The phyllosphere comprises the aboveground parts of plants. Like the belowground rhizosphere, the phyllosphere includes a community of commensal microbes.
“Each leaf indeed creates a specific environment in which only some microorganisms can thrive,” explains French botanist Philippe Lemanceau.
At the beginning of the growing season, the microbial communities in the phyllosphere are strongly influenced by what is in the air and soil. As leaves grow they gradually develop their own microflora colonies. “Distinct plant species growing in the same location, and therefore submitted to the same inoculum, develop distinct phyllosphere microbial communities,” observes Lemanceau.
Some microbes live on the surface of leaves while others reside inside as endophytes. “The phyllosphere represents one of the most abundant habitats for microbiota colonization,” reports Chinese botanist Sheng Yang He. “Compared with roots, leaves have a larger apoplast, which facilitates the gas exchange essential for photosynthesis and provides a largely air-filled internal space for microbiota colonization,” adds Chinese botanist Xiu-Fang Xin.
Nurturing the right microbiome is critical to a leaf’s health. A leaf innately knows how to husband its microflora.
P. Lemanceau et al, “Plant communication with associated microbiota in the spermosphere, rhizosphere and phyllosphere,” Advances in Botanical Research 82: 101-113 (2017).
Tao Chen et al, “A plant genetic network for preventing dysbiosis in the phyllosphere,” Nature (8 April 2020).