Plant Productivity Research Articles

PhSPEAR1 Participates in Regulating the Branch Development of Petunia

Petunia hybrida is an economically important ornamental plant species. Branching in ornamental plants is closely associated with their ornamental traits, and branching is a significant agronomic trait in petunia, which shapes plant architecture and production cost. Although there are few studies regarding the involvement of the SPEAR genes in lateral branch development, they are known to regulate the development of plant organs. The PhSPEAR1 gene in petunia, an ortholog of Arabidopsis SPEAR1, was isolated for study. According to the results of real-time quantitative PCR (qRT-PCR), PhSPEAR1 was primarily expressed in the roots. The nucleus-specific fluorescence signal indicated that PhSPEAR1 was localized in the nucleus. An increase in PhSPEAR1 expression was induced by cytokinin or decapitation. Overexpression of PhSPEAR1 increased lateral branches in Arabidopsis. Based on our findings, PhSPEAR1 participates significantly in the regulation of branch number in petunia.

Elucidating the Role of SlBBX31 in Plant Growth and Heat-Stress Resistance in Tomato.

Heat stress inhibits plant growth and productivity. Among the main regulators, B-box zinc-finger (BBX) proteins are well-known for their contribution to plant photomorphogenesis and responses to abiotic stress. Our research pinpoints that SlBBX31, a BBX protein harboring a conserved B-box domain, serves as a suppressor of plant growth and heat tolerance in tomato (Solanum lycopersicum L.). Overexpressing (OE) SlBBX31 in tomato exhibited yellowing leaves due to notable reduction in chlorophyll content and net photosynthetic rate (Pn). Furthermore, the pollen viability of OE lines obviously decreased and fruit bearing was delayed. This not only affected the fruit setting rate and the number of plump seeds but also influenced the size of the fruit. These results indicate that SlBBX31 may be involved in the growth process of tomato, specifically in terms of photosynthesis, flowering, and the fruiting process. Conversely, under heat-stress treatment, SlBBX31 knockout (KO) plants displayed superior heat tolerance, evidenced by their improved membrane stability, heightened antioxidant enzyme activities, and reduced accumulation of reactive oxygen species (ROS). Further transcriptome analysis between OE lines and KO lines under heat stress revealed the impact of SlBBX31 on the expression of genes linked to photosynthesis, heat-stress signaling, ROS scavenging, and hormone regulation. These findings underscore the essential role of SlBBX31 in regulating tomato growth and heat-stress resistance and will provide valuable insights for improving heat-tolerant tomato varieties.

The B-box protein BBX13/COL15 suppresses photoperiodic flowering by attenuating the action of CONSTANS in Arabidopsis.

The optimal timing of transition from vegetative to floral reproductive phase is critical for plant productivity and agricultural yields. Light plays a decisive role in regulating this transition. The B-box (BBX) family of transcription factors regulates several light-mediated developmental processes in plants, including flowering. Here, we identify a previously uncharacterized group II BBX family member, BBX13/COL15, as a negative regulator of flowering under long-day conditions. BBX13 is primarily expressed in the leaf vasculature, buds, and flowers, showing a similar spatial expression pattern to the major flowering time regulators CO and FT. bbx13 mutants flower early, while BBX13-overexpressors exhibit delayed flowering under long days. Genetic analyses showed that BBX13 acts upstream to CO and FT and negatively regulates their expression. BBX13 physically interacts with CO and inhibits the CO-mediated transcriptional activation of FT. In addition, BBX13 directly binds to the CORE2 motif on the FT promoter, where CO also binds. Chromatin immunoprecipitation data indicates that BBX13 reduces the in vivo binding of CO on the FT promoter. Through luciferase assay, we found that BBX13 inhibits the CO-mediated transcriptional activation of FT. Together, these findings suggest that BBX13/COL15 represses flowering in Arabidopsis by attenuating the binding of CO on the FT promoter.

Effects of UV-B and UV-C Spectrum Supplementation on the Antioxidant Properties and Photosynthetic Activity of Lettuce Cultivars.

