Indole-3-acetic Acid Research Articles

Enhancing heavy metal phytoremediation in landfill soil by Chrysopogon zizanioides (L.) roberty through the application of bacterial-biochar pellets

This work investigated the performance of bacterial-biochar pellets (BBP) on promoting heavy metal phytoremediation by Chrysopogon zizanioides (L.) Roberty planted in landfill soil. Micrococcus sp. MU1, an indole-3-acetic acid (IAA)-producing bacterium, was incorporated into biochar pellets (MU1-BBP). MU1-BBP contained a high number of viable bacterial cells with 90 % viability after storage at 4°C for two months. In addition, it had a greater survival capability in heavy metals-contaminated landfill soil than MU1-free cells. The application of MU1-BBP significantly promoted the growth performance and chlorophyll synthesis of C. zizanioides planted in landfill soil. Cd, Cu, Pb and Zn were mostly retained in the roots relative to the shoots of C. zizanioides. The accumulation of Cd, Cu, Pb, and Zn in the roots of C. zizanioides were significantly boosted by MU1-BBP inoculation. Plants with MU1-BBP inoculation enhanced the accumulation coefficient (AC) of all four heavy metals. The values of AC values of Cd, Cu, and Zn in C. zizanioides with MU1-BBP inoculation were greater than 1.0. However, translocation factors of all four metals were low. The findings suggest C. zizanioides may be a good heavy metal phytostabilizer. The findings support the potential of bacterial-biochar pellets to enhance the efficiency of heavy metal phytostabilization of C. zizanioides in landfill sites.

The effectiveness of encapsulated salicylic acid as a treatment to enhance abiotic stress tolerance stems from maintaining proper hormonal homeostasis.

Climate change induces significant abiotic stresses that adversely affect crop yields. One promising solution to improve plant resilience under adverse conditions is the application of exogenous salicylic acid (SA). However, its negative effects on growth and development are a concern. Encapsulation with protective materials like amorphous silica and chitosan has demonstrated a controlled release of SA, minimizing the detrimental impacts. In this work, we elucidate the physiological mechanisms behind this protective mechanism. We employed in vitro cultivation of Arabidopsis, comparing plant responses to both free and encapsulated SA under conditions of salt or mannitol stress, combined or not with high temperature (30°C). Plants treated with encapsulated SA displayed an enhanced tolerance to these stresses that was due, at least in part, to the maintenance of physiological endogenous SA levels, which in turn regulate indole-3-acetic acid (IAA) homeostasis. The activity of the Arabidopsis "DR5::GFP" reporter line supported this finding. Unlike plants treated with free SA (with altered DR5 activity under stress), those treated with encapsulated SA maintained similar activity levels to control plants. Moreover, stressed plants treated with free SA overexpressed genes involved in the SA biosynthesis pathway, leading to increased SA accumulation in roots and rosettes. In contrast, plants treated with encapsulated SA under stress did not exhibit increased expression of EDS1, PAL1, and NPR1 in roots, or of PAL1, PBS3, and NPR1 in rosettes. This indicates that these plants likely experienced lower stress levels, possibly because the encapsulated SA provided sufficient defense activation without triggering pleiotropic effects.

Micropropagation of Two Varieties of Vitis vinifera Cabernet Franc and Pinot Noir, Comparison of Physiological and Production Parameters

Grapevine (Vitis vinifera) is considered one of the most important fruit crops in the world, and the Cabernet Franc and Pinot Noir varieties have high commercial value. The aim of this study was to compare the in vitro performance of both varieties from explant establishment to in vitro rooting, testing different hormone concentrations. It started from mother plants obtained in vitro, from which uninodal cuttings were taken for micropropagation. Disinfection consisted of washing with 70% alcohol and 20% sodium hypochlorite, with sterile water rinses. Explants were placed in a laminar flow chamber under aseptic conditions in a sterile growth medium. They were grown in a culture chamber with 16 hours of light: 8 hours of darkness and a temperature of 25°C. Establishment, growth, rooting and contamination data were recorded for eight weeks. The culture media used were Experiment 1: 50% Murashige and Skoog (MS) [1] medium; Experiment 2: MS at 50% plus indoleacetic acid (IAA) at 0.01%. The data were statistically analyzed; Cabernet Franc and Pinot Noir had similar production standards, high vigor, good in vitro growth and direct rooting. Both varieties performed better on the auxin enriched medium.

