Increased Chlorophyll Content Research Articles

Effect of Gas Exchange Rate, Vessel Type, Planting Density, and Genotype on Growth, Photosynthetic Activity, and Ion Uptake of In Vitro Potato Plants

The growth of high-quality in vitro potato plants (Solanum stenotomum subsp. stenotomum, Solanum stenotomum subsp. goniocalyx, and Solanum tuberosum subsp. andigena) is affected by multiple biological, operational, and environmental factors. Research on in vitro culture is frequently focused on the species, explant, composition of the culture medium, and incubation conditions, but only limited information is available on the effect of the gas exchange rate and volume of in vitro culture vessels under variable planting densities. In the present study, these factors were evaluated with a set of seven diverse potato landraces. The results were compared to the plants’ responses in routinely used in vitro culture vessels, i.e., 13 × 100 mm and 25 × 150 mm test tubes, and GA7® magenta vessels. In vitro potato plants grown in plastic vessels equipped with a HEPA filter delivering a high gas exchange rate developed thicker stems (0.95 mm), a higher total average leaf area (2.51 cm2), increased chlorophyll content in leaves (32.2 ppm), and lower moisture content in their tissues (90.1%) compared to filter systems with lower gas exchange rates. A high planting density of 10 × 10 plants per vessel (360 and 870 mL) negatively affected the average stem width and root length but increased the plant height (3.4 cm). High fluctuations of ion-uptake of NO3−, Ca++, K+, and Na+ were observed between genotypes, with some accessions having a 4.6-times higher Ca++-ion concentration in their tissues (190–234 ppm). The in vitro plants developed more robust stems, longer roots, and larger leaves within in vitro culture vessels equipped with a HEPA filter (high gas exchange rate) compared to the control vessels, in contrast to the chlorophyll content in leaves, which was higher in plants grown in narrow test tubes. Depending on the purpose of the subculture of in vitro plants, their growth and development can be molded using different gas exchange rates, planting densities, and vessel volumes.

Green synthesized iron oxide nanoparticles as a potential regulator of callus growth, plant physiology, antioxidative and microbial contamination in Oryza sativa L.

In tissue culture, efficient nutrient availability and effective control of callus contamination are crucial for successful plantlet regeneration. This study was aimed to enhance callogenesis, callus regeneration, control callus contamination, and substitute iron (Fe) source with FeO-NPs in Murashige and Skoog (MS) media. Nanogreen iron oxide (FeO-NPs) were synthesized and well characterized with sizes ranging from 2 to 7.5 nm. FeO-NPs as a supplement in MS media at 15 ppm, significantly controlled callus contamination by (80%). Results indicated that FeCl3-based FeO-NPs induced fast callus induction (72%) and regeneration (43%), in contrast FeSO4-based FeO-NPs resulted in increased callus weight (516%), diameter (300%), number of shoots (200%), and roots (114%). Modified media with FeO-NPs as the Fe source induced fast callogenesis and regeneration compared to normal MS media. FeO-NPs, when applied foliar spray, increased Plant fresh biomass by 133% and spike weight by 350%. Plant height increased by 54% and 33%, the number of spikes by 50% and 265%, and Chlorophyll content by 51% and 34% in IRRI-6 and Kissan Basmati, respectively. Additionally, APX (Ascorbate peroxidase), SOD (Superoxide dismutase), POD (peroxidase), and CAT (catalase) increased in IRRI-6 by 27%, 29%, 283%, 62%, while in Kissan Basmati, APX increased by 70%, SOD decreased by 28%, and POD and CAT increased by 89% and 98%, respectively. Finally, FeO-NPs effectively substituted Fe source in MS media, shorten the plant life cycle, and increase chlorophyll content as well as APX, SOD, POD, and CAT activities. This protocol is applicable for tissue culture in other cereal crops as well.

Physiological and metabolomic analyses reveal the mechanism by which exogenous spermine improves drought resistance in alfalfa leaves (Medicago sativa L.)