Indoor farming systems enable plant production in precisely controlled environments. However, implementing stable growth conditions and the absence of stress stimulants can weaken plants' defense responses and limit the accumulation of bioactive, health-beneficial phytochemicals. A potential solution is the controlled application of stressors, such as supplemental ultraviolet (UV) light. To this end, we analyzed the efficiency of short-term pre-harvest supplementation of the red-green-blue (RGB, LED) spectrum with ultraviolet B (UV-B) or C (UV-C) light to boost phytochemical synthesis. Additionally, given the biological harm of UV radiation due to high-energy photons, we monitored plants' photosynthetic activity during treatment and their morphology as well as sensory attributes after the treatment. Our analyses showed that UV-B radiation did not negatively impact photosynthetic activity while significantly increasing the overall antioxidant potential of lettuce through enhanced levels of secondary metabolites (total phenolics, flavonoids, anthocyanins), carotenoids, and ascorbic acid. On the contrary, UV-C radiation-induced anthocyanin accumulation in the green leaf cultivar significantly harmed the photosynthetic apparatus and limited plant growth. Taken together, we showed that short-term UV-B light supplementation is an efficient method for lettuce biofortification with healthy phytochemicals, while UV-C treatment is not recommended due to the negative impact on the quality (morphology, sensory properties) of the obtained leafy products. These results are crucial for understanding the potential of UV light supplementation for producing functional plants.

AI-Based Integrated Smart Process Sensor for Emulsion Control in Industrial Application

In industry, reliable process supervision is essential to ensure efficient, safe, and high-quality production. The droplet size distribution represents a critical quality attribute for emulsification processes and should be monitored. For emulsion characterization, image-based analysis methods are well-known but are often performed offline, leading to a time-delayed and error-prone process evaluation. The use of an integrated smart process sensor to characterize the emulsification process over time enables the real-time evaluation of the entire system. The presented integrated smart process sensor consists of an optical measurement flow cell built into a camera system. The overall system is placed in a bypass system of a production plant for emulsification processes. AI-based image evaluation is used in combination with a feature extraction method (You Only Look Once version 4 (YOLOv4) and Hough circle (HC)) to characterize the process over time. The sensor system is installed in the plant and tested with different cosmetic products. Various iteration, prototyping, and test steps for the final sensor design are performed prior to this in a laboratory test setup. The results indicate robust and accurate detection and determination of the droplet size in real time to improve product control and save time. For benchmarking the integrated smart process sensor, the results are compared with common analysis methods using offline samples.

Process Modelling of Integrated Bioethanol and Biogas Production from Organic Municipal Waste

One of the key guidelines in the European waste management policy is the diversion of waste from landfills, preventing harmful effects on human health and the environment and ensuring that economically valuable waste materials are efficiently recycled and reused through proper management. The organic fraction of municipal waste is abundant and contains biodegradable ingredients such lignocellulose, starch, lipids, pectin, and proteins, making it suitable for biotechnological production. Taking into account that a large amount of organic waste is disposed of in landfills, within this work, the amount of organic waste disposed of in the landfill in Banja Luka was considered. Four simulation model scenarios of the integrated production of bioethanol and biogas are generated, and their process and economic aspects are discussed. In the first two modelled scenarios, the pretreatment conditions (1% sulfuric acid and a different neutralization agent) were varied, while in the other two, the share of the amount of raw material used for the production of bioethanol, i.e., biogas, was varied (split factor: 10–90%). The modelled plant, with a designed capacity of 6 tons/h of organic waste, is a significant bioethanol producer, generating 5,000,000 L/year. The profitability indicators, when examined, revealed that dedicating a portion of the organic municipal waste input exclusively to biogas production leads to decreased process efficiency. Based on the modeled process parameters, ethanol’s minimum feasible selling price is $0.6616 per liter, while regarding the composition of organic municipal waste, carbohydrates have the most significant impact on the viability of the process. The developed model represents an excellent basis for further development of this integrated bioprocess in such a way that it can be modified with new process parameters or economic or ecological indicators and used at all levels of bioprocess design. Additionally, the obtained sustainable integrated bioethanol and biogas production plant models could support forthcoming steps in municipal waste management by providing reliable data on the conditions under which the integrated process of bioethanol and biogas production would take place, as well as the technical feasibility and economic profitability of such organic municipal waste utilization.