Lysinibacillus sphaericus Isolated from Dolomite and Copper Ore Contaminated Kaljani River Basin Exhibits High Copper Tolerance and Plant Growth Promoting Property

The purpose of this present study is to explore and decipher copper tolerant plant growth promoting bacteria from dolomite contaminated soil. Lysinibacillus sphaericus (NJCT1) isolated from tea garden soil near Kaljani river bank has been found to exhibit multifaceted characteristics and has shown its ability to tolerate copper up-to 40 mg/ml. Further, its ability to tolerate other heavy metals were also assessed and the result revealed that it can tolerate iron, zinc and aluminum upto 100 mg/ml, while for lead and arsenic it showed tolerance upto 10 mg/ml. GC-MS analysis showed that L. sphaericus (NJCT1) produced 16 compounds, among them, tromethamine, 2-methylbutanoic acid, 2,4,6-(1H,3H,5H)-pyrimidinetrione, 2-piperidinone, 3,5,5-trimethylhexyl acetate and cis-3-hexenyl propionate were found to exhibit various important biological properties. Also, this isolate was positive for phosphate solubilization and is capable of producing ammonia, HCN, siderophore, and 17.12 µg/ml of indole acetic acid. In seed germination, seeds treated with NJCT1 demonstrated 100% germination rate with 111-time increase in seedling vigor index. Further, in pot study, significant increase in all the growth parameters of NJCT1 treated Vigna radiata and Phaseolus vulgaris gave a strong indication that this strain can be a promising candidate for reclamation and revitalization of dolomite and copper ore affected tea garden soil.

Elimination of ineffective inorganic salt component in medium for indole‐3‐acetic acid synthesis by Serratia plymuthica UBCF_13 and its effect on the growth of chili seedlings

Indole‐3‐acetic acid (IAA) is an essential phytohormone that controls a variety of plant growth mechanisms. Bacteria can produce IAA to stimulate plant growth, with its production influenced by the culture conditions. Serratia plymuthica UBCF_13 is recognized as an IAA‐producing bacterium, exhibiting maximum IAA production in a yeast medium comprising yeast extract, sucrose, K2HPO4, MgSO4, NaCl, and CaCO3. However, prior studies optimizing individual inorganic salt components indicated minimal impact on IAA synthesis within this medium. This study aimed to eliminate the unnecessary inorganic salt components and the medium was then applied to investigate the IAA biosynthesis pathway and the plant growth‐promoting assay. The elimination assay consisted of yeast sucrose medium devoid of K2HPO4, MgSO4, NaCl, or CaCO3, and yeast sucrose medium containing only MgSO4 and CaCO3. Various indole compounds were then added to the revised medium composition to investigate the IAA biosynthesis pathway of UBCF_13 using high‐performance liquid chromatography (HPLC). Furthermore, the effect of UBCF_13 culture supernatant, cultivated in the new medium, on chili plant growth was evaluated. The highest IAA production (138.8 µg/mL) was observed in the yeast sucrose with CaCO3 and MgSO4 (elimination of K2HPO4 and NaCl). The presence of indole‐3‐acetamide (IAM) compound from the medium extracts, supplemented with multiple indole compounds, revealed that UBCF_13 may use the IAM pathway. The application of UBCF_13 supernatant enhanced the shoot, root length, fresh weight, and germination time of chili seeds by 37.7%, 49.3%, 204.3%, and 38.6%, respectively. This study demonstrated that eliminating K2HPO4 and NaCl provided a new culture medium composition conducive to IAA production by UBCF_13. Moreover, the UBCF_13 extract has the potential to promote plant growth.

Biocontrol potentiality of <i>Burkholderia vietnamiensis</i> nrv12 against the rice blast fungus <i>magnaporthe oryzae</i>

Rice blast disease, caused by the pathogenic fungus Magnaporthe oryzae, is a widespread infection leading to serious crop loss worldwide. In order to achieve sustainable agriculture, root-associated bacteria have been applied to manage fungal diseases and promote growth. The present study aimed to evaluate in vitro the growth-promoting ability and in vivo biocontrol activity against M. oryzae of rice rhizosphere bacterium. Out of sixty-eight isolates recovered from the rhizosphere of blast-infected rice plants, isolate NRV12 exhibited the highest antifungal activity against M. oryzae SH, with an inhibition percentage of 72.7±3.44%. By analysis of 16S rRNA sequence associated with morphology, physiological and biochemical tests, the strain was identified as Burkholderia vietnamiensis. In addition, NRV12 produced hydrolytic enzymes (amylase, cellulase, protease), indole acetic acid (IAA), exhibited nitrogen-fixing potential and the ability to solubilize phosphate and zinc. Innoculation with NRV12 significantly promoted in vivo rice seedling growth to 23.3% as compared to the non-bacteria-treated seedlings. Importantly, infected rice seedlings treated with NRV12 led to a 40% disease reduction in rice blast. These findings suggest that NRV12 is a valuable and promising isolate with biocontrol potential against rice blast caused by M. oryzae.