IntroductionAlfalfa (Medicago sativa L.) is a globally important legume crop with high nutritional and ecological value. Drought poses a serious threat to alfalfa acreage and yields. Spermine (Spm) has been shown to protect plants from drought damage. The aim of this study was to clarify the mechanism of exogenous Spm to improve drought resistance of alfalfa. MethodsIn this study, we root applied 0.1, 0.5, and 1 mM Spm to Gannong No. 3 (G3) alfalfa under drought stress, and then determined their physiological and metabolic changes. ResultsThe results showed that exogenous Spm increased chlorophyll content, chlorophyll fluorescence parameters and gas exchange parameters, enhanced antioxidant enzymes activity, improved ascorbic acid-glutathione (AsA-GSH) cycle, increased osmoregulatory substances content, reduced hydrogen peroxide and superoxide anion levels, and inhibited malondialdehyde accumulation in alfalfa under drought stress, thereby increasing plant height and leaf relative water content and enhancing drought tolerance of alfalfa. The redundancy analysis of the above physiological indicators showed that the addition of the optimal Spm to improve drought tolerance of alfalfa under drought stress was mainly achieved by increasing catalase activity and improving the ASA-GSH cycle. In addition, metabolomics analysis revealed that exogenous Spm increased the content of oxobutanedioic acid, citric acid, fumaric acid and malic acid to enhance the tricarboxylic acid cycle. Meanwhile, exogenous Spm increased endogenous Spm and proline (Pro) content to resist drought stress by enhancing Spm and Pro metabolism. Moreover, exogenous Spm increased the accumulation of the signaling substance abscisic acid. DiscussionIn conclusion, exogenous Spm enhanced drought resistance of alfalfa leaves under drought stress.

Effects of shading on morphology, photosynthesis characteristics, and yield of different shade-tolerant peanut varieties at the flowering stage

IntroductionIn maize and peanut intercropping, shading emerges as a critical factor for restricting peanut growth, yield, and quality.MethodsThis study investigated the impact of 30% shade on shade-tolerant [Huayu 22 (HY22) and Fuhua 12 (FH12)] and shade-sensitive [Nonghua 11 (NH11) and Nonghua 5(NH5)] peanut varieties, with non-shaded condition as the control (CK). The effects of shade stress on plant morphology, photosynthetic characteristics, dry-matter accumulation, chloroplast ultra-microstructure, yield, and quality of different shade-tolerant peanut varieties were examined.ResultsCompared to that in the control, shade stress led to an elongation of the main stem, shortening of the lateral branches, and reduction in the leaf area. However, these changes were less significant in the shade-tolerant than in the shade-sensitive peanut varieties, with minimal effect on the elongation of the main stem height and shortening of the lateral branches. Differences in leaf area became significant during the later stages of shade stress, particularly pronounced in the shade-sensitive peanut varieties. To enhance light capture by leaves, the shade-tolerant peanut varieties exhibited increased chlorophyll content and chloroplast grain-layer numbers. The decrease in the chlorophyll a/b ratio was more pronounced in the shade-tolerant than in the shade-sensitive peanut varieties, with significant differences. However, reduced activities of ribulose 1,5-biphosphate (RuBP) carboxylase/oxygenase and fructose 1,6-biphosphate aldolase (FBA) resulted in decreased net photosynthetic rates, particularly evident in the shade-sensitive peanut varieties during the late shade period. Shade stress led to decreased dry-matter accumulation, reduced weight of 100 fruits and kernels, and a significant decline in yield in the shade-sensitive cultivars. Shading also affected peanut-kernel quality. Compared with that in the control, the protein content increased and amino-acid (except cysteine) content decreased in the shade-tolerant cultivars.DiscussionUnder shade stress, shade tolerant peanut varieties have increased the yield by improving the photosynthetic efficiency, which provided a reference for rational selection of shade tolerant peanut varieties in maize and peanut intercropping system.

Alleviative Effect of Exogenous Application of Fulvic Acid on Nitrate Stress in Spinach (Spinacia oleracea L.)

Salt stress could be a significant factor limiting the growth and development of vegetables. In this study, Fulvic Acid (FA) (0.05%, 0.1%, 0.15%, 0.2%, and 0.25%) was applied under nitrate stress (150 mM), with normal Hoagland nutrient solution as a control to investigate the influence of foliar spray FA on spinach growth, photosynthesis, and oxidative stress under nitrate stress. The results showed that nitrate stress significantly inhibited spinach growth, while ROS (reactive oxygen species) accumulation caused photosystem damage, which reduced photosynthetic capacity. Different concentrations of FA alleviated the damage caused by nitrate stress in spinach to varying degrees in a concentration-dependent manner. The F3 treatment (0.15% FA + 150 mM NO3−) exhibited the most significant mitigating effect. FA application promoted the accumulation of biomass in spinach under nitrate stress and increased chlorophyll content, the net photosynthetic rate, the maximum photochemical quantum yield of PSII (Photosystem II) (Fv/Fm), the quantum efficiency of PSII photochemistry [Y(II)], the electron transport rate, and the overall functional activity index of the electron transport chain between the PSII and PSI systems (PItotal); moreover, FA decreased PSII excitation pressure (1 − qP), quantum yields of regulated energy dissipation of PSII [Y(NPQ)], and the relative variable initial slope of fluorescence. FA application increased superoxide dismutase, peroxidase, and catalase activities and decreased malondialdehyde, H2O2, and O2− levels in spinach under nitrate stress. FA can enhance plant resistance to nitrate by accelerating the utilization of light energy in spinach to mitigate excess light energy and ROS-induced photosystem damage and increase photosynthetic efficiency.

