Increasing photosynthetic productivity of cereal bioenergy crops as affected by the water content in leaves under mycorrhization of the root system

Purpose. To determine photosynthetic productivity of miscanthus gigantheus and switchgrass as affected by leaf water content under mycorrhization of their roots. Methods. Field, laboratory, and statistical. Results. The obtained results indicate that the use of vesicular-arbuscular mycorrhizal (VAM) preparations Mycofriend (fungus Trichoderma harzianum RIFAI.), Mikovital (fungus Tuber melanosporum VITTAD.), and nitrogen-fixing preparation Florobacillin (Bacillus subtilis Cohn.) helps to increase water content in the leaves of such cereal bioenergy crops as miscanthus gigantheus and switchgrass. In particular, in all vegetation periods, in the treatments with Mycofriend, the water content in miscanthus gigantheus leaves was higher by 11.2–20.1% than in the control, while in switchgrass it was higher by 16.9–20.5% than in the control. In the treatments with Mikovital and Florobacillin, leaf water content ranged in miscanthus from 7.1 to 15.6% and from 5.8 to 11.7%, respectively, and in switchgrass, from 11.6 to 14.7% and from 7.0 to 10.2%, respectively. The photosynthetic productivity of these crops is affected by the water content in the leaves. There is a close correlation between these factors (correlation coefficient 0.95–0.96). Conclusions. Root application of biological plant products Mycofriend, Mikovital and Florobacillin improves water content in the leaves of cereal bioenergy crops, such as miscanthus gigantheus and switchgrass, and increases their photosynthetic productivity.

Increasing photosynthetic productivity of crops as affected by water content in their leaves under mycorrhization of the root system

Purpose. To investigate the effect of pre-sowing seed treatment with vesicular-arbuscular mycorrhizal (VAM) and bacterial preparations on the leaf water content and photosynthetic productivity of agricultural crops (winter wheat, corn, sunflower and soybean) under mycorrhization of their roots. Methods. Field, laboratory, and statistical. Results. The results of studies on determining the effect of pre-sowing treatment of seeds of such agricultural crops as soft winter wheat, common corn, annual sunflower and soybean culturally vesucular-arboscular drugs Mikovital (mushroom Tuber melanosporum VITTAD.) Micofrend (mushroom Trichoderma harzianum. (bacteria Bacillus subtilis Cohn.) on the water content of leaves and the productivity of photosynthesis of plants by mycorrhization of their root system. It was found that the implementation of this measure provides a steady increase in the water content of leaves and the productivity of photosynthesis of agricultural crops. In particular, the water content of leaves of soft winter wheat plants, common corn, annual sunflower and cultivated soybeans for the use of the preparations Mikovital, Mikofrend and Florobatsilin was 1.6–77.3 % more than in the control. According to the indicators of the water content of the leaves, the productivity of photosynthesis of crops increased by 8.3–57.1 % in comparison with the control, which indicates a significant effect of this factor on the growth and development of plants. Conclusions. Pre-sowing seed treatment with vesicular-arbuscular products Mikovital, Mycofrend, and bacterial product Florabacillin promotes a steady increase in the leaf water content and photosynthetic productivity in winter bread wheat, maize, annual sunflower, and soybean.

Integration of physiologically relevant photosynthetic energy flows into whole genome models of light-driven metabolism

Characterizing photosynthetic productivity is necessary to understand the ecological contributions and biotechnology potential of plants, algae, and cyanobacteria. Light capture efficiency and photophysiology have long been characterized by measurements of chlorophyll fluorescence dynamics. However, these investigations typically do not consider the metabolic network downstream of light harvesting. In contrast, genome-scale metabolic models capture species-specific metabolic capabilities but have yet to incorporate the rapid regulation of the light harvesting apparatus. Here we combine chlorophyll fluorescence parameters defining photosynthetic and non-photosynthetic yield of absorbed light energy with a metabolic model of the pennate diatom Phaeodactylum tricornutum. This integration increases the model predictive accuracy regarding growth rate, intracellular oxygen production and consumption, and metabolic pathway usage. Additionally, our simulations recapitulate the link between mitochondrial dissipation of photosynthetically-derived electrons and the redox state of the photosynthetic electron transport chain. We use this framework to assess engineering strategies for rerouting cellular resources toward bioproducts. Overall, we present a methodology for incorporating a common, informative data type into computational models of light-driven metabolism for characterization, monitoring and engineering of photosynthetic organisms.