Differential responses of the phyllosphere abundant and rare microbes of Eucommia ulmoides to phytohormones

Phyllosphere microbiota play a crucial role in plant productivity and adaptation, and the abundant and rare microbial taxa often possess distinct characteristics and ecological functions. However, it is unclear whether the different subcommunities of phyllosphere microbiota respond variably to the factors that influence their formation, which limits the understanding of community assembly. The effects of two phytohormones, namely, indole-3-acetic acid (IAA) and N6-(delta 2-isopentenyl)-adenine (IP), on the phyllosphere microbial subcommunities of Eucommia ulmoides were investigated using potted experiments. The results demonstrated that the phytohormones induced significant variations in the composition, diversity, and function of the abundant microbial subcommunity in the phyllosphere of E. ulmoides, however, their effects on the rare subcommunity were negligible, and their effects on the moderate subcommunity were between those of the abundant and rare taxa. The phytohormones also induced significant alterations in the phenotypic and physiological properties of E. ulmoides, which indirectly affected the phyllosphere microbial community. Leaf thickness and average leaf area were the main phenotypic variables that affected the composition of the phyllosphere microbial community. The total alkaloid content and activity of superoxide dismutase (SOD) were the main physiological variables that affected the composition of the phyllosphere microbial community. The phenotypic and physiological indices of E. ulmoides explained the variations in the phyllosphere microbial subcommunities in descending order: abundant > moderate > rare taxa. These variables explained a significant proportion of the variations in the abundant taxa, and an insignificant proportion of the variations in the rare taxa. This study improves our understanding of the assembly of the phyllosphere microbiota, which provides important theoretical knowledge for future sustainable agriculture and forestry management based on the precise regulation of phyllosphere microbiota.

Anti-oomycete activity and plant growth promoting properties of avocado fungal endophytes

Fungal endophytes are known as promising plant growth-promoting microorganisms. Surprisingly, despite the economic importance of avocado, the antimicrobial and plant growth-promoting properties of its fungal endophytes have seldom been investigated. Our objectives were to evaluate the anti-oomycete activity of avocado fungal endophytes and assess their potential plant growth-promoting properties, using Arabidopsis thaliana as a model plant. In total, 89 fungal isolates were obtained from the roots of avocado trees and grouped into 24 morphotypes. One isolate per morphotype was randomly selected to assess its antagonistic activity against Phytophthora cinnamomi through dual culture assays. The strongest inhibition of P. cinnamomi was induced by endophytic fungi belonging to the Fusarium, Mortierella and Penicillium genera. The six most promising fungal isolates were selected to assess their plant growth-promoting traits in co-inoculation assays with A. thaliana. All tested fungal endophytes were able to modify the plant root architecture and increase the number of lateral roots. Moreover, an accumulation of auxins was detected in the xylem and meristematic zone of plants inoculated with Mortierella sp. PC-T3-3.1 and Metapochonia sp. PC-T2-4.2, whilst auxin accumulation was restricted to the emerging lateral roots of plants inoculated with Penicillium sp. C-T0-3.1. Indole quantification showed that Penicillium sp. C-T0-3.1 produced the highest concentration of indole acetic acid (IAA) and indole butyric acid (IBA), despite the lack of auxin responsiveness in plants in the co-inoculation assays. Mortierella sp. PC-T3-3.1 and Metapochonia sp. PC-T2-4.2 produced more IAA and IBA when co-inoculated with A. thaliana than when growing alone, which suggests that sensing of plant signals could induce the production of auxin-like compounds by these two endophytes. Collectively, our findings contribute to elucidate the mechanisms underpinning the plant growth-promoting activity of avocado fungal endophytes, which will be key to harness their full metabolic potential.

Radicle Growth Regulation of Root Parasitic Plants by Auxin-related Compounds.

Root parasitic plants in the Orobanchaceae, such as Striga and Orobanche, cause significant damage to crop production. The germination step of these root parasitic plants is induced by host-root-derived strigolactones. After germination, the radicles elongate toward the host and invade the host root. We have previously discovered that a simple amino acid, tryptophan (Trp), as well as its metabolite, the plant hormone indole-3-acetic acid (IAA), can inhibit radicle elongation of Orobanche minor. These results suggest that auxin plays a crucial role in the radicle elongation step in root parasitic plants. In this report, we used various auxin chemical probes to dissect the auxin function in the radicle growth of O. minor and Striga hermonthica. We found that synthetic auxins inhibited radicle elongation. In addition, auxin receptor antagonist, auxinole, rescued the inhibition of radicle growth by exogenous IAA. Moreover, a polar transport inhibitor of auxin, N-1-naphthylphthalamic acid, affected radicle bending. We also proved that exogenously applied Trp is converted into IAA in O. minor seeds, and auxinole partly rescued this radicle elongation. Taken together, our data demonstrate a pivotal role for auxin in radicle growth. Thus, manipulation of auxin function in root parasitic plants should offer a useful approach to combat these parasites.

