TY - JOUR
T1 - Modelling sugar diffusion across plant leaf cuticles: the effect of free water on substrate availability to phyllosphere bacteria
AU - Van der Wal, A.
AU - Leveau, J.H.J.
N1 - Reporting year: 2011
Metis note: 4907; WAG; ME
PY - 2011
Y1 - 2011
N2 - We present a continuous model for the diffusion of sugars across intact plant leaf cuticles. It is based on the flow of sugars from a source, representing the leaf apoplast, to a sink, in the shape of a hemispherical drop of water on the outside of the cuticle. Flow is a function of the difference between sugar concentrations CSource and CSink, permeability P of the cuticle, volume VSink of the water drop, as well as its contact angle α with the cuticle surface. Using a bacterial bioreporter for fructose, and a two-compartment experimental set-up consisting of isolated cuticles of walnut (Juglans regia) carrying water droplets while floating on solutions with increasing concentrations of fructose, we determined a value of 1 × 10−6 m h−1 for P. Using this value, we explored different scenarios for the leaching of sugars across plant leaf cuticles to reveal in quantitative terms how diffusion takes longer when VSink increases, P decreases or α increases. Bacterial growth was modelled as a function of changes in P, α and VSink and was consistent with observations or suggestions from the literature in relation to the availability of free water on leaves. These results are discussed in the light of bacteria as ecosystem engineers, i.e. with the ability to modify the plant leaf surface environment in favour of their own survival, e.g. by increasing cuticle leakage or leaf wetness. Our model represents a first step towards a more comprehensive model which will enhance our quantitative understanding of the factors that play a role in nutrient availability to bacterial colonizers of the phyllosphere, or plant leaf surface.
AB - We present a continuous model for the diffusion of sugars across intact plant leaf cuticles. It is based on the flow of sugars from a source, representing the leaf apoplast, to a sink, in the shape of a hemispherical drop of water on the outside of the cuticle. Flow is a function of the difference between sugar concentrations CSource and CSink, permeability P of the cuticle, volume VSink of the water drop, as well as its contact angle α with the cuticle surface. Using a bacterial bioreporter for fructose, and a two-compartment experimental set-up consisting of isolated cuticles of walnut (Juglans regia) carrying water droplets while floating on solutions with increasing concentrations of fructose, we determined a value of 1 × 10−6 m h−1 for P. Using this value, we explored different scenarios for the leaching of sugars across plant leaf cuticles to reveal in quantitative terms how diffusion takes longer when VSink increases, P decreases or α increases. Bacterial growth was modelled as a function of changes in P, α and VSink and was consistent with observations or suggestions from the literature in relation to the availability of free water on leaves. These results are discussed in the light of bacteria as ecosystem engineers, i.e. with the ability to modify the plant leaf surface environment in favour of their own survival, e.g. by increasing cuticle leakage or leaf wetness. Our model represents a first step towards a more comprehensive model which will enhance our quantitative understanding of the factors that play a role in nutrient availability to bacterial colonizers of the phyllosphere, or plant leaf surface.
U2 - 10.1111/j.1462-2920.2010.02382.x
DO - 10.1111/j.1462-2920.2010.02382.x
M3 - Article
VL - 13
SP - 792
EP - 797
JO - Environmental Microbiology
JF - Environmental Microbiology
SN - 1462-2912
IS - 3
ER -