The growing human population has drastically reduced agricultural land per capita during the last few decades. As the horizontal expansion of crop production is limited, alternative measures need to be employed to maximize crop growth to ensure global food security (Singh et al., 2020). Although initially viewed as a panacea for agriculture, the continual use of synthetic fertilizers and pesticides has resulted in a loss in soil quality in many world regions. In addition, nutrient use efficiency remains low for many added nutrients (e.g., N, S, P) (Baweja et al., 2020). Thus, an integrated approach to agriculture with a reduced reliance on agrochemicals is essential to sustain civilization and agroecosystem health. Plant-associated and growth-promoting microorganisms (PGPMs) reside in the close vicinity of plants (rhizosphere, phyllosphere) and are naturally selected communities through evolution. The targeted application of plant-associated beneficial microbes in crop production systems could help support more environmentally-friendly crop production systems by reducing atmospheric pollution (e.g., greenhouse gas emissions), improving water quality (e.g., from reduced N and P losses), enhancing crop quality, promoting soil health and creating more biodiverse agricultural systems (Banik, 2021). This can only be achieved, however, if we understand the basis of plant-microbe interactions. Ultimately, advances in agronomic approaches, selection of suitable crop cultivars, and personalized microbiomes will enable us to enhance biotic and abiotic stress tolerance to build resilience in cropping systems.
Plant-associated beneficial microbes can promote crop production, induce defense response, and promote growth under stress conditions. These microbes produce a wide range of bioactive compounds and plant growth regulators to elicit physiochemical changes and biochemical processes under environmental stress. These fundamental processes involve oxidative defense pathways, signal transduction cascades, secondary metabolite production, and altered nutrient uptake alongside maintaining the integrity of photosystems (Garbeva and Weisskopf, 2020). Additionally, plants regulate the composition and activity of their associated bacterial community (Bag et al., 2022). Microbes of the rhizomicrobiome play key roles in nutrient acquisition and assimilation, improved soil texture, secreting, and modulating extracellular molecules such as hormones, secondary metabolites, antibiotics, and various signal compounds, all leading to the enhancement of plant growth. Plant growth-promoting rhizobacteria (PGPR) are isolated from the rhizosphere and exert substantial benefits to plants in terms of enhanced nutrient availability and hormone production. Further, PGPR improved root development and plant enzymatic activity. These beneficial impacts of PGPR have been verified in several plant species. Plant growth-promoting rhizobacteria are also reported to increase plant tolerance against salinity, drought, and heavy metals. Plants inoculated with different PGPR strains manifested minimal oxidative injury alongside a better antioxidant system. Besides, plants inoculated with PGPR strains also had a higher photosynthetic activity with lesser damage to photosystems. PGPR strains enhanced the phytoremediation ability of plants. PGPR strains induce substantial physiological and biochemical alterations in host plants and thereby diminish the intensity of damage due to abiotic stresses. For instance, ACC deaminase-producing bacteria can be used for bio-augmentation and seed priming to enhance crop stress tolerance and yield potential. In this context, 1-aminocyclopropane-1-carboxylate is released in root exudates, where it is converted into ammonia and α-ketobutyrate, producing ethylene with a marked effect on plant growth and function under stress (Ali et al., 2021).
Thus focusing on the importance of the underlying physicochemical processes induced by plant growth-promoting microbes (PGPMs), a total of five manuscripts have been accepted for publication in this issue to improve our understanding of the mechanisms and functions of microbes in agriculturally important crops. In an in silico study Bhanja et al., line Quinine from Phosphate-Solubilizing Microbes encoding genes displayed higher content of GCs at different positions, gene adaptability, and codon usage bias. Another article by Gohil et al., showed that Bacillus sp. Strain PG-8, isolated from fermented cow products enhanced the growth of Arachis hypogea. Two review articles by Mandal et al., and Inbaraj demonstrated recent updates on plant-associated beneficial microbes mediated alleviation of abiotic stress. Another review article by Pattnaik et al., demonstrated the roles of agriculturally important microorganisms in the uptake of essential soil nutrients.
In recent years, microbial-assisted reclamation of agricultural contamination is getting popular to enhance crop productivity. The application of most of these microbial-based technologies is very limited as several malfunctions occur during field application. However, more research should be carried out to minimize all the lacuna for utilization of microbes under field conditions.
Funding
Science & Engineering Research Board (SERB, Project File No. SRG/2020/000586), Department of Science and Technology, Government of India, and University Grants Commission (UGC, sanction order no. F. 30-509/2020 (BSR)], India gave funding support to AB.
Acknowledgments
We would like to thank the Chief Editor for giving us the opportunity to edit the Research Topic. Submissions Team Manager and the Journal Specialist for their consistent technical support. Avishek Banik would like to acknowledge Science & Engineering Research Board, Department of Science and Technology, Government of India, and University Grants Commission, India for extramural funding.
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Author contributions
All authors listed have made a substantial, direct, and intellectual contribution to the work and approved it for publication.
Conflict of interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
References
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Summary
Keywords
plant associated microbes, stress tolerance, plant physiology and biochemistry, bio-stimulants, plant growth promotion
Citation
Banik A, Ashraf MA, Govindan G and Arasu MV (2022) Editorial: Plant-growth promoting microbes: A Green approach to enhance crop productivity. Front. Agron. 4:991329. doi: 10.3389/fagro.2022.991329
Received
11 July 2022
Accepted
25 July 2022
Published
08 August 2022
Volume
4 - 2022
Edited and reviewed by
Davey Jones, Bangor University, United Kingdom
Updates
Copyright
© 2022 Banik, Ashraf, Govindan and Arasu.
This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Avishek Banik, avishekbanik5@gmail.com
†Present address: Ganesan Govindan Department of Genetic Engineering, SRM Institute of Science and Technology, Kattankulathur, Tamil Nadu, India
This article was submitted to Plant-Soil Interactions, a section of the journal Frontiers in Agronomy
Disclaimer
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.