Disease protection and allelopathic interactions of seed-transmitted endophytic pseudomonads of invasive reed grass (Phragmites australis)

• Published in: Plant and soil Vol. 422; no. 1/2; pp. 195 - 208
• Main Authors: White, James F., Kingsley, Kathryn I., Kowalski, Kurt P., Irizarry, Ivelisse, Micci, April, Soares, Marcos A., Bergen, Marshall S.
• Format: Journal Article
• Language: English
• Published: Cham Springer 01.01.2018; Springer International Publishing; Springer Nature B.V
• Subjects: Bacteria; Biodiversity; Biomedical and Life Sciences; Common reed; Damping; Damping-off; Disease resistance; Ecology; Endophytes; Germination; Grasses; Growth rate; Intracellular; Life Sciences; Meristems; Mortality; Phragmites; Phragmites australis; Physiological aspects; Plant growth; Plant Physiology; Plant protection; Plant Sciences; Plant-soil relationships; Protected plants; Pseudomonas; Pseudomonas fluorescens; Regular Article; Rumex crispus; Seed germination; Seedlings; Seeds; Soil bacteria; Soil microorganisms; Soil Science & Conservation; Strains (organisms); Symbiosis; Rhizophagy; Bioherbicide; Ecosystem engineering; Microbiome; Reactive oxygen
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-016-3169-6

Background and aims Non-native Phragmites australis (haplotype M) is an invasive grass that decreases biodiversity and produces dense stands. We hypothesized that seeds of Phragmites carry microbes that improve seedling growth, defend against pathogens and maximize capacity of seedlings to compete with other plants. Methods We isolated bacteria from seeds of Phragmites, then evaluated representatives for their capacities to become intracellular in root cells, and their effects on: 1.) germination rates and seedling growth, 2.) susceptibility to damping-off disease, and 3.) mortality and growth of competitor plant seedlings (dandelion (Taraxacum officionale F. H. Wigg) and curly dock (Rumex crispus L.)). Results Ten strains (of 23 total) were identified and characterized; seven were identified as Pseudomonas spp. Strains Sandy LB4 (Pseudomonas fluorescens) and West 9 (Pseudomonas sp.) entered root meristems and became intracellular. These bacteria improved seed germination in Phragmites and increased seedling root branching in Poa annua. They increased plant growth and protected plants from damping off disease. Sandy LB4 increased mortality and reduced growth rates in seedlings of dandelion and curly dock. Conclusions Phragmites plants associate with endophytes to increase growth and disease resistance, and release bacteria into the soil to create an environment that is favorable to their seedlings and less favorable to competitor plants.