Photosynthetic Capability Research Articles

Biotechnological Advances in Vanillin Production: From Natural Vanilla to Metabolic Engineering Platforms

Vanillin, an aromatic aldehyde, is one of the most popular flavors worldwide, extensively used in the food, cosmetics, pharmaceutical, and agrochemical industries. Despite its widespread use, less than 1% of the total vanillin production is natural, with the majority being synthesized chemically. While chemical synthesis can help to meet the growing demand for vanillin, a strong market trend has rapidly developed for products created from natural ingredients, including natural vanillin. Given the labor-intensive process of extracting vanillin from vanilla pods, there is a critical need for new metabolic engineering platforms to support the biotechnological production of nature-identical vanillin. This review highlights the significance of vanillin in various markets, its diverse applications, and the current state of bio-engineered production using both prokaryotic and eukaryotic biological systems. Although recent advancements have demonstrated successful vanillin production through biocatalytic approaches, our focus was to provide a current and innovative overview of vanillin bioengineering across various host systems with special consideration placed on microalgae, which are emerging as promising platforms for vanillin production through metabolic engineering. The use of these systems to support the biotechnological production of vanillin, while leveraging the photosynthetic capabilities of microalgae to capture CO2 and convert it into biomass, can significantly reduce the overall carbon footprint.

Marine Cyanobacteria-Assisted Metallic Nanoparticles: A Review on Anticancer Activity and Mechanism of Action

Marine cyanobacteria, known as blue-green algae, are ancient microorganisms with oxygenic photosynthetic capability. They have diverse biochemical capabilities, including production of bioactive secondary metabolites. We studied the anti-cancer properties of cyanobacterial nanoparticles through various literatures. We focused on mechanistic studies of the anticancer properties of metal and metal oxide nanoparticles. Our research gathered information from patent databases, conference abstracts, publications, and news releases, as well as PubMed searches for peer-reviewed articles and Google searches for gray literature. We used strict criteria for selecting sources, and our search ended on 30 October, 2022. Metal nanoparticles, such as gold and silver, have unique physicochemical properties, making them suitable for therapeutic applications in nanomedicine. Cyanobacteria-assisted synthesis is environmentally sustainable and results in mild reaction conditions and minimal toxic byproducts. These nanoparticles have potential applications in cancer therapy, including drug delivery systems and targeted therapies. This study further explored the mechanistic aspects of cancer development, emphasising the role of genetic mutations, uncontrolled cell growth, and metastasis. Cyanobacterial biogenic nanoparticles demonstrate cytotoxicity, apoptosis induction, ROS generation, and immunomodulation, contributing to their anticancer efficacy. Additionally, these nanoparticles serve as carriers for drug delivery, enabling the targeted and controlled release of therapeutic agents. The review ends by emphasising how crucial it is to comprehend how cyanobacteria extract assists metallic nanoparticles. Cyanobacterial biogenic synthesis using microemulsion synthesis methods, UV-initiated photoreduction, microwave assistance, and polymer/polysaccharide-mediated approaches was investigated. The field of marine cyanobacteria, biogenic metal nanoparticles, and their anticancer potential is dynamic and has important implications for future therapeutic approaches.

Foliar application of Verticillium dahliae Aspf2‐like protein improved the heat tolerance of creeping bentgrass by regulating photosynthetic and antioxidant capabilities

AbstractContinuous high ambient temperature in hot summer months leads to a sharp decline in turf quality of cool‐season turfgrass. Verticillium dahliae Aspf2‐like protein (VDAL) is a secretory protein of V. dahliae that can improve crop yield and resistance to disease, but its role in improving heat tolerance of cool‐season turfgrass has not been reported so far. The objectives of this study were to explore the effect and mechanism of foliar application of VDAL on improving heat tolerance in cool‐season creeping bentgrass (Agrostis stolonifera) and to further examine the advantage of foliar spraying with VDAL in mitigating summer bentgrass decline (SBD) in the US transition zone or other regions with similar climate. The results demonstrated that the optimal dose of VDAL for improving thermotolerance of two creeping bentgrass cultivars (heat‐tolerant 13 M and heat‐sensitive Seaside II) was screened as 0.2 g L−1 based on analyses of chlorophyll content, photochemical efficiency of PSII, and cell membrane stability under controlled heat stress conditions. Foliar application of the optimal dose of VDAL significantly restricted chlorophyll loss under heat stress and also alleviated heat‐induced declines in net photosynthetic rate, transpiration rate, stomatal conductance, and water use efficiency. In addition, overaccumulations of superoxide anion radical and hydrogen peroxide could be significantly alleviated by the exogenous application of VDAL through improving the activity of antioxidant enzymes including superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase in two cultivars. A further 2‐year field trial showed that foliar application of VDAL improved turf quality, chlorophyll content, photochemical efficiency, and cell membrane stability of the two cultivars during hot summer months of 2022 and 2023. The results indicate that the appropriate dose of VDAL plays a positive role in photosynthetic performance and antioxidant capacity for thermotolerance of creeping bentgrass, and foliar application of VDAL could be considered an effective approach for alleviating SBD.