The roles of photochemical and non-photochemical quenching in regulating photosynthesis depend on the phases of fluctuating light conditions

The induction and relaxation of photochemistry and non-photochemical quenching (NPQ) are not instantaneous and require time to respond to fluctuating environments. There is a lack of integrated understanding on how photochemistry and NPQ influence photosynthesis in fluctuating environments. We measured the induction and relaxation of chlorophyll a fluorescence and gas exchange in poplar and cotton at varying temperatures under saturating and fluctuating lights. When the light shifted from dark to high, the fraction of open reaction centers in photosystem II (qL) gradually increased while NPQ increased suddenly and then remained stable. Temperature significantly changed the response of qL but not that of NPQ during the dark to high light transition. Increased qL led to higher photosynthesis but their precise relationship was affected by NPQ and temperature. qL was significantly related to biochemical capacity. Thus, qL appears to be a strong indicator of the activation of carboxylase, leading to the similar dynamics between qL and photosynthesis. When the light shifted from high to low intensity, NPQ is still engaged at a high level, causing a stronger decline in photosynthesis. Our finding suggests that the dynamic effects of photochemistry and NPQ on photosynthesis depend on the phases of environmental fluctuations and interactive effects of light and temperature. Across the full spectra of light fluctuation, the slow induction of qL is a more important limiting factor than the slow relaxation of NPQ for photosynthesis in typical ranges of temperature for photosynthesis. The findings provided a new perspective to improve photosynthetic productivity with molecular biology under natural fluctuating environments.

Influence of the growth regulator “Regoplant” and microfertilizer “Ultramag Kombi” on photosynthetic activity of potatoes in the forest-steppe zone Republic of North Ossetia-Alania

The purpose of the work is to study the influence of the growth regulator “Regoplant” and microfertilizer “Ultramag Kombi” on the photosynthetic productivity of the potatoes of the Barna variety based on the results of field experiments in the forest-steppe zone Republic of North Ossetia-Alania. Methods. Studies on the tasks were carried out in 2018–2020. at the experimental site of the NCRIMFA branch of the VSC of RAS in the conditions of the forest-steppe zone Republic of North Ossetia-Alania according to generally accepted methods. The soil of the experimental plot is medium-power heavy loamy leached chernozem, lined with pebbles. Results. It is established, that biological products under identical soil and weather conditions assisted different progress of plants and approach of phases of vegetation. For all variants of the experiment, the number of stems increased by 0,3–0,7 pcs., the height of the stems of potato plants – by 3,8–4,9 cm in comparison with the control. An intense increase in the mass of tops occurred when using a tank mixture (growth regulator “Regoplant” (25 ml/ha) + microfertilizer “Ultramag Combi” (0,75 l/ha)) – by 74 g/bush, or 15.5 % compared with the control variant. During the growing season, the sum of the photosynthetic potential (FP) was 1,070 thousand m2 •days/ha in the control, and on average 1198–1406 thousand m2•days/ha in the experimental variants. The greatest accumulation of dry matter was noted when using a tank mixture – 917 g/m2. The maximum pure photosynthetic productivity was observed in experimental variant IV – 6,52 g/m2•day compared to the control option. Scientific novelty. For the first time in the forest-steppe zone Republic of North Ossetia-Alania the effect of the growth regulator “Regoplant” and microfertilizer “Ultramag Kombi” on photosynthetic activity of potatoes was studied. Practical significance. The studies carried out make it possible to recommend in potato production the use of a tank mixture of an effective growth regulator “Regoplant” at a dose of 25 ml/ha and microfertilizer “Ultramag Combi” at a dose of 0,75 l/ha, as an ecologically safe and low-cost agricultural method when processing vegetative plants, providing an increase in yield and quality of tubers.

Identification of the photosynthetic potential of spring oat varieties in the Lower Volga Re-gion

In 2017-2019, in the agro-climatic conditions of the Lower Volga region, the experience of studying spring oat varieties of different ecological and geographical origin from the world collection of VIR was laid, in order to determine their photosynthetic potential, and to identify varieties with high photosynthetic productivity. Over the years of research, the most adapted varieties of this crop were selected, their photosynthetic potential was determined, and the intensity of photosynthesis during the reproductive period of development (during the main growth phases) of spring oats in the conditions of the Lower Volga region was analyzed. On average, for 3 years of studying the collection varieties of spring oats in terms of the net productivity of photosynthesis, samples were noted: Myrtle, Athlete, Urs guara, Urs penca, p. 1. 3326 It was determined that with the growth of (FP) and (BPF), the yield of oats also increased. Since this indicator directly depends on the physiological and bioclimatic processes occurring in plants during ontogenesis. In the highest yield in 2017, it varied from 0.66 to 2.01 / ha. In 2018, the minimum yield values for all varieties were obtained from 0.51 t / ha of the Dookie 10 variety to 1.78 t / ha of the Mir variety. In the conditions of 2019, the yield variability by variety was from 0.60 t / ha to 1.94 t / ha. Thus, out of the 8 studied varieties, 5 were identified - p.1. 3326, Guara Urs, Urs foam, Athlete, Myrtle, as highly productive, and therefore the most resistant to abiotic stresses of the conditions of the Lower Volga region.

