Chlorophyll Content Research Articles

Mixed application of raw amino acid powder and Trichoderma harzianum fertilizer for the prevention and management of apple replant disease

Apple replant disease (ARD) is mainly caused by biological factors, and it severely restricts the development of the apple industry. The use of biological control measures to alleviate ARD is critically important for the sustainable development of the apple industry. The effects of raw amino acid powder and Trichoderma harzianum fertilizer on plant biomass, leaf and root indexes, soil physical and chemical properties, soil enzyme activity, and the soil fungal community were studied under pot and field conditions using Malus hupehensis Rehd. seedlings and grafted trees (Fuji New 2001/M9T337) as experimental materials. We found that the application of the materials significantly promoted plant growth, increased the leaf photosynthesis and chlorophyll content, root respiration rate, root antioxidant enzyme activity, and soil enzyme activity, significantly decreased the number of Fusarium sp. in soil, and significantly increased the abundance of beneficial bacteria. In conclusion, the mixed application of raw amino acid powder and Trichoderma harzianum fertilizer can is an effective method for the prevention and management of ARD.

Magnesium-Doped Carbon Quantum Dot Nanomaterials Alleviate Salt Stress in Rice by Scavenging Reactive Oxygen Species to Increase Photosynthesis.

Salt stress has strongly impacted the long-term growth of eco-friendly farming worldwide. By targeting the oxidative stress induced by salt, the utilization of biomass-derived carbon dots (CDs) that possess high-efficiency antioxidant properties, are nontoxic, and have excellent biocompatibility represents a viable and effective approach for enhancing the salt tolerance of plants. In this study, we blended magnesium oxide nanoparticles with carbon sources derived from durian shells to construct Mg-doped carbon dots (Mg-CDs) through a hydrothermal reaction. We demonstrated that the foliar application of 150 μg/mL Mg-CDs to rice plants after treatment with 100 mM salt effectively increased the plant height (9.52%), fresh weight (22.41%), dry weight (33.33%), K+ content (21.46%), chlorophyll content (36.21%), and carotenoid content (16.21%); decreased the malondialdehyde (MDA) (9.43%), Na+ (25.75%), H2O2 (17.50%), and O2•- contents (37.99%); and promoted the photosynthetic system and antioxidant activity. Transcriptome analysis revealed that Mg-CD pretreatment triggered transcriptional reprogramming in rice seedlings. The enrichment analysis of the Kyoto Encyclopedia of Genes and Genomes pathways based on trend groups of gene expression patterns of Profile 8 and Profile 15 indicated that priming with Mg-CDs activated stress signaling- and defense-related pathways, such as metabolic pathways, biosynthesis of secondary metabolites, and photosynthesis pathways. These activations subsequently prompted the expression of genes related to the mitogen-activated protein kinase signaling pathway, hormone signal transduction, the oxidative stress response, and the photosynthetic system. This study demonstrated that the use of Mg-CDs represents a potential strategy to increase plant salt tolerance, creating the possibility for the regulation of crop salinity stress and offering valuable advancements in sustainable agriculture.

The addition of humic acid into soil contaminated with microplastics enhanced the growth of black gram (Vigna mungo L. Hepper) and modified the rhizosphere microbial community.