Responses of Physiological Traits and Soil Properties in Pinus thunbergia and Euonymus japonicus Saplings under Drought and Cadmium (Cd) Stress

Pinus thunbergii and Euonymus japonicus are two species commonly found in arid and semi-arid areas; however, their responses in terms of physiological traits and soil properties under drought and cadmium (Cd) stress are not clear. In this study, we carried out single and combined stress treatments consisting of drought and Cd on saplings of P. thunbergii and E. japonicus and investigated the responses in terms of the physiological traits and soil properties of both species. For both species, under single Cd stress, Cd was observed in both the xylem and phloem, while the root Cd2+ flow rate fluctuated at different levels of Cd stress. Under both single and combined stress, as the stress level increased, the abscisic acid (ABA) content of the leaves and roots increased significantly, while the indole-3-acetic acid (IAA) content of the leaves and roots decreased significantly. Moreover, the non-structural carbohydrate (NSC) content of the leaves, stems, and roots, as well as the leaf chlorophyll content, decreased significantly. Under drought stress, the xylem water potential and hydraulic conductivity significantly decreased, which was exacerbated by Cd stress; this led to a more significant decrease in water potential and hydraulic conductivity under the combined stresses. Meanwhile, no significant changes in the conduit lumen diameter and double-wall thickness were observed, except for the double cell wall thickness of the P. thunbergii tracheid, which increased. In addition, both the single stresses and the combined stress of drought and Cd induced significant changes in the soil properties of the two species, i.e., the ammonium nitrogen, nitrate nitrogen, and effective phosphorus of the soil increased significantly, and the increase in content was more significant under combined stress. The diversity of the soil microbial community of P. thunbergii saplings significantly increased, while no change was found in its microbial community abundance under the single stresses and combined stress; however, the diversity and abundance of the soil microbial community in E. japonicus saplings showed the opposite pattern, which indicates that the effect of Cd on soil microorganisms is more significant than the effect of drought. The activity of sucrase and catalase in P. thunbergii soil fluctuated under the single stress and combined stress when compared, and the activity of sucrase in the soil of the E. japonicus species decreased. However, its catalase activity increased significantly under the single drought and Cd stress and combined stress when compared. We found that the combined stresses exacerbated the effects of the single stress in both species. Our study provides more detailed information on the responses in terms of the physiological traits and soil properties of the two species under single and combined stress consisting of drought and Cd.

Screening for drought-tolerant mungbean root nodule bacteria with multiple plant growth promoting traits in Aridisol

Mungbean (Vigna radiata L. Wilczek) is an economically important legume crop grown across India. The growth and yield of the crop have been declining over the recent years due to climate change which leads to decrease in soil moisture. Applications of drought-tolerant plant growth-promoting (PGP) rhizobial strains have been found to enhance crop productivity under water deficiency. Therefore, the objective of this study was to screen the bacterial strains from the mungbean root nodule that may help in improving the plant growth under drought condition. Bacteria were isolated from mungbean root nodules and screened for in vitro drought-tolerance using different concentrations of PEG 6000 at 10, 20, 30 and 40 %, and temperature-tolerance at 30, 35, 40 and 45 °C. In primary screening, out of 98 root nodule bacterial isolates tested, only 25 % showed drought-tolerance at 40 % polyethylene glycol (PEG)-6000 while 22 % of bacteria survived at 45 °C. During secondary screening on combined stress-tolerance, only 8 % of isolates showed tolerance of 40 % PEG-6000 at 45 °C. The in vitro drought-tolerance of bacteria varied significantly according to their sampling region/district. Various PGP traits, i.e., nitrogen fixation, phosphate solubilization, and production of indole acetic acid, ammonia, and 1-aminocyclopropane-1-carboxylate (ACC) deaminase, were analyzed in isolated stress-tolerant bacteria, which may contribute towards stress-tolerance and crop productivity in mungbean. The most promising drought-tolerant nodule bacterial isolates were identified as Rhizobium sp. and Pseudomonas indica, respectively by 16S rRNA sequencing. Moreover, bacterial isolates MuJs52b, MuJs53b, MuJs72a and MuBk32b, which exhibited drought-tolerance of 40 % PEG-6000 and different PGP activities, were used as bioinoculant on mungbean plants grown under moderate to severe drought at 50 and 25 % of field capacity (FC) in pot experiment. Bacteria inoculated plants showed maximum increase in nodule dry weight (56.5 %) and shoot dry weight (87.5 %) per plant even under severe drought at 25 % FC. The results indicated that application of four potential nodule bacterial isolates, which were able to tolerate drought stress of 40 % PEG-6000, and having multiple PGP traits, showed stimulation of the mungbean growth even up to 25 % FC. These plant growth-promoting nodule bacterial strains may be used for the enhancement of mungbean crop productivity under drought stress and could be used as biofertilizer.

