Promising bacterial genera for agricultural practices: An insight on plant growth-promoting properties and microbial safety aspects

Microbial treatment has recently been attracting attention as a sustainable agricultural strategy addressing the current problems caused by unreasonable agricultural practices. However, the mechanism through which microbial inoculants promote plant growth is not well understood. In this study, two phosphate-solubilizing bacteria (PSB) were screened, and their growth-promoting abilities were explored. At day 7 (D7), the lengths of the root and sprout with three microbial treatments, M16, M44, and the combination of M16 and M44 (Com), were significantly greater than those with the non-microbial control, with mean values of 9.08 and 4.73, 7.15 and 4.83, and 13.98 and 5.68 cm, respectively. At day 14 (D14), M16, M44, and Com significantly increased not only the length of the root and sprout but also the underground and aboveground biomass. Differential metabolites were identified, and various amino acids, amino acid derivatives, and other plant growth-regulating molecules were significantly enhanced by the three microbial treatments. The profiling of key metabolites associated with plant growth in different microbial treatments showed consistent results with their performances in the germination experiment, which revealed the metabolic mechanism of plant growth-promoting processes mediated by screened PSB. This study provides a theoretical basis for the application of PSB in sustainable agriculture.

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Bioinoculants in Technological Alleviation of Climatic Stress in Plants

10.5772/intechopen.97340 ◽

2021 ◽

Author(s):

Rafia Younas ◽

Shiza Gul ◽

Rehan Ahmad ◽

Ali Raza Khan ◽

Mumtaz Khan ◽

...

Keyword(s):

Plant Growth ◽

Cold Stress ◽

Stress Proteins ◽

Global Climate ◽

Agricultural Practices ◽

Plant Growth Promoting Rhizobacteria ◽

Growth And Yield ◽

Plant Growth Promoting ◽

Growth Promoting ◽

Semi Arid

Global climate change is leading to a series of frequent onset of environmental stresses such as prolonged drought periods, dynamic precipitation patterns, heat stress, and cold stress on plants and commercial crops. The increasing severity of such stresses is not only making agriculture and related economic sector vulnerable but also negatively influences plant diversity patterns. The global temperature of planet Earth has risen to 1.1°C since the last 19th century. An increase in surface temperature leads to an increase in soil temperature which ultimately reduces water content in the soil, thereby, reducing crop growth and yield. Moreover, this situation is becoming more intense for agricultural practices in arid and semi-arid regions. To overcome climatically induced stresses, acclimatization of plant species via bioinoculation with Plant Growth Promoting Rhizobacteria (PGPR) is becoming an effective approach. The PGPR are capable of colonizing rhizosphere (exophytes) as well as plant organs (endophytes), where they trigger an accumulation of osmolytes for osmoregulation or improving gene expression of heat or cold stress proteins, or by signaling the synthesis of phytohormones, metabolites, proteins, and antioxidants to scavenge reactive oxygen species. Thus, PGPR exhibiting multiple plant growth-promoting traits can be employed via bioinoculants to improve the plant’s tolerance against unfavorable stress conditions.

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Deciphering the Symbiotic Plant Microbiome: Translating the Most Recent Discoveries on Rhizobia for the Improvement of Agricultural Practices in Metal-Contaminated and High Saline Lands

Agronomy ◽

10.3390/agronomy9090529 ◽

2019 ◽

Vol 9 (9) ◽

pp. 529 ◽

Cited By ~ 6

Author(s):

Agnese Bellabarba ◽

Camilla Fagorzi ◽

George C. diCenzo ◽

Francesco Pini ◽

Carlo Viti ◽

...

Keyword(s):

Plant Growth ◽

Crop Yield ◽

Heavy Metal Contamination ◽

Agricultural Practices ◽

Plant Growth Promoting Rhizobacteria ◽

Plant Genome ◽

Biotic And Abiotic Stresses ◽

Beneficial Effects ◽

Plant Growth Promoting ◽

Growth Promoting

Rhizosphere and plant-associated microorganisms have been intensely studied for their beneficial effects on plant growth and health. These mainly include nitrogen-fixing bacteria (NFB) and plant-growth promoting rhizobacteria (PGPR). This beneficial fraction is involved in major functions such as plant nutrition and plant resistance to biotic and abiotic stresses, which include water deficiency and heavy-metal contamination. Consequently, crop yield emerges as the net result of the interactions between the plant genome and its associated microbiome. Here, we provide a review covering recent studies on PGP rhizobia as effective inoculants for agricultural practices in harsh soil, and we propose models for inoculant combinations and genomic manipulation strategies to improve crop yield.