Microplastics have polluted agricultural soils, posing a substantial risk to crop productivity. Moreover, the presence of microplastic pollution has caused a disturbance in the composition of the microbial community in the soil surrounding plant roots, therefore impacting the growth of beneficial bacteria. A study was conducted to examine if humic acid (HA) can counteract the harmful effects of microplastics (MPs) on the growth of black gram crops and the composition of the rhizosphere soil microbial community, to reduce the negative impacts of microplastics on these microorganisms and crops. The research was carried out using mud pots and the plastic utilized for the experiment consisted of 60% high-density polyethylene (HDPE) and 40% polypropylene (PP). The soil was enriched with lignite-based potassium humate, which had a pH range of 8.0-9.5 and with 65% humic acid. The experiment consisted of six treatments: T1, which served as the control without HA and MP; T2, which involved the use of HA at a concentration of 0.15% w/w; T3, which involved the use of MP at a concentration of 0.2% w/w; T4, which involved the use of MP at a concentration of 0.4% w/w; T5, which involved the combination of HA at a concentration of 0.15% w/w and MP at a concentration of 0.2% w/w; and T6, which involved the combination of HA at a concentration of 0.15% w/w and MP at a concentration of 0.4% w/w. The plant growth characteristics, including germination percentage, nodule number, and chlorophyll content, were measured. In addition, the DNA obtained from the rhizosphere soil was analyzed using metagenomics techniques to investigate the organization of the microbial population. Seedlings in soil polluted with MP exhibited delayed germination compared to seedlings in uncontaminated soil. Following 60days of growth, the soil samples treated with T5 (0.2% MP and 0.15% HA w/w) had the highest population of bacteria and rhizobium, with counts 5.58 ± 0.02 and 4.90 ± 0.02CFUg-1 soil. The plants cultivated in T5 had the most elevated chlorophyll-a concentration (1.340 ± 0.06mgg-1), and chlorophyll-b concentration (0.62 ± 0.02mgg-1) while those cultivated in T3 displayed the lowest concentration of chlorophyll-a (0.59 ± 0.02mgg-1) and chlorophyll-b (0.21 ± 0.04mgg-1). Within the phylum, Proteobacteria had the highest prevalence in all treatments. However, when the soil was polluted with MPs, its relative abundance was reduced by 8.4% compared to the control treatment (T1). Conversely, treatment T5 had a 3.76% rise in relative abundance when compared to treatment T3. The predominant taxa found in soil polluted with MP were Sphingomonas and Bacillus, accounting for 19.3% of the total. Sphingomonas was the predominant genus (21.2%) in soil polluted with MP and supplemented with humic acid. Humic acid can be used as a soil amendment to mitigate the negative effects of MPs and enhance their positive advantages. Research has demonstrated that incorporating humic acid into soil is a viable method for maintaining the long-term integrity of soil's physical, chemical, and biological characteristics.

An Innovative Approach: Alleviating Cadmium Toxicity in Grapevine Seedlings Using Smoke Solution Derived from the Burning of Vineyard Pruning Waste.

Although plant-derived smoke solutions (SSs) have exhibited growth-promoting properties in various plant species, their potential role in mitigating heavy metal stress, specifically in grapevines, has remained unexplored and unreported. This knowledge gap prompted the present study to evaluate the efficacy of foliar application of SSs derived from vineyard pruning waste at concentrations of 0%, 0.5%, 1%, and 2% in mitigating Cadmium (Cd) phytotoxicity in grape saplings. In our study, cadmium stress was induced by applying 10 mg/kg CdCl2 to the root area of the saplings, in conjunction with fertilizers. Our findings showed that exposure to Cd toxicity impeded the growth of grapevine saplings, adversely affecting shoot and root length, as well as fresh weight. Furthermore, it resulted in a reduction in chlorophyll content, stomatal conductance, and leaf water content while significantly increasing membrane damage and lipid peroxidation. Notably, the application of 0.5% SS enhanced grapevine sapling growth and alleviated Cd stress-induced damage by more effectively regulating physiological and biochemical responses compared to the control and other concentrations. Based on our results, under Cd stress conditions, the application of 0.5% SS effectively increased chlorophyll content, relative water content (RWC), stomatal conductance (1.79 mmol.m-2.sn-1), and total phenolic content (1.89 mg.g-1), whereas it significantly reduced malondialdehyde (MDA) levels and membrane damage (1.35 nmol.g-1). Additionally, it significantly elevated the activities of antioxidant enzymes, including superoxide dismutase (SOD) (2.16 U.mg-1), catalase (CAT) (1.55 U.mg-1), and ascorbate peroxidase (APX) (3.03 U.mg-1). The study demonstrated that plant-derived SS mitigates Cd stress in grapevines by enhancing antioxidative defence mechanisms.

