Leucocalocybe mongolica inoculation enhances rice growth by reallocating resources from flavonoid defense to development via MYB/bHLH/WRKY networks

Three bacterial isolates selected as plant growth-promoting endophytic bacteria (PGPEB) from “Klutuk” banana (Musa balbisiana L.) gained scrutiny for first-time testing on black rice. The presented study pursued an investigation on the impact of endophytic bacteria inoculation obtained from “Klutuk” banana plants on the growth and production traits of black rice. For this research, the three bacterial isolates (K10, K324, and K111) served as inoculums for black rice seeds, testing for synergism. The three isolates inoculation into black rice plants used both single and consortium inoculation methods. With agar media, black rice growth observation began 14 days after plantation (DAP) while on soil, at 30 and 140 DAP with inoculation. Three isolates did not show any antagonistic reactions. Overall, isolate K10 showed less significant improvement in growth and yield traits of black rice compared with two other isolates, i.e., K324 and K111. With agar media, the endophytic bacteria inoculations did not show a significant effect on the growth of black rice, and even isolate K324 was inhibiting in action. However, on soil media, isolate K324 significantly enhanced the number of roots and shoot length in black rice compared with the control at 30 DAP. The single inoculation with isolate K111 has caused increased productivity based on the weight of the root, dry grain weight per clum, plant height, root length, leaf length, and panicle length in black rice. Isolate K324 promotes the growth of black rice on the soil media at 30 DAP, while isolate K111 improves the production traits on the soil media at 140 DAP. The study findings provide a significant basis for the positive impact of endophytic bacterial inoculation on black rice growth and yield traits.

Sheath blight (ShB) of rice caused by Rhizoctonia solani is an economically important disease, causing significant yield losses. In this study, the growth promoting activities of commercial formulation of a bioagent, Bacillus subtilis MBI 600 (Integral®) and its compatibility with rice fungicides were evaluated. Integral was evaluated for growth promotion in rice on four cultivars (Cocodrie, Catahoula, Neptune, and Trenasse) under in vitro conditions. Treated rice seeds were incubated for 7 days, and the shoot and root lengths were measured. Rice cv. Cocodrie seeds were treated with strain MBI 600 at various concentrations and seeded in pots containing field soil in GH in a randomized complete block design. Germination and seedling lengths were measured at 7 and 15 days after sowing (DAS). The strain MBI 600 was found to produce siderophores. Seed treatment with Integral significantly increased shoot and root lengths at all concentrations in cvs. Cocodrie, Catahoula, and Trenasse under in vitro conditions. The shoot lengths ranged from 39 to 42 mm at a concentration of 2.20 x 109 cfu/ml in all CV’s. At 2.20 x 109 cfu/ml, the root lengths ranged from 47 to 69 mm. The shoot and root lengths of control seedlings were each up to 20 mm. Seed treatment with 2.20 x 108 and 2.20 x 109 cfu/ml significantly increased seedling emergence (81 to 89%) compared to 2.20 x 106 and 2.20 x 107 cfu/ml, and control (61%) under GH conditions. Similarly, seed treatment with 2.20 x 109 cfu/ml of MBI 600 resulted in the highest shoot and root lengths (335 and 166 mm respectively). Integral has good tolerance to hexaconazole, propiconazole, and validamycin; moderate tolerance to tricyclazole; and poor tolerance to benomyl and mancozeb at 1000 ppm. Integral showed compatibility to carbendazim and azoxystrobin up to 400 ppm. Overall, our results suggest that Integral produces siderophores, promoted rice seedling emergence and growth, and is compatible with rice fungicides.

