Understanding How Seed Treatment with Beneficial Bacteria Boosts Corn Growth

Jim Crocker
29th May, 2024

Understanding How Seed Treatment with Beneficial Bacteria Boosts Corn Growth

Image Source: Natural Science News, 2024

Key Findings

  • The study took place in Darjeeling, India, focusing on actinobacteria from tea plant rhizospheres to promote maize growth
  • Actinobacteria like Micrococcus sp. AB420, Kocuria sp. AB429, and Brachybacterium sp. AB440 enhance nutrient availability and root development
  • Biopriming maize seeds with these actinobacteria significantly improved shoot and root lengths and boosted antioxidative defenses
  • Specific actinobacteria modulated the JA pathway, delaying disease progression and enhancing maize's resistance to pathogens
Plant growth-promoting rhizobacteria (PGPR) are gaining attention as eco-friendly alternatives to traditional agrochemicals. A recent study by Bose Institute[1] evaluated the effectiveness of actinobacteria isolated from the rhizosphere of tea plants in Darjeeling, India, in promoting plant growth and enhancing stress tolerance in maize plants. The study identified nine different genera of actinobacteria from the tea rhizosphere through 16S rRNA gene ribotyping. Among these, Micrococcus sp. AB420 showed the highest phosphate solubilization, Kocuria sp. AB429 exhibited the most siderophore production, and Brachybacterium sp. AB440 demonstrated the highest indole-3-acetic acid (IAA) production. These traits are crucial for plant growth as they enhance nutrient availability and stimulate root development. When maize seeds were bioprimed with these actinobacterial isolates, significant growth improvements were observed compared to untreated controls. Notably, Paenarthrobacter sp. AB416 and Brachybacterium sp. AB439 led to the greatest increases in shoot and root lengths. This biopriming also triggered enhanced enzymatic and non-enzymatic antioxidative defenses in maize seedlings, thereby reducing the burden of reactive oxygen species (ROS). ROS are harmful byproducts of metabolic processes that can cause oxidative stress and damage plant cells if not adequately managed[2]. To delve deeper into the mechanisms behind this enhanced stress tolerance, three specific actinobacterial isolates—Brevibacterium sp. AB426, Streptomyces sp. AB427, and Brachybacterium sp. AB440—were selected to study their role in induced systemic resistance (ISR) in maize. ISR is a plant's enhanced defensive capacity against a broad spectrum of pathogens and is often mediated by signaling pathways involving salicylic acid (SA) and jasmonic acid (JA). The expression profiles of key genes involved in the SA and JA pathways indicated that bio-priming with Brevibacterium sp. AB426 and Brachybacterium sp. AB440 predominantly modulated the JA pathway. This modulation was associated with a delay in disease progression caused by the biotrophic pathogen Ustilago maydis, suggesting that bio-priming effectively enhances the plant's ability to cope with biotic stress. This study builds on previous research that has highlighted the role of plant-microbe interactions in enhancing stress tolerance. For instance, peanut plants treated with Brachybacterium saurashtrense showed improved growth and stress resilience under nitrogen-deficient conditions by modulating physio-biochemical activities and host-gene expression[3]. Similarly, the manipulation of antioxidant systems in plants has been shown to mitigate oxidative stress and improve environmental stress tolerance[2]. Furthermore, the study's findings align with earlier research on pathogenesis-related (PR) proteins and antimicrobial peptides (AMPs), which are crucial components of plant innate immunity. Overexpression of PR genes has been shown to enhance resistance to both biotic and abiotic stresses, making them promising candidates for developing stress-tolerant crop varieties[4]. The actinobacteria-induced ISR observed in this study offers a complementary approach to genetic engineering by harnessing natural microbial interactions to boost plant defenses. In summary, the study by Bose Institute provides valuable insights into the potential of PGPR, specifically actinobacteria, to promote plant growth and enhance stress tolerance through mechanisms such as nutrient solubilization, ROS scavenging, and modulation of defense signaling pathways. These findings pave the way for the development of sustainable agricultural practices that leverage beneficial microbes to improve crop resilience and productivity.

AgricultureBiochemPlant Science

References

Main Study

1) Exploring the dynamics of ISR signaling in maize upon seed priming with plant growth promoting actinobacteria isolated from tea rhizosphere of Darjeeling.

Published 29th May, 2024

Journal: Archives of microbiology

Issue: Vol 206, Issue 6, May 2024

Related Studies

2) Roles of enzymatic and nonenzymatic antioxidants in plants during abiotic stress.

https://doi.org/10.3109/07388550903524243

3) Interaction of the novel bacterium Brachybacterium saurashtrense JG06 with Arachis hypogaea leads to changes in physio-biochemical activity of plants to cope with nitrogen starvation conditions.

https://doi.org/10.1016/j.plaphy.2021.07.007

4) Pathogenesis-related proteins and peptides as promising tools for engineering plants with multiple stress tolerance.

https://doi.org/10.1016/j.micres.2018.04.008


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