Diazotrophic Endophytes of Poplar and Willow for Growth Promotion of Rice Plants in Nitrogen‐Limited Conditions

Abstract

Rice (Oryza sativa L.) is one of the most important staple food crops. Its cultivation requires a relatively high input of N fertilizers; however, rice plants do not absorb a significant proportion of added fertilizers, resulting in soil and water pollution. The use of diazotrophic (N‐fixing) endophytes can provide benefits for rice cultivation by reducing the demand of N fertilizers. Diazotrophic endophytes from the early successional plant species poplar (Populus trichocarpa Torr. & A. Gray) and willow (Salix sitchensis C. A. Sanson ex Bong.) were added to rice seedlings. Inoculated rice plants were grown in N‐limited conditions in the greenhouse, and plant physical characteristics were assessed. Endophyte‐inoculated rice plants had greater biomass, higher tiller numbers, and taller plant stature than mock‐inoculated controls. Endophyte populations were quantified and visualized in planta within rice plants using fluorescent microscopy. The endophytes colonized rice plants effectively in both roots and foliage. These results demonstrated that diazotrophic endophytes of the eudicots poplar and willow can colonize rice plants and enhance plant growth in N‐limited conditions.

Influences of Climate on Phyllosphere Endophytic Bacterial Communities of Wild Poplar

“…Poplar (Populus) and willow (Salix) trees of the Salicaceae have a wide global distribution, both in native riparian forests across the Northern Hemisphere and in planted forests, accounting for more than 95 million hectares globally (fao.org). Native poplar trees have a diverse microbiota, many with the ability to fix dinitrogen gas, solubilize phosphate, and promote plant growth and health especially under abiotic stresses such as drought and nutrient limitation (Doty et al, 2005Xin et al, 2009;Khan et al, 2012Khan et al, , 2015Khan et al, , 2016Kandel et al, 2015Kandel et al, , 2017Doty, 2016;Aghai et al, 2019). Beneficial microbiota have been isolated from hybrid poplar trees grown in contaminated sites, in field sites, or in tissue culture (Moore et al, 2006;Ulrich et al, 2008;Barac et al, 2009;Scherling et al, 2009;Taghavi et al, 2009).…”

Principles for engineering microbial composition and ecosystem functioning

“…Delivery parameters (dose and frequency) may be considered as the last measure to increase invasion success. Probiotic development is a booming industry, where markets values for human and animal products alone are expected to exceed $50 billion by 2022 (31), while interest in plant probiotics is also increasing (32)(33)(34). A better understanding of fundamental principles that enhance the establishment and resilience of microbial inoculants has the potential to increase successful engineering of microbial communities for applications in human health, agriculture, bioenergy, and biotechnology.…”

Effectiveness of Plant Beneficial Microbes: Overview of the Methodological Approaches for the Assessment of Root Colonization and Persistence

“…Similarly, Kandel et al (2015) used trans-conjugant GFPtagged strains of Burkholderia sp., Rhizobium tropici PTD1, and Rahnella sp. WP5 to evaluate their colonization abilities in rice plants ( Table 1).…”

“…The use of GFP allowed the evaluation the colonization abilities of tagged Burkholderia sp., Rhizobium tropici PTD1, and Rahnella sp. WP5 in rice plants grown in N-free MS agar for twenty days in a growth chamber (Kandel et al, 2015; Table 2).…”