PIN2-mediated self-organizing transient auxin flow contributes to auxin maxima at the tip of Arabidopsis cotyledons.

Directional auxin transport and formation of auxin maxima are critical for embryogenesis, organogenesis, pattern formation, and growth coordination in plants, but the mechanisms underpinning the initiation and establishment of these auxin dynamics are not fully understood. Here we show that a self-initiating and -terminating transient auxin flow along the marginal cells (MCs) contributes to the formation of an auxin maximum at the tip of Arabidopsis cotyledon that globally coordinates the interdigitation of puzzle-shaped pavement cells in the cotyledon epidermis. Prior to the interdigitation, indole butyric acid (IBA) is converted to indole acetic acid (IAA) to induce PIN2 accumulation and polarization in the marginal cells, leading to auxin flow toward and accumulation at the cotyledon tip. When IAA levels at the cotyledon tip reaches a maximum, it activates pavement cell interdigitation as well as the accumulation of the IBA transporter TOB1 in MCs, which sequesters IBA to the vacuole and reduces IBA availability and IAA levels. The reduction of IAA levels results in PIN2 down-regulation and cessation of the auxin flow. Hence, our results elucidate a self-activating and self-terminating transient polar auxin transport system in cotyledons, contributing to the formation of localized auxin maxima that spatiotemporally coordinate pavement cell interdigitation.

Characterization of endophytic bacteria isolated from wild rice plants in the Mekong Delta, Vietnam

Abstract. Thi QVC, Minh NLK, Thuy NP, Tat TQ, Tran T. 2024. Characterization of endophytic bacteria isolated from wild rice plants in the Mekong Delta, Vietnam. Biodiversitas 25: 2576-2585. Endophytic bacteria bring many benefits to plants, such as stimulating plant growth and inhibiting many microbial pathogens that cause plant diseases. Hence, this investigation aimed to evaluate the association of endophytic bacteria with wild rice (Oryza rufipogon) that can fix nitrogen, solubilize phosphorus and produce indole-3-acetic acid (IAA). Twelve-five bacterial strains were recovered from wild rice stems and roots collected from Vinh Long and Tien Giang provinces of the Mekong Delta. Among these strains, six had phosphorus solubilizing and seven had nitrogen-fixing activity. Strain BR3.5 fixed the highest nitrogen, i.e. ammonia (NH4+) content of 0.109 ± 0.002 mg/L after eight-day incubation. However, the highest phosphorus solubilization was recorded in two isolates, RR3.7 and RR1.1, with clear zone diameters of 0.800 ± 0.020 mm and 0.800 ± 0.030 mm, respectively. In addition, bacterial strains could synthesize IAA, and BR2.5 produced the highest, i.e., 0.067 ± 0.002 ?g/mL, IAA after eight-day incubation. Notably, strain BR3.5 exhibited multiple activities like nitrogen fixation (0.109 ± 0.002 mg/L), phosphorus solubilization (1.02 ± 0.002 mm), and IAA synthesis (0.056 ± 0.00 ?g/mL). Strain BR3.5 was identified as Pantoea sp. based on 16S rRNA gene sequencing (92.69% similarity) together with morpho-physiological and biochemical characteristics. The findings indicate that strain BR3.5 may be used for the production of biofertilizers for rice farming.

Isolation and characterization of plant growth promoting rhizobacteria (PGPR) from rhizosphere of Helianthus annuus L.