Nitrogen status of durum wheat derived from Sentinel-2 satellite data in Central Italy

In agriculture, nitrogen (N) is a key element in plant nutrition that affects, both positively and negatively, the productive and qualitative results of the crop. Accurate quantification of nitrogen levels is crucial for devising effective plant nutrition strategies. The objective of this study was to validate a novel method to estimate the N content at different phenological stages of durum wheat (Triticum durum Desf. cv. Iride) under different N management strategies (chemical synthetic fertilizer - SYN and organic fertilizer - ORG) in Italy, using the Nitrogen Nutrition Index (NNI)as a diagnostic tool for improving nitrogen fertilization timing and doses. The NNI is the ratio between the actual crop nitrogen content (Na) and the optimal level (Nc) required for ideal growth conditions.On ground level, Leaf Area Index (LAI) , Canopy reflectance, leaf chlorophyll content (LCC) and N concentration in leaves were measured. At landscape level, LAI and Canopy Chlorophyll Indices (CIs) were derived from Sentinel 2 (S2) multispectral images captured on the same days as the ground measurements: Chlorophyll Indexes were used for estimating the canopy chlorophyll content, CCC. Na in leaves and canopy were calculated from LCC and CCC respectively.In the study area, Nc is Nc=4.65LAI–0.35, R2=0.92. Among the tested Chlorophyll Indices (CIs) regression models, the linear regression was the more accurate to predict Na content, even though most of the tested Chlorophyll Indices (CIs) showed an R2 > 0.8,a. The best-performing spectral index in both calibration and validation steps resulted from the IRECI, with R2=0.90 and RMSE=0.31. The developed NNI well-captured the seasonal N dynamic for durum wheat, under different N management and meteorological conditions. The NNI calculated from S2 data for crop N status assessment, showed to be an accurate estimation of the Nitrogen Nutrition Index and can be used for the fertilization plans without costly on ground measurements.

Phytomonitoring of Air Pollution Around Brick Kilns in Urban Area: Exploring the Potential of Plants for the Remediation of Pollutants

This study examines the impacts of various pollutants on foliar biochemical parameters, including relative water content (RWC), total chlorophyll, leaf extract pH, and ascorbic acid content, and their relationship with the Air Pollution Tolerance Index (APTI). RWC, a crucial indicator of plant resilience, showed a significant positive correlation with APTI values (r = 0.4503, p < 0.05). Species with higher RWC, such as Carica papaya and Cassia fistula, demonstrated enhanced tolerance to pollutants, with RWC values reaching up to 85%. Chlorophyll content, which is vital for photosynthesis, exhibited a significant reduction in polluted areas, with levels ranging from 0.28 to 3.23 mg/g (p < 0.05). Notably, Cassia fistula had high APTI values but lower chlorophyll content, reflecting the complex relationship between tolerance and chlorophyll levels. Leaf extract pH was significantly lower in polluted areas, with pH values consistently below 7, correlating with higher APTI values (p < 0.05). Ascorbic acid content, an important antioxidant, was significantly higher in plants exposed to pollution, with positive correlations to APTI (r = 0.9214) and pH levels (r = 0.62). Principal Component Analysis (PCA) identified that pH, ascorbic acid, and APTI were positively correlated, while total chlorophyll and RWC showed opposing trends. Sensitivity analysis indicated that RWC (95.84% impact on Carica papaya and 85.92% on Cassia fistula) and pH were the primary factors influencing APTI and Metal Accumulation Index (MAI) values. The findings underscore the role of RWC, chlorophyll, pH, and ascorbic acid as biomarkers for plant responses to pollution and highlight the effectiveness of species with high MAI values in heavy metal accumulation and environmental monitoring.

Double infection of Nicotiana benthamiana with AMV and WCMV increases both virus concentrations and synergistically changes both host organelle ultrastructure and chlorophyll content