Prevalent irregular rainfall, flooding for weed control, and unleveled fields in the middle and lower reaches of the Yangtze River all contribute to flooding stress on germination and growth of direct‐seeded rice ( Oryza sativa L.). Herein, some experiments were conducted so as to assess the effects of seed priming with selenium (Se) on the germination and growth of rice under hypoxia. The experiment was arranged in a completely randomized factorial design with two factors and five replicates. Factors included Se concentration (0, 30, and 60 μmol/L) and duration of flooding stress (0, 2, 4, and 8 days). The experimental results showed that Se accelerated seed germination and increased emergence index and final emergence percentage. Additionally, Se increased shoot and root lengths and dry weights, but high Se concentration (60 μmol/L) reduced 18‐day‐old seedling dry weight under long‐term flooding (8 days). Furthermore, Se reduced malondialdehyde content and increased starch hydrolysis efficiency in seeds, superoxide dismutase, peroxidase, catalase, and glutathione peroxidase activities and seedling soluble protein and total chlorophyll contents. Se improved seedling total Se and organic Se contents while increasing total dry weight and yield. Notably, the highest yield was obtained after a 4‐day flooding period. Although Se priming favored rice seedling emergence and growth under flooding conditions, Se concentrations equal or above 60 μmol/L increased the risk of seedling death during long‐term flooding (≥8 days).

Peptide deformylase (PDF) belongs to a conserved enzyme family critical for N-terminal methionine excision (NME), an essential protein maturation process in prokaryotes and eukaryotic organelles (chloroplasts, mitochondria). To explore the potential functions of OsPDFs in Oryza sativa, this study employed bioinformatics approaches and experimental validation to systematically identify and analyze the OsPDF gene family. Three OsPDF genes (OsPDF1A, OsPDF1B, OsPDF1B2) were identified in rice. These genes are exclusively distributed on chromosome 1. The biophysical properties of these proteins showed that OsPDF1A and OsPDF1B are alkaline proteins, while OsPDF1B2 is acidic, and all are hydrophilic with moderate thermostability potential. Synteny analysis revealed closer evolutionary relationships between Oryza sativa and the monocot Triticum aestivum than with dicots, reflecting conserved PDF function in gramineous plants. Analysis of cis-acting elements in the 2000 bp upstream region of OsPDF gene promoters revealed numerous elements associated with abiotic stress response and hormone regulation. Furthermore, quantitative real-time PCR (qRT-PCR) data supported these findings, indicating that OsPDF1A and OsPDF1B were upregulated under low-temperature stress, and all three OsPDF genes were transcriptionally activated by heat, salt and UV-B stresses, indicating their active involvement in rice growth, development, and abiotic stress tolerance. In summary, OsPDFs exhibit significant functions in rice's stress adaptation, growth, and development. This study not only enhances our understanding of the OsPDF gene family's genomic, evolutionary, and functional characteristics, but also provides new perspectives and foundational data for further exploring their regulatory mechanisms in protein maturation and abiotic stress responses, as well as their potential applications in rice stress tolerance breeding.

Upland rice can overcome major challenges through the insertion of silicate fertilization and the presence of plant growth-promoting microorganisms (PGPMs) during its cultivation, as these factors promote an increase in vigor and plant disease resistance. Two consecutive experiments were conducted to evaluate the beneficial effects of silicon fertilization combined with the PGPM, Pseudomonas fluorensces, Burkholderia pyrrocinia, and a pool of Trichoderma asperellum, in upland rice seedlings, cultivar BRS Primavera CL: (a) E1, selecting PGPM type and Si doses for rice growth promotion and leaf blast supression, and (b) E2, evaluating physiological characteristics correlated with mechanisms involved in the higher vegetative growth in highlighted treatments from E1. In E1, 2Sitha-1 combined with the application of T. asperellum pool or PGPM mixture increased 54% in root dry matter biomass and 35 and 65% in shoot and root lengths, respectively; it also suppressed 99% of rice blast severity. In E2, shoot and root dry matter biomass and length, photosynthetic rate, water use efficiency, total soluble sugar, and chloroplastidic pigments were superior in BRS Primavera CL seedlings treated with 2Sitha-1 and T. asperellum pool or PGPM mixture. Higher salicilic and jasmonic acid levels were found in seedlings treated with Si and T. asperellum pool, individually. These physiological characteristics may explain, in part, the higher vigor of upland rice seedlings promoted by the synergistic effect between silicate fertilization and beneficial microorganisms.