Plant growth-promoting rhizobacteria (PGPR) support plant growth through direct and indirect mechanisms. To investigate PGPR strains that support plant growth, 21 bacterial isolates, mostly Bacillus ssp. and Pseudomonas ssp., were isolated from different rhizospheric soils of sunflowers in Kırşehir districts in 2020. All isolates were characterized morphologically, biochemically by screening under in vitro conditions for plant growth-promoting properties such as nitrogen fixation, IAA (indoleacetic acid) production, siderophore production, HCN (hydrogen cyanide) production, inorganic phosphate solubility. It was also screened for extracellular enzyme production and antifungal activity against Fusarium oxysporum. Among the 21 isolates, 3 isolates (MH-35-4, MH-49-4, MH-64-3) fixed nitrogen, 2 isolates (MH-59-6, MH-64-3), produced siderophores, 8 isolates (MH-35-4, MH-35-6, MH-54-3, MH-54-4, MH-59-1, MH-59-2, MH-59-4, MH-59-8) produced HCN, 6 isolates (MH-35-6, MH-54-4, MH-59-1, MH-59-2, MH-59-4, MH-59-8) produced IAA, and 7 isolates (MH-35-4, MH-35-6, MH-59-1, MH-59-2, MH-59-4, MH-59-8, MH-64-3) solubilized inorganic phosphate. Additionally, only 2 isolates (MH-54-3, MH-54-4) were positive amylase tests, 8 isolates (MH-35-6, MH-54-4, MH-59-1, MH-59-2, MH-59-4, MH-59-6, MH-59-7, MH-59-8) were positive citrate tests, 8 isolates (MH-35-1, MH-35-4, MH-35-7, MH-49-4, MH-54-4, MH-59-6, MH-59-7, MH-64-3) were positive protease tests, and 6 isolates (MH-35-1, MH-35-3, MH-35-7, MH-54-3, MH-54-4, MH-59-7) were positive gelatin hydrolysis tests. Among 21 isolates, 38% were determined as hydrogen cyanide producers, 10% as siderophore producers, 29% IAA producers, 33% as phosphate solubilizers and 14% as nitrogen fixers. Isolate MH-35-6 showed the highest antifungal activity against Fusarium oxysporum with an inhibition rate of 53.57%. This was followed by isolates MH-54-1 (51.19%), MH-54-3 (47.61%) and MH-59-2 (38.09%), respectively. Therefore, our study reveals that bacteria that promote plant growth in sunflowers can be used to increase crop yield and as a biocontrol agent.

Effects of Photoperiod and Light Quality on Germination and Growth of Camellia sinensis 'HuangKui'.

Light, as a critical environmental factor, plays a pivotal role in photosynthesis, ultimately influencing the timing of bud flush in tea plants. However, the synergistic effects of different photoperiods and light qualities on the timing of bud flush in the albino tea cultivar 'HuangKui' (later germination variety) remain unknown. Thus, the objective of this study was to investigate the effects of different photoperiods (12L/12D, 14L/10D, 16L/8D, and 18L/6D, where L = the number of daylight hours and D = the number of hours of darkness) and ratios of red (R) to blue (B) light (R/B 1:1, R/B 1:2, R/B 1:3, and R/B 2:1) on the germination and growth of the albino tea variety 'HuangKui'. In our study, we examined how different photoperiods and red light and blue light affected tea germination and growth by investigating the timing of bud flush, photosynthesis, chlorophyll content, and growth indicators. First, our study showed that 'HuangKui' germinated 4 days, 2 days, and 1 day earlier under the 16L/8D photoperiod at the one bud and one leaf period compared with plants cultivated under the 12L/12D, 14L/10D, and 18L/6D photoperiods under light simulating the solar spectrum. Also, the growth of 'HuangKui' was maximumly promoted under the 16L/8D photoperiod treatment. Additionally, the earliest germination of 'HuangKui' was observed for the 16L/8D photoperiod under the R/B 2:1 (red/blue) treatment compared with the other treatments. Moreover, the greatest plant height, length of the new shoots, and new leaf areas were detected in the albino tea variety 'HuangKui' under R/B 2:1. Moreover, the contents of auxin (indole acetic acid, IAA) and trans-zeatin (tZ) under R/B 2:1 were significantly higher than those under the R/B 1:1 and control treatments with the 16L/8D photoperiod. Additionally, the auxin-related expression levels of CsIAA13, CsGH3.1, CsAUX1, and CsARF2 under the R/B 2:1 treatment were significantly higher than those in the control. The expression of CsARR-B, a positive regulator of cytokinin-related genes, was significantly higher under the R/B 2:1 treatment than under the control treatment, while the opposite result was found for the expression of the negative regulator CsARR-A. Therefore, the R/B 2:1 treatment with the 16L/8D photoperiod was an appropriate means of timing the bud flush for the albino tea variety 'HuangKui', which may be related to IAA or tZ signal transduction. In conclusion, our research offers a novel lighting strategy that promotes the germination and growth of albino tea cultivars.