Japonolirion osense, a close relative of the mycoheterotrophic genus Petrosavia, exhibits complete autotrophic capabilities

The plant kingdom exhibits a diversity of nutritional strategies, extending beyond complete autotrophy. In addition to full mycoheterotrophs and holoparasites, it is now recognized that a greater number of green plants than previously assumed use partly of fungal carbon. These are termed partial mycoheterotrophs or mixotrophs. Notably, some species exhibit a dependency on fungi exclusively during early ontogenetic stages, referred to as initial mycoheterotrophy. Japonolirion osense, a rare plant thriving in serpentinite soils, emerges as a potential candidate for initial mycoheterotrophy or mixotrophy. Several factors support this hypothesis, including its diminutive sizes of shoot and and seeds, the establishment of Paris-type arbuscular mycorrhizal associations, its placement within the Petrosaviales—largely composed of fully mycoheterotrophic species—and its ability to face the challenging conditions of its environment. To explore these possibilities, our study adopts a multidisciplinary approach, encompassing stable isotope abundance analyses, in vitro experiments, anatomical analyses, and comparative plastome analyses. Our study aims to (1) determine whether J. osense relies on fungal carbon during germination, indicating initial mycoheterotrophy, (2) determine if it employs a dual carbon acquisition strategy as an adult, and (3) investigate potential genomic reductions in photosynthetic capabilities. Contrary to expectations, our comprehensive findings strongly indicate that J. osense maintains complete autotrophy throughout its life cycle. This underscores the contrasting nutritional strategies evolved by species within the Petrosaviales.

Improving global gross primary productivity estimation using two-leaf light use efficiency model by considering various environmental factors via machine learning

Distinguishing gross primary productivity (GPP) into sunlit (GPPsu) and shaded (GPPsh) components is critical for understanding the carbon exchange between the atmosphere and terrestrial ecosystems under climate change. Recently, the two-leaf light use efficiency (TL-LUE) model has proven effective for simulating global GPPsu and GPPsh. However, no known physical method has focused on integrating the overall constraint of intricate environmental factors on photosynthetic capability, and seasonal differences in the foliage clumping index (CI), which most likely influences GPP estimation in LUE models. Here, we propose the TL-CRF model, which uses the random forest technique to integrate various environmental variables, particularly for terrestrial water storage (TWS), into the TL-LUE model. Moreover, we consider seasonal differences in CI at a global scale. Based on 267 global eddy covariance flux sites, we explored the functional response of vegetation photosynthesis to key environmental factors, and trained and evaluated the TL-CRF model. The TL-CRF model was then used to simulate global eight-day GPP, GPPsu, and GPPsh from 2002 to 2020. The results show that the relative prediction error of environmental stress factors on the maximum LUE is reduced by approximately 52 % when these factors are integrated via the RF model. Thus the accuracy of global GPP estimation (R2 = 0.87, RMSE = 0.94 g C m−2 d−1, MAE = 0.61 g C m−2 d−1) in the TL-CRF model is greater than that (R2 = 0.76, RMSE = 2.18 g C m−2 d−1, MAE = 1.50 g C m−2 d−1) in the TL-LUE model, although this accuracy awaits further investigation among the released GPP products. TWS exerts the greatest control over ecosystem photosynthesis intensity, making it a suitable water indicator. Furthermore, the results confirm an optimal minimum air temperature for photosynthesis. Overall, these findings indicate a promising method for producing a new global GPP dataset, advancing our understanding of the dynamics and interactions between photosynthesis and environmental factors.

High-quality genome of a novel Thermosynechococcaceae species from Namibia and characterization of its protein expression patterns at elevated temperatures.