This study investigates the impact of exogenous calcium and gamma-aminobutyric acid (GABA) supplementation on rice growth and stress tolerance under white-backed planthopper (WBPH) infestation. We evaluated several phenotypic traits, including shoot/root length, leaf width, tiller number, panicle length, and relative water content, alongside physiological markers such as oxidative stress indicators, antioxidant enzymes activities, hormonal levels, and amino acids biosynthesis. Our results indicate that WBPH stress significantly reduces growth parameters but calcium and GABA supplementation markedly enhance shoot length (by 26% and 36%) and root length (by 38% and 64%), respectively, compared to WBPH-infested plants. Both supplementations also reduced oxidative stress, as evidenced by decreased H2O2 and O2•− levels and a lower electrolyte leakage. Notably, calcium and GABA treatments increased antioxidant enzyme activities, with GABA boosting catalase (CAT) activity by 800%, peroxidase (POD) by 144%, and superoxide dismutase (SOD) by 62% under WBPH stress. Additionally, calcium and GABA enhanced the accumulation of stress hormones (abscisic acid ABA) and salicylic acid (SA) and promoted stomatal closure, contributing to improved water conservation. This study reveals that calcium regulates the GABA shunt pathway, significantly increasing GABA and succinate levels in both root and shoot. Furthermore, calcium and GABA supplementation enhance the biosynthesis of key amino acids and improve ion homeostasis, particularly elevating calcium (Ca), iron (Fe), and magnesium (Mg) levels under WBPH stress. Overall, this study highlights the potential of exogenous calcium and GABA as effective strategies for enhancing rice plant tolerance to WBPH infestation by modulating various physiological and biochemical mechanisms. Further research is warranted to fully elucidate the underlying mechanisms of action.

In the present investigation, fungal and bacterial bioagents which were effective against pathogen of bacterial leaf blight disease of rice (Xanthomonas oryzae pv. oryzae) was tested for their effect on germination of rice seeds and growth of nursery seedlings under laboratory and glasshouse conditions. Two isolates of fluorescent pseudomonas isolated from rice phylloplane (Pf 83 and FLP 88), Trichoderma species were isolated from soil of rice field (isolate 40) and Trichoderma harzianum isolated from rice phylloplane. Two commercial formulations (PBA-1 and PBA-2) were tested in the present investigation and compared with chemical treatment (0.76 g Emison + 0.18 g Streptocycline / kg seeds) and untreated check. Under laboratory conditions, chemical treatment was found most effective in increasing seed germination (43.90%) followed by Pf 83 and PBA-1 (34.15 %). Bioagent formulations were significantly effective in increase in root and shoot length as compared to check and chemical treatment. Under glasshouse conditions, maximum increase (29.42%) in seedlings emergence was exhibited by chemical treatment. Maximum increase in root length (100.15%) and shoot length (50.06%) was recorded with FLP 88 and T. harzianum, respectively. Bioagent formulations also increased fresh and dry root weight over check and chemical treatment. All bioagents formulations were effective over chemical treatment and check in increasing fresh shoot weight. Results of the present study revealed that in the absence of pathogen of bacterial leaf blight of rice, fungal and bacterial bioagents significantly enhanced germination of rice seeds and growth of nursery seedlings.

Direct-seeded rice (DSR) faces low iron bioavailability due to the plurality in the oxidation states of iron. Rapid ferrous oxidation in low-irrigation soils poses a challenge to the optimum supply of iron for the initial growth in rice. Using advancements in nanotechnology, a new iron formulation, iron sulfide-impregnated sepiolite nanocomposite (FeS-Sp NC), was prepared by an in situ combination of ferrous and sulfide ions on a sepiolite matrix under ultrasonic irradiation. Nanopriming of rice seeds (PR 126) with FeS-Sp NC at an optimized dose (500 μg/g) for 12 h revealed a notable enhancement in seedling growth metrics, namely, germination percentage (15.39%), shoot length (40.54%), root length (21.67%), seedling fresh weight (15.57%), dry weight (11.36%), and vigor index (28.50%) with augmented iron content, outperforming traditionally used FeSO4 (at an optimized dose of 750 μg/g). Enhanced activity of defensive enzymes (in shoot, root), viz. SOD (13.81%; 8.78%), APX (16.66%; 3.31%), CAT (10.84%; 13.83%), and PPO (150.41%, 191.30%) indicated a stronger defense mechanism. The elevated levels of total phenolics (49.81%; 28.79% in shoot and root respectively), flavonoids (21.75% in roots), DPPH (37.15% in roots), and ABTS (13.79% in roots) as compared to FeSO4 further rationale the invigoration of the rice seeds. Overall, FeS-Sp NC-infused nanopriming presented superior invigoration potential over FeSO4 mediated by an antioxidative defense mechanism due to enhanced iron assimilation in seedlings, offering a promising solution for iron modulation under sustainable agricultural practices.