Hippocampal Serotonin and Responses to Immobilization Stress in Rats Treated with Metformin

Background: Stress-related illnesses and depression are rising in modern society. Selective serotonin reuptake inhibitors as well as other antidepressants, are also not very effective and commonly exhibit partial remission, suggesting the need for novel therapeutic agents for treating anxiety and depression. Objective: The present study was designed to investigate serotonergic mechanisms in the potential anxiolytic and stress-reducing effects of metformin. Method: In the first experiment, rats were given two doses (50 and 100mg/kg) of metformin to monitor the effects of repeated administration on motor activity, anxiety, and 5-HT-1A receptor expression in the hippocampus and raphe nuclei. The second experiment was conducted in 2 parts, in 2a. experiment, control, and metformin (50 mg/kg) treated rats were immobilized for 2 hours for 5 consecutive days. Food intake and body weight were monitored daily and anxiety-like behavior was monitored on days 2 and 6. On day 6, rats were again immobilized for 2 hours, and after termination of stress rats were sacrificed to collect the hippocampus for HPLC-EC analysis of serotonin (5-hydroxytryptamine; 5-HT) and 5-hydroxy indole acetic acid (5-HIAA). In 2b. experiment, control, and metformin (50 mg/kg) treated rats were immobilized for 2 hours, and after 2 hours rats were sacrificed to collect the hippocampus for HPLC-EC analysis of 5-HT and 5-HIAA. Results: We found that metformin treatment exhibited anxiety reduction associated with greater expression of 5-HT-1A receptor in the hippocampus and reduced expression in the raphe nuclei. Immobilization stress-induced food intake and body weight deficits were comparable in control and metformin-treated rats, but the anxiogenic effects of stress were smaller in the metformintreated group. Stress-induced decreases of hippocampal 5-HT were smaller in metformin-treated than in control rats. Conclusion: Metformin can reduce stress-induced anxiety mediated via an increase in hippocampal 5-HT levels and 5-HT-1A heteroreceptor expression.

In vitro morphogenesis and micro-morpho-anatomical developments in Moringa concanensis Nimmo.: An endemic tree of Indian sub-continent

Moringa concanensis Nimmo. is a regionally important and underutilized medicinal tree of the Indian subcontinent. An in vitro morphogenesis protocol for Moringa concanensis has been developed using seedling-derived explants. The cotyledonary node explants were found to be the most suitable exhibiting cent-percent bud break with each regenerating 2.33±0.76 shoots of 1.32±0.69 cm length within 15 days on 1.0 mg/L 6-benzyl aminopurine (BAP) supplemented modified Murashige and Skoog Medium (MMS) media. The rate of shoot multiplication increased up to 10.17±2.54 shoots/inoculum by sub-culturing of regenerated shoots on 0.5 mg/L BAP along with 0.1 mg/L Indole acetic acid (IAA). The in vitro cloned shoots were rooted using both in vitro and ex-vitro methods by applications of root-inducing auxins, indole butyric acid (IBA), and naphthalene acetic acid (NAA). IBA proved to be more effective and induced roots in all in vitro raised shoots. It produced 17.72±4.83 roots/shoot with 2.12±0.88 cm length on 1/4th strength MMS media fortified with 1.0 mg/L of IBA. Ex vitro rooted plantlets with concurrent acclimatization were achieved by pre-treating shoot bases with IBA at 250 ppm for 5 min. Comparative micro-morpho-anatomical evaluation of leaf and stem revealed differentiation of non-glandular trichomes, anomocytic stomata, and vascular tissue development under applied in vitro conditions, which suggests the survivability of plantlets. Sixty percent of the in vitro regenerated plants survived in the field. It is the foremost report on in vitro morphogenesis of Moringa concanensis protocol using cotyledonary nodal explant and ex vitro rooting method. The tissue culture methods defined and developed can be used for large-scale multiplications of Moringa concanensis as non-conventional approaches.

Physiological and genomic insights into a psychrotrophic drought-tolerant bacterial consortium for crop improvement in cold, semiarid regions

The agricultural land in the Indian Himalayan region (IHR) is susceptible to various spells of snowfall, which can cause nutrient leaching, low temperatures, and drought conditions. The current study, therefore, sought an indigenous psychrotrophic plant growth-promoting (PGP) bacterial inoculant with the potential to alleviate crop productivity under cold and drought stress. Psychrotrophic bacteria preisolated from the night-soil compost of the Lahaul Valley of northwestern Himalaya were screened for phosphate (P) and potash (K) solubilization, nitrogen fixation, indole acetic acid (IAA) production, siderophore and HCN production) in addition to their tolerance to drought conditions for consortia development. Furthermore, the effects of the selected consortium on the growth and development of wheat (Triticum aestivum L.) and maize (Zea mays L.) were assessed in pot experiments under cold semiarid conditions (50 % field capacity). Among 57 bacteria with P and K solubilization, nitrogen fixation, IAA production, siderophore and HCN production, Pseudomonas protegens LPH60, Pseudomonas atacamensis LSH24, Psychrobacter faecalis LUR13, Serratia proteamaculans LUR44, Pseudomonas mucidolens LUR70, and Glutamicibacter bergerei LUR77 exhibited tolerance to drought stress (-0.73 MPa). The colonization of wheat and maize seeds with these drought-tolerant PGP strains resulted in a germination index >150, indicating no phytotoxicity under drought stress. Remarkably, a particular strain, Pseudomonas sp. LPH60 demonstrated antagonistic activity against three phytopathogens Ustilago maydis, Fusarium oxysporum, and Fusarium graminearum. Treatment with the consortium significantly increased the foliage (100 % and 160 %) and root (200 % and 133 %) biomasses of the wheat and maize plants, respectively. Furthermore, whole-genome sequence comparisons of LPH60 and LUR13 with closely related strains revealed genes associated with plant nutrient uptake, phytohormone synthesis, siderophore production, hydrogen cyanide (HCN) synthesis, volatile organic compound production, trehalose and glycine betaine transport, cold shock response, superoxide dismutase activity, and gene clusters for nonribosomal peptide synthases and polyketide synthetases. With their PGP qualities, biocontrol activity, and ability to withstand environmental challenges, the developed consortium represents a promising cold- and drought-active PGP bioinoculant for cereal crops grown in cold semiarid regions.