Thermophilic cyanobacteria thrive in extreme environments, making their thermoresistant enzymes valuable for industrial applications. Common habitats include hot springs, which act as evolutionary accelerators for speciation due to geographical isolation. The family Thermosynechococcaceae comprises thermophilic cyanobacteria known for their ability to thrive in high-temperature environments. These bacteria are notable for their photosynthetic capabilities, significantly contributing to primary production in extreme habitats. Members of Thermosynechococcaceae exhibit unique adaptations that allow them to perform photosynthesis efficiently at elevated temperatures, making them subjects of interest for studies on microbial ecology, evolution, and potential biotechnological applications. In this study, the genome of a thermophilic cyanobacterium, isolated from a hot spring near Okahandja in Namibia, was sequenced using a PacBio Sequel IIe long-read platform. Cultivations were performed at elevated temperatures of 40, 50, and 55°C, followed by proteome analyses based on the annotated genome. Phylogenetic investigations, informed by the 16S rRNA gene and aligned nucleotide identity (ANI), suggest that the novel cyanobacterium is a member of the family Thermosynechococcaceae. Furthermore, the new species was assigned to a separate branch, potentially representing a novel genus. Whole-genome alignments supported this finding, revealing few conserved regions and multiple genetic rearrangement events. Additionally, 129 proteins were identified as differentially expressed in a temperature-dependent manner. The results of this study broaden our understanding of cyanobacterial adaptation to extreme environments, providing a novel high-quality genome of Thermosynechococcaceae cyanobacterium sp. Okahandja and several promising candidate proteins for expression and characterization studies.

Diversity and specificity of molecular functions in cyanobacterial symbionts

Cyanobacteria are globally occurring photosynthetic bacteria notable for their contribution to primary production and production of toxins which have detrimental ecosystem impacts. Furthermore, cyanobacteria can form mutualistic symbiotic relationships with a diverse set of eukaryotes, including land plants, aquatic plankton and fungi. Nevertheless, not all cyanobacteria are found in symbiotic associations suggesting symbiotic cyanobacteria have evolved specializations that facilitate host-interactions. Photosynthetic capabilities, nitrogen fixation, and the production of complex biochemicals are key functions provided by host-associated cyanobacterial symbionts. To explore if additional specializations are associated with such lifestyles in cyanobacteria, we have conducted comparative phylogenomics of molecular functions and of biosynthetic gene clusters (BGCs) in 984 cyanobacterial genomes. Cyanobacteria with host-associated and symbiotic lifestyles were concentrated in the family Nostocaceae, where eight monophyletic clades correspond to specific host taxa. In agreement with previous studies, symbionts are likely to provide fixed nitrogen to their eukaryotic partners, through multiple different nitrogen fixation pathways. Additionally, our analyses identified chitin metabolising pathways in cyanobacteria associated with specific host groups, while obligate symbionts had fewer BGCs. The conservation of molecular functions and BGCs between closely related symbiotic and free-living cyanobacteria suggests the potential for additional cyanobacteria to form symbiotic relationships than is currently known.

Integrated Benefits to Agriculture with Trichoderma and Other Endophytic or Root-Associated Microbes.

The use of endophytic microbes is increasing in commercial agriculture. This review will begin with a strain selection. Most strains will not function well, so only a few provide adequate performance. It will also describe the endophyte-plant relationship and the fungi and bacteria involved. Their abilities to alleviate biotic (diseases and pests) and abiotic stresses (drought, salt, and flooding) to remediate pollution and increase photosynthetic capabilities will be described. Their mechanisms of action will be elucidated. These frequently result in increased plant yields. Finally, methods and practices for formulation and commercial use will be described.

A photo-driven bioanode based on MXene-decorated graphene

We fabricated a photo-driven bioanode on laser-induced graphene (LIG) using a facile one-step laser-scribed technique. Nb4C3Tx MXene was decorated on the LIG surface to induce a high surface area for immobilizing the photocatalyst. The thylakoid membrane extracted from Spinacia oleracea utilizes its intrinsic photosynthetic and catalytic capability for efficient energy conversion. A platinum-based gas diffusion electrode is used as the cathode material, allowing for charge transfer and oxygen reduction to produce water. The bioelectrochemical activities of the as-fabricated thylakoid-based biofuel cells were investigated. Upon illumination, the assembled biofuel cell exhibited an open circuit voltage of 0.45 V, a maximum photocurrent density of 68.69 µA/cm2, and a power density of 7.24 µW/cm2. The unique features of thylakoid membranes, Nb4C3Tx MXene, and the LIG substrate play a critical role in producing high-performance photo-biofuel cells. Our approach presents a promising strategy for harnessing the biochemical energy of plants to generate bioelectricity.

Mineralogical and microbial characterization of alkali hot spring microbial mats and deposits in Pong Dueat Pa Pae hot spring, Northern Thailand.

