Pseudomonas putida UW4 increases horticulture crop quality and stress tolerance during severe drought stress

Drought stress is a major contributor to horticulture crop loss and can lead to heightened levels of stress ethylene in plants.
This is particularly detrimental in ornamental horticulture crops where ethylene leads to stunted growth and early flower senescence.
Ornamental crops are often exposed to drought stress during post-production shipping and retailing, which reduces crop quality and resiliency in the consumer’s garden.
The application of plant growth promoting rhizobacteria (PGPR) has gained interest in the horticulture sector as a tool to increase crop quality and tolerance to abiotic stresses.
In particular, Pseudomonas putida UW4 has been shown to reduce endogenous levels of ethylene in plants while stimulating growth under different abiotic stresses via activity of the enzyme ACC deaminase.
However, UW4 has not been documented for its use in increasing the quality and stress tolerance of ornamental crops subjected to drought stress.
Reduction of stress ethylene in planta can prevent stunted growth and flowering, while maintaining photosynthetic health of plants subjected to drought stress.
In our study, we utilized an in vitro assay to quantify the activity of ACC deaminase in the UW4 strain.
We then evaluated the influence of UW4 application on the quality and stress tolerance of drought stressed Petunia × hybrida (petunia) and Pelargonium × hortorum (geranium) in a production scale trial.
Application of UW4 improved the quality of crops by increasing plant size in both species and increasing flower number in petunia.
Application of UW4 also had a positive effect on geranium stress tolerance, increasing the photosynthetic health while reducing the electrolyte leakage in leaves throughout drought stress and recovery.
Our study demonstrates a novel use for UW4 to be implemented into ornamental horticulture production systems to increase crop quality and stress tolerance.
Overall, this work can lead to more sustainable and profitable production, while providing consumers with plants better suited for adverse conditions.

IV International Symposium on Horticulture in Europe – SHE2021

N.P. Nordstedt, M.L. Jones

abiotic stress, horticulture, PGPR, ethylene, electrolyte leakage, photosynthetic health, ACC deaminase

https://doi.org/10.17660/ActaHortic.2021.1327.71