Nematode Diversity and Root-Knot Nematode Management Approaches for Sustainable Mulberry Production

Mulberry ecosystems are beset by the clandestine menace of nematodes, precipitating devastating consequences on plant productivity. This review highlights the importance of nematode diversity in mulberry ecosystems and explores various eco-friendly and sustainable approaches for managing the root-knot nematode, Meloidogyne incognita involving cultural, biological and host resistance methods. Various eco-friendly management strategies viz., cultural approaches like summer deep ploughing, mulching and trap crops; biological methods like bio-agents and plant extracts; and resistant varieties against the root-knot nematode infecting mulberry are reviewed and discussed providing an impetus for integrating multiple approaches for effective and sustainable root-knot nematode management.

Persistent legacy effects on soil metagenomes facilitate plant adaptive responses to drought.

Both chronic and acute drought alter the composition and physiology of soil microbiomes, with implications for globally important processes including carbon cycling and plant productivity. When water is scarce, selection favors microbes with thicker peptidoglycan cell walls, sporulation ability, and constitutive osmolyte production (Schimel, Balser, and Wallenstein 2007)-but also the ability to degrade complex plant-derived polysaccharides, suggesting that the success of plants and microbes during drought are inextricably linked. However, communities vary enormously in their drought responses and subsequent interactions with plants. Hypothesized causes of this variation in drought resilience include soil texture, soil chemistry, and historical precipitation patterns that shaped the starting communities and their constituent species (Evans, Allison, and Hawkes 2022). Currently, the physiological and molecular mechanisms of microbial drought responses and microbe-dependent plant drought responses in diverse natural soils are largely unknown (de Vries et al. 2023). Here, we identify numerous microbial taxa, genes, and functions that characterize soil microbiomes with legacies of chronic water limitation. Soil microbiota from historically dry climates buffered plants from the negative effects of subsequent acute drought, but only for a wild grass species native to the same region, and not for domesticated maize. In particular, microbiota with a legacy of chronic water limitation altered the expression of a small subset of host genes in crown roots, which mediated the effect of acute drought on transpiration and intrinsic water use efficiency. Our results reveal how long-term exposure to water stress alters soil microbial communities at the metagenomic level, and demonstrate the resulting "legacy effects" on neighboring plants in unprecedented molecular and physiological detail.

Drought Stress Effects and Ways for Improving Drought Tolerance in Impatiens walleriana Hook.f.—A Review

Drought is one of the main abiotic stresses affecting plant growth and development. Reduced plant yield and quality are primarily caused by the reductions in photosynthesis, mineral uptake, metabolic disorders, damages from the increased production of reactive oxygen species, and many other disruptions. Plants utilize drought resistance mechanisms as a defense strategy, and the systems’ activation is dependent upon several factors, including plant genotype, onthogenesis phase, drought intensity and duration, and the season in which the drought occurs. Impatiens walleriana is a worldwide popular flowering plant recognized for its vibrant flower colors, and is an indispensable plant in pots, gardens and other public areas. It prefers well-draining, moisturized soil, and does not perform well in overly dry or waterlogged conditions. Consequently, inadequate water supply is a common problem for this plant during production, transportation, and market placement, which has a substantial impact on plant performance overall. This review article outlines certain features of morphological, physiological, and molecular alterations induced by drought in ornamental, drought-sensitive plant species I. walleriana, as well as research carried out to date with the aim to improve the drought tolerance. Stress proteins aquaporins and dehydrins, whose molecular structure was described for the first time in this plant species, are highlighted specifically for their role in drought stress. Furthermore, the effective improvement of drought tolerance in I. walleriana by exogenous application of Plant Growth Regulators and Plant Growth-Promoting Bacteria is discussed in detail. Finally, this review can provide valuable insights for improving plant resilience and productivity in the face of water scarcity, which is critical for sustainable agriculture and horticulture.

Integrated Analysis of Metabolomics, Flavoromics, and Transcriptomics for Evaluating New Varieties of Amomum villosum Lour.

