Symbiosis between cyanobacteria and plants: from molecular studies to agronomic applications

Structure and dynamics of microbial communities associated with the resurrection plant Boea hygrometrica in response to drought stress

MAIN CONCLUSION

The resurrection plant Boea hygrometrica selectively recruits and assembles drought-specific microbial communities across the plant-soil compartments, which may benefit plant growth and fitness under extreme drought conditions. Plant-associated microbes are essential for facilitating plant growth and fitness under drought stress. The resurrection plant Boea hygrometrica in natural habitats with seasonal rainfall can survive rapid desiccation, yet their interaction with microbiomes under drought conditions remains unexplored. This study examined the bacterial and fungal microbiome structure and drought response across plant-soil compartments of B. hygrometrica by high-throughput amplicon sequencing of 16S rRNA gene and internal transcribed spacer. Our results demonstrated that the diversity, composition, and functional profile of the microbial community varied considerably across the plant-soil compartments and were strongly affected by drought stress. Bacterial and fungal diversity was significantly reduced from soil to endosphere and belowground to aboveground compartments. The compartment-specific enrichment of the dominant bacteria phylum Cyanobacteriota and genus Methylorubrum in leaf endosphere, genera Pseudonocardia in rhizosphere soil and Actinoplanes in root endosphere, and fungal phylum Ascomycota in the aboveground compartments and genera Knufia in root endosphere and Cladosporium in leaf endosphere composed part of the core microbiota with corresponding enrichment of beneficial functions for plant growth and fitness. Moreover, the recruitment of dominant microbial genera Sphingosinicella and Plectosphaerella, Ceratobasidiaceae mycorrhizal fungi, and numerous plant growth-promoting bacteria involving nutrient supply and auxin regulation was observed in desiccated B. hygrometrica plants. Our results suggest that the stable assembled drought-specific microbial community of B. hygrometrica may contribute to plant survival under extreme environments and provide valuable microbial resources for the microbe-mediated drought tolerance enhancement in crops.

Recent advances in nanotechnology-based modifications of micro/nano PET plastics for green energy applications

Poly(ethylene terephthalate) (PET) plastic is an omnipresent synthetic polymer in our lives, which causes negative impacts on the ecosystem. It is crucial to take mandatory action to control the usage and sustainable disposal of PET plastics. Recycling plastics using nanotechnology offers potential solutions to the challenges associated with traditional plastic recycling methods. Nano-based degradation techniques improve the degradation process through the influence of catalysts. It also plays a crucial role in enhancing the efficiency and effectiveness of recycling processes and modifying them into value-added products. The modified PET waste plastics can be utilized to manufacture batteries, supercapacitors, sensors, and so on. The waste PET modification methods have massive potential for research, which can play major role in removing post-consumer plastic waste. The present review discusses the effects of micro/nano plastics in terrestrial and marine ecosystems and its impacts on plants and animals. Briefly, the degradation and bio-degradation methods in recent research were explored. The depolymerization methods used for the production of monomers from PET waste plastics were discussed in detail. Carbon nanotubes, fullerene, and graphene nanosheets synthesized from PET waste plastics were delineated. The reuse of nanotechnologically modified PET waste plastics for potential green energy storage products, such as batteries, supercapacitors, and sensors were presented in this review.

Diversified molecular adaptations of inorganic nitrogen assimilation and signaling machineries in plants

Plants evolved sophisticated machineries to monitor levels of external nitrogen supply, respond to nitrogen demand from different tissues and integrate this information for coordinating its assimilation. Although roles of inorganic nitrogen in orchestrating developments have been studied in model plants and crops, systematic understanding of the origin and evolution of its assimilation and signaling machineries remains largely unknown. We expanded taxon samplings of algae and early-diverging land plants, covering all main lineages of Archaeplastida, and reconstructed the evolutionary history of core components involved in inorganic nitrogen assimilation and signaling. Most components associated with inorganic nitrogen assimilation were derived from the ancestral Archaeplastida. Improvements of assimilation machineries by gene duplications and horizontal gene transfers were evident during plant terrestrialization. Clusterization of genes encoding nitrate assimilation proteins might be an adaptive strategy for algae to cope with changeable nitrate availability in different habitats. Green plants evolved complex nitrate signaling machinery that was stepwise improved by domains shuffling and regulation co-option. Our study highlights innovations in inorganic nitrogen assimilation and signaling machineries, ranging from molecular modifications of proteins to genomic rearrangements, which shaped developmental and metabolic adaptations of plants to changeable nutrient availability in environments.

The Roles of Plant-Growth-Promoting Rhizobacteria (PGPR)-Based Biostimulants for Agricultural Production Systems

The application of biostimulants has been proven to be an advantageous tool and an appropriate form of management towards the effective use of natural resources, food security, and the beneficial effects on plant growth and yield. Plant-growth-promoting rhizobacteria (PGPR) are microbes connected with plant roots that can increase plant growth by different methods such as producing plant hormones and molecules to improve plant growth or providing increased mineral nutrition. They can colonize all ecological niches of roots to all stages of crop development, and they can affect plant growth and development directly by modulating plant hormone levels and enhancing nutrient acquisition such as of potassium, phosphorus, nitrogen, and essential minerals, or indirectly via reducing the inhibitory impacts of different pathogens in the forms of biocontrol parameters. Many plant-associated species such as Pseudomonas, Acinetobacter, Streptomyces, Serratia, Arthrobacter, and Rhodococcus can increase plant growth by improving plant disease resistance, synthesizing growth-stimulating plant hormones, and suppressing pathogenic microorganisms. The application of biostimulants is both an environmentally friendly practice and a promising method that can enhance the sustainability of horticultural and agricultural production systems as well as promote the quantity and quality of foods. They can also reduce the global dependence on hazardous agricultural chemicals. Science Direct, Google Scholar, Springer Link, CAB Direct, Scopus, Springer Link, Taylor and Francis, Web of Science, and Wiley Online Library were checked, and the search was conducted on all manuscript sections in accordance with the terms Acinetobacter, Arthrobacter, Enterobacter, Ochrobactrum, Pseudomonas, Rhodococcus, Serratia, Streptomyces, Biostimulants, Plant growth promoting rhizobactera, and Stenotrophomonas. The aim of this manuscript is to survey the effects of plant-growth-promoting rhizobacteria by presenting case studies and successful paradigms in various agricultural and horticultural crops.