Regulation of seed soaking with indole-3-butyric acid potassium salt (IBA-K) on rapeseed (Brassica napus L.) seedlings under NaCl stress

The growth and yield of rapeseed are significantly hampered by salt stress. Indole-3-butyric Acid Potassium Salt (IBA-K) has been found to alleviate the impact of salt stress on plant growth. However, the regulatory effect of IBA-K dipping on salt-stressed rapeseed remains unclear. To explore the implications of IBA-K on the growth and development of rapeseed during the seedling stage, we conducted potting experiments using the Huayouza 62 variety. Five different concentrations of IBA-K for seed soaking (0, 10, 20, 40, 80 mg·L− 1) were tested. The promotional impact of IBA-K on rapeseed demonstrated an initial increase followed by a decline, reaching a peak at 20 mg·L− 1. Therefore, 20 mg·L− 1 was determined as the optimal concentration for subsequent experiments. To further understand the mechanism of IBA-K’s action on salt-stressed rapeseed seedlings, we utilized the moderately salt-resistant cabbage rapeseed variety Huayouza 158R and the highly salt-resistant Huayouza 62 as specimens. The investigation focused on their response and repair mechanisms under 150 mmol·L− 1 NaCl stress. The findings demonstrated that compared with the sole NaCl stress, the 20 mg·L− 1 IBA-K seed soaking treatment under salt stress significantly enhanced the plant height, stem diameter, and leaf area of both rapeseed varieties. It also led to greater biomass accumulation, increased chlorophyll content, and improved photosynthetic efficiency in rapeseed. Furthermore, this treatment bolstered the activity of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), while significantly reducing the levels of electrolyte leakage (EL) and malondialdehyde (MDA). Consequently, it alleviated the membrane lipid peroxidation damage induced by NaCl stress, enhanced the accumulation of soluble proteins, maintained cellular osmotic pressure, and effectively mitigated the adverse effects of NaCl stress on rapeseed.

Assessment of amoxicillin (AMX) removal from aqueous medium through Rhapis-based bioretention system.

Antibiotics can be effectively removed from wastewater using constructed wetlands (C.W.s). However, little is known about using attractive garden plants in C.W.s to eliminate antibiotics. Thus, the current study aims to treat amoxicillin (AMX)-contaminated wastewater through a Rhapis excelsa-based bioretention system (BS). The investigation was done at 15days hydraulic retention time (HRT) under two conditions: set-1, varied AMX 5 to 25ppm with constant NPK (nitrogen, phosphorus, potassium) source; and set-2, varied NPK sources with constant AMX (25ppm). During the study, it was observed that in the set-1 condition with increasing AMX concentration, the removal of AMX through BS decreased; however, in the set-2 experiment, with enhancing NPK source, the performance of the BS treating 25-ppm AMX-contaminated wastewater increased. AMX removal of 2.3%, 66.3%, 60.6%, 52.2%, 46.7%, and 44.9% was achieved for control, BS-1, BS-2, BS-3, BS-4, and BS-5, respectively, during set-1 experiment. However, in the set-2 experiment, 23.4% (control), 43.3% (BS-1), 60.3% (BS-2), 75.9% (BS-3), 88.8% (BS-4), and 99% (BS-5) AMX removal were achieved. Removing pollutants like AMX, COD, PO43--P, NO3--N, and NH4+-N followed first-order kinetics. A positive correlation of COD with AMX was observed through principal component analysis and correlation matrix. The microbial community study was also covered to prioritize the role of microbes in treating AMX through BSs. The AMX treatment through Rhapis excelsa-based BS supported plant growth and development with increasing chlorophyll content, fresh weight, and C, H, N value.

Heat shock factor ZmHsf17 positively regulates phosphatidic acid phosphohydrolase ZmPAH1 and enhances maize thermotolerance.