Amomum villosum Lour. (A. villosum) is the original plant of the medicinal and culinary spice Amomi Fructus (Sharen) and is an important economic crop in the Lingnan region of China. During the cultivation and production of A. villosum, prolonged reliance on single asexual reproduction has exacerbated the degradation of its varieties, leading to inconsistent yields and quality. Building upon earlier cultivar selection efforts, this study provides a comprehensive evaluation of two newly bred A. villosum varieties (A11 and A12) from perspectives including plant traits, product characteristics, active ingredients, and multi-omics analysis. It was found that A12 plants display enhanced robustness, more aromatic fruits, higher yields, and elevated levels of bornyl acetate, A11 shows the advantage of a high camphor content, and the different metabolites and differentially expressed genes of the two varieties were significantly enriched in multiple metabolic pathways. Additionally, A12 contained more terpenoids and substances with aromatic odors such as sweet, fruity, floral, and green. Furthermore, a key gene (Wv_032842) regulating the acetylation of bornyl was discovered, and its significantly higher expression, in A12. In conclusion, this study has a guiding significance for the evaluation of germplasm resources and the breeding of excellent varieties of A. villosum.

Genomic insights and biocontrol potential of ten bacterial strains from the tomato core microbiome.

Despite their adverse environmental effects, modern agriculture relies heavily on agrochemicals to manage diseases and pests and enhance plant growth and productivity. Some of these functions could instead be fulfilled by endophytes from the plant microbiota, which have diverse activities beneficial for plant growth and health. We therefore used a microbiome-guided top-down approach to select ten bacterial strains from different taxa in the core microbiome of tomato plants in the production chain for evaluation as potential bioinoculants. High-quality genomes for each strain were obtained using Oxford Nanopore long-read and Illumina short-read sequencing, enabling the dissection of their genetic makeup to identify phyto-beneficial traits. Bacterial strains included both taxa commonly used as biofertilizers and biocontrol agents (i.e. Pseudomonas and Bacillus) as well as the less studied genera Leclercia, Chryseobacterium, Glutamicibacter, and Paenarthorbacter. When inoculated in the tomato rhizosphere, these strains promoted plant growth and reduced the severity of Fusarium Crown and Root Rot and Bacterial Spot infections. Genome analysis yielded a comprehensive inventory of genes from each strain related to processes including colonization, biofertilization, phytohormones, and plant signaling. Traits directly relevant to fertilization including phosphate solubilization and acquisition of nitrogen and iron were also identified. Moreover, the strains carried several functional genes putatively involved in abiotic stress alleviation and biotic stress management, traits that indirectly foster plant health and growth. This study employs a top-down approach to identify new plant growth-promoting rhizobacteria (PGPRs), offering an alternative to the conventional bottom-up strategy. This method goes beyond the traditional screening of the strains and thus can expand the range of potential bioinoculants available for market application, paving the way to the use of new still underexplored genera.

Enhancing environmental and economic benefits of constructed wetlands through plant recovery: A life cycle perspective

Plant recovery plays a vital role in reclaiming bioresources from constructed wetland wastewater treatment systems. A comprehensive understanding of the environmental impacts and economic benefits associated with various wetland plant resourcing methods is critical for advancing both plant resource recovery and the application of wetlands in wastewater treatment. In this study, life cycle assessment was employed to evaluate the environmental impacts and costs of seven wetland plant recovery methods. In addition, the potential benefits of extending plant resource recovery within system boundaries were explored to enhance the overall advantages of constructed wetlands for wastewater treatment. The use of wetland plants for biofertilizer production had the lowest environmental impact (−8.52E-03), whereas the use of wetland plants for biochar production was the most cost-effective approach (−0.80€/kg). The introduction of a plant resource recovery component could significantly reduce the environmental impacts of constructed wetland wastewater treatment systems. The environmental impacts and costs of constructed wetland wastewater treatment systems that incorporate plant resource recovery into the system boundary are better than activated sludge methods and highly efficient algal ponds, except for the global warming potential (GWP). The use of plants for biofertilizer production could cut the environmental impacts of constructed wetland wastewater treatment systems by up to 85 % and the costs by 65 %, making it the most suitable method of plant use. Additionally, prioritizing the reduction of greenhouse gas emissions from constructed wetlands should be a primary optimization goal. The findings of this study provide valuable support for the implementation of wetland plant resourcing in constructed wetland wastewater treatment systems.

