Recent advances in PGPR-mediated resilience toward interactive effects of drought and salt stress in plants.

The present crisis at hand revolves around the need to enhance plant resilience to various environmental stresses, including abiotic and biotic stresses, to ensure sustainable agriculture and mitigate the impact of climate change on crop production. One such promising approach is the utilization of plant growth-promoting rhizobacteria (PGPR) to mediate plant resilience to these stresses. Plants are constantly exposed to various stress factors, such as drought, salinity, pathogens, and nutrient deficiencies, which can significantly reduce crop yield and quality. The PGPR are beneficial microbes that reside in the rhizosphere of plants and have been shown to positively influence plant growth and stress tolerance through various mechanisms, including nutrient solubilization, phytohormone production, and induction of systemic resistance. The review comprehensively examines the various mechanisms through which PGPR promotes plant resilience, including nutrient acquisition, hormonal regulation, and defense induction, focusing on recent research findings. The advancements made in the field of PGPR-mediated resilience through multi-omics approaches (viz., genomics, transcriptomics, proteomics, and metabolomics) to unravel the intricate interactions between PGPR and plants have been discussed including their molecular pathways involved in stress tolerance. Besides, the review also emphasizes the importance of continued research and implementation of PGPR-based strategies to address the pressing challenges facing global food security including commercialization of PGPR-based bio-formulations for sustainable agricultural.

Performance of Plant-Growth-Promoting Rhizobacteria (PGPR) Isolated from Sandy Soil on Growth of Tomato (Solanum lycopersicum L.).

The plant-growth-promoting rhizobacteria (PGPR) in the rhizosphere affect plant growth, health, and productivity, as well as soil-nutrient contents. They are considered a green and eco-friendly technology that will reduce chemical-fertilizer usage, thereby reducing production costs and protecting the environment. Out of 58 bacterial strains isolated in Qassim, Saudi Arabia, four strains were identified by the 16S rRNA as the Streptomyces cinereoruber strain P6-4, Priestia megaterium strain P12, Rossellomorea aquimaris strain P22-2, and Pseudomonas plecoglossicida strain P24. The plant-growth-promoting (PGP) features of the identified bacteria involving inorganic phosphate (P) solubilization, the production of indole acetic acid (IAA), and siderophore secretion were assessed in vitro. Regarding the P solubilization, the previous strains' efficacy reached 37.71%, 52.84%, 94.31%, and 64.20%, respectively. The strains produced considerable amounts of IAA (69.82, 251.70, 236.57, and 101.94 µg/mL) after 4 days of incubation at 30 °C. Furthermore, the rates of siderophore production reached 35.51, 26.37, 26.37, and 23.84 psu, respectively, in the same strains. The application of the selected strains in the presence of rock phosphate (RP) with tomato plants under greenhouse conditions was evaluated. The plant growth and P-uptake traits positively and significantly increased in response to all the bacterial treatments, except for some traits, such as plant height, number of leaves, and leaf DM at 21 DAT, compared to the negative control (rock phosphate, T2). Notably, the P. megaterium strain P12 (T4), followed by R. aquimaris strain P22-2 (T5), revealed the best values related to plant height (at 45 DAT), number of leaves per plant (at 45 DAT), root length, leaf area, leaf-P uptake, stem P uptake, and total plant P uptake compared to the rock phosphate. The first two components of the PCA (principal component analysis) represented 71.99% (PCA1 = 50.81% and PCA2 = 21.18%) of the variation at 45 DAT. Finally, the PGPR improved the vegetative-growth traits of the tomato plants through P solubilization, IAA, and siderophore production, and ameliorated the availability of nutrients. Thus, applying in PGPR in sustainable agriculture will potentially reduce production costs and protect the environment from contamination by chemical fertilizers and pesticides.

Exploring the Plant Growth-Promotion of Four Streptomyces Strains from Rhizosphere Soil to Enhance Cucumber Growth and Yield.

