[Effects of effective microorganisms on growth promotion and the rhizosphere eukaryotic community structure of pepper in Xinjiang, China]. / å¤åˆèŒå‰‚å¯¹æ–°ç–†è¾£æ¤’çš„ä¿ƒç”Ÿæ•ˆæžœå’Œæ ¹é™ çœŸæ ¸ç”Ÿç‰©ç¾¤è½ç»“æž„çš„å½±å“.

Effective microorganisms (EM) might alleviate deterioration of soil environmental quality and yield decline of pepper (Capsicum annuum) caused by continuous replanting and imbalanced fertilizer application in Xinjiang. We investigated the effects of applying EM microbial agent on the growth of pepper plants, yield, soil nutrient content, soil enzyme activity, and rhizosphere eukaryotic community. The results showed that the application of EM microbial agent increased plant height, stem diameter, leaf length, leaf width and root length by 22.6%, 35.3%, 33.3%, 29.7% and 15.1%, respectively. It also increased fruit width, individual fruit weight, and yield by 5.3%, 42.9%, and 74.7%, respectively. After the application of EM microbial agent, the levels of soil available nitrogen increased by 10.2% and 5.8% during the flowering and maturity stages, respectively. Similarly, available phosphorus increased by 10.4% and 13.4%, respectively. The soil sucrase activity was increased by 40.7%, 14.6%, and 9.3% during the seedling, flowering, and maturity stages, respectively. Urease activity was also increased by 7.9%, 10.2%, and 11.5%, respectively. Furthermore, the application of EM microbial agent increased soil peroxidase activity by 16.8% and 44.6% at flowering and maturity stages, respectively. The application of microbial agent significantly altered the ß-diversity of the rhizosphere eukaryotic community in pepper plants. Specifically, microbial agent increased the relative abundances of populations belonging to Enchytraeus and Sminthurides genera, which could contribute to soil improvement and nutrient cycling. Compared to the CK, the relative abundance of pathogenic microorganisms including Olpidium and Aplanochytrium genera decreased by 98.0% and 89.3%, and the relative abundance of the Verticillium decreased to 0. These results demonstrated that EM microbial agent could increase soil nutrient content, enhance soil enzyme activity, and reduce soil pathogenic fungi in the pepper cultivation areas of Xinjiang, thus achieving beneficial effects on pepper growth and fruit yield.

Microplastic accumulation and oxidative stress in sweet pepper (Capsicum annuum Linn.): Role of the size effect.

Microplastics (MPs), which are widely dispersed in terrestrial environments, threaten crop growth and human food security. However, plant accumulation and phytotoxicity related to the size effects of MPs remain insufficiently explored. This study investigated the accumulation and toxicity of two sizes of MPs on Capsicum annuum Linn. (C. annuum) through fluorescence tracing and antioxidant defense system assessment. The results revealed that the size of MPs significantly impacts their accumulation characteristics in C. annuum roots, leading to variations in toxic mechanisms, including oxidative stress and damage. Smaller MPs and higher exposure concentrations result in more pronounced growth inhibition. C. annuum roots have a critical size threshold for the absorption of MPs of approximately 1.2 µm. MPs that enter the root tissue exhibit an aggregated form, with smaller-sized MPs displaying a greater degree of aggregation. MP exposure induces oxidative stress in root tissues, with high concentrations of smaller MPs causing lipid peroxidation. Analysis of the IBR values revealed that C. annuum roots utilize ascorbic acid (ASA) to prevent oxidative damage caused by larger MPs. Conversely, smaller MPs primarily induce superoxide dismutase (SOD) and glutathione (GSH). These results emphasize the significant impact of MP size on plant antioxidant defense response mechanisms, laying the foundation for further investigating the implications for human health.

Maintaining quality of postharvest green pepper fruit using melatonin by regulating membrane lipid metabolism and enhancing antioxidant capacity.

Green pepper quality often deteriorates during storage because of membrane lipid damage and oxidative stress. This study investigated the effects of exogenous melatonin (MT) on green pepper storage quality, membrane lipids, and antioxidant metabolism. The results showed that MT increased the activities of superoxide dismutase, catalase, ascorbate peroxidase, peroxidase, monodehydroascorbate reductase, and dehydroascorbate reductase in green peppers compared to the control group. It upregulated expression of multiple enzymes; reduced accumulation of reactive oxygen species such as dehydroascorbic acid, H2O2, and O2.-; and maintained high ascorbic acid, glutathione, coenzyme II, and nicotinamide adenine dinucleotide while reducing oxidized glutathione levels. In addition, MT decreased lipoxygenase and phospholipase D activities, downregulated ReLOX and RePLD expression, and delayed the degradation of phosphatidylcholine, phosphatidylethanolamine, and oleic, linoleic, and linolenic acids in green peppers. These results suggest that MT helps to improve the chilling injury and quality of green peppers and extends shelf life.