Heat stress (HS) adversely impacts plant growth, development and grain yield. Heat shock factors (Hsf), especially HsfA2 subclass, play a pivotal role in the transcriptional regulation of genes in response to HS. In this study, the coding sequence of maize ZmHsf17 was cloned. ZmHsf17 contains conserved domains: DNA binding, oligomerization and transcriptional activation. The protein was nuclear localized and had transcription activation activity. Yeast two hybrid and split luciferase complementary assays confirmed the interaction of ZmHsf17 with members of the maize HsfA2 subclass. Overexpression of ZmHsf17 in maize significantly increased chlorophyll content and net photosynthesis rate of maize leaves, and enhanced the stability of cellular membranes. Through integrative analysis of ChIP-seq and RNA-seq datasets, ZmPAH1, encoding phosphatidic acid phosphohydrolase of lipid metabolic pathways, was identified as a target gene of ZmHsf17. The promoter fragment of ZmPAH1 was bound by ZmHsf17 in protein-DNA interaction experiments in vivo and in vitro. Lipidomic data also indicates that the overexpression of ZmHsf17 increased levels of some critical membrane lipid components of maize leaves under HS. This research provides new insights into the role of the ZmHsf17-ZmPAH1 module in regulating thermotolerance in maize.

Possibility of using industrial by-product combinations to remediate cadmium and arsenic contaminated soil

It is inevitable to produce by-products in industrial and mining production, and how to deal with these by-products has become a major environmental issue. Meanwhile, many studies have shown that applying soil amendments is a feasible measure for effectively controlling soil pollution. Finding low-cost and efficient soil passivators is an effective way to safely utilize polluted soil. This article provides a method of “treating contamination with waste”. Through spinach pot experiments, different proportions and doses of granite powder (A, quarry waste), market purchased conditioner (B), “granite powder+iron sulfate mineral (titanium powder industrial waste)” (C), and “granite powder+iron sulfate mineral+market purchased conditioner” (CB) were used to treat soil co-contaminated with cadmium (Cd) and arsenic (As). The results indicate that amendments affect the available Cd and As in soil by changing soil pH and cation exchange capacity. The amendment of A, B, C, and CB all has remarkable reduction rates of soil available Cd at 65.48 %, 57.02 %, 61.37 %, and 43.15 %, respectively, compared to the control. Both A and B increase the available As content in the soil and the As content in spinach. However, both C and CB reduced the available As content in the soil by 60.32 % and 12.48 %. CB treatment could simultaneously reduce the accumulation of Cd and As in spinach, increase chlorophyll content, and promote spinach growth. It was worth noting that the 3 % CB treatment has the best effect, with Cd and As content in spinach stems and leaves decreasing by 51.13 % - 69.62 % and 35.46 % - 59.53 %, respectively, and the repair cost being as low as 76.5 $ ton−1. Therefore, the combined application of granite powder, market purchased conditioner, and iron sulfate minerals for the remediation of Cd and As co-polluted soil was a cost-effective and environmentally friendly technology. However, applying these soil composite amendments also requires attention to adjusting with the soil type and with pollution type, which we are currently studying.

Increasing Fertilization Efficiency of Biomass Ash by the Synergistically Acting Digestate and Extract from Water Plants Sequestering CO2 in Sorghum Crops.

The utilization of biomass ash in sustainable agriculture and increasing its fertilizing efficiency by biological agents, potentially sequestering CO2, have become important issues for the global economy. The aim of this paper was to investigate the effects of ash from sorghum (Sorghum bicolor L. Moench) and Jerusalem artichoke (Helianthus tuberosus L.) biomass, a biogas plant digestate, and a Spirodela polyrhiza extract, acting alone or synergistically, on soil fertility and the development, health and physiological properties of sorghum plants. The results show novel information concerning differences in the composition and impact of ash, depending on its origin, soil properties and sorghum plant development. Sorghum ash was more effective than that from Jerusalem artichoke. Ash used alone and preferably acting synergistically with the digestate and Spirodela polyrhiza extract greatly increased soil fertility and the growth, biomass yield and health of sorghum plants. These improvements were associated with an increased chlorophyll content in leaves, better gas exchange (photosynthesis, transpiration, stomatal conductance), greater enzyme activity (acid and alkaline phosphatase, RNase, and total dehydrogenase), and a higher biomass energy value. The developed treatments improved environmental conditions by replacing synthetic fertilizers, increasing the sequestration of CO2, solving the ash storage problem, reducing the need for pesticides, and enabling a closed circulation of nutrients between plant and soil, maintaining high soil fertility.