Quantitative resistance loci to southern rust mapped in a temperate maize diversity panel

Southern rust is a severe foliar disease of maize (Zea mays) resulting from infection with the obligate biotrophic fungus Puccinia polysora. This disease reduces photosynthetic productivity, which in turn reduces yields, with the greatest yield losses (up to 50%) associated with earlier onset infections. P. polysora urediniospores overwinter only in tropical and subtropical regions but cause outbreaks when environmental conditions favor initial infection. Increased temperatures and humidity during the growing season combined with an increased frequency of moderate winters are likely to increase the frequency of severe southern rust outbreaks in the US corn belt. In summer 2020, a severe outbreak of southern rust was observed in eastern Nebraska (NE), USA. We scored a replicated maize association panel planted in Lincoln, NE for disease severity and found that disease incidence and severity showed significant variation among maize genotypes. Genome-wide association studies identified four loci associated with significant quantitative variation in disease severity. These loci were associated with candidate genes with plausible links to quantitative disease resistance. A transcriptome-wide association study identified additional genes associated with disease severity. Together, these results indicate that substantial diversity in resistance to southern rust exists among current temperate-adapted maize germplasm, including several candidate loci that may explain the observed variation in resistance to southern rust.

Induced Volatile Emissions, Photosynthetic Characteristics, and Pigment Content in Juglans regia Leaves Infected with the Erineum-Forming Mite Aceria erinea

Persian walnut (Juglans regia L., Juglandaceae), one of the essential nut crops, is affected by different diseases, including mite attacks which result in gall and erineum formation. As the proportion of leaf area covered by mite galls or erineum is typically relatively low, the impact on tree photosynthetic productivity is often considered minor, and no pest control management is usually suggested. However, the effect of erineum-forming mites on walnut photosynthesis might be disproportionately larger than can be predicted from the leaf area impacted. In the present study, we studied how the foliage photosynthetic characteristics, pigment contents, and stress-induced volatile organic compounds scaled with the severity of infection varied from 0% (control trees) to 9.9%, by erineum-forming mite Aceria erinea in J. regia. Both leaf net assimilation rate (up to 75% reduction) and stomatal conductance (up to 82%) decreased disproportionately, increasing infection severity. Leaf total chlorophyll and β-carotene contents also decreased with infection severity, although the reduction was less than for photosynthetic characteristics (28% for chlorophyll and 25% for β-carotene). The infection induced significant emissions of green leaves volatiles ((Z)-3-hexenol, (E)-2-hexenal, (Z)-3-hexenyl acetate and 1-hexanol), monoterpenes and the homoterpene 3-(E)-4,8-dimethyl-1,3,7-nonatriene, and these emissions scaled positively with the percentage of leaf area infected. These results collectively indicate that erineum-forming mite infection of walnut leaves results in profound modifications in foliage physiological characteristics that can significantly impact tree photosynthetic productivity.

Selection-Enriched Genomic Loci (SEGL) Reveals Genetic Loci for Environmental Adaptation and Photosynthetic Productivity in Chlamydomonas reinhardtii.

This work demonstrates an approach to produce and select hybrid algal strains exhibiting increased photosynthetic productivity under multiple environmental conditions. This simultaneously addresses two major impediments to improving algal bioenergy production: 1) generating new genetic variants with improved performance; and 2) disentangling complex interactions between genetic and physiological factors contributing to these improvements. We pooled progeny generated from mating two environmental isolates of the green alga Chlamydomonas reinhardtii and cultured the pools under multiple environmental conditions. Strains from the outcompeting populations showed substantial (in some cases over 3 fold) increases in productivity over the parental lines under certain environments related to biomass production, including laboratory conditions as well as hyperoxia, fluctuating light, high salinity and high temperature. The results indicate that C. reinhardtii has remarkable, untapped, directed evolution capacity that may be harnessed using breeding and competition approaches. The populations were deep sequenced at multiple time points to identify “Selection- Enriched Genomic Loci” (SEGL) that accumulated in the populations, and thus likely confer increased fitness under the respective environmental conditions. With improved resolution, SEGL mapping can identify allelic combinations used for targeted breeding approaches, generating elite algal lines with multiple desirable traits, as well as to further understand the genetic and mechanistic bases of photosynthetic productivity.