Characterization of the GGP gene family in potato (Solanum tuberosum L.) and Pepper (Capsicum annuum L.) and its expression analysis under hormonal and abiotic stresses.

GDP-L-galactose phosphorylase (GGP) is a key rate-limiting enzyme in plant ascorbic acid synthesis, which plays an important role in plant growth and development as well as stress response. However, the presence of GGP and its function in potato and pepper are not known. In this study, we first identified two GGP genes in each potato and pepper genomes using a genome-wide search approach. We then analyzed their physicochemical properties, conserved domains, protein structures and phylogenetic relationships. Phylogenetic tree analysis revealed that members of the potato and pepper GGP gene families are related to eggplant (Solanum melongena L.), Arabidopsis (Arabidopsis thaliana L.), tobacco (Nicotiana tabacum L.) and tomato (Solanum lycopersicum L.), with tomato being the most closely related. The promoter sequences mainly contain homeopathic elements such as light-responsive, hormone-responsive and stress-responsive, with light-responsive elements being the most abundant. By analyzing the structure of the genes, it was found that there is no transmembrane structure or signal peptide in the GGP gene family of potatoes and peppers, and that all of its members are hydrophilic proteins. The expression profiles of different tissues show that StGGP1 has the highest expression levels in leaves, StGGP2 has the highest expression levels in stamens, and CaGGPs have the highest expression levels in the early stages of fruit development (Dev1). It was found that StGGPs and CaGGPs genes showed different response to phytohormones and abiotic stresses. Abscisic acid (ABA) treatment induced the most significant change in the expression of StGGPs, while the expression of CaGGPs showed the most pronounced change under methyl jasmonate (MeJA) treatment. StGGPs responded mainly to dark treatment, whereas CaGGPs responded mainly to NaCl stress. These results provide an important basis for a detailed study about the functions of GGP homologous genes in potato and pepper in response to abiotic stresses.

Mitigation of drought stress in chili plants (Capsicum annuum L.) using mango fruit waste biochar, fulvic acid and cobalt.

Drought stress can have negative impacts on crop productivity. It triggers the accumulation of reactive oxygen species, which causes oxidative stress. Limited water and nutrient uptake under drought stress also decreases plant growth. Using cobalt and fulvic acid with biochar in such scenarios can effectively promote plant growth. Cobalt (Co) is a component of various enzymes and co-enzymes. It can increase the concentration of flavonoids, total phenols, antioxidant enzymes (peroxidase, catalase, and polyphenol oxidase) and proline. Fulvic acid (FA), a constituent of soil organic matter, increases the accessibility of nutrients to plants. Biochar (BC) can enhance soil moisture retention, nutrient uptake, and plant productivity during drought stress. That's why the current study explored the influence of Co, FA and BC on chili plants under drought stress. This study involved 8 treatments, i.e., control, 4 g/L fulvic acid (4FA), 20 mg/L cobalt sulfate (20CoSO4), 4FA + 20CoSO4, 0.50%MFWBC (0.50 MFWBC), 4FA + 0.50MFWBC, 20CoSO4 + 0.50MFWBC, 4FA + 20CoSO4 + 0.50MFWBC. Results showed that 4 g/L FA + 20CoSO4 with 0.50MFWBC caused an increase in chili plant height (23.29%), plant dry weight (28.85%), fruit length (20.17%), fruit girth (21.41%) and fruit yield (25.13%) compared to control. The effectiveness of 4 g/L FA + 20CoSO4 with 0.50MFWBC was also confirmed by a significant increase in total chlorophyll contents, as well as nitrogen (N), phosphorus (P), and potassium (K) in leaves over control. In conclusion4g/L, FA + 20CoSO4 with 0.50MFWBC can potentially improve the growth of chili cultivated in drought stress. It is suggested that 4 g/L FA + 20CoSO4 with 0.50MFWBC be used to alleviate drought stress in chili plants.

Lysine 2-hydroxyisobutyrylation proteomics analyses reveal the regulatory mechanism of CaMYB61-CaAFR1 module in regulating stem development in Capsicum annuum L.