CfSGR1 and CfSGR2 from Cryptomeria fortunei exhibit contrasting responses to hormones and abiotic stress in transgenic Arabidopsis

Stay-green (SGR) genes are pivotal regulatory genes in the context of plant chlorophyll metabolism, but few studies on SGR homologues in Cryptomeria fortunei have been previously reported. We cloned two CfSGR genes and overexpressed them in Arabidopsis to explore their functions. Full-length CfSGR1 and CfSGR2 are 1265 and 1197 bp, encompassing open reading frames (ORFs) encoding 274 and 276 amino acids, respectively. SGRs exhibited high conservation in higher plants, and phylogenetic analysis indicated that SGRs from monocots and gymnosperms cluster in a clade. The proteins localized to chloroplasts and showed no transcriptional activity in yeast cells. The CfSGR gene expressions were induced by abiotic stresses and hormones. Under conditions of darkness, abscisic acid (ABA), salt, drought, or freezing stress, CfSGR2-transgenic Arabidopsis exhibited a delay in leaf yellowing compared to the WT, which was attributed to increased chlorophyll content and enhanced photosynthetic capacity. These transgenic plants exhibited improved resistance to stress via upregulated expression of resistance-related genes, increased antioxidant enzyme activities, and reduced malondialdehyde content and electrolyte leakage rate. In contrast, CfSGR1-transgenic plants may accelerate leaf yellowing and exhibit reduced stress resistance. Our findings highlight potential divergence in the functions of CfSGR genes concerning plant growth and development and responses to abiotic stresses or hormones, providing a scientific foundation for future breeding of stress-resistant C. fortunei cultivars.

Role of SbNRT1.1B in cadmium accumulation is attributed to nitrate uptake and glutathione-dependent phytochelatins biosynthesis

Phytoremediation of cadmium (Cd)-polluted soil by using sweet sorghum displays a tremendous potential as it is a fast-growing, high biomass and Cd tolerant energy plant. Previous study has demonstrated SbNRT1.1B expression change is in accordance with enhanced Cd accumulation by external nitrate supply in sweet sorghum. Nevertheless, underlying mechanism of SbNRT1.1B response to Cd stress is still elusive. SbNRT1.1B exhibited a positive response to Cd stress in sweet sorghum. Overexpressing SbNRT1.1B increased primary root length, shoot fresh weight, nitrate and chlorophyll concentrations compared with Col-0 under Cd stress, while complementary SbNRT1.1B rescued these decreased values in mutant chl1–5. Cd concentrations in overexpressing SbNRT1.1B, complementary SbNRT1.1B and Col-0 lines were 3.2–4.1, 2.5–3.1 and 1.2–2.1 folds of that in chl1–5. Consistent with Cd concentrations, non-protein thiol (NPT), reduced glutathione (GSH) and phytochelatins (PCs) concentrations as well as the related genes expression levels showed the same trends under Cd stress. GSH biosynthesis inhibitor failed to reverse the patterns of GSH-dependent PCs concentrations changes in different lines, suggesting that SbNRT1.1B plays an upstream role in GSH-dependent PCs biosynthesis under Cd treatment. Altogether, SbNRT1.1B enhances nitrate concentrations contributing to increased chlorophyll concentrations and GSH-dependent PCs metabolites biosynthesis, thereby improving growth and Cd concentrations in plants.

The alleviating effect on the growth, chlorophyll synthesis, and biochemical defense system in sunflowers under cadmium stress achieved through foliar application of humic acid

BackgroundWith the progress of industrialization and urbanization, cadmium (Cd) pollution in farmland is increasingly severe, greatly affecting human health. Sunflowers possess high resistance to Cd stress and great potential for phytoremediation of Cd-contaminated soil. Previous studies have shown that humic acid (HA) effectively mitigates plant damage induced by Cd; however, its alleviating effects on sunflower plants under Cd stress remain largely unknown.ResultsWe employed four different concentrations of HA (50, 100, 200, and 300 mg L−1) via foliar application to examine their ability to alleviate Cd stress on sunflower plants' growth, chlorophyll synthesis, and biochemical defense system. The results revealed that Cd stress not only reduced plant height, stem diameter, fresh and dry weight, and chlorophyll content in sunflower plants but also altered their chlorophyll fluorescence characteristics compared to the control group. After Cd stress, the photosynthetic structure was damaged and the number of PSII reactive centers per unit changed. Application of 200 mg L−1 HA promotes sunflower growth and increases chlorophyll content. HA significantly enhances antioxidant enzyme activities (SOD, POD, CAT, and APX) and reduces ROS content (O2−, H2O2 and −OH). Totally, Application of 200 mg L−1 HA had the best effect than other concentrations to alleviate the Cd-induced stress in sunflower plants.ConclusionsThe foliar application of certain HA concentration exhibited the most effective alleviation of Cd-induced stress on sunflower plants. It can enhance the light energy utilization and antioxidant enzyme activities, while reduce ROS contents in sunflower plants. These findings provide a theoretical basis for using HA to mitigate Cd stress in sunflowers.