Hot spring environments encompass broad physicochemical ranges, in which temperature and pH account for crucial factors shaping hot spring microbial community and diversity. However, the presence of photosynthetic microbial mats adjacent to boiling hot spring vents, where fluid temperatures extend beyond photosynthetic capability, questions the microbial profiles and the actual temperatures of such adjacent mats. Therefore, this study aims to characterize thermophilic microbial communities at Pong Dueat Pa Pae hot spring using next-generation sequencing, including investigating hot spring mineralogy. Results suggest that Pong Dueat Pa Pae hot spring precipitates comprise mainly silica which also acts as the main preservative medium for microbial permineralization. Molecular results revealed the presence of cyanobacterial and Chloroflexi species in the thick, orange and green subaerial mats surrounding the vents, suggesting the mats would be at least 30°C cooler than source vents despite constantly receiving geyser splashes. Bacterial abundance was considerably higher than archaeal (97.9% versus 2.1%). Cyanobacterial (mainly Synechococcus and Leptolygbya) and Chloroflexi species (mainly Roseiflexus) accounted for almost half (40.04%) of the bacterial community, while DHVEG-6 and Thaumarchaeota comprised dominant members (> 90%) of the archaeal fraction. This study updates and provides insights into thermophilic microbial community composition and mineralogy of hot springs in Thailand.

Different Phenotypic, Photosynthetic, and Physiological Responses to Flooding between Q. nuttallii and Q. palustris.

Flooding stress is an increasingly serious problem in wetlands, often affecting large areas of crops and timber production areas. The current study aimed to explore the species differences in responses to flooding stress between Q. nuttallii and Q. palustris in an outdoor environment. All the tested plants survived after a 60-day flooding treatment that left 5 cm of water above the soil surface. This suggests that the two species are flood-tolerant, so they can be applied in the construction of riparian protection forests and wetland restoration. Compared with control conditions, flooding treatment significantly decreased seedling height and diameter and the Pn, Gs, Tr, Fv/Fm, ABS/CSm, TR0/CSm, ET0/CSm, RE0/CSm, IAA, and GA3 content and significantly increased the content of MDA, H2O2, soluble sugars, SOD, POD, ADH, ABA, and JA. Under control conditions, Q. nuttallii showed significantly greater growth and photosynthetic capability than Q. palustris. In contrast, Q. palustris exhibited less inhibition of growth and photosynthesis, oxidative stress levels, and antioxidant enzyme activities than Q. nuttallii under flooding conditions. The findings indicate that Q. palustris has better defense mechanisms against the damage caused by flooding stress than Q. nuttallii. Q. nuttallii was more sensitive and responsive to flooding than Q. palustris.

Ruscus Species Distributed in Türkiye

Ruscus species are represented by seven species in the world and four of these species (R. aculeatus L., R. hypoglossum L., R. hypophyllum L. and R. colchicus Yeo) grow naturally in the flora of Turkiye. Other Ruscus species (R. hyrcanus Woronow., R. x microglossus Bertol. and R. streptophyllus Yeo) are naturally distributed in different parts of the world. Ruscus species grow between 80 and 100 cm tall. These species have numerous evergreen leaf-like flattened structures, which have photosynthetic capability, on branched stems known as cladodes. The small violet flowers are situated on the center of cladodes. Their orange-red fruits are 5-10 mm in diameter. Ruscus species are perennial plants. In addition to their use as outdoor plants in landscape architecture, these species are mostly used as cut greens for flower arrangements and medicinal purposes, as well as for cosmetic products. Ruscus species are also known as geophytes due to the structure of their storage organs (rhizomes), which are located under the soil surface. In this compilation study, our main aims were to provide information about these species, which grow naturally in Türkiye’s flora and are uncontrollably collected from nature and put on the market, to reveal their potential for evaluation as ornamental plants and to increase awareness about these valuable native species to protect our genetic resources. The distribution regions in nature, various morphological properties and different usage areas of four Ruscus species naturally grown in Türkiye are given in detail.