Plant stems constitute the most abundant renewable resource on earth. The function of lysine (K)-2-hydroxyisobutyrylation (Khib), a novel post-translational modification (PTM), has not yet been elucidated in plant stem development. Here, by assessing typical pepper genotypes with straight stem (SS) and prostrate stem (PS), we report the first large-scale proteomics analysis for protein Khib to date. Khib-modifications influenced central metabolic processes involved in stem development, such as glycolysis/gluconeogenesis and protein translation. The high Khib level regulated gene expression and protein accumulation associated with cell wall formation in the pepper stem. Specially, we found that CaMYB61 knockdown lines that exhibited prostrate stem phenotypes had high Khib levels. Most histone deacetylases (HDACs, e.g., switch-independent 3 associated polypeptide function related 1, AFR1) potentially function as the "erasing enzymes" involved in reversing Khib level. CaMYB61 positively regulated CaAFR1 expression to erase Khib and promote cellulose and hemicellulose accumulation in the stem. Therefore, we propose a bidirectional regulation hypothesis of "Khib modifications" and "Khib erasing" in stem development, and reveal a novel epigenetic regulatory network in which the CaMYB61-CaAFR1 molecular module participating in the regulation of Khib levels and biosynthesis of cellulose and hemicellulose for the first time.

Peppermint Essential Oil and Its Major Volatiles as Protective Agents against Soft Rot Caused by Fusarium sambucinum in Cera Pepper (Capsicum pubescens).

Cera pepper (Capsicum pubescens) is an exotic fruit considered as a rich source of nutraceuticals with known benefits for human health and also an economic resource for local producers in Mexico. The present investigation reports on the in vitro and in situ antifungal activity of the essential oil from Mentha piperita and its two major volatiles (menthol and menthone) against Fusarium sambucinum, which is a causal agent of soft rot in cera pepper. The application of these components in pepper fruits previously infected with F. sambucinum caused a significant delay (p<0.05) in the emergence of soft rot symptoms. This effect was reflected in the maintenance of pH and fruit firmness during a period of 10 days. The nutrimental content of the fruits (protein, fiber, fat and other proximate parameters) was conserved in the same period of time. The nutraceutical content of these fruits was estimated by the quantification of seven carotenoids (violaxanthin, cis-violaxanthin, luteoxanthin, antheraxanthin, lutein, zeaxanthin and ß-carotene), ascorbic acid and capsaicinoids (capsaicin and dihydrocapsaicin). According to our results, the essential oil from M. Piperita and its major volatiles exerted a preservative effect on these metabolites. Our findings demonstrated that the essential oil of M. Piperita and its major volatiles represent an ecological alternative for the control of fusariosis caused by F. sambucinum in cera peppers under postharvest conditions.

The flavin monooxygenase Bs3 triggers cell death in plants, impairs growth in yeast and produces H2O2 in vitro.

The pepper resistance gene Bs3 triggers a hypersensitive response (HR) upon transcriptional activation by the corresponding effector protein AvrBs3 from the bacterial pathogen Xanthomonas. Expression of Bs3 in yeast inhibited proliferation, demonstrating that Bs3 function is not restricted to the plant kingdom. The Bs3 sequence shows striking similarity to flavin monooxygenases (FMOs), an FAD- and NADPH-containing enzyme class that is known for the oxygenation of a wide range of substrates and their potential to produce H2O2. Since H2O2 is a hallmark metabolite in plant immunity, we analyzed the role of H2O2 during Bs3 HR. We purified recombinant Bs3 protein from E. coli and confirmed the FMO function of Bs3 with FAD binding and NADPH oxidase activity in vitro. Translational fusion of Bs3 to the redox reporter roGFP2 indicated that the Bs3-dependent HR induces an increase of the intracellular oxidation state in planta. To test if the NADPH oxidation and putative H2O2 production of Bs3 is sufficient to induce HR, we adapted previous studies which have uncovered mutations in the NADPH binding site of FMOs that result in higher NADPH oxidase activity. In vitro studies demonstrated that recombinant Bs3S211A protein has twofold higher NADPH oxidase activity than wildtype Bs3. Translational fusions to roGFP2 showed that Bs3S211A also increased the intracellular oxidation state in planta. Interestingly, while the mutant derivative Bs3S211A had an increase in NADPH oxidase capacity, it did not trigger HR in planta, ultimately revealing that H2O2 produced by Bs3 on its own is not sufficient to trigger HR.