The genus Streptomyces is the most abundant and essential microbes in the soil microbial community. Streptomyces are familiar and have great potential to produce a large variety of bioactive compounds. This genus considers an efficient biofertilizer based on its plant growth-promoting activities. Based on their ability to produce a wide varieties of bioactive molecules, the present study aimed to explore the potential plant growth promotion of four Streptomyces strains and their role in enhancing cucumber growth and yield under greenhouse conditions. Streptomyces sp. strain HM2, Streptomyces thinghirensis strain HM3, Streptomyces sp. strain HM8, and Streptomyces tricolor strain HM10 were chosen for the current study. Plant growth-promoting (PGP) features, i.e., indole acetic acid (IAA) production, siderophore excretion, and solubilizing phosphate, were evaluated in vitro. All four strains produced IAA, siderophore, and immobilized inorganic phosphate. Following 4 days of incubation at 30 °C, strains HM2, HM3, HM8, and HM10 produced copious amounts of IAA (18, 22, 62, and 146 µg/mL, respectively) and siderophores (42.59, 40.01, 16.84, 64.14% SU, respectively). At the same time, P solubilization efficacy scored 64.3%, 84.4%, 57.2%, and 81.6% with the same frequency. During in planta evaluation, selected Streptomyces strains combined with rock phosphate were assessed as biofertilizers on the growth and yield of cucumber plants. Under all treatments, positive and significant differences in studied traits were manifested except dry stem matter (SDM), net assimilation rate (NAR), relative growth rate (RGR), and fruit firmness (FF). Treatment T4 (rock phosphate + strain HM3) followed by T5 (rock phosphate + strain HM8) revealed the best results for plant height (PH), number of leaves per plant (NLPP), root length (RL), number of fruits per plant (NFPP), fruit length (FL), fruit diameter (FD), fruit fresh weight per plant (FFWPP), soil P (SP) after 21 DAT, and soil P at the end of the experiment. Notably, T6 (rock phosphate + strain HM10) caused a considerable increase in leaf area (LA). Plant growth-promoting bacteria enhance plant growth and yield through phosphorus solubilizing, improve nutrient availability, produce phytohormones, and support plant growth under abiotic stress. These features are important for sustainable agriculture and reducing environmental pollution with chemical fertilizers and pesticides.

Crop microbiome: their role and advances in molecular and omic techniques for the sustenance of agriculture.

MAIN CONCLUSION: This review is an effort to provide in-depth knowledge of microbe's interaction and its role in crop microbiome using combination of advanced molecular and OMICS technology to translate this information for the sustenance of agriculture. Increasing population, climate change and exhaustive agricultural practices either influenced nutrient inputs of soil or generating biological and physico-chemical deterioration of the soils and affecting the agricultural productivity and agro-ecosystems. Alarming concerns toward food security and crop production claim for renewed attention in microbe-based farming practices. Microbes are omnipresent (soil, water, and air) and their close association with plants would help to accomplish sustainable agriculture goals. In the last few decades, the search for beneficial microbes in crop production, soil fertilization, disease management, and plant growth promotion is the thirst for eco-friendly agriculture. The crop microbiome opens new paths to utilize beneficial microbes and manage pathogenic microbes through integrated advanced biotechnology. The crop microbiome helps plants acquire nutrients, growth, resilience against phytopathogens, and tolerance to abiotic stresses, such as heat, drought, and salinity. Despite the emergent functionality of the crop microbiome as a complicated constituent of the plant fitness, our understanding of how the functionality of microbiome influenced by numerous factors including genotype of host, climatic conditions, mobilization of minerals, soil composition, nutrient availability, interaction between nexus of microbes, and interactions with other external microbiomes is partially understood. However, the structure, composition, dynamics, and functional contribution of such cultured and uncultured crop microbiome are least explored. The advanced biotechnological approaches are efficient tools for acquiring the information required to investigate the microbiome and extract data to develop high yield producing and resistant variety crops. This knowledge fills the fundamental gap between the theoretical concepts and the operational use of these advanced tools in crop microbiome studies. Here, we review (1) structure and composition of crop microbiome, (2) microbiome-mediated role associated with crops fitness, (3) Molecular and -omics techniques for exploration of crop microbiome, and (4) current approaches and future prospectives of crop microbiome and its exploitation for sustainable agriculture. Recent -omic approaches are influential tool for mapping, monitoring, modeling, and management of crops microbiome. Identification of crop microbiome, using system biology and rhizho-engineering, can help to develop future bioformulations for disease management, reclamation of stressed agro-ecosystems, and improved productivity of crops. Nano-system approaches combined with triggering molecules of crop microbiome can help in designing of nano-biofertilizers and nano-biopesticides. This combination has numerous merits over the traditional bioinoculants. They stimulate various defense mechanisms in plants facing stress conditions; provide bioavailability of nutrients in the soil, helps mitigate stress conditions; and enhance chances of crops establishment.

Native Plant Growth-Promoting Rhizobacteria for Growth Promotion of Lettuce from Qassim, Saudi Arabia.