To clarify the synergistic pathogenic mechanism of Nicotiana benthamiana double infection with alfalfa mosaic virus (AMV) and white clover mosaic virus (WCMV), AMV and WCMV co-inoculation of N. benthamiana as treatment and single inoculation of AMV or WCMV and phosphate buffer solution (pH 7.0, PBS) as control, respectively. The concentrations and the relative expression of AMV and WCMV coat proteins were determined by a double antibody sandwich enzyme-linked immune sorbent assay (DAS-ELISA) and real-time fluorescence quantitative PCR (RT-qPCR) in a double infection of N. benthamiana with AMV and WCMV. Meanwhile, virion morphology, ultrastructure morphology, and chlorophyll content were observed and determined by electron microscopy. The results showed that the diseased symptoms were more serious, and virus concentration and relative expression of AMV and WCMV coat proteins were also higher in N. benthamiana double infection with AMV and WCMV than in AMV or WCMV single infection. The main symptoms manifested as severe mottle mosaic, shrinkage, and chlorosis. The concentrations of AMV and WCMV were 182.23pg/mL and 148.77pg/mL of double infection with AMV and WCMV, which were 1.75-fold and 1.62-fold than AMV and WCMV single infection, respectively. The relative expression of AMV and WCMV coat proteins was 4.25-fold and 2.50-fold than the single virus infection, respectively. Electron microscopy also observed that chloroplast malformation, cell membrane deformation, contents dissolution, grana lamella disorder, fat granules increased and enlarged, starch granules enlarged, and mitochondria were seriously malformed in a double infection of N. benthamiana with AMV and WCMV. The chlorophyll content was significantly lower for double infection with AMV and WCMV than for AMV or WCMV single-infected and CK, reduced by 31.52%, 22.83%, and 76.09%, respectively. This is the first report of a double infection of N. benthamiana with AMV and WCMV that increases both virus concentrations and synergistically changes both host organelle ultrastructure and chlorophyll content.

Effect of viral-inoculation on the morphology, physiology, and phytochemistry of parsley (Petroselinum crispum)

Petroselinum crispum known as parsley is widely used in raw material food and culinary. In this study, the effects of three different viruses, parsley yellow leaf curl virus (PYLCV), sesame curly top virus (SeCTV), and cucumber mosaic virus (CMV), on parsley morphological, physiological, biochemical, and phytochemical characteristics, were investigated. To repeat the entire experiment, the study was conducted over two growing seasons using a completely randomized design. The results showed that all three viruses significantly reduced plant biomass, photosynthesis, greenness, and chlorophyll content. The Fv/Fm ratio, results revealed that PYLCV was more stress-inducing than SeCTV and CMV. Although PYLCV reduced essential oil (EO) content, SeCTV and CMV increased EO content. In addition to changes in all physiological and morphological parameters of parsley during virus-inoculation, the main component of parsley EO, myristicin, ranged from 37% to 73%. These results have profound implications for sustainable viral disease management, emphasizing the importance of understanding virus impacts on important plants to enhance crop resilience and ensure food quality and safety. This knowledge is crucial for optimizing phytochemical production and mitigating the effects of viral infections.

The dwarf & pale leaf mutation reduces chloroplast numbers, resulting in sugar depletion that inhibits leaf growth of maize seedlings

Plant growth is ultimately driven by cell division and expansion, but how these processes are regulated to mediate a wide range of genotypic variation in organ size is still poorly understood. To address this, we screened an EMS maize mutant population to identify a new EMS maize dwarf mutant with small, pale-yellow leaves (dpl). The mutation was mapped to a region of 11.58Mb at the 3’ end of chromosome 7. We identified Zm00001d022394 as a potential causal gene for the dpl phenotype, encoding a pentatricopeptide repeat-containing (PPR) family protein involved in chloroplast gene expression and function, explaining the pale color of dpl. Mature dpl leaves are thinner and shorter due to a reduced number of cells of approximately normal length. The chloroplasts of dpl are reduced in size and number, correlating with a decreased chlorophyll content, however chloroplast ultrastructure was not affected. Consistent with the reduced chlorophyll content photosynthetic rate of dpl were reduced by 50% and a 30 reduction of Fv/Fm suggests photoinhibition. As a consequence, soluble and insoluble sugar levels are severely reduced throughout the leaf growth zone. At the cell level reduced cell division rates and size of the division zone, explain the reduced leaf elongation rate (LER). The growth of dpl leaves can be restored by supplying growing leaves with sucrose through their cut tips, which also restores sucrose levels in the division zone of maize leaf, demonstrating that limited sugar availability explains the reduced growth phenotype. Inversely, we phenocopied the mutant growth phenotype by inhibiting photosynthetic electron transport in wild type plants with DCMU (3-(3,4-dichlorophenyl)-1,1-dimethylurea). Our study of dpl provides a functional link between inhibition of photosynthesis, soluble sugar flux to the leaf growth zone, the regulation of cell division and whole leaf growth.