Identification of Compounds with Potential Therapeutic Uses from Sweet Pepper (Capsicum annuum L.) Fruits and Their Modulation by Nitric Oxide (NO).

Plant species are precursors of a wide variety of secondary metabolites that, besides being useful for themselves, can also be used by humans for their consumption and economic benefit. Pepper (Capsicum annuum L.) fruit is not only a common food and spice source, it also stands out for containing high amounts of antioxidants (such as vitamins C and A), polyphenols and capsaicinoids. Particular attention has been paid to capsaicin, whose anti-inflammatory, antiproliferative and analgesic activities have been reported in the literature. Due to the potential interest in pepper metabolites for human use, in this project, we carried out an investigation to identify new bioactive compounds of this crop. To achieve this, we applied a metabolomic approach, using an HPLC (high-performance liquid chromatography) separative technique coupled to metabolite identification by high resolution mass spectrometry (HRMS). After chromatographic analysis and data processing against metabolic databases, 12 differential bioactive compounds were identified in sweet pepper fruits, including quercetin and its derivatives, L-tryptophan, phytosphingosin, FAD, gingerglycolipid A, tetrahydropentoxylin, blumenol C glucoside, colnelenic acid and capsoside A. The abundance of these metabolites varied depending on the ripening stage of the fruits, either immature green or ripe red. We also studied the variation of these 12 metabolites upon treatment with exogenous nitric oxide (NO), a free radical gas involved in a good number of physiological processes in higher plants such as germination, growth, flowering, senescence, and fruit ripening, among others. Overall, it was found that the content of the analyzed metabolites depended on the ripening stage and on the presence of NO. The metabolic pattern followed by quercetin and its derivatives, as a consequence of the ripening stage and NO treatment, was also corroborated by transcriptomic analysis of genes involved in the synthesis of these compounds. This opens new research perspectives on the pepper fruit's bioactive compounds with nutraceutical potentiality, where biotechnological strategies can be applied for optimizing the level of these beneficial compounds.

Mediation of induced systemic resistance by the plant growth-promoting rhizobacteria Bacillus pumilus S2-3-2.

Plant-rhizobacteria interaction and co-evolution developed adaptive strategies which may help the plant survive in nature. Plant rhizosphere soil isolates were analyzed to investigated the effects of rhizobacteria for promoting plant growth and suppress plant disease. Bacterial strains which isolated from plant rhizosphere soil were screened for elicitation of induced systemic resistance (ISR) on tobacco. Strain S2-3-2 results in significant reduction of disease severity on tobacco, it was identified as Bacillus pumilus by multilocus sequence analysis (MLSA). Strain S2-3-2 was deeper studied for pepper plant growth promotion and biological control activity against pepper bacterial spot disease. It was found that the pepper disease severity was decreased when the roots were drenched with strain S2-3-2, and the pepper plants had a higher weight and chlorophyll content, as compared with the mock-treated plants. Transcriptional expression of pathogenesis-related (PR) protein genes in pepper was analyzed by real-time PCR, gene expressions of CaPR1, CaPR4, and CaPR10 were increased when the plants were treated with strain S2-3-2. Moreover, strain S2-3-2 was tested for the production of indole-3-acetic acid (IAA), and it was determined to emit volatiles that enhance the growth of the tobacco plants. Interesting, heat-killed S2-3-2 enhance the pepper root growth, increase the gene expressions of CaPR4 and CaPR10 after pathogen challenge for 6 h, but limited to suppress the pepper bacterial spot disease as compare to the mock-treated plants. Strain S2-3-2 can be a potential biological control agent on the plant root for plant growth promoting and disease suppression.

Exogenously supplied silicon (Si) improves cadmium tolerance in pepper (Capsicum annuum L.) by up-regulating the synthesis of nitric oxide and hydrogen sulfide.

The current research was aimed to observe the interactive role of silicon-generated hydrogen sulfide (H2S) and nitric oxide (NO) on tolerance of pepper (Capsicum annum L.) plants to cadmium (Cd). Thus, the pepper plants were subjected to control (no Cd) or cadmium stress with and without Si supplementation. Significant decreases were found in plant dry weights, water potential, PSII maximum efficiency, glutathione (GSH), total chlorophyll, relative water content, Ca2+ and K+ concentrations and ascorbate, but there was a significant increase in H2O2, MDA, electron leakage (EL), proline, key antioxidant enzymes' activities, and endogenous Cd, NO and H2S in the Cd-stressed plants. Silicon enhanced Cd tolerance of the pepper plants by lowering the leaf Cd concentration, oxidative stress, enhancing the antioxidant defence system, leaf Si content, photosynthetic traits and plant growth as well as the contents of NO, proline and H2S. Furthermore, foliar-applied NO scavenger, cPTIO, and that of H2S, hypotaurine (HT), significantly decreased the levels of H2S alone, but cPTIO effectively reduced the concentrations of NO and H2S accumulated by Si in the Cd-stressed plants. The positive effect of Si was eliminated by cPTIO, but not by HT, suggesting that both molecules were involved in Si-induced improvement in Cd tolerance of the pepper plants.