Light Environment and Photosynthetic Capacities of Leaves at Different Locations within Eggplant Canopies in a Greenhouse in Ontario, Canada

To effectively manage crop production in a greenhouse, it is essential to understand the natural light environment and physiological responses of the plants to light. This study investigated the dynamics of photosynthetic photon flux densities (PPFD) and light quality within the canopies of greenhouse-grown eggplant (Solanum melongena) and the photosynthetic capacities of leaves at different locations within the canopies. The light environment was quantified at 0.2-m intervals within (intra-canopy) and adjacent to (extra-canopy) the crop canopy on both sunny and cloudy days within a commercial greenhouse located in Leamington, Ontario, Canada. Our results indicated a linear decline in extra-canopy PPFD on both sunny and cloudy days, but an exponential decrease in intra-canopy PPFD. The intra-canopy PPFD decreased by 91% and 76% between 0 m and 0.4 m from the canopy apex on sunny and cloudy days, respectively. The lower canopy (0.6–1.2 m) light spectrum consisted largely of far-red light, equal amounts of red light and green light, with a lower percentage of blue light. Parameters derived from leaf-level light response curves indicated that the light-saturated net carbon exchange rate, light saturation point, and light compensation point decreased as the distance from canopy apex increased, whereas quantum yield was unaffected. Thus, leaves in the lower canopy were less efficient at using high PPFD, but they displayed no deterioration of photosynthetic machinery. Based solely on photosynthetic capabilities, leaves between 0 and 1.0 m from the canopy apex should not be removed to decrease the total plant sink strength.

First report of cucurbit yellow stunting disorder virus infecting cucurbit crops in Jamaica.

The increasing prevalence of whitefly-transmitted viruses affecting cucurbit crops has emerged as a significant concern for global cucurbit production. Two of the most widely prevalent threats in the Americas are cucurbit yellow stunting disorder virus (CYSDV) and cucurbit chlorotic yellows virus (CCYV) (Crinivirus, Closteroviridae). These viruses induce similar foliar symptoms on cucurbit crops (Mondal et al., 2023) leading to loss of photosynthetic capability and decreased yields. Cantaloupe (Cucumis melo), watermelon (Citrullus lanatus), and cucumber (Cucumis sativus) are major cucurbit crops in St. Elizabeth, Jamaica, which is the principal fruit and vegetable producing region of the country. In August 2018, foliar symptoms were observed on cantaloupe, watermelon, and cucumber plants in several commercial farms in St. Elizabeth. These symptoms, mainly on the older leaves, consisted of severe yellowing or interveinal mottle and they appeared more pronounced on cantaloupe and cucumber plants compared to watermelon. Growers noticed the production of smaller than normal fruit. Disease incidence ranged from 10 to 100% and whiteflies (Bemisia tabaci Gennadius) were observed in the fields. To identify virus(es) associated with the disease, six plants (cantaloupe [n = 3], cucumber [n = 1] and watermelon [n = 2) exhibiting symptoms were sampled from four fields for preliminary screening. Total RNA was extracted from leaf tissues as described in Tamang et al. (2021) and samples tested by a multiplex reverse transcription RT-PCR method that targeted the RNA-dependent RNA polymerase (RdRp) of the whitefly transmitted viruses, CYSDV, CCYV, squash vein yellowing virus (SqVYV), and the aphid- transmitted cucurbit aphid-borne yellows virus (CABYV) (Mondal et al. 2023). RT-PCR amplified the expected 494-bp fragment of the CYSDV RdRp gene (Mondal et al., 2023) from two symptomatic plants; one cantaloupe, one cucumber, as well as from CYSDV-infected control plants but not from healthy controls. Further testing was conducted during the June-August 2020 growing season after similar symptoms were observed on additional farms in St. Elizabeth and two regions, Manchester and Clarendon, located to the east of St. Elizabeth. Twenty-one cucurbit leaf samples (11 cantaloupe, seven watermelon and two cucumber from St. Elizabeth and one cantaloupe from Clarendon) exhibiting foliar yellowing progressing from the crown outward, and mottling were collected. Whiteflies (5) from these fields in St. Elizabeth and 20 asymptomatic weed samples were also collected and sent to the USDA-ARS laboratory at Salinas, CA. Total RNA from leaf samples was extracted as described above and tested for CYSDV, CCYV, and CABYV. Total leaf DNA was also extracted (Mondal et al. 2016) and assayed with PCR (Gilbertson 2001) to detect the presence of the whitefly-transmitted cucurbit leaf crumple virus (CuLCrV), a begomovirus, commonly found in the southeastern United States (Gadhave et al., 2018; Keinath et al., 2018). Nineteen of the 21 cucurbit samples tested positive for the presence of CYSDV by RT-PCR (Mondal et al. 2023). Of the 19 CYSDV-positive samples, 13 cantaloupe, one cucumber, and five watermelon samples were singly infected with CYSDV, and one cantaloupe sample was infected with both CYSDV and CABYV. Amplicons of the Jamaica isolate from cantaloupe were sequenced (OR399555) and a 494 nt section of the RdRp gene was found to share 100% sequence identity to the Arizona 1 isolate (EF547827.1). The presence of CYSDV, was further confirmed using a second set of primers that amplified a 394-nt portion of the CYSDV coat protein gene (Polston et al., 2008). Among the weed samples, CABYV was detected in one sample from a Leonotis nepetifolia plant (Lamiaceae) and two Cleome sp. (Capparaceae) collected from St. Elizabeth. None of the crop and weed samples tested positive for CCYV or CuLCrV. DNA from whiteflies was extracted and assayed with PCR using species specific primers (Chen et al. 2016). All whiteflies were identified as B. tabaci cryptic species MEAM1, which is widely known an efficient vector of CYSDV (Berdiales, et al. 1999). This is the first report of CYSDV in Jamaica and its first known occurrence in these hosts within the country. Further monitoring of cucurbit crops and the whitefly vector is warranted to better understand the epidemiology.

