Effect of Volatile Compounds Produced by Selected Bacterial Endophytes in Promoting Plant Growth

Maheshwari, Asha; Mmbaga, Margaret T.; Bhusal, Bandana; Christine, Ondzighi-Assoume

doi:10.21273/hortsci15668-21

Cited by 3 publications

(1 citation statement)

References 32 publications

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“…Studies have shown that biochar plus PGPMs can improve soil quality and nutrient availability through activation of beneficial soil enzyme activity in tree plantations [ 117 ]. There is evidence that volatile organic compounds (VOCs) released by bacterial cells, including Bv , can induce increased growth in certain crops [ 118 ]. Other potential mechanisms for increased plant growth and health status with biochar and Bacillus biofertilizers include beneficial nutrient immobilization and release cycles triggered by microbial activity [ 74 ], pH and soil moisture changes [ 61 ], disease suppression by Bv [ 77 , 119 ], production of antibiotic lipopeptides by Bv [ 120 , 121 ], successful colonization by PGPMs of substrates via lipopeptide and biofilm production [ 121 , 122 ], and iron-chelating siderophore production in Bv [ 74 ].…”

Section: Discussionmentioning

confidence: 99%

Biochar-biofertilizer combinations enhance growth and nutrient uptake in silver maple grown in an urban soil

2023

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Declining tree health status due to pollutant impacts and nutrient imbalance is widespread in urban forests; however, chemical fertilizer use is increasingly avoided to reduce eutrophication impacts. Biochar (pyrolyzed organic waste) has been advocated as an alternative soil amendment, but biochar alone generally reduces plant N availability. The combination of biochar and either organic forms of N or Plant Growth Promoting Microbes (PGPMs) as biofertilizers may address these challenges. We examined the effects of two wood biochar types with Bacillus velezensis and an inactivated yeast (IY) biofertilizer in a three-month factorial greenhouse experiment with Acer saccharinum L. (silver maple) saplings grown in a representative urban soil. All treatments combining biochars with biofertilizers significantly increased sapling growth, with up to a 91% increase in biomass relative to controls. Growth and physiological responses were closely related to nutrient uptake patterns, with nutrient vector analyses indicating that combined biochar and biofertilizer treatments effectively addressed nutrient limitations of both macronutrients (N, P, K, Mg, Ca), and micronutrients (B, Fe, Mn, Mo, Na, S, and Zn). Biochar-biofertilizer treatments also reduced foliar concentrations of Cu, suggesting potential to mitigate toxic metal impacts common in urban forestry. We conclude that selected combinations of biochar and biofertilizers have substantial promise to address common soil limitations to tree performance in urban settings.

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Section: Discussionmentioning

confidence: 99%

Biochar-biofertilizer combinations enhance growth and nutrient uptake in silver maple grown in an urban soil

2023

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Efficient fluorescence‐based localization technique for real‐time tracking endophytes route in host‐plants colonization

Ondzighi‐Assoume

Bhusal

et al. 2022

Plant Direct

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Bacterial isolates that enhance plant growth and suppress plant pathogens growth are essential tools for reducing pesticide applications in plant production systems. The objectives of this study were to develop a reliable fluorescence‐based technique for labeling bacterial isolates selected as biological control agents (BCAs) to allow their direct tracking in the host‐plant interactions, understand the BCA localization within their host plants, and the route of plant colonization. Objectives were achieved by developing competent BCAs transformed with two plasmids, pBSU101 and pANIC‐10A, containing reporter genes eGFP and pporRFP , respectively. Our results revealed that the plasmid‐mediated transformation efficiencies of antibiotic‐resistant competent BCAs identified as PSL, IMC8, and PS were up 84%. Fluorescent BCA‐tagged reporter genes were associated with roots and hypocotyls but not with leaves or stems and were confirmed by fluoresence microscopy and PCR analyses in colonized Arabidopsis and sorghum. This fluorescence‐based technique's high resolution and reproducibility make it a platform‐independent system that allows tracking of BCAs spatially within plant tissues, enabling assessment of the movement and niches of BCAs within colonized plants. Steps for producing and transforming competent fluorescent BCAs, as well as the inoculation of plants with transformed BCAs, localization, and confirmation of fluorescent BCAs through fluorescence imaging and PCR, are provided in this manuscript. This study features host‐plant interactions and subsequently biological and physiological mechanisms implicated in these interactions. The maximum time to complete all the steps of this protocol is approximately 3 months.

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Bacterial volatile organic compounds (VOCs) promote growth and induce metabolic changes in rice

Almeida

Araujo²,

Mulato³

et al. 2023

Front. Plant Sci.

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Plant growth-promoting bacteria (PGPB) represent an eco-friendly alternative to reduce the use of chemical products while increasing the productivity of economically important crops. The emission of small gaseous signaling molecules from PGPB named volatile organic compounds (VOCs) has emerged as a promising biotechnological tool to promote biomass accumulation in model plants (especially Arabidopsis thaliana) and a few crops, such as tomato, lettuce, and cucumber. Rice (Oryza sativa) is the most essential food crop for more than half of the world’s population. However, the use of VOCs to improve this crop performance has not yet been investigated. Here, we evaluated the composition and effects of bacterial VOCs on the growth and metabolism of rice. First, we selected bacterial isolates (IAT P4F9 and E.1b) that increased rice dry shoot biomass by up to 83% in co-cultivation assays performed with different durations of time (7 and 12 days). Metabolic profiles of the plants co-cultivated with these isolates and controls (without bacteria and non-promoter bacteria—1003-S-C1) were investigated via1H nuclear magnetic resonance. The analysis identified metabolites (e.g., amino acids, sugars, and others) with differential abundance between treatments that might play a role in metabolic pathways, such as protein synthesis, signaling, photosynthesis, energy metabolism, and nitrogen assimilation, involved in rice growth promotion. Interestingly, VOCs from IAT P4F9 displayed a more consistent promotion activity and were also able to increase rice dry shoot biomass in vivo. Molecular identification by sequencing the 16S rRNA gene of the isolates IAT P4F9 and E.1b showed a higher identity with Serratia and Achromobacter species, respectively. Lastly, volatilomes of these and two other non-promoter bacteria (1003-S-C1 and Escherichia coli DH5α) were evaluated through headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry. Compounds belonging to different chemical classes, such as benzenoids, ketones, alcohols, sulfide, alkanes, and pyrazines, were identified. One of these VOCs, nonan-2-one, was validated in vitro as a bioactive compound capable of promoting rice growth. Although further analyses are necessary to properly elucidate the molecular mechanisms, our results suggest that these two bacterial isolates are potential candidates as sources for bioproducts, contributing to a more sustainable agriculture.

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Effect of Volatile Compounds Produced by Selected Bacterial Endophytes in Promoting Plant Growth

Cited by 3 publications

References 32 publications

Biochar-biofertilizer combinations enhance growth and nutrient uptake in silver maple grown in an urban soil

Biochar-biofertilizer combinations enhance growth and nutrient uptake in silver maple grown in an urban soil

Efficient fluorescence‐based localization technique for real‐time tracking endophytes route in host‐plants colonization

Bacterial volatile organic compounds (VOCs) promote growth and induce metabolic changes in rice

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