The role of nitrate reductase in brassinosteroid-induced endogenous nitric oxide generation to improve cadmium stress tolerance of pepper plants by upregulating the ascorbate-glutathione cycle.

A study was performed to assess if nitrate reductase (NR) participated in brassinosteroid (BR)-induced cadmium (Cd) stress tolerance primarily by accelerating the ascorbate-glutathione (AsA-GSH) cycle. Prior to initiating Cd stress (CdS), the pepper plants were sprayed with 0.5 µM 24-epibrassinolide (EBR) every other day for 10 days. Thereafter the seedlings were subjected to control or CdS (0.1 mM CdCl2) for four weeks. Cadmium stress decreased the plant growth related attributes, water relations as well as the activities of monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR), but enhanced proline content, leaf Cd2+ content, oxidative stress-related traits, activities of ascorbate peroxidase (APX) and glutathione reductase (GR), and the activities of antioxidant defence system-related enzymes as well as NR activity and endogenous nitric oxide content. EBR reduced leaf Cd2+ content and oxidative stress-related parameters, enhanced plant growth, regulated water relations, and led to further increases in proline content, AsA-GSH cycle-related enzymes' activities, antioxidant defence system-related enzymes as well as NR activity and endogenous nitric oxide content. The EBR and the inhibitor of NR (tungstate) reversed the positive effects of EBR by reducing NO content, showing that NR could be a potential contributor of EBR-induced generation of NO which plays an effective role in tolerance to CdS in pepper plants by accelerating the AsA-GSH cycle and antioxidant enzymes.

Parasitoids diversity in organic Sweet Pepper (Capsicum annuum) associated with Basil (Ocimum basilicum) and Marigold (Tagetes erecta ) / Diversidade de parasitoides em Pimentão Orgânico (Capsicum annuum) associado com Manjericão (Ocimum basilicum ) e Cravo Amarelo (Tagetes erecta)

Abstract The sweet pepper (Capsicum annuum L.) is one of the most important crops in Brazilian farming. Many insect are related to this crop, compromising the quantity and quality of the fruit, representing a production problem. Vegetable diversification is one of the main elements that can be managed for suppressing undesirable insect populations in organic production, once that supports the presence of natural enemies. The basil Ocimum basilicum L. and the marigold Tagetes erecta L. are attractive and nutritious plants for parasitoids, being important candidates for diversified crops. This study evaluated the parasitoids attracted by the association of basil and marigold to organic sweet pepper crop. The experiment comprised three treatments: a) sweet pepper monoculture; b) sweet pepper and basil intercropping; c) sweet pepper and marigold intercropping. Hymenopteran parasitoids were collected over 14 weeks. 268 individuals from 12 families and 41 taxa were collected. Sweet pepper monoculture, sweet pepper-basil intercropping, and sweet pepper-marigold intercropping hosted 40, 98, and 130 individuals and richness of 24, 24, and 23, respectively. Furthermore, the insects of greater abundance in the basil and marigold were different to those collected in the monoculture. The number of parasitoids increased in the associations of sweet pepper with basil and marigold, providing advantages in the use of vegetable diversification for the organic pepper crops management.