Synergistic effects of arbuscular mycorrhizal fungi and biochar are highly beneficial to Ligustrum lucidum seedlings in Cd-contaminated soil.

Cadmium (Cd) contamination is a widespread environmental issue. There is a lack of knowledge about the impacts of applying arbuscular mycorrhizal fungi (AMF) and biochar, either alone or in their combination, on alleviating Cd phytotoxicity in Ligustrum lucidum. Therefore, a pot experiment was conducted in a greenhouse, where L. lucidum seedlings were randomly subjected to four regimes of AMF treatments (inoculation with sterilized AMF, with Rhizophagus irregularis, Diversispora versiformis, alone or a mixture of these two fungi), and two regimes of biochar treatments (with or without rice-husk biochar), as well as three regimes of Cd treatments (0, 15, and 150mgkg-1), to examine the responses of growth, photosynthetic capabilities, soil enzymatic activities, nutritional concentrations, and Cd absorption of L. lucidum plants to the interactive effects of AMF, biochar, and Cd. The results demonstrated that under Cd contaminations, AMF alone significantly increased plant total dry weight, soil pH, and plant nitrogen (N) concentration by 84%, 3.2%, and 13.2%, respectively, and inhibited soil Cd transferring to plant shoot by 42.2%; biochar alone significantly enhanced net photosynthetic rate, soil pH, and soil catalase of non-mycorrhizal plants by 16.4%, 9%, and 11.9%, respectively, and reduced the soil Cd transferring to plant shoot by 44.7%; the additive effect between AMF and biochar greatly enhanced plant total dry weight by 101.9%, and reduced the soil Cd transferring to plant shoot by 51.6%. Furthermore, dual inoculation with D. versiformis and R. irregularis conferred more benefits on plants than the single fungal species did. Accordingly, amending Cd-contaminated soil with the combination of mixed-fungi inoculation and biochar application performed the best than either AMF or biochar alone. These responses may have been attributed to higher mycorrhizal colonization, soil pH, biomass accumulation, and biomass allocation to the roots, as well as photosynthetic capabilities. In conclusion, the combined use of mixed-fungi involving D. versiformis and R. irregularis and biochar addition had significant synergistic effects on enhancing plant performance and reducing Cd uptake of L. lucidum plants in Cd-contaminated soil.

First report of Spiroplasma citri associated with disease symptoms in field-grown hemp (Cannabis sativa L.) in the Pacific Northwest.