Piper aduncum L. (Piperaceae) has great potential for economic exploration because of the proven use of its essential oil in the agriculture and in the human health. A technique that improves its propagation, as the tissue culture, becomes necessary. Some parameters must be determined for the successful cultivation in vitro. Thus, this study aimed to determine the salts concentration of MS medium, temperature, luminosity and light quality for in vitro culture of this species. The following treatments were conducted: 1/4MS, 1/2MS, MS and 2MS; 20℃, 25℃, 30℃ and 35℃; monochromatic blue, red and white lights and the combination of red and blue, using light emitting diodes (LEDs); luminosities of 17, 37, 48 and 73 μmol·m-2·s-1 obtained with cool white fluorescent lamp. After 35 days, the treatments were analyzed. To determine the salts concentration of MS, the variables were evaluated: number of shoots, leaves and roots, length and width of leaves, length and dry mass of root and shoots and percentage of death by necrosis. To the plantlets under different temperatures, length and dry mass of shoot and root, number of shoots, number, length and width of leaves and survival and rooting percentages were measured. The plantlets that were maintained under different luminosities were evaluated for length of shoot and root, dry mass of leaf and root. To evaluate the growth under the LEDs, the length and dry mass of shoot and root, number of shoots and roots, percentage of rooting and sprouting were assessed. The medium 1/4MS and the medium 1/2MS showed better responses for number and length of root, leaf width and shoot length. The temperature 25℃ provided the highest number of leaves, length of shoot and root, root dry mass and rooting percentage. The luminosity 73 μmol·m-2·s-1 provided higher values in length of root and dry mass of leaf and root. The red LED provided plantlets with greater growth. Thus, for the in vitro cultivation of Piper aduncum, 1/4MS, environment temperature of 25℃, light intensity of 73 μmol·m-2·s-1 and environments with red light to obtain high quality plantlets for propagation of this species are recommended.

Ризобактерії, які стимулюють ріст рослин, широко поширені в ризосфері рослин. Вони забезпечують живлення та продукують деякі антибіотичні речовини для пригнічення фітопатогенів і сприяння росту рослин. Тому вивчення алелопатії є дуже важливою частиною взаємодії між ризобактеріями та рослиною. Streptomyces, рід актиноміцетів, добре відомий своїми біоактивними метаболітами, головним чином – антибіотиками, гормонами та гідролазою, які можуть впливати на ріст рослин. У цьому дослідженні було оцінено алелопатію метаболітів штаму Streptomyces sp. HU2014 на пшеницю та мишій зелений з використанням індексу відповіді RI. Негативні значення RI вказували на пригнічення росту рослин; позитивні показники свідчили про стимуляцію їх росту. Чотири фракції (F2, F4, F6 та F8) з безклітинних фільтратів культурального бульйону HU2014 мали певний вплив на довжину проростків та коренів рослин. Для пшениці результати показали, що фракція F2 при 10 мг/мл мала найбільш виразний ефект пригнічення довжини проростків (RI=-0,53) і кореня (RI=-0,22). Однак фракція F2 при 1 мг/мл сприяла збільшенню довжини проростка (RI=0,01). Фракції F4 і F6 при 10 мг/мл мали найбільше пригнічення довжини проростків та коренів. Для фракції F8 зафіксовано найбільше зменшення довжини проростків (RI = -0,66) при 5 мг/мл і довжини кореня (RI = -0,66) при 10 мг/мл. Для мишію зеленого фракція F2 при 10 мг/мл пригнічувала як довжини проростків (RI = -0,73), так і кореня (RI =-1,00). Фракція F4 показала найвище пригнічення проростку (RI = -0,69) при 5 мг/мл і кореня (RI = -0,85) при 10 мг/мл. Фракція F6 мала найвище пригнічення довжини проростка (RI = -0,59) при 10 мг/мл і кореня (RI = -0,80) при 5 мг/мл. Фракція F8 показала найвищий рівень інгібування довжини проростка (RI = -0,47) при 5 мг/мл і кореня (RI = -0,93) при 10 мг/мл. З наведених вище результатів ми можемо зробити висновок, що чотири фракції мали алелопатичний вплив на довжину проростків і коренів двох досліджуваних видів рослин, за винятком фракції F2 при 1 мг/мл, яка сприяла збільшенню довжини пагонів пшениці. Таким чином, на ранній стадії росту рослин низька концентрація алелопатичних речовин, які продукує HU2014, може сприяти росту пшениці, тоді як ці речовини пригнічують ріст мишію зеленого. Тому цей штам може бути перспективним як у якості біофунгіциду, так і – біогербіциду.