Studies on the Response of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) to Multicolour Light System

Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) commonly known as rust red flour beetle was a universal pest of stored produce with an extensive feeding diversity. The management of T. castaneum in field conditions was through fumigation and spraying of suitable insecticides. Even though many plant products were found effective against pests in invitro conditions, they could not be mixed with the stored produce for fear of losing the table quality. Physical forces seemed to be good alternatives to chemical treatment as far as stored grain pests were concerned. The use of gamma and UV radiations, microwaves and ultrasonic sound waves against T. castaneum and other stored grain pests had been tried by many authors. The objectives of this study were to check the adult beetles and final instar grubs of T. castaneum to different colours of light and it showedpreference for clear tungsten (white) light, while they were averse to red coloured light. This trend was explicit even after the entrainment of beetles to red colour light for further generations. Based on these results it could be presumed that T. castaneum adults preferred to move away from red coloured light. By changing the colour of bright light to dark lighting in warehouses, it could be possible to manage T. castaneum in small measure. Total eradication of stored product pests like T. castaneum was at least possibility and the selection of a proper management system could help to solve the stored produce pest problem to a greater magnitude.

The use of breeding indices when estimating winter durum wheat productivity

Special attention is currently being paid to the role of genetic and physiological systems that contribute to improving productivity and can be estimated in the form of indices.The current study was carried out in the southern part of the Rostov region at the experimental plots of the FSBSI «ARC “Donskoy”» in 2021–2023 aimed at studying the breeding indices of promising winter durum wheat varieties and lines and their effect on productivity. There have been considered such breeding indices as Mexican, Canadian, ear potential, plant productivity and prospects.Considering the Mexican index, which reflects the capabilities of the mechanical tissues of straw, there have been identified 8 samples Lakomka, Khrizolit, Pridonie, 536/19, 971/19, 1147/19, 1174/19, 1037/17 with high values (0.020–0.023 g/cm) in comparison with the standard variety Kristella. The Canadian index ranged from 4.93 pcs./cm for the standard variety to 7.13 pcs./cm for the variety Khrizolit. According to ear potential index, the varieties and lines varied from 0.082 cm/cm for the standard variety Kristella to 0.097 cm/cm for the line 536/19. The index of prospects shows the ability of straw to transport plastic substances into grain. According to this indicator, the studied samples ranged from 42.7% (the variety Grafit) to 55.4% (the line 536/19). According to the classification, the winter durum wheat varieties and lines varied from low (IPR < 7.0; grain weight per ear was up to 1.5 g) to high productivity (IPR > 11.0; grain weight per ear was more than 2.0 g). In these studies, there was a significant correlation between yield and the ear potential index (r = 0.57 ± 0.22).

Determination of Factors Affecting the Cumin Production Decision of Agricultural Enterprises: The Case of Konya Province

Turkey has vast agricultural lands and diverse climatic conditions, and different plant species can be cultivated. Especially, Konya province, located in the Central Anatolia Region, is an important agricultural centre in Turkey. Konya province, which has a polyculture production pattern, stands out in the production of medicinal and aromatic plants due to its favourable climatic conditions and soil structure. In Turkey, 26.33% of cumin, which is among the medicinal and aromatic plants, is produced in Konya province. This study aims to determine the factors affecting cumin production. For this purpose, 65 cumin producers determined by proportional sampling method were interviewed. The data obtained through these interviews were analysed by using the Analytic Hierarchy Process (AHP) method to determine the weights of the criteria affecting the cumin production decision of the agricultural enterprises. In the process of determining the criteria influencing the cumin production decision, the opinions of subject experts working in universities, public institutions and organizations and producers were taken. Among the criteria determined as yield, price, labour requirement, water requirement, ease of marketing, mechanisation, input costs, cultivation knowledge, soil structure and subsidies, the most important criterion was found to be price with 28.11%. Price criterion is followed by input cost 22.57%, water requirement 12.13%, yield 8.71%, cultivation knowledge 8.43%, subsidies 6.82%, ease of marketing 4.74%, soil structure 3.63%, mechanisation 2.54% and labour requirement 2.25%. It is thought that the solution of the mechanisation problem will make a significant contribution to cumin production as it will reduce the need for labour force.