Copper sulfate-induced stress in Spinach: Metabolic pathway disruption and plant response

Copper sulfate (CuSO4) stress profoundly affects plant growth by interfering with key metabolic pathways. This disruption leads to significant alterations in various physiological parameters, ultimately impacting the overall health and productivity of the plant. This study assessed the impact of CuSO4 stress on spinach (Spinacia oleracea L.) through a pot experiment using CuSO4 concentrations of 0, 75, 125, and 175 ppm. We noticed that at 75 ppm, CuSO4 improved plant height and the concentration of soluble sugar and ascorbic acid compared to the control. Additionally, amino acid, phenol, proline, fresh weight, and moisture content peaked at 175 ppm. Conversely, at 125 and 175 ppm, plant height, dry weight, leaf area, and concentrations of ascorbic acid and sugar significantly decreased. Moreover, at 175 ppm, there were substantial decreases in chlorophyll a (14.8%), chlorophyll b (73.6%), carotenoids (15%), and photosynthetic rates compared to the control. However, the chlorophyll a to chlorophyll b ratio increased by 29.53% at 175 ppm. In addition, protein and phenol contents diminished at 75 and 125 ppm. Elevated CuSO4 levels increased non-protein thiol levels while reducing the activities of superoxide dismutase, catalase, ascorbate peroxidase, and glutathione peroxidase. Stress hormones such as abscisic acid, jasmonic acid, and ethylene increased with CuSO4 stress, whereas growth hormones indol-acetic acid and gibberellic acid declined. This study demonstrates that spinach shows improved growth and metabolic function at 75 ppm CuSO4, indicating tolerance to mild stress. However, higher CuSO4 concentrations (125 and 175 ppm) significantly reduce growth parameters, chlorophyll content, and enzyme activities, highlighting the need for careful CuSO4 management in agriculture to avoid adverse effects on plant health and productivity.

How to combine soil and plant indicators to manage nitrogen fertilisation in vineyards?

ContextAlthough grapevine nitrogen (N) needs are moderate, N fertilisation in vineyards requires carefully management because berry development, aromatic composition and hence winemaking are largely influenced by N nutrition. Our objective was to develop a method for reasoned N fertilisation between and during the seasons. MethodsSpecific sensitivities of soil and plant indicators to N supply and availability were estimated and indicator robustness was quantified using contrasted environmental conditions, crop management and N fertilisation in an experimental network comprising five vineyards in southern France over four successive years. The effects of four N fertilisation treatments combining contrasted amounts, forms and timing on the indicators were tested using linear models. Multiple factorial multiple analysis was used to study the effect of environmental and management factors on indicator sensitivity to mineral N fertilisation at budburst. ResultsYield, soil mineral nitrogen at budburst, chlorophyll concentration (SPAD) at veraison, leaf nitrogen content and yeast assimilable nitrogen (YAN) at harvest, were all sensitive to N fertilisation after four years. Different effects of the N treatments were observed from year three for SPAD and from year one for YAN. Additionally, SPAD and YAN indicators distinguished contrasted strategies based on different timings of N supply or the form of N fertiliser. Lastly, the response of the SPAD and YAN indicators was only slightly influenced by pedoclimatic conditions or cultural practices, at least for the variables tested here. ConclusionTwo N indicators measured from veraison (SPAD) to harvest (YAN), can provide valuable information for tactical and long-term fertilisation decisions. Notably, early SPAD information may improve technical vineyard management of interactions between fertilisation and other practices (e.g. weed control or tillage) that interfere with plant N nutrition and enable later correction of YAN values. Combining these indicators with non-destructive imaging techniques should improve N and mineral monitoring in general.

BoaCRTISO regulates the color and glossiness of Chinese kale through its effects on pigment, abscisic acid, and cuticular wax biosynthesis