Genome-wide identification of Saccharum Sec14-like PITP gene family reveals that ScSEC14-1 is positively involved in disease resistance

Phosphatidylinositol transfer protein (PITP) plays an important role in lipid metabolism and plant immune response, however its function is less well-known in sugarcane (Saccharum spp.). In this study, 51 SsPITP genes clustered into four groups (I, III, IV, and V), were identified in S. spontaneum. Results showed that expansion of the SsPITP gene family was mainly through whole genome/segmental replication and dispersed replication events, while purification selection was the main driving force for its evolution. Besides, the SsPITP gene family contained cis-regulatory elements related to light, hormone, and stress response in promoter regions. Interestingly, SsPITPs were differentially expressed under Sporisorium scitamineum stress. Furthermore, due to the continuous high expression of SsPITP29 in the sugarcane resistant variety after being infected with S. scitamineum, its homologous gene ScSEC14–1 with 99.69 % amino acid identity was cloned from the sugarcane hybrid cultivar. The results of transient expression in tobacco epidermal cells showed that the ScSEC14–1 protein was localized on the cell membrane and nucleus. Notably, overexpression of ScSEC14–1 increased the expression of phospholipase C genes in transgenic plants by activating the phosphatidylinositol/calcium/MAPK signaling pathways and plant hormone signal transduction, increasing chlorophyll content and catalase activity, reducing malondialdehyde content, thus enhancing disease resistance. This work will help to systematically understand the characteristics of sugarcane Sec14-like PITP gene family and the disease resistance function of the ScSEC14–1.

Functional analysis of maize GRAS transcription factor gene ZmGRAS72 in response to drought and salt stresses

Abiotic stresses, such as drought and salt, are major factors affecting plant growth, development, and productivity. The GRAS gene family is a class of transcriptional regulators in plants that influence plant responses to various biotic and abiotic stresses. In this study, we cloned the maize (Zea mays L.) GRAS gene ZmGRAS72 and preliminarily analyzed its biological function. ZmGRAS72 was highly expressed in maize stems and young leaves, and was induced by abiotic stress and phytohormone treatments. Transient expression assays of maize protoplasts showed that ZmGRAS72 was localized to the nucleus. Heterologous expression of ZmGRAS72 in A. thaliana significantly improved plant tolerance to drought and salt stresses, increased chlorophyll content, decreased malondialdehyde content, and enhanced peroxidase activity. In addition, heterologous expression of ZmGRAS72 in A. thaliana upregulated or downregulated the expression levels of abscisic acid biosynthesis genes (NCED3), signaling genes (ABI1, ABI2, ABI4, and ABI5), and stress-related genes (RD22, RD29A, and KIN1) under abiotic stress. These results indicate that ZmGRAS72 may be responsive to abiotic stress, which forms a basis for further research on the mechanisms underlying the action of ZmGRAS72 in maize.

Optimizing cotton growth in saline soil: Compound microbial agent modulates indigenous bacteria to enhance photosynthesis and vegetative-reproductive balance