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Roles of Plant Growth-Promoting Rhizobacteria (PGPR) in Stimulating Salinity Stress Defense in Plants: A Review

International Journal of Molecular Sciences ◽

10.3390/ijms22063154 ◽

2021 ◽

Vol 22 (6) ◽

pp. 3154

Author(s):

Dung Minh Ha-Tran ◽

Trinh Thi My Nguyen ◽

Shih-Hsun Hung ◽

Eugene Huang ◽

Chieh-Chen Huang

Keyword(s):

Salt Stress ◽

Plant Growth ◽

Crop Yields ◽

Agricultural Practices ◽

Plant Growth Promoting Rhizobacteria ◽

Significant Loss ◽

Seed Vigor ◽

Plant Growth Promoting ◽

Growth Promoting ◽

Seed Biopriming

To date, soil salinity becomes a huge obstacle for food production worldwide since salt stress is one of the major factors limiting agricultural productivity. It is estimated that a significant loss of crops (20–50%) would be due to drought and salinity. To embark upon this harsh situation, numerous strategies such as plant breeding, plant genetic engineering, and a large variety of agricultural practices including the applications of plant growth-promoting rhizobacteria (PGPR) and seed biopriming technique have been developed to improve plant defense system against salt stress, resulting in higher crop yields to meet human’s increasing food demand in the future. In the present review, we update and discuss the advantageous roles of beneficial PGPR as green bioinoculants in mitigating the burden of high saline conditions on morphological parameters and on physio-biochemical attributes of plant crops via diverse mechanisms. In addition, the applications of PGPR as a useful tool in seed biopriming technique are also updated and discussed since this approach exhibits promising potentials in improving seed vigor, rapid seed germination, and seedling growth uniformity. Furthermore, the controversial findings regarding the fluctuation of antioxidants and osmolytes in PGPR-treated plants are also pointed out and discussed.

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Plant growth promoting traits of psychrotolerant bacteria: A boon for agriculture in hilly terrains

Plant Science Today ◽

10.14719/pst.2018.5.1.352 ◽

2018 ◽

Vol 5 (1) ◽

pp. 24-28 ◽

Cited By ~ 3

Author(s):

B Patni ◽

A S Panwar ◽

P Negi ◽

Gopal Krishna Joshi

Keyword(s):

Low Temperature ◽

Plant Growth ◽

Extreme Environments ◽

Agricultural Practices ◽

Plant Growth Promoting Bacteria ◽

Psychrotolerant Bacteria ◽

The World ◽

Plant Growth Promoting ◽

Growth Promoting ◽

Plant Growth Promoting Traits

Plant growth promoting bacteria (PGPB) are well known to promote plant growth in a number of ways. It is important to study plant growth promoting potential of bacteria capable of growing in extreme environments to establish their role in promoting agricultural yield under harsh conditions. Psychrophilic or psychrotolerant bacteria with plant growth promoting traits may improve the quality of agricultural practices in hilly terrain. The agricultural importance of such microbes stems from the fact that the world over temperate agro-ecosystems are characterized by low temperatures and short growing seasons that subject both plant and microbial life to cold temperature induced stress. Hence, there is a need to identify potential microbes that retain their functional traits under low temperature conditions. Such microbes can be used to enhance the agricultural yields in low temperature areas of the world. This review describes plant growth promoting activities identified in cold adapted bacteria.

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The multifaceted plant-beneficial rhizobacteria toward agricultural sustainability

Plant Protection Science ◽

10.17221/130/2020-pps ◽

2021 ◽

Vol 57 (No. 2) ◽

pp. 95-111

Author(s):

Olubukola Babalola ◽

Oluwaseun Adeyinka Fasusi

Keyword(s):

Plant Growth ◽

Soil Fertility ◽

Crop Production ◽

Agricultural Practices ◽

Modern Method ◽

Growth And Yield ◽

Agricultural Sustainability ◽

Plant Growth Promoting ◽

Promote Plant Growth ◽

Growth Promoting

Agricultural practices depend mainly on the use of chemical fertilisers, pesticides, and herbicides which have caused serious health hazards and have also contributed to the pollution of the environment at large. The application of plant-beneficial rhizobacteria in agrarian practices has become paramount in increasing soil fertility, promoting plant growth, ensuring food safety, and increasing crop production to ensure sustainable agriculture. Beneficial rhizobacteria are soil microorganisms that are eco-friendly and serve as a modern method of improving the plant yield, protecting the plant and soil fertility that pose no harm to humans and the environment. This eco-friendly approach requires the application of beneficial rhizobacteria with plant growth-promoting traits that can improve the nutrient uptake, enhance the resistance of plants to abiotic and biotic stress, protect plants against pathogenic microorganisms and promote plant growth and yield. This review article has highlighted the multitasking roles that beneficial rhizobacteria employ in promoting plant growth, food production, bioremediation, providing defence to plants, and maintaining soil fertility. The knowledge acquired from this review will help in understanding the bases and importance of plant-beneficial rhizobacteria in ensuring agricultural sustainability and as an alternative to the use of agrochemicals.