Carotenoid isomerase (CRTISO) is an important enzyme in carotenoid biosynthesis, and it catalyzes the conversion of lycopene precursors to lycopene in several plant species. However, the role of CRTISO in other biochemical processes during plant growth and development remains unclear. Here, we showed that Chinese kale boacrtiso mutants have distinctive characteristics, including a yellow-green hue and glossy appearance, and this contrasts with the dark green and glaucous traits observed in wild-type (WT) plants. Analysis of pigments in mutants revealed that the reduction in the content of carotenoids and chlorophylls contributed to the yellow-green coloration observed in mutants. An examination of cuticular waxes in Chinese kale indicated that there was a decrease in both the total wax content and the content of individual waxes in boacrtiso mutants (bearing a mutation of BoaCRTISO), which may be caused by the decrease of abscisic acid (ABA) content. The expression of carotenoid, chlorophyll, ABA, and wax biosynthesis genes was down-regulated in boacrtiso mutants. This finding confirms that BoaCRTISO regulates the biosynthesis of pigments, ABA, and cuticular waxes in Chinese kale. Our results provide new insights into the interplay between plant pigment and cuticular wax metabolic pathways in Brassica vegetables.

SWATH-MS based proteomics reveals the role of photosynthesis related proteins and secondary metabolic pathways in the colored leaves of sweet olive (Osmanthus fragrans)

Colored leaves, a notable horticultural trait, have high research and ornamental value. The evergreen sweet olive (Osmanthus fragrans), one of the top ten traditional flowers in China, has been cultivated for more than two thousand years. However, in recent years, an increasing number of O. fragrans cultivars with colored leaves have been cultivated for their ornamental value. To study the molecular mechanism underlying the observed changes in leaf color, we selected O. fragrans ‘Yinbi Shuanghui’ (Y), which has yellow-white leaves, and O. fragrans ‘Sijigui’ (S), which has green leaves, as materials. Pigment content measurement showed that the chlorophyll, carotenoid and anthocyanin contents in Y were lower than in S. According to the SWATH-MS sequencing results, a total of 3,959 proteins were quantitatively identified, 1,300 of which were differentially expressed proteins (DEPs), including 782 up-regulated and 518 down-regulated proteins in Y compared to S. Functional enrichment analysis of DEPs revealed that down-regulated expression of photosynthesis related proteins may lead to the inhibition of chlorophyll synthesis in Y, this may be the main cause of leaf color change. Moreover, a protein interaction prediction model also showed that proteins such as PetC, PsbO, PsbP, and PsbQ were key proteins in the interaction network, and the up-regulated proteins participating in the anthocyanin and carotenoid pathways may be related to the formation of yellow-white leaves. Taken together, our findings represent the first SWATH-MS-based proteomic report on colored leaf O. fragrans and reveal that chlorophyll synthesis and secondary metabolism pathways contribute to the changes in leaf color.

Effects of different drying methods on the nutritional components, microstructure, and metabolomic profile of Spirulina maxima

Spirulina maxima (S. maxima) is considered a potential solution to address the issue of human food security. In this study, three drying methods were employed: spray drying (SD), freeze drying (FD), and vacuum drying (VD), to process fresh S. maxima (FS). A comprehensive nutritional evaluation was conducted using principal component analysis and cluster analysis, along with an untargeted metabolomics study. The results indicated that after SD, FD, and VD treatments, the phycocyanin content decreased by 23 %, 9 %, and 80 %, respectively, compared to that of the FS. The polysaccharide content also significantly decreased by 36 %, 33 %, and 67 %, respectively. Comprehensive analysis showed that SD resulted in the least loss of nutritional indicators in S. maxima. Further metabolomics analysis revealed that prolonged exposure to high temperatures can lead to metabolic disruptions in 2-oxocarboxylic acid metabolism, purine metabolism, amino acid biosynthesis, and starch and sucrose metabolism. Additionally, the levels of coproporphyrin I and coproporphyrin III increased which ultimately led to a decrease in chlorophyll and phycocyanin contents. Therefore, VD resulted in the poorest quality of S. maxima. This study provided a theoretical basis for the quality assessment of S. maxima in response to drying.

Effect of different drying temperature settings on the color characteristics of Tencha

Color is critical factor in the commercialization of Matcha. In this study, sensory evaluation, color difference analysis, as well as targeted and non-targeted analyses were employed to investigate the impact of different drying temperature settings on the color characteristics of Tencha. The findings revealed that compared to a single drying temperature setting, a two-stage or multi-stage drying process more effectively preserved the color quality of Tencha. Specifically, a setting involving an initial period of high-temperature drying followed by low-temperature drying (samples T_6, T_7, T_10, and T_13) resulted in superior tea color quality, characterized by higher chlorophyll content and lower levels of lutein and β-carotene. Chemometric analysis identified chlorophylls and their derivatives (chlorophyll a/b, pheophytin a/b, pyropheophytin a/b) as the key factors influencing Tencha's color. These results can provide valuable insights for optimizing tea processing methods to enhance quality.