Hemp (Cannabis sativa L.) is grown for cannabinoid oil production in Oregon. During the 2021 and 2022 growing seasons, plants with leaf curling, puckering, chlorotic mosaic, fasciation, and vein clearing were observed in disease surveys of Oregon hemp fields (Fig. 1). Symptoms were present on 1-10% of 2-4-month-old plants in fields located in Benton, Clackamas, Deschutes, Jackson, Josephine, Lane, Linn, Marion, Morrow, and Polk counties between July and September. Leaf and stem samples were collected from 38 symptomatic plants. Symptoms resembled those caused by beet leafhopper-vectored (BLH, Circulifer tenellus Baker) curtovirus or phytoplasma infection. Therefore, total nucleic acids were extracted (Dellaporta et al. 1983) from leaf material, and PCR conducted on all 38 samples to detect curtovirus coat proteins (BCTV-1/2 primers; Rondon et al. 2016) and 16S rRNA of phytoplasmas (nested primers P1/P7 followed by FU/RU; Lorenz et al. 1995). No curtoviruses or phytoplasmas were detected in any samples. Spiroplasma citri is also transmitted by BLH, so PCR was conducted with primers targeting the putative P89 adhesin gene and spiralin gene of S. citri (Yokomi et al. 2008). For all samples, PCR using P89F/R primers resulted in a 707 bp amplicon, and a 675 bp amplicon with Spiralin-f/r primers. PCR products were purified with ExoSapIT (Applied Biosystems, Waltham, MA), and two representative samples (ScH1; ScH2) were Sanger sequenced (EuroFins, Lancaster, PA) in the forward and reverse direction. Pairwise aligned P89 sequences were found to be 99 to 100% (ScH1: 633/637 bp; ScH2: 654/654 bp) identical to S. citri accession KT377386. Aligned/span>spiralin sequences were found to be 99 to 100% (ScH1: 661/664 bp; ScH2: 647/647 bp) identical to S. citri accession CP013197 in the NCBI GenBank Database. All sequences were deposited into GenBank (accession no. OQ969983, OQ992766, OQ969984, OQ969986). Frozen leaf material from one sample was used to culture S. citri according to Lee and Davis (1984). Leaf tissue was surface sterilized for 60 s in 1% NaOCl in 70% ethanol, cut into pieces in LD8 broth, and incubated for 25 min at 25˚C. The solution was passed through a 0.45um filter and incubated for 14 days at 30°C with constant shaking (150 rpm). Then, cultures were centrifuged for 2 min at 12,000 rpm to pelletize, resuspended in 100µL sterile distilled water and passed through a 0.2um filter. From this culture, 2 µL of broth was used as template for both the P89F/R and Spiralin-f/r primer sets. Amplicons were purified and sequenced as above (accession nos. OQ969982, OQ969985). Leaf tissue from both representative samples (ScH1 and ScH2) were positive for S. citri using double antibody sandwich ELISA (Agdia, Inc., Elkhart, IN) following manufacturer instructions. These results from sequencing, culturing, and ELISA testing indicate the hemp samples were infected with S. citri. To our knowledge this is the first report of disease symptoms in hemp associated with S. citri in Oregon and the Pacific Northwest. Infection by S. citri can limit yield by reducing photosynthetic capability of the plant and distortion of plant growth. Other pathogens like curtoviruses and phytoplasmas have also been detected in hemp in Oregon and the U.S. (Hu 2021; Rivedal et al. 2022), and the addition of S. citri associated with disease symptoms indicates a need for BLH management research. This discovery has implications for arid regions with other S. citri hosts including cruciferous plants, carrots, and tree fruit crops, all of which were grown near the sampled hemp fields in this study.

Altered fatty acid composition confers improved drought acclimation in maize

Drought induces alteration in membrane lipid composition in plants; however, still little is known about whether membrane lipid remodeling plays a role in plant drought acclimation, including both drought tolerance and recovery, especially in crops. Here, we imposed natural progressive drought and re-watering in 18 maize genotypes at the seedling stage, and analyzed the physiological responses, drought tolerance and drought acclimation capabilities, contents of lipids, and fatty acid compositions. The results showed that drought caused significant reductions in shoot dry weight, relative water content, Fv/Fm, total lipid content, and double bond index (DBI) in most genotypes, while re-watering partially recovered these reductions. Meanwhile, the total lipid content, fatty acid composition, and DBI were also changed obviously in response to drought and re-watering. In order to explore the relationship between membrane lipid change and plant drought response, we did a principal component analysis. The results showed that C18:3 fatty acid contributed greatly to drought tolerance, and C16:2 and C16:3 fatty acids were more responsible for drought recovery. Meanwhile, DBI showed significant positive correlations with shoot dry weight and relative water content, but a negative association with lipid peroxidation, and more importantly, DBI was important for both drought tolerance and recovery. These alterations in membrane lipid composition may facilitate increasing membrane fluidity and decreasing membrane damage, thus maintaining the high photosynthetic capability under drought. Our results suggest that lipid remodeling is important for drought tolerance and recovery in crops, and different fatty acid species have different roles in crop drought acclimation.

Engineering photo-methylotrophic Methylobacterium for enhanced 3-hydroxypropionic acid production during non-growth stage fermentation

This study explored the potential of methanol as a sustainable feedstock for biomanufacturing, focusing on Methylobacterium extorquens, a well-established representative of methylotrophic cell factories. Despite this bacterium’s long history, its untapped photosynthetic capabilities for production enhancement have remained unreported. Using genome-scale flux balance analysis, it was hypothesized that introducing photon fluxes could boost the yield of 3-hydroxypropionic acid (3-HP), an energy- and reducing equivalent-consuming chemicals. To realize this, M. extorquens was genetically modified by eliminating the negative regulator of photosynthesis, leading to improved ATP levels and metabolic activity in non-growth cells during a two-stage fermentation process. This modification resulted in a remarkable 3.0-fold increase in 3-HP titer and a 2.1-fold increase in its yield during stage (II). Transcriptomics revealed that enhanced light-driven methanol oxidation, NADH transhydrogenation, ATP generation, and fatty acid degradation were key factors. This development of photo-methylotrophy as a platform technology introduced novel opportunities for future production enhancements.

