The aerial parts of plants create a habitat for microorganisms known as the phyllosphere, by analogy to the term rhizosphere. The leaf surface provides a natural habitat for the growth and multiplication of phyllosphere microorganisms. In addition, the presence of wax in the cuticle and leaf exudates helps these microorganisms to adhere to the surface.
The amino acids, glucose and sucrose, present in the leaf exudates are essential for these microorganisms, as they provide nutrition for their development. Similarly, water released during transpiration provides moisture for growth (Bashir et al., 2021 Carvalho et al., 2020, Stone et al., 2018).
Schematic representation of the main components of the phyllosphere.
By Morris, 2002
Phyllosphere microorganisms are important for plant growth as they promote growth in various ways as indicated below (Bashir et al., 2021 Carvalho et al., 2020, Stone et al., 2018):
- Some phyllosphere microorganisms such as cyanobacteria and nitrogen-fixing bacteria such as Azotobacter fix atmospheric nitrogen and provide it to plant growth.
- Phyllosphere microorganisms produce various plant growth hormones, such as indole acetic acid (IAA), which plants use for growth.
- They provide a stimulus for the production of phytoalexins by plants. Phytoalexins are defensive chemicals produced by plants in the presence of pathogens.
- They decompose leaves and help in the formation of humus after plant leaf fall.
- Some phyllosphere organisms have antagonistic effects against pathogenic fungi and therefore protect plants from fungal diseases. They are able to colonise the leaf surface by forming a biofilm that protects the leaves. In addition, they compete with pathogenic microorganisms for habitat and nutrients.
There is growing evidence that microorganisms present in the phyllosphere contribute to plant health, not only by improving the nutritional status of the host plant, but also by providing defence and resistance to pathogens against abiotic stresses. The use of strategies that respect the plant phyllosphere is paramount to improve the physiological and productive status of the crop.
BIOAdapta® consists of microbiome-based solutions. The use of the integral BIOAdapta® solution in crops increases the presence of beneficial microorganisms in the phyllosphere, displacing foliar pathogens from their ecological niche.
Lettuce leaf priming tests with the integral BIOAdapta® solution demonstrates the respect and protection of phyllosphere microorganisms.
Lettuce leaf priming tests with leaves treated in different culture media.
On the other hand, tests carried out under controlled conditions verify that the use of the set of BIOAdapta® solutions in foliar applications increases the absorption of nutrients in lettuce plants (nitrogen, potassium and phosphorus) significantly with a 100% fertilised control and a control with a single application of fertiliser, in addition to the improvement of the foliar and root biomass of the plants.
BIOAdapta® offers multi-purpose advantages and meets these objectives: Facilitate and achieve efficient use of resources, mitigate the effects of climate change, increase crop yields and increase profitability.
References
Bashir, I., Assad, R., War, A. F., Rafiq, I., Sofi, I. A., Reshi, Z. A., & Rashid, I. (2021). Application of Phyllosphere Microbiota as Biofertilizers. In Microbiota and Biofertilizers, Vol 2 (pp. 311-327). Springer, Cham.
Carvalho, C. R., Dias, A. C., Homma, S. K., & Cardoso, E. J. (2020). Phyllosphere bacterial assembly in citrus crop under conventional and ecological management. PeerJ, 8, e9152.
Stone, B. W., Weingarten, E. A., & Jackson, C. R. (2018). The role of the phyllosphere microbiome in plant health and function. Annual Plant Reviews online, 533-556.
Morris, C. E., Barnes, M. B., & McLean, R. J. C. (2002). Biofilms on leaf surfaces: implications for the biology, ecology and management of populations of epiphytic bacteria. Phyllosphere microbiology, 139-155.