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Plant Growth Promoting Rhizobacterial Biofertilizers for Sustainable Crop Production: The Past, Present, and Future

10.20944/preprints202009.0650.v1 ◽

2020 ◽

Author(s):

Becky N. Aloo ◽

Billy A. Makumba ◽

Ernest R. Mbega

Keyword(s):

Plant Growth ◽

Crop Production ◽

Crop Yields ◽

Agricultural Practices ◽

Plant Growth Promoting Rhizobacteria ◽

Full Potential ◽

Sustainable Crop Production ◽

Indigenous Plant ◽

Plant Growth Promoting ◽

Growth Promoting

The world’s population is increasing and so are agricultural activities to match the growing demand for food. Conventional agricultural practices generally employ artificial fertilizers to increase crop yields, but these have multiple environmental and human health effects. For decades, environmentalists and sustainability researchers have focused on alternative crop fertilization mechanisms to address these challenges, and biofertilizers have constantly been researched, recommended, and even successfully-adopted for several crops. Biofertilizers are microbial formulations made of indigenous plant growth-promoting rhizobacteria (PGPR) which can naturally improve plant growth either directly or indirectly, through the production of phytohormones, solubilization of soil nutrients, and production of iron-binding metabolites; siderophores. Biofertilizers, therefore, hold immense potential as tools for sustainable crop production especially in the wake of climate change and global warming. Despite the mounting interest in this technology, their full potential has not yet been realized. This review updates our understanding of the PGPR biofertilizers and sustainable crop production. It evaluates the history of these microbial products, assesses their present state of utilization, and also critically propounds on their future prospects for sustainable crop production. Such information is desirable to fully evaluate their potential and can ultimately pave the way for their increased adoption for crop production.

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Plant Microbiota Beyond Farming Practices: A Review

Frontiers in Sustainable Food Systems ◽

10.3389/fsufs.2021.624203 ◽

2021 ◽

Vol 5 ◽

Author(s):

Mathieu Delitte ◽

Simon Caulier ◽

Claude Bragard ◽

Nicolas Desoignies

Keyword(s):

Plant Growth ◽

Microbial Communities ◽

Agricultural Practices ◽

Farming Practices ◽

Smart Farming ◽

Plant Growth Promoting ◽

Plant Microbiota ◽

Growth Promoting ◽

Chemical Inputs ◽

Beneficial Traits

Plants have always grown and evolved surrounded by numerous microorganisms that inhabit their environment, later termed microbiota. To enhance food production, humankind has relied on various farming practices such as irrigation, tilling, fertilization, and pest and disease management. Over the past few years, studies have highlighted the impacts of such practices, not only in terms of plant health or yields but also on the microbial communities associated with plants, which have been investigated through microbiome studies. Because some microorganisms exert beneficial traits that improve plant growth and health, understanding how to modulate microbial communities will help in developing smart farming and favor plant growth-promoting (PGP) microorganisms. With tremendous cost cuts in NGS technologies, metagenomic approaches are now affordable and have been widely used to investigate crop-associated microbiomes. Being able to engineer microbial communities in ways that benefit crop health and growth will help decrease the number of chemical inputs required. Against this background, this review explores the impacts of agricultural practices on soil- and plant-associated microbiomes, focusing on plant growth-promoting microorganisms from a metagenomic perspective.

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Engineering root microbiomes for healthier crops and soils using beneficial, environmentally safe bacteria

Canadian Journal of Microbiology ◽

10.1139/cjm-2018-0315 ◽

2019 ◽

Vol 65 (2) ◽

pp. 91-104 ◽

Cited By ~ 13

Author(s):

Pilar Martínez-Hidalgo ◽

Maskit Maymon ◽

Flora Pule-Meulenberg ◽

Ann M. Hirsch

Keyword(s):

Plant Growth ◽

Human Health ◽

Green Revolution ◽

Agricultural Practices ◽

Plant Growth Promoting Bacteria ◽

Negative Effects ◽

Growth And Survival ◽

Plant Growth Promoting ◽

Growth Promoting ◽

Critical Mineral

The Green Revolution developed new crop varieties, which greatly improved food security worldwide. However, the growth of these plants relied heavily on chemical fertilizers and pesticides, which have led to an overuse of synthetic fertilizers, insecticides, and herbicides with serious environmental consequences and negative effects on human health. Environmentally friendly plant-growth-promoting methods to replace our current reliance on synthetic chemicals and to develop more sustainable agricultural practices to offset the damage caused by many agrochemicals are proposed herein. The increased use of bioinoculants, which consist of microorganisms that establish synergies with target crops and influence production and yield by enhancing plant growth, controlling disease, and providing critical mineral nutrients, is a potential solution. The microorganisms found in bioinoculants are often bacteria or fungi that reside within either external or internal plant microbiomes. However, before they can be used routinely in agriculture, these microbes must be confirmed as nonpathogenic strains that promote plant growth and survival. In this article, besides describing approaches for discovering plant-growth-promoting bacteria in various environments, including phytomicrobiomes and soils, we also discuss methods to evaluate their safety for the environment and for human health.

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