Resumo O pimentão (Capsicum annuum L.) é um dos vegetais mais importantes dentre os cultivados no Brasil. Muitos insetos pragas estão relacionados a esta cultura, comprometendo a quantidade e a qualidade do pimentão, tornando-se um grande problema para a produção. A diversificação vegetal é um dos principais componentes a serem manejados para suprimir as populações de pragas na produção orgânica, devido ao apoio a inimigos naturais das pragas. O manjericão ( Ocimum basilicum L.) e cravo amarelo (Tagetes erecta L.) são plantas atrativas e nutritivas para parasitoides, importantes candidatas em cultivos diversificados. Este trabalho avaliou os parasitoides atraídos pela associação de manjericão e cravo amarelo em cultivo de pimentão orgânico. O experimento foi composto por três tratamentos: a) monocultura de pimentão; B) pimentão consorciado com manjericão; C) pimentão consorciado com cravo amarelo. Foram coletadas amostras de parasitoides himenópteros durante 14 semanas. Os espécimes foram identificados até o menor nível de taxonomia possível. Foram coletados 268 indivíduos ao longo de 12 famílias e 41 táxons. Os tratamentos de monocultura, pimentão consorciado com manjericão e pimentão consorciado com cravo amarelo resultaram em 40, 98 e 130 indivíduos e riqueza de espécies de 24, 24 e 23, respectivamente. Além disso, os insetos de maior abundância coletados no manjericão e cravo amarelo, foram diferentes daqueles coletados na monocultura. Houve um aumento na abundância de parasitoides nas associações de pimentão com manjericão e cravo amarelo, proporcionando vantagens no uso da diversificação vegetal, podendo ser usada no manejo do pimentão orgânico.

Biostimulatory activities of Ascophyllum nodosum extract in tomato and sweet pepper crops in a tropical environment.

This study evaluated the effectiveness of a commercially available Ascophyllum nodosum alkaline extract as a plant growth stimulant and defense elicitor against foliar diseases of tomato and sweet pepper caused by Xanthomonas campestris pv. vesicatoria and Alternaria solani in a tropical environment. Foliar applications of 0.5% A. nodosum extract (AN) at 10-day intervals resulted in significant (P < 0.05) increase in plant growth parameters, including plant height (40%), leaf number (50%), plant dry biomass (52%), root length (59%) and chlorophyll content (20%) compared to control. Treated plants also had a significantly higher number of flower clusters, flower numbers, fruits per cluster and total harvested fruit yield. The Ascophyllum extract significantly (P < 0.05) reduced disease incidence by the pathogens in both crops under greenhouse and field conditions. The combinatory treatment of seaweed extract and a minimum dose of contact fungicide in field trials, recorded the overall lowest disease levels (60% reduction) and highest yield (57% increase). Investigations into the mechanisms of disease suppression revealed the effects of the extract in inducing the activities of defense-related enzymes including phenylalanine ammonia lyase, peroxidase, polyphenol oxidase, chitinase and ß-1,3-glucanase, as well as the levels of total phenolic compounds. The effect on SA, JA and ET-mediated signalling defense pathways was examined by quantifying expression levels of marker genes including PR1-a, PinII and ETR-1, for the above pathways respectively. Both crop plants treated with A. nodosum extract had significantly higher expression levels of the PinII and ETR-1 marker genes than controls. This was coupled with a marked increase in gene transcripts involved in auxin (IAA), gibberellin (Ga2Ox) and cytokinin (IPT) biosynthesis, which provides possible evidence for induced growth in plants treated with AN extract. Cross-talks between growth and defense responses as a result of seaweed extract application could evidently implicate the benefits of seaweed extract usage in sustainable crop production.

Root inoculation of green bell pepper (Capsicum annum) with Bacillus amyloliquefaciens BBC047: effect on biochemical composition and antioxidant capacity.

BACKGROUND: Consumption of bell peppers is recommended because of their bioactive compound content and their positive effects on health. Growth-promoting rhizobacteria are popular because of their ability to promote plant growth by improving the fixation of nutrients or by inducing a systemic response. Green bell pepper (Capsicum annum) roots were inoculated with an autochthonous strain of Bacillus amyloliquefaciens, at different stages of development: T1, inoculation in the seedbed before transplant; T2, inoculation at and after transplant; T3, inoculation in the seedbed, at and after transplant. Bell pepper plants without inoculation were considered as control. Physicochemical composition and antioxidant activity of the fruits were measured to select the best treatment. RESULTS: T1 increased crude proteins, fat, Ca, Fe, vitamin C, total phenolic content, antioxidant capacity by DPPH and by ORAC. On the other hand, T1 decreased reducing sugars, K and Cu content. No significant differences for total carbohydrates, ash and photosynthetic pigments were found. CONCLUSION: Inoculated green bell peppers have enhanced its functional value and could be considered as an important source of bioactive compounds with elevated antioxidant activity. © 2019 Society of Chemical Industry.

Cultivar-specific responses in red sweet peppers grown under shade nets and controlled-temperature plastic tunnel environment on antioxidant constituents at harvest.