<b>Background and Objective:</b> Plant Growth-Promoting Rhizobacteria (PGPR) are a group of bacteria that colonize plant roots and enhance the growth and productivity of plants. However, only those PGPR that is acclimatized to the local soil conditions performs well. The present study aims to pick up effective PGPR isolates from local soil and utilize them as potential bio-inoculants to enhance lettuce plant growth. <b>Materials and Methods:</b> Rhizospheric soil samples were obtained from each of six desert plant species in the Qassim region and 45 bacterial isolates were obtained. Four of them were identified and tested for growth-promoting activities by application to the soil in which lettuce was grown under greenhouse conditions. <b>Results:</b> The selected bacterial isolates were identified as <i>Bacillus cereus</i> BW-201B, <i>Pseudomonas aeruginosa</i> AMU1, <i>Pseudomonas putida</i> CNE30 and <i>Enterobacter</i> sp. CZGRY7. Application of these four isolates to the soil in which lettuce was grown under greenhouse conditions resulted in significant increases in shoot height, shoot weight, chlorophyll levels and the percentages of N, P and K compared with those of control treatment. <b>Conclusion:</b> These findings suggest that local soil bacterial strains represent excellent bioinoculants for growth and yield increase in lettuce under local agro-climatic conditions in Saudi Arabia. Our approach might offer a good alternative for the chemical-free farming of lettuce.

Does less surgical trauma result in better outcome in management of iatrogenic tracheobronchial laceration?

BACKGROUND: Iatrogenic tracheobronchial injury is a rare, but severe complication of endotracheal intubation. Risk factors are emergency intubation, percutaneous dilatational tracheostomy and intubation with double lumen tube. Regarding these procedures, underlying patients often suffer from severe comorbidities. The aim of this study was to evaluate the results of a standardized treatment algorithm in a referral center with focus on the surgical approach. METHODS: Sixty-four patients with iatrogenic tracheal lesion were treated in our department by standardized management adopted to clinical findings between 2003 and 2019. Patients with superficial laceration were treated conservatively. In the case of transmural injury of the tracheal wall and necessity of mechanical ventilation, patients underwent surgery. We decided on a cervical surgical approach for lesions limited to the trachea. In case of involvement of a main bronchus we performed thoracotomy. Data were evaluated retrospectively. RESULTS: In 19 patients the tracheal lesion occurred in elective intubation and in 17 patients during emergency intubation. In 23 cases a tracheal tear occurred during percutaneous dilatational tracheostomy and in three patients at replacement of a tracheostomy tube. Two patients received laceration during bronchoscopy. Twenty-nine patients underwent surgery with cervical approach and 14 underwent thoracotomy. There was no difference in the mortality of these groups. Treatment of tracheal tear was successful in 62 individuals. Nine patients died of multi organ dysfunction syndrome (MODS), two of them during surgery. CONCLUSIONS: Iatrogenic tracheal laceration is a life-threatening complication and the mortality after tracheal injury is high, even in a specialized thoracic unit. Conservative management in patients with superficial tracheal lesion is a feasible procedure. In case of complete laceration of tracheal wall, surgical therapy is recommendable, whereby several approaches of surgical management seem to be equivalent.

Radon activity measurements in irrigation water from Qassim Province by RAD7.

The present study deals with investigating radon level in groundwater, which is being used for irrigation in the environs of Qassim province, Saudi Arabia. Ninety nine samples of groundwater were collected from eight cities in Qassim province. Radon concentrations in the collected water samples were measured with RAD7 electronic radon detector connected to RAD- H2O accessory (Durridge Co., USA). The concentration of (222)Rn in 99 irrigation groundwater samples ranged from 1.20 to 15.43 Bq l-1Radon level in? 5 samples 2 from Al-Asyah, 2 from Al shamasia and one sample from Al Moznib exceeded the permissible level of radon 11 Bq l-1 in groundwater. The total annual effective dose varied with increase in radon concentration. The calculated effective dose per liter (EDL) and annual effective dose (AED) ranged from 6.1 to 77.15 nSvL-1 and 4.45 to 56.16 µSv y-1, respectively. It was evident that the total annual effective doses resulting from radon in 95% from groundwater in Qassim area were significantly lower than the permissible limit of 1 mSv y-1 for the public.

Evaluation of fungal chitosan as a biocontrol and antibacterial agent using fluorescence-labeling.

Chitosan is a precious biological polysaccharide that could be applied in several fields. Fluorescein isothiocyanate-labeled chitosan (FITC-CTS) was synthesized as a macromolecular fluorophore added to fungal chitosan from Aspergillus niger, to investigate the interaction mechanism and antibacterial performance of (FITC-CTS) against Escherichia coli and Micrococcus leteus. Fluorescence imaging was used to demonstrate chitosan effect on the bacterial cells. Fluorescence density of treated bacteria with FITC-CTS was correlated with viable cell number. Electron micrographs of treated E. coli with fungal chitosan revealed that chitosan principally interact with bacterial cell wall, causing cell wall lyses with exposure time prolongation. Fungal chitosan could be proposed for bacterial growth control as a powerful, natural and safe alternative to synthetic and chemical bactericides. Fluorescence labeling proved to be an efficient tool for determining the antimicrobial activity of chitosan.