The Impact of Photosynthetic Characteristics and Metabolomics on the Fatty Acid Biosynthesis in Tea Seeds.

The synthesis of tea fatty acids plays a crucial role in determining the oil content of tea seeds and selecting tea tree varieties suitable for harvesting both leaves and fruits. However, there is limited research on fatty acid synthesis in tea trees, and the precise mechanisms influencing tea seed oil content remain elusive. To reveal the fatty acid biosynthesis mechanism, we conducted a photosynthetic characteristic and targeted metabolomics analysis in comparison between Jincha 2 and Wuniuzao cultivars. Our findings revealed that Jincha 2 exhibited significantly higher net photosynthetic rates (Pn), stomatal conductance (Gs), and transpiration rate (Tr) compared with Wuniuzao, indicating the superior photosynthetic capabilities of Jincha 2. Totally, we identified 94 metabolites with significant changes, including key hormone regulators such as gibberellin A1 (GA1) and indole 3-acetic acid (IAA). Additionally, linolenic acid, methyl dihydrojasmonate, and methylthiobutyric acid, precursors required for fatty acid synthesis, were significantly more abundant in Jincha 2 compared with Wuniuzao. In summary, our research suggests that photosynthetic rates and metabolites contribute to the increased yield, fatty acid synthesis, and oil content observed in Jincha 2 when compared with Wuniuzao.

Silicon application mitigated the adverse effects of salt stress and deficit irrigation on drip-irrigated greenhouse tomato

Tomato (Solanum lycopersicum L.) is an important vegetable crop around the world, and water scarcity and soil salinization are two major unfavorable factors limiting the fruit yield and quality of greenhouse tomato in arid and semi-arid regions. The application of exogenous silicon has been reported to enhance tomato yield under salt or drought stress, but its effect under combined salt-drought stress remains unclear. A two-season (autumn 2021 and spring 2022) experiment was conducted with three irrigation levels (I1, 90%−100% θf, where θf is the field capacity; I2, 70%−80% θf; I3, 50%−60% θf), two soil salinity levels (S0, 0.1%, g/g; S1, 0.4%, g/g) and two silicon application rates (T0, 0 mM; T1, 2.4 mM) to explore their combined effects on leaf silicon content, photosynthetic parameters, fruit yield, nutrient yield, crop water productivity (WP), nitrogen uptake and utilization, nutrient water productivity (NWP) and economic benefit of drip-irrigated greenhouse tomato. The results showed that deficit irrigation and salt stress exerted significant inhibiting effects on leaf silicon content, photosynthetic parameters, tomato yield, and water-nitrogen productivity, but the inhibition was alleviated by silicon application, which increased leaf silicon content by 67.0%, net photosynthetic rate (Pn) by 25.3%, fruit yield by 12.3%, WP by 11.9%, nutrient yield by 10.0% (titratable acids) - 27.4% (soluble sugars) and NWP by 9.2% (titratable acids) - 26.1% (soluble sugars) on average. The average fruit yield over the two growing seasons was 66.01, 54.29 and 44.31 t ha−1 under I1, I2 and I3, and the silicon application increased average leaf silicon content by 71.9%, 65.2% and 63.0%, Pn by 11.1%, 12.9% and 7.6%, and fruit yield by 12.8%, 16.2%, and 8.1% at the three irrigation levels, respectively. Plant nitrogen uptake (NU) and nitrogen partial factor productivity (NPFP) increased but nitrogen use efficiency (NUE) tended to decrease with the increasing irrigation level, while silicon application improved NUE by 3.9% and 2.2% and NPFP by 13.8% and 11.7% in the two growing seasons, respectively. Silicon application significantly increased net profit by 24.3% and 17.7% in autumn 2021 and spring 2022, respectively. According to the principal component analysis, I1T1S0 ranked first in both growing seasons. The correlation matrix showed that fruit yield was positively correlated with leaf silicon content, Pn, stomatal conductance, WP, NU, NUE, NPFP, nutrient yield and net profit, while it had negative correlation with NWP. In conclusion, exogenous silicon application can improve the fruit yield and nutrient yield of drip-irrigated greenhouse tomato by enhancing leaf silicon content and photosynthetic capability under drought-stressed and salt-affected conditions.