Antioxidant constituents such as carotenoids (capsanthin, phytoene, lutein, ß-cryptoxanthin), polyphenols content (p-coumaric, ferulic, p-hydroxybenzoic, caffeic acid, sinapic acid, and quercetin-3-glucoside) and marketable yield were investigated in 11 sweet pepper cultivars grown under controlled temperature plastic tunnel and white shade net. Marketable yield was not affected by either of the environments, while the interaction between cultivar and growing environment significantly affected the accumulation of antioxidant constituents. The principal component analysis illustrated that controlled temperature plastic tunnel improved the accumulation of carotenoid components and ascorbic acid and vitamin C content in most cultivars. On the contrary, white shade nets favoured the accumulation of phenolic compounds and ORAC activity in most cultivars. A strong correlation was noted between phytoene and carotenoid components in this study (capsanthin r = 0.60; P < 0.001; lutein r = 0.75; P < 0.001; ß-carotene r = 0.78; P < 0.001) while ORAC correlated with phenolic compounds. Based on this study, it is possible to refine the choice of environment and cultivar to enhance individual antioxidant constituent groups to improve health benefits for consumers.

Characterization of the hot pepper (Capsicum frutescens) fruit ripening regulated by ethylene and ABA.

BACKGROUND: Ripening of fleshy fruits has been classically defined as climacteric or non-climacteric. Both types of ripening are controlled by plant hormones, notably by ethylene in climacteric ripening and by abscisic acid (ABA) in non-climacteric ripening. In pepper (Capsicum), fruit ripening has been widely classified as non-climacteric, but the ripening of the hot pepper fruit appears to be climacteric. To date, how to regulate the hot pepper fruit ripening through ethylene and ABA remains unclear. RESULTS: Here, we examined ripening of the hot pepper (Capsicum frutescens) fruit during large green (LG), initial colouring (IC), brown (Br), and full red (FR) stages. We found a peak of ethylene emission at the IC stage, followed by a peak respiratory quotient at the Br stage. By contrast, ABA levels increased slowly before the Br stage, then increased sharply and reached a maximum level at the FR stage. Exogenous ethylene promoted colouration, but exogenous ABA did not. Unexpectedly, fluridone, an inhibitor of ABA biosynthesis, promoted colouration. RNA-sequencing data obtained from the four stages around ripening showed that ACO3 and NCED1/3 gene expression determined ethylene and ABA levels, respectively. Downregulation of ACO3 and NCED1/3 expression by virus-induced gene silencing (VIGS) inhibited and promoted colouration, respectively, as evidenced by changes in carotenoid, ABA, and ethylene levels, as well as carotenoid biosynthesis-related gene expression. Importantly, the retarded colouration in ACO3-VIGS fruits was rescued by exogenous ethylene. CONCLUSIONS: Ethylene positively regulates the hot pepper fruit colouration, while inhibition of ABA biosynthesis promotes colouration, suggesting a role of ABA in de-greening. Our findings provide new insights into processes of fleshy fruit ripening regulated by ABA and ethylene, focusing on ethylene in carotenoid biosynthesis and ABA in chlorophyll degradation.

Development of a direct transformation method by GFP screening and in vitro whole plant regeneration of Capsicum frutescens L

Background: Capsicum is a genus of an important spice crop that belongs to the chili lineage. However, many Capsicum species (family Solanaceae) are known to be recalcitrant to genetic transformation and in vitro regeneration, thus hampering the effort in using Capsicum species for detailed biological investigation. In this study, we have developed an optimized protocol for the direct transformation of Capsicum frutescens L. cv. Hot Lava using a biolistic particle delivery system. In addition, a procedure for in vitro whole plant regeneration from the hypocotyl explants of C. frutescens was established. Results: In this study on the biolistic system, explant target distance, bombardment helium (He) pressure, and the size of the microcarrier were the key parameters to be investigated. The optimized parameters based on the screening of GFP expression were determined to have a target distance of 6 cm, helium pressure of 1350 psi, and gold particle (microcarrier) size of 1.6 µm. The greatest number of shoots was obtained from hypocotyls as explants using Murashige and Skoog medium supplemented with 5.0-mg/L 6-benzylaminopurine and 0.1-mg/L 1-naphthaleneacetic acid. On an average, five shoots per explant were formed, and of them, one shoot managed to form the root and developed into a whole plant. Conclusions: We obtained an optimized protocol for the biolistic transformation of chili and in vitro regeneration of chili plantlets. The establishment of the protocols will provide a platform for molecular breeding and biological studies of chili plants.