Ria RP, Lakitan B, Negara ZP. 2020. Effects of water table, seedling density and transplanting time on vegetative growth of black sticky rice at floating seedbed. Jurnal Lahan Suboptimal : Journal of Suboptimal Lands 9(2): 167-174.Study on black sticky rice cultivation in South Sumatera is seldom carry out. The objective of this study was to evaluate the effect of water table and population density on the growth of rice during seedling preparation at floating seedbed; furthermore, this study aimed to evaluate the effect of transplanting time on vegetative growth of black sticky rice. The research was started in May 2018 in Palembang. Black sticky variety used in this research was Toraja variety. The raft used is made from 1,5 l plastic bottles which are arranged to reach 2x1 meters in size. This study was conducted by two stages. The first stage was for water table and population density treatments laid on split plot design. The second stage was for transplanting time utilizing completely randomized factorial design. Statistically, results showed water table and population density significantly influensced root length of black sticky rice and transplanting time 14 DAS haad an effect on the leaf length , leaf width and leaf area.

Summary Drought and heat stress are a global concern affecting crop productivity. The current study investigated the daily shoot and root length growth of 48 elite African sorghum genotypes and two commonly grown check varieties in response to heat and drought stresses applied individually and in combination at the early (7-day-old) and late (21-day-old) seedling stages. Genotype, stress, and their interaction significantly affected root and shoot length at both stages. Our findings indicated that the combined stresses suppressed daily shoot length growth at both stages. Drought, heat, and combined stresses equally suppressed daily root length growth during the early seedling growth stage, and drought applied separately showed the highest negative effect on root length at the late seedling stage. In general, the stress treatments showed the utmost negative effects in daily shoot and root length growth at early seedling stage than the late stage. Heat stress induced the highest relative growth reduction of 78% in hypocotyl length followed by combined stresses at 77.6% and 70.8% for drought stress. The average hypocotyl length changes ranged between 0.37 and 2.31 mm per day at early seedling stage. Root length daily growth was reduced by 69.1% under combined stress, 67.6% under heat stress, and 63.3% under drought stress at early seedling stage. Root length changes ranged between 0.35 and 2.96 mm per day at early seedling stage. At late seedling stage, the highest relative daily growth reduction was observed in shoot length (36.6%) under combined stresses while drought stress induced the highest relative daily root length reduction of 10.8%. The average shoot length changes ranged between 5.1 and 8.1 mm per day at late seedling stage while root length changes ranged between 2.7 and 3.5 mm. In reference to the independent genotypic effects, genotype IS13904 displayed the highest performance in hypocotyl and root length growth at the early seedling stage. At the late seedling stage, genotypes IS6994 and NPGRC1478 showed tolerance to at least two of the assessed stress conditions in terms of daily root length growth. Genotypes IS30164, IS30015, and IS9567 showed similar resistance in shoot growth. The overall analysis of both shoot and root daily length growth at both seedling stages revealed the resistance of genotypes NPGRC1478 and IS30164 to drought stress applied separately and combined stressors. The identified sorghum genotypes can be used as potential donors towards tolerance to combined stresses at both seedling stages and are recommended for utilization in hot and dry agroecologies of sub-Saharan Africa due to their potential vigour in early establishment.