Inoculation with Bacillus megaterium CNPMS B119 and Bacillus subtilis CNPMS B2084 improve P-acquisition and maize yield in Brazil.

Phosphorus (P) is a critical nutrient for plant growth, yet its uptake is often hindered by soil factors like clay minerals and metal oxides such as aluminum (Al), iron (Fe), and calcium (Ca), which bind P and limit its availability. Phosphate-solubilizing bacteria (PSB) have the unique ability to convert insoluble P into a soluble form, thereby fostering plant growth. This study aimed to assess the efficacy of inoculation of Bacillus megaterium B119 (rhizospheric) and B. subtilis B2084 (endophytic) via seed treatment in enhancing maize yield, grain P content, and enzyme activities across two distinct soil types in field conditions. Additionally, we investigated various mechanisms contributing to plant growth promotion, compatibility with commercial inoculants, and the maize root adhesion profile of these strains. During five crop seasons in two experimental areas in Brazil, Sete Lagoas-MG and Santo Antônio de Goiás-GO, single inoculations with either B119 or B2084 were implemented in three seasons, while a co-inoculation with both strains was applied in two seasons. All treatments received P fertilizer according to plot recommendations, except for control. Both the Bacillus strains exhibited plant growth-promoting properties relevant to P dynamics, including phosphate solubilization and mineralization, production of indole-3-acetic acid (IAA)-like molecules, siderophores, exopolysaccharides (EPS), biofilms, and phosphatases, with no antagonism observed with Azospirillum and Bradyrizhobium. Strain B2084 displayed superior maize root adhesion compared to B119. In field trials, single inoculations with either B119 or B2084 resulted in increased maize grain yield, with relative average productivities of 22 and 16% in Sete Lagoas and 6 and 3% in Santo Antônio de Goiás, respectively. Co-inoculation proved more effective, with an average yield increase of 24% in Sete Lagoas and 11% in Santo Antônio de Goiás compared to the non-inoculated control. Across all seasons, accumulated grain P content correlated with yield, and soil P availability in the rhizosphere increased after co-inoculation in Santo Antônio de Goiás. These findings complement previous research efforts and have led to the validation and registration of the first Brazilian inoculant formulated with Bacillus strains for maize, effectively enhancing and P grain content.

Urease-producing bacteria with plant growth-promoting ability that may tolerate and remove cadmium from aqueous solution

Urease-producing bacteria (UPB) are widely present in soil and play an important role in soil ecosystems. In this study, 65 UPB strains were isolated from cadmium (Cd)-polluted soil around a lead-zinc mine in Yunnan Province, China. The Cd tolerance, removal of Cd from aqueous solution, production of indoleacetic acid (IAA) and plant growth-promoting effects of these materials were investigated. The results indicate that among the 65 UPB strains, four strains with IAA-producing ability were screened and identified as Bacillus thuringiensis W6-11, B. cereus C7-4, Serratia marcescens W11-10, and S. marcescens C5-6. Among the four strains, B. cereus C7-4 had the highest Cd tolerance, median effect concentration (EC50) of 59.94 mg/L. Under Cd 5 mg/L, S. marcescens C5-6 had the highest Cd removal from aqueous solution, up to 69.83%. Under Cd 25 mg/kg, inoculation with B. cereus C7-4 significantly promoted maize growth in a sand pot by increasing the root volume, root surface area, and number of root branches by 22%, 29%, and 20%, respectively, and plant height and biomass by 16% and 36%, respectively, and significantly increasing Cd uptake in the maize roots. Therefore, UPB is a potential resource for enhancing plant adaptability to Cd stress in plants with Cd-polluted habitats.