Salt-tolerant composite plant growth-promoting rhizobacteria (STC-PGPR) can alleviate salt stress, though its complexity makes its stability and mechanisms in indeterminate-growing crops unclear. We tested STC-PGPR on two cotton (Gossypium hirsutum L.) varieties (G1: Xinluzao 72, G2: Zhongmiansuo 49), with two microbial treatments (B1: none, B2: with STC-PGPR) and three salinity levels (S1: 0 g NaCl kg−1, S2: 4 g NaCl kg−1, S3: 8 g NaCl kg−1). The pot experiment used a three-factor completely randomized design in a greenhouse, with NaCl mixed into the soil before transplanting. STC-PGPR (Paenibacillus polymyxa SC2, Bacillus velezensis DSYZ, Lactobacillus casei DY-3, and Saccharomyces cerevisiae DY-4) was applied 14 days post-transplant and during flowering and boll development. STC-PGPR was diluted with water and applied to the rhizosphere. Results showed that under S1, STC-PGPR increased G2’s seed cotton dry matter accumulation (Sc) by 25.1 %. Under S2, STC-PGPR increased G1’s boll dry matter accumulation (Bo) from 0.21 g to 7.7 g per pot. Other STC-PGPR treatments were less effective due to overdeveloped vegetative organs, highlighting the need for balanced vegetative and reproductive growth. High salinity reduced STC-PGPR effectiveness under S3. Random forest analysis identified crucial indicators regulated by STC-PGPR that significantly affected reproductive organ dry matter accumulation (P<0.001). Bioinformatics and correlation analyses showed biomarkers enriched by STC-PGPR influenced these indicators, not STC-PGPR directly. In S1, G2B2’s biomarkers enhanced stomatal conductance, increasing the net photosynthetic rate (Pn) and promoting dry matter accumulation. They also increased stem diameter and inhibited vegetative growth, enhancing transport and channeling energy to reproductive organs. In S2, G1B2’s biomarkers reduced leaf thickness, increased chlorophyll content to enhance Pn, and extended the maturation period. This enabled cotton to accumulate more photosynthetic products and allocate them to reproductive organs. This study demonstrates that STC-PGPR enhances productivity under salt stress, providing insights for optimizing saline soil cultivation.

Effects of Individual and Combined Applications of Seaweed Extracts and Plant Growth-Promoting Rhizobacteria (PGPR) on Plant Growth and Physio-Biochemical Properties of Soft Wheat and Faba Bean

ABSTRACT The research on carbon materials and plants primarily focuses on their use in soil, showing variable effects. However, significant gaps exist regarding their impact under stress conditions (such as drought, salinity, etc.) and their interactions with plant physiological processes. Long-term effects on plant health and ecosystems are understudied, as are their interactions with other biofertilizers like algae extracts and plant growth-promoting rhizobacteria (PGPR). The aim of the present study was to evaluate the effects of seaweed extracts and PGPR on plant growth and some physio-biochemical properties of soft wheat (Triticum aestivum L.) and faba bean (Vicia faba L.). Two concentrations of aqueous extract from two seaweeds, Fucus spiralis (F) and Ulva rigida (U), and the PGPR bacillus strain solution S48 (S48S) were used either individually or in combination. All treatments were applied as foliar sprays. The findings showed that the combined application of Fucus spiralis extract [25%] (F), Ulva rigida extract [50%] (U), along with the PGPR S48 bacillus strain solution (S48S) promoted plant growth (50.93 cm for faba bean) and root development (17.90 cm for wheat). This treatment also resulted in increased chlorophyll content (3.25 mg/g Fresh Weight (FW) in soft wheat and 3.93 mg/g FW in faba bean), proteins (14.66 µg/mg FW in soft wheat and 23.79 µg/mg FW in faba bean), amino acids (0.46 mg/g FW in soft wheat and 0.56 mg/g FW in faba bean), and total carbohydrates (529.8 µg/ml in soft wheat and 340.7 µg/ml in faba bean) as compared to controls. On the other hand, the nitrate reductase activity was enhanced by seaweed extract application in both crops. Phosphorus (P) uptake by soft wheat and faba bean was significantly improved following the application of Ulva rigida extract [50%] (U), the PGPR S48 bacillus strain solution (S48S), and the co-treatment of Fucus spiralis extract [25%] (F) with the PGPR S48 bacillus strain solution (S48S). The findings suggest that the combined application of Fucus spiralis extract (F) and Ulva rigida extract (U) with the PGPR S48 bacillus strain solution (S48S) can significantly improve plant growth and nutrient absorption in durum wheat and faba bean. This offers a sustainable alternative to chemical fertilizers, reducing pollution and promoting healthier ecosystems. Furthermore, these biological treatments enhance plant resilience to abiotic stresses, potentially increasing yields in challenging conditions. By reducing reliance on chemical fertilizers, these practices can save money for farmers and advance sustainable agriculture.

Dynamic physiological response of tef to contrasting water availabilities.