Early Root and Shoot Elongation of Selected Warm-Season Perennial Grasses

Catalase can decompose hydrogen peroxide in plants under controlled and stressed conditions. In a stressed environment, an increase in hydrogen peroxide production makes catalase activity a major defense system for plant growth. The current study was conducted to evaluate the catalase activity of the pre-isolated and identified bacterial strains Bacillus aryabhattai (AN30), Bacillus megaterium (AN24), Bacillus megaterium (AN31) and Bacillus megaterium (AN35) and their potential for rice seedling growth promotion. These strains were characterized for quantitative catalase, urease, siderophore and exopolysaccharide production using LB media. Subsequently, the effectiveness of these strains was checked by quantifying the catalase activity in the rhizosphere, roots and shoots of rice seedlings. The secretion of organic and phenolic compounds produced by the tested strains in liquid culture was also investigated. Plant growth parameters were also studied in a growth room trial. Our results showed that the strain AN24 showed the maximum catalase activity (1.36 mol cm−1), urease activity (1.35 mol cm−1) and exopolysaccharide (4.20 µg mL−1) and siderophore (2.32%) production in LB media. All tested strains showed significantly higher catalase activity in soil compared to the control. Among sole applications, strain AN24 showed better results; however, the consortium application of strains AN24 + AN30 + AN35 + AN31 showed the maximum improvement in dry biomass, shoot and root length, and increase in catalase activity of rice seedlings. The results showed that a consortium of these Bacillus strains with catalase activity has greater potential to enhance the antioxidant defense system and growth promotion of rice seedlings. However, further experimentation under natural conditions is required before using these strains as potential bioinoculants for improving rice growth and yield.

Global climate change poses a significant threat to plant growth and crop yield and is exacerbated by environmental factors, such as drought, salinity, greenhouse gasses, and extreme temperatures. Plant growth-promoting rhizobacteria (PGPR) help plants withstand drought. However, the mechanisms underlying PGPR-plant interactions remain unclear. Thus, this study aimed to isolate PGPR, Bacillus megaterium strains CACC109 and CACC119, from a ginseng field and investigate the mechanisms underlying PGPR-stimulated tolerance to drought stress by evaluating their plant growth-promoting activities and effects on rice growth and stress tolerance through in vitro assays, pot experiments, and physiological and molecular analyses. Compared with B. megaterium type strain ATCC14581, CACC109 and CACC119 exhibited higher survival rates under osmotic stress, indicating their potential to enhance drought tolerance. Additionally, CACC109 and CACC119 strains exhibited various plant growth-promoting activities, including phosphate solubilization, nitrogen fixation, indole-3-acetic acid production, siderophore secretion, 1-aminocyclopropane-1-carboxylate deaminase activity, and exopolysaccharide production. After inoculation, CACC109 and CACC119 significantly improved the seed germination of rice (Oryza sativa L.) under osmotic stress and promoted root growth under stressed and non-stressed conditions. They also facilitated plant growth in pot experiments, as evidenced by increased shoot and root lengths, weights, and leaf widths. Furthermore, CACC109 and CACC119 improved plant physiological characteristics, such as chlorophyll levels, and production of osmolytes, such as proline. In particular, CACC109- and CACC119-treated rice plants showed better drought tolerance, as evidenced by their higher survival rates, greater chlorophyll contents, and lower water loss rates, compared with mock-treated rice plants. Application of CACC109 and CACC119 upregulated the expression of antioxidant-related genes (e.g., OsCAT, OsPOD, OsAPX, and OsSOD) and drought-responsive genes (e.g., OsWRKY47, OsZIP23, OsDREB2, OsNAC066, OsAREB1, and OsAREB2). In conclusion, CACC109 and CACC119 are promising biostimulants for enhancing plant growth and conferring resistance to abiotic stresses in crop production. Future studies should conduct field trials to validate these findings under real agricultural conditions, optimize inoculation methods for practical use, and further investigate the biochemical and physiological responses underlying the observed benefits.