Crecimiento y eficiencia fotoquímica del fotosistema II en plántulas de 2 variedades de Capsicum annuum L. inoculadas con rizobacterias u hongos micorrícicos arbusculares / Growth and photochemical efficiency of photosystem II in seedlings of two varieties of Capsicum annuum L. inoculated with rhizobacteria and arbuscular mycorrhizal fungi

Una alternativa para el manejo sustentable en el cultivo de Capsicum annuum L. se ha enfocado en el uso de bacterias promotoras del crecimiento vegetal (BPCV) y hongos micorrícicos arbusculares (HMA). Esta investigación seleccionó BPCV y HMA sobre la base de su efecto en plantas de chile Bell Pepper y jalapeño. Se utilizaron 5 cepas bacterianas aisladas de diferentes localidades del estado de México (P61 [Pseudomonas tolaasii], A46 [P. tolaasii], R44 [Bacillus pumilus], BSP1.1 [Paenibacillus sp.] y OLs-Sf5 [Pseudomonas sp.]) y 3 tratamientos con HMA (H1 [consorcio aislado de la rizosfera de chile en el estado de Puebla], H2 [Rhizophagus intraradices]y H3 [consorcio aislado de la rizosfera de limón del estado de Tabasco]). Además, se incluyó un tratamiento fertilizado (solución Steiner 25%) y un testigo absoluto. Plántulas de chile jalapeño «Caloro¼ y pimiento Bell Pepper «California Wonder¼ fueron inoculadas con HMA en el momento de la siembra y con BPCV 15 días después de emerger, y crecidas bajo condiciones de cámara de ambiente controlado. En chile jalapenño, la mejor cepa bacteriana fue P61 y el mejor tratamiento de HMA fue el H1; en Bell Pepper la mejor cepa fue R44 y los mejores HMA fueron el H3 y el H1. Estos microorganismos incrementaron el crecimiento de plántulas de chile jalapenño y Bell Pepper en comparación con el testigo sin fertilizar. Asimismo, P61 y R44 beneficiaron positivamente la capacidad fotosintética del PSII.

Plant growth promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF) are a biological alternative for the sustainable management of Capsicum annuum L. This research work evaluated the effects of both PGPR and AMF on bell pepper and jalapeno pepper plants. Five bacterial strains isolated from several locations in Estado de Mexico were used: [P61 (Pseudomonas tolaasii), A46 (P. tolaasii), R44 (Bacillus pumilus), BSP1.1 (Paenibacillus sp.), and OLs-Sf5 (Pseudomonas sp.)], and three treatments with AMF [H1 (consortium isolated from pepper crops in the State of Puebla), H2 (Rhizophagus intraradices), and H3 (consortium isolated from the rhizosphere of lemon trees, State of Tabasco)]. In addition, a fertilized treatment (Steiner nutrient solution at 25%) and an unfertilized control were included. Seedlings of "Caloro" jalapeno pepper and "California Wonder" bell pepper were inoculated with AMF at seed sowing, and PGPR were inoculated after 15 days of seedling emergence; seedlings were grown under plant growth chamber conditions. P61 bacterium and H1 AMF consortia were the most effective microorganisms for jalapeno pepper whereas R44 bacterium and AMF H3 and H1 were the most effective for bell peppers, when compared to the unfertilized control. Furthermore, P61 and R44 bacteria showed beneficial effects on PSII efficiency.

New insights into the cellular responses to iron nanoparticles in Capsicum annuum.

In this study, the anatomical and ultrastructural responses of Capsicum annuum to iron nanoparticles (Fe NPs) were determined. The results showed that the bio-effects of Fe NPs on plants could be positive or negative, depending on the additive concentrations. Low concentrations of Fe NPs were found to promote plant growth. Light and electron microscope analyses showed that the Fe NPs promoted plant growth by altering the leaf organization, and increasing the chloroplast number and grana stacking, as well as regulating the development of vascular bundles. Meanwhile, it was found that the Fe NPs could be absorbed in the roots, and then transported to the central cylinder in bio-available forms, where they were translocated and utilized by the leaves and stems. In contrast, high concentrations of Fe NPs appeared to be harmful to the plants, and the majority of Fe NPs were aggregated into cell walls and transported via the apoplastic pathway in the roots, which may potentially block the transfer of iron nutrients. Taken together, the aforementioned data showed that the rational use of Fe NPs could alleviate iron deficiency, and Fe NPs could be an ideal supply for Fe2+ ions fertilizers in agriculture.