Global climate change is leading to increased frequency of extreme climatic events, higher temperatures and water scarcity. Tef (Eragrostis tef (Zucc.) Trotter) is an underutilized C4 cereal crop that harbors a rich gene pool for stress resilience and nutritional quality. Despite gaining increasing attention as an "opportunity" crop, physiological responses and adaptive mechanisms of tef to drought stress have not been sufficiently investigated. This study was aimed to characterize the dynamic physiological responses of tef to drought. Six selected tef genotypes were subjected to high-throughput whole-plant functional phenotyping to assess multiple physiological responses to contrasting water regimes. Drought stress led to a substantial reduction in total, shoot and root dry weights, by 59%, 62% and 44%, respectively (averaged across genotypes), and an increase of 50% in the root-to-shoot ratio, relative to control treatment. Drought treatment induced also significant reductions in stomatal conductance, transpiration, osmotic potential and water-use efficiency, increased chlorophyll content and delayed heading. Tef genotypes exhibited diverse water-use strategies under drought: water-conserving (isohydric) or non-conserving (anisohydric), or an intermediate strategy, as well as variation in drought-recovery rate. Genotype RTC-290b exhibited outstanding multifaceted drought-adaptive performance, including high water-use efficiency coupled with high productivity under drought and control treatments, high chlorophyll and transpiration under drought, and faster drought recovery rate. This study provides a first insight into the dynamic functional physiological responses of tef to water deficiency and the variation between genotypes in drought-adaptive strategies. These results may serve as a baseline for further studies and for the development of drought-resistant tef varieties.

Potassium alleviates fluoride accumulation and enhances fluoride tolerance in Camellia sinensis

Tea plants [Camellia sinensis (L.) O. Kuntze] are hyperaccumulators of fluoride (F), but excessive F will harm the photosynthesis and metabolic activities of tea plants. Potassium (K) is one of the essential macronutrients of tea plants, which can enhance the photosynthesis of tea plants and their stress resistance. However, there are fewer studies on K in the accumulation of F in tea plants. In this study, we set three K treatment concentrations of 0 mM, 5 mM, 10 mM and finally found that when the tea plants were treated with F, exogenously applied 5 mM K treatment increased chlorophyll content, photosynthesis, and antioxidant enzyme activity, and reduced the extent of cellular damage, where starch particles content was reduced and the interstices of the chloroplast grana layer were more compact. After K treatment, the F content of new shoots decreased, and the flow rate of absorption of K by roots under F treatment was significantly increased through the Non-invasive Micro-test Technology (NMT), and 5 mM K treatment could effectively stabilize the membrane potential of roots. In addition, after K treatment, the relative expression of the F exporter CsFEX in tea plants was significantly upregulated, while the stress resistance gene expression of CsHAKs in tea plants was downregulated. Above all, appropriate K application could effectively alleviate the hyperaccumulation and stress effects of F on tea plants.

Integrated multi-omic analysis reveals the carbon metabolism-mediated regulation of polysaccharide biosynthesis by suitable light intensity in Bletilla striata leaves

Bletilla striata, valued for its medicinal and ornamental properties, remains largely unexplored in terms of how light intensity affects its physiology, biochemistry, and polysaccharide formation. In this 5-month study, B. striata plants were exposed to three different light intensities: low light (LL) (5–20 μmol m−2·s−1), middle light (ML) (200 μmol m−2·s−1), and high light (HL) (400 μmol m−2·s−1). The comprehensive assessment included growth, photosynthetic apparatus, chlorophyll fluorescence electron transport, and analysis of differential metabolites based on the transcriptome and metabolome data. The results indicated that ML resulted in the highest plant height and total polysaccharide content, enhanced photosynthetic apparatus performance and light energy utilization, and stimulated carbon metabolism and carbohydrate accumulation. HL reduced Chl content and photosynthetic apparatus functionality, disrupted OEC activity and electron transfer, stimulated carbon metabolism and starch and glucose accumulation, and hindered energy metabolism related to carbohydrate degradation and oxidation. In contrast, LL facilitated leaf growth and increased chlorophyll content but decreased plant height and total polysaccharide content, compromised the photosynthetic apparatus, hampered light energy utilization, stimulated energy metabolism related to carbohydrate degradation and oxidation, and inhibited carbon metabolism and carbohydrate synthesis. Numerous genes in carbon metabolism were strongly related to polysaccharide metabolites. The katE and cysK genes in carbon metabolism were strongly related not only to polysaccharide metabolites, but also to genes involved in polysaccharide biosynthesis. Our results highlight that light intensity plays a crucial role in affecting polysaccharide biosynthesis in B. striata, with carbon metabolism acting as a mediator under suitable light intensity conditions.