Dynamics of endophytic and epiphytic bacterial communities of Indian cultivated and wild rice ( Oryza spp.) genotypes

Mechanism of betterment towards growth and induction of defense in rice (Oryza sativa L.) by biopriming with bacterial endophytes isolated from wild rice

Utilizing beneficial microorganisms associated with plants, particularly endophytes, is becoming more and more prevalent since it supports the physiological health and evolutionary adaption of the host. The range of enhanced endophytic bacteria found in wild rice makes it a promising resource for sustainable agriculture. Current study focused on benefits of bacterial endophytes isolated from tissues of wild rice plants' roots, stems, and leaves for managing the health and development of rice (Oryza sativa L.) plants. Bacterial endophytes were characterized using 16 S rRNA. Treatments with Priestia megaterium (NRRI EB 1) and Priestia aryabhattai (NRRI EB 2) outperformed the other isolates in rice growth enhancement activities significantly. The biocontrol efficacy of bacterial endophytes was tested against Xanthomonas oryzae pv. oryzae and Rhizoctonia solani and percentage of inhibition was higher in NRRI EB 1 by 79.32-80.83 % and in NRRI EB 2 by 79.69-80.45 %. Bio-priming the seeds with specific endophytic bacterial strains led to a decrease in average germination time, an increase in seedling vigor, and total chlorophyll content. Additionally, they generated greater amounts of soluble phosphate (40.91-83.70 μg/mL) and indole acetic acid (28.10-60.18 μg/mL), which are in the midst of encouraging more plant development. Higher expressions of defense enzymes in comparison to the control, including catalase (>220 % in root and shoot), peroxidase (>200 % in shoot and root), and superoxide dismutase (>150 % in shoot and root) illustrates the rice crop's resilience to withstand stress. The activity of the mentioned enzymes was further validated through the activation of corresponding defense genes such as DEFENSIN (>2-fold), PAL (>3-fold), PR-3 (>2-fold), POX (>2-fold) and LOX (>1-fold) in relation to the untreated plants. The possibility exists to extract advantageous endophytic bacteria from wild rice species, potentially rewilding the microbiome of cultivated rice cultivars and fostering their deployment.

Strategies to fortify the nutritional values of polished rice by implanting selective traits from brown rice: A nutrigenomics-based approach

Whole-grain cereals are important components of a healthy diet. It reduces the risk of many deadly diseases like cardiovascular diseases, diabetes, cancer, etc. Brown rice is an example of whole grain food, which is highly nutritious due to the presence of various bioactive compounds (flavonoids, phenolics, vitamins, phytosterols, oils, etc.) associated with the rice bran layer of brown rice. White rice is devoid of the nutritious rice bran layer and thus lacks the bioactive compounds which are the major attractants of brown rice. Therefore, to confer health benefits to the public at large, the nutrigenomic potential of white rice may be improved by integrating the phytochemicals associated with the rice bran layer of brown rice into it via biofortification processes like conventional breeding, agronomic practices, metabolic engineering, CRISPR/Cas9 technology, and RNAi techniques. Thus, this review article focuses on improving the nutritional qualities of white/polished rice through biofortification processes, utilizing new breeding technologies (NBTs).

Microbial Community, Metabolic Potential and Seasonality of Endosphere Microbiota Associated with Leaves of the Bioenergy Tree Paulownia elongata × fortunei

The microbial structure and metabolic function of plant-associated endophytes play a key role in the ecology of various environments, including trees. Here, the structure and functional profiles of the endophytic bacterial community, associated with Paulownia elongata × fortunei, in correlation with seasonality, were evaluated using Biolog EcoPlates. Biolog EcoPlates was used to analyse the functional diversity of the microbiome. The total communities of leaf endophyte communities were investigated using 16S rRNA V5–V7 region amplicon deep sequencing via Illumina MiSeq. Community level physiological profiling (CLPP) analysis by the Biolog EcoPlate™ assay revealed that the carboxylic acids (19.67–36.18%) and amino acids (23.95–35.66%) were preferred by all by all communities, whereas amines and amides (0.38–9.46%) were least used. Seasonal differences in substrate use were also found. Based on the sequencing data, mainly phyla Proteobacteria (18.4–97.1%) and Actinobacteria (2.29–78.7%) were identified. A core microbiome could be found in leaf-associated endophytic communities in trees growing in different locations. This work demonstrates the application of Biolog EcoPlates in studies of the functional diversity of microbial communities in a niche other than soil and shows how it can be applied to the functional analyses of endomicrobiomes. This research can contribute to the popularisation of Biolog EcoPlates for the functional analysis of the endomicrobiome. This study confirms that the analysis of the structure and function of the plant endophytic microbiome plays a key role in the health control and the development of management strategies on bioenergy tree plantations.