Comparative Analyses of Green Plantlet Regeneration in Barley (Hordeum vulgare L.) Anther Culture

The efficient doubled haploid (DH) plant production methods play a key role in accelerating the breeding of new varieties and hybrids in cultivated plants. Consequently, DH plant production methods are continuously improving for barley (Hordeum vulgare L.) breeding and research programs. Two plant regeneration (FHGR and K4NB) and three rooting media (MSr, N6I and ½N6I + Ca) were compared with four F1 barley cross-combinations to clarify the effect of medium on the regeneration of green and albino plantlets and acclimatization. The plant regeneration efficiency was higher using K4NB medium (74.53 green plantlets/100 anthers and 30.85 albino/100 anthers) compared to FHGR (55.77 green plantlets/100anthers and 21.32 albino/100 anthers). The percentage of acclimatization was highest when the K4NB regeneration medium was combined with the MSr rooting medium. Altogether, 61.83% of the anther culture-derived plantlets of 8 cross-combinations acclimatized to the greenhouse conditions, and 1403 acclimatized plantlets were produced from the F1 cross-combinations. Haploid (22.52%), diploid (69.37%) and tetraploid (8.11%) plantlets were identified among the 111 tested green plantlets by flow cytometric analyses. The tetraploid lines can be explored to offer new scopes for future barley research and breeding directions. Nearly one thousand DH plants have been integrated into our barley breeding program.

Techno-Economic and CO2 Emissions Analysis of the Molten Carbonate Fuel Cell Integration in a DRI Production Plant for the Decarbonization of the Steel Industry

Developing low-carbon systems for the steel industry is increasingly considered necessary for contributing to the targets of CO2 emission reduction requested by modern environmental policies. This work focuses on a process for decarbonizing primary steel production by integrating an MCFC system in a DRI production plant based on the Energiron ZR process configuration. An MCFC system can be used to remove CO2 from the flue gases while producing electricity and reducing the net electric consumption of the DRI plant. The reference scenario, the carbon capture case, and an additional hydrogen-based H-DRI system using high temperature electrolysis are simulated using Aspen Plus to evaluate and compare their energy and environmental performance. The results show that even considering the additional power consumption of the complete carbon capture and separation system, the overall electrical consumption of the carbon capture case is decreased by 78 % and the direct CO2 emissions by up to 95 %. Furthermore, reduced electricity consumption reduces scope 2 emissions, increasing the sustainability of the process in the steel industry. On the other hand, the H-DRI case decreases primary energy consumption by 24 % but significantly increase electricity requirement; thus, it represents a better future solution when cheap low-CO2 electricity is available. The plant configurations are compared economically by retrieving investment and operational costs from the open literature to estimate the levelized cost of DRI and the cost of CO2 avoided. The results show that installing the MCFC and the anode purification system increases the investment costs by 38 % compared to a conventional plant. However, the lower electricity consumption and carbon tax expenditure lead to a comparable final DRI product cost. Contrarily, due to the electrolyzer high investment and operational costs, the additional marginal DRI cost of the H-DRI case is 31 % higher. Finally, the sensitivity analysis on the main variable costs shows that, independently from the electricity and natural gas price, the carbon capture case is economically competitive to the reference scenario, considering a carbon tax of 60 €/tCO2 or higher. At the same time, the H-DRI solution requires low electricity prices to be competitive. In conclusion, even if, in the long term, the objective is to completely replace the use of fossil fuels with renewable energy, in the short term, the implementation of MCFC in the DRI plant can significantly reduce the environmental impact of primary steel production without significant economic penalization.

Tropospheric ozone pollution increases the sensitivity of plant production to vapor pressure deficit across diverse ecosystems in the Northern Hemisphere

Tropospheric ozone (O3) pollution often accompanies droughts and heatwaves, which could collectively reduce plant productivity. Previous research suggested that O3 pollution can alter plant responses to drought by interfering with stomatal closure while drought can reduce stomatal conductance and provide protection against O3 stress. However, the interactions between O3 pollution and drought stress remain poorly understood at ecosystem scales with diverse plant functional types. To address this research gap, we used 10-year (2012−2021) satellite near-infrared reflectance of vegetation (NIRv) observations, reanalysis data of vapor pressure deficit (VPD), soil moisture (SM), and air temperature (Ta), along with O3 measurements and reanalysis data across the Northern Hemisphere to statistically disentangle the interconnections between NIRv, VPD, SM, and Ta under varying O3 levels. We found that high O3 concentrations significantly exacerbate the sensitivity of NIRv to VPD while have no notable impacts on the sensitivity of NIRv to Ta or SM for all plant functional types, indicating an enhanced combined impact of VPD and O3 on plants. Specifically, the sensitivity of NIRv to VPD increased by >75 % when O3 anomalies increased from the lowest 10 to the highest 10 percentiles across diverse plant functional types. This is likely because long-term exposure to high O3 concentrations can inhibit stomatal closure and photosynthetic enzyme activities, resulting in reduced water use efficiency and photosynthetic efficiency. This study highlights the need to consider O3 in understanding plant responses to climate factors and that O3 can alter plant responses to VPD independently of Ta and SM.