Comprehensive analysis of Capsicum annuum CaLhcs uncovered the roles of CaLhca5.1 and CaLhcb1.7 in photosynthesis and stress tolerance

The light-harvesting chlorophyll a/b-binding proteins (Lhcs) are integral to plants' capture and transfer of light energy during photosynthesis. However, the Lhc gene family remains unexplored in pepper. In this study, 37 CaLhcs (Capsicum annuum Lhc) were identified from the reference genome and classified into five subfamilies (Lhca, Lhcb, CP24, CP26, and CP29) based on phylogenetic relationships and conserved domains, with members of each subfamily displaying similar conserved motifs and gene structures. cis-element analysis revealed an enrichment of light-responsive elements within CaLhcs (46.1 %). Transcriptome analysis showed that most CaLhcs are specifically expressed in leaves, flowers, and pericarp and are responsive to stressors, including NaCl, cold, heat, H2O2, and d-mannitol. Post-transcriptional regulation analysis identified 11 miRNAs that target nine CaLhcs through cleavage. RT-qPCR analysis validated the involvement of CaLhcs in response to NaCl stress. Localization studies confirmed that CaLhca4.1, CaLhcb1.1, CaLhca1.7, CaLhcb1.11, and CaLhcb6.1 are chloroplast-localized, whereas CaLhca5.1 localizes in the nucleus. Overexpression of CaLhcb1.7 and CaLhca5.1 increased chlorophyll content and net photosynthetic rate, enhancing photosynthesis. Additionally, CaLhcb1.7 and CaLhca5.1 reduced ROS accumulation, bolstering the plant's resistance to pathogens and salt stress. These findings provide a foundation for further exploration of CaLhcs in photosynthesis and stress tolerance mechanisms.

Higher endogenous abscisic acid confers greater tolerance to saline-alkaline stress in Petunia hybrida

Saline-alkaline stress not only leads to reduced crop yields but also diminishes the ornamental value of flowers. While petunia exhibits tolerance to saline-alkaline stress, research on the mechanisms underlying this tolerance remains unreported. We investigated the physiological and molecular mechanisms underlying saline-alkaline stress tolerance using two petunia genotypes (Haishishenlou and Mitchell Diploid) with differing tolerance levels. Haishishenlou exhibited less inhibition of growth under saline-alkaline stress compared to Mitchell Diploid, as indicated by higher biomass. Higher endogenous concentration of abscisic acid (ABA) and greater expression levels of ABA biosynthetic genes and lower expression levels of ABA catabolic genes in Haishishenlou than in Mitchell Diploid were observed when challenged by saline-alkaline stress, suggesting that a higher concentration of ABA may underpin the greater tolerance of Haishishenlou to saline-alkaline stress than that of Mitchell Diploid. Under saline-alkaline conditions, Haishishenlou displayed higher chlorophyll content, photosynthetic rates, Pro and soluble sugars content, as well as higher activities of catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD), and a lower Na+/K+ ratio. Exogenous application of ABA alleviated the growth inhibition induced by saline-alkaline stress, promoted the accumulation of proline and soluble sugar, reduced reactive oxygen species (ROS) content and Na+/K+ ratio, and improved antioxidative capacity. These results indicated that a higher endogenous concentration of ABA may underpin the greater tolerance of petunia seedlings to saline-alkaline stress, and exogenous ABA improves the saline-alkaline tolerance of petunia seedlings.

