilizer sources on soybean yield performance under different environmental conditions. Methods: A field trial was executed in two sites during the 2018/19 and 2019/20 summer planting seasons. The experimental design involved a 2 × 2 × 5 factorial fitted into a randomized complete block design (RCBD) with four replications. The experiment consisted of two plant densities, a lower plant density of 66 666 plants/ha and a higher plant density of 111 111 plants/ha. The five different types of fertilizer treatments were single superphosphate, monoammonium phosphate, zinc sulphate added to single superphosphate, zinc sulphate added to monoammonium phosphate and control. Result: The results showed that plant density has a significant effect (P less than 0.05) on soybean number of pods per plant and the field biomass yield. Soybean planted under lower plant density conditions produced a significantly larger number of pods per plant during both planting seasons, whereas higher plant density conditions resulted in a higher soybean field biomass yield during the 2018/19 planting season. It was observed that soybean treated with monoammonium phosphate had higher seed mass.

Diversification of ergot alkaloids and heritable fungal symbionts in morning glories

Heritable microorganisms play critical roles in life cycles of many macro-organisms but their prevalence and functional roles are unknown for most plants. Bioactive ergot alkaloids produced by heritable Periglandula fungi occur in some morning glories (Convolvulaceae), similar to ergot alkaloids in grasses infected with related fungi. Ergot alkaloids have been of longstanding interest given their toxic effects, psychoactive properties, and medical applications. Here we show that ergot alkaloids are concentrated in four morning glory clades exhibiting differences in alkaloid profiles and are more prevalent in species with larger seeds than those with smaller seeds. Further, we found a phylogenetically-independent, positive correlation between seed mass and alkaloid concentrations in symbiotic species. Our findings suggest that heritable symbiosis has diversified among particular clades by vertical transmission through seeds combined with host speciation, and that ergot alkaloids are particularly beneficial to species with larger seeds. Our results are consistent with the defensive symbiosis hypothesis where bioactive ergot alkaloids from Periglandula symbionts protect seeds and seedlings from natural enemies, and provide a framework for exploring microbial chemistry in other plant-microbe interactions.

Learning of a mimic odor combined with nectar nonsugar compounds enhances honeybee pollination of a commercial crop

The increasing demand on pollination services leads food industry to consider new strategies for management of pollinators to improve their efficiency in agroecosystems. Recently, it was demonstrated that feeding beehives food scented with an odorant mixture mimicking the floral scent of a crop (sunflower mimic, SM) enhanced foraging activity and improved recruitment to the target inflorescences, which led to higher density of bees on the crop and significantly increased yields. Besides, the oral administration of nonsugar compounds (NSC) naturally found in nectars (caffeine and arginine) improved short and long-term olfactory memory retention in conditioned bees under laboratory conditions. To test the effect of offering of SM-scented food supplemented with NSC on honeybees pollinating sunflower for hybrid seed production, in a commercial plantation we fed colonies SM-scented food (control), and SM-scented food supplemented with either caffeine, arginine, or a mixture of both, in field realistic concentrations. Their foraging activity was assessed at the hive and on the crop up to 90 h after treatment, and sunflower yield was estimated prior to harvest. Our field results show that SM + Mix-treated colonies exhibited the highest incoming rates and densities on the crop. Additionally, overall seed mass was significantly higher by 20% on inflorescences close to these colonies than control colonies. Such results suggest that combined NSC potentiate olfactory learning of a mimic floral odor inside the hive, promoting faster colony-level foraging responses and increasing crop production.