Insights into endophytic bacterial diversity of rice grown across the different agro-ecological regions of West Bengal, India

Endophytes have recently garnered importance worldwide and multiple studies are being conducted to understand their important role and mechanism of interaction inside plants. But before we indulge in their functions it is necessary to dig into the microbiome. This will help to get a complete picture of the microbes intrinsic to their host and understand changes in community composition with respect to their habitats. To fulfil this requirement in our study we have attempted to dissect the endophytic diversity in roots of rice plant grown across the various agro-ecological zones of West Bengal by undergoing amplicon analysis of their 16S rRNA gene. Based on the measured environmental parameters agro-ecological zones can be divided into two groups: nutrient dense groups, representing zones like Gangetic, Northern hill and Terai-Teesta zone characterised by soil with higher levels of nitrogen (N) and total organic carbon and nutrient low groups representing Coastal saline, Red-laterite and Vindhyan zone mainly characterised by high electroconductivity and pH. Gammaproteobacteria, Alphaproteobacteria, Bacilli and Bacteroidetes were mostly abundant in nutrient dense sites whereas Clostridia and Planctomycetes were concentrated in nutrient low sites. Few genera (Aeromonas, Sulfurospirillum, Uliginosibacterium and Acidaminococcus) are present in samples cultivated in all the zones representing the core microbiome of rice in West Bengal, while some other genera like Lactococcus, Dickeya, Azonexus and Pectobacterium are unique to specific zone. Hence it can be concluded that this study has provided some insight in to the endophytic status of rice grown across the state of West Bengal.

Characterization of halotolerant, pigmented, plant growth promoting bacteria of groundnut rhizosphere and its in-vitro evaluation of plant-microbe protocooperation to withstand salinity and metal stress

The use of plant associated, indigenous beneficial microbes for sustainable agriculture is getting worldwide acceptance as they successfully colonize at different plant niche under stress conditions to enhance the crop productivity. They also generate several plant growth regulators and protect plants from adversity like presence of salts and metals. In the present study, indigenous, halotolerant, plant growth promoting (PGP) bacterial isolates were isolated from the saline rhizospheric soil of groundnut plants aiming to investigate its in-vitro metal remediation capabilities under saline stress condition. Two pigmented bacteria were selected based on their phenotypic, biochemical, physiological and PGP characters and identified as members of family Bacillaceae (Bacillus and Halobacillus) based on 16S rRNA gene sequence similarity. The pigments were extracted, tested for different antioxidant properties and identified by GC-MS and FT-IR spectra. Simultaneously, both strains exhibited a wide range of salinity (NaCl≥25%), metal resistance (Zinc≈1700mgkg^-1, Aluminium≈1800mgkg^-1, Lead≈1800mgkg^-1), pH (6-10), PGP attributes (indole - 1.05-3.15μgml^-1, ammonia - 0.13-19.95mmolml^-1, nitrite - 0.07-0.26mmolml^-1) and antibiotics sensitivity revealing their wide range of metabolic diversity. In-vitro inoculation of groundnut seedlings with selected isolates under salinity (1% NaCl) and metal (Zn, Al and Pb) stress had a positive impact on different plant physiological parameters (lesser lignification, intact proto xylem and cortical parenchyma) which was correlated with PGP attributes. Microwave plasma atomic emission spectroscopy analysis of seedling samples also detected less amount of metals in plants treated with bacteria indicating, an establishment of plant-microbe protocooperation to withstand salinity and metal stress. This strategy can be implemented to improve crop production in saline metal polluted agriculture fields.