Biodegradable microplastics induce profound changes in lettuce (Lactuca sativa) defense mechanisms and to some extent deteriorate growth traits

The development of agricultural technologies has intensified the use of plastic in this sector. Products of plastic degradation, such as microplastics (MPs), potentially threaten living organisms, biodiversity and agricultural ecosystem functioning. Thus, biodegradable plastic materials have been introduced to agriculture. However, the effects of biodegradable plastic substitutes on soil ecosystems are even less known than those of traditional ones. Here, we studied the effects of environmentally relevant concentrations of MPs prepared from a biodegradable plastic (a starch-polybutylene adipate terephthalate blend, PBAT-BD-MPs) on the growth and defense mechanisms of lettuce (Lactuca sativa) in CLIMECS system (CLImatic Manipulation of ECosystem Samples). PBAT-BD-MPs in the highest concentrations negatively affected some traits of growth, i.e., dry weight percentage, specific leaf area, and both C and N contents. We observed more profound changes in plant physiology and biochemistry, as PBAT-BD-MPs decreased chlorophyll content and triggered a concerted response of plant defense mechanisms against oxidative stress. In conclusion, exposure to PBAT-BD-MPs induced plant oxidative stress and activated plant defense mechanisms, leading to oxidative homeostasis that sustained plant growth and functioning. Our study highlights the need for in-depth understanding of the effect of bioplastics on plants.

Biofilmed-PGPR: Next-Generation Bioinoculant for Plant Growth Promotion in Rice under Changing Climate

The exopolysaccharide matrix of the diazotrophic cyanobacteria was used to integrate the phosphorus (P) and potassium (K) solubilizing bacteria for enhanced survival of the plant growth-promoting bacteria and, ultimately, survival of bacteria in the rhizosphere for better plant growth. A new biofilm-based formulation comprising the diazotrophic cyanobacteria Anabaena AMP2, phosphorus-solubilizing Bacillus megaterium var. phosphaticum PB1, and potassium-solubilizing Rhizobium pusense KRBKKM1 was tested for efficacy in rice. The growth medium with half-strength BG-11 medium supplemented with 3% glucose showed best for biofilm formation under in vitro conditions. Analysis of the methanolic extract of the cyanobacterial-bacterial biofilm (CBB) showed antioxidants, such as 2-methoxy phenol and pentadecane, which are proven to improve plant-microbe interactions and plant growth promotional activity, respectively. Treatment of rice seeds with CBB extract at 10 mL or 20 mL/100 g showed significant enhancement in germination percentage and seedling length. Therefore, a pot culture experiment with the CBB formulations was carried out, and different growth and yield parameters were recorded. Principal component analysis showed that the plant growth, yield, soil dehydrogenase activity, and soil chlorophyll content were positively correlated with rice plants amended with vermiculite-based CBB at 2 kg/hm2 followed by a spray with aqueous CBB formulation at 5 mL/L on 15 and 30 d after the rice transplanting (T6) grown with a 25% reduced level of NPK chemical fertilizers than the recommended dose. Further, Pearson correlation analysis showed that yield was positively correlated with soil dehydrogenase (r = 0.92**) and soil chlorophyll content (r = 0.96**). We concluded that CBB could be used as a novel biofilm-based bio-inoculant to increase rice productivity and crop fitness as a component in integrated nutrient management and sustainable organic farming strategies with reduced chemical fertilizers.

Screening of saline-alkali tolerant microorganisms and their promoting effects on rice growth under saline-alkali stress

Soil salinization poses a global challenge, and cultivating rice on saline-alkali lands is a recognized strategy for exploiting and ameliorating these challenging environments, however, the yield and quality of rice are significantly lower compared to cultivation on non-saline lands. This study focused on the utilization of saline-alkali tolerant plant-growth-promoting microorganisms (PGPRs) and organic matter. Four PGPR strains were identified and subsequently fermented and propagated, and then combined in equal proportions and mixed with cow manure compost to prepare a PGPR amendment. This amendment was applied to rice cultivated in pots under saline-alkali stress. Agronomic traits were monitored at various growth stages to assess the amendment's impact on rice development. The results showed that under moderate saline-alkali stress, PGPR amendments significantly improved the physicochemical indicators of rice. Compared with the control group, rice plant height, root length and chlorophyll content increased by 113.56%, 43.19% and 95.43%, respectively. The antioxidant enzyme increased by 39.86%, and the levels of soluble sugars and proteins increased by 20.91% and 27.28%, respectively. Notably, rice under moderate saline-alkali stress showed greater improvements in response to the amendment compared to rice under mild stress conditions. These findings suggest that the amendments effectively mitigate the adverse effects of saline-alkali stress on rice growth, thereby offering a viable strategy for enhancing crop productivity in affected areas.