EARLY NODULIN93 acts via cytochrome c oxidase to alter respiratory ATP production and root growth in plants.

EARLY NODULIN 93 (ENOD93) has been genetically associated with biological nitrogen fixation in legumes and nitrogen use efficiency in cereals, but its precise function is unknown. We show that hidden Markov models define ENOD93 as a homolog of the N-terminal domain of RESPIRATORY SUPERCOMPLEX FACTOR 2 (RCF2). RCF2 regulates cytochrome oxidase (CIV), influencing the generation of a mitochondrial proton motive force in yeast (Saccharomyces cerevisiae). Knockout of ENOD93 in Arabidopsis (Arabidopsis thaliana) causes a short root phenotype and early flowering. ENOD93 is associated with a protein complex the size of CIV in mitochondria, but neither CIV abundance nor its activity changed in ruptured organelles of enod93. However, a progressive loss of ADP-dependent respiration rate was observed in intact enod93 mitochondria, which could be recovered in complemented lines. Mitochondrial membrane potential was higher in enod93 in a CIV-dependent manner, but ATP synthesis and ADP depletion rates progressively decreased. The respiration rate of whole enod93 seedlings was elevated, and root ADP content was nearly double that in wild type without a change in ATP content. We propose that ENOD93 and HYPOXIA-INDUCED GENE DOMAIN 2 (HIGD2) are the functional equivalent of yeast RCF2 but have remained undiscovered in many eukaryotic lineages because they are encoded by two distinct genes.

Geographic bioprospection of maize rhizoplane-associated bacteria for consortia construction and impact on plant growth and nutrient uptake under low P availability

Application of beneficial microbial consortia for improving plant growth and productivity is considered a major approach to attain sustainable crop production. The construction of plant growth promoting (PGP) bacterial consortia (BC) is reliant on the design of microbial systems based on tuned inter-species interactions with known ecological functions. In this study, maize rhizoplane-associated bacteria were isolated from seven distinct agricultural regions in Morocco. Taxonomic and functional (related to phosphorus “P” use) diversity of 107 rhizoplane bacterial isolates were explored to construct BC while preserving the diversity of the niche they were isolated from. Thirty-six BC were generated, including 28 intra-zone consortia, seven intra-region consortia and one global BC. Quantification of three functional genes: glucose dehydrogenase encoding gene (gcd), pyrroloquinoline quinone (pqqC), and alkaline phosphatase encoding gene (phoD), involved in P cycling, confirmed the presence of gcd in nineteen BC, pqqC in eight BC and phoD in only one BC. In vitro functional characterization revealed that all BC were able to solubilize/mineralize P (50–88 ppm) through the production of organic acids and acid phosphatase (25 – 280 nmol.h−1). Assessment of above- and below-ground parameters of 45-day old maize plants identified five potential niche-constructed “intra-zone” BC (BC-6, -11, -12, -14, and -18) notably in terms of plant biomass, shoot nutrient (N, P, K) uptake and induced root morphological and physiological traits. These BC were associated with increased rhizosphere available P (80 ppm) and decreased microbial biomass P (17 ppm) while the remaining BC significantly increased microbial biomass P (30 ppm) at the expense of a decreased rhizosphere available P (35 ppm) with no significant effect on plant nutrient uptake and biomass. These findings demonstrate that intra-zone BC constructed from the same niche outperformed the intra- and inter-region consortia, supporting the niche-conservatism approach to construct P-efficient BC. This study lays a technical foundation for the construction of synthetic microbial consortia for plant growth and nutrient acquisition, through the optimization of inter-species bacterial interactions.