| Plant root hairs are subcellular extensions from the root epidermis that are hypothetically important in the acquisition of immobile resources such as phosphorus. Previous work with Arabidopsis thaliana has shown that root hair length, growth rate, and density is highly regulated by phosphorus availability. The goal of this research was to determine the importance of root hairs in overall plant phosphorus nutrition, characterize the response of increased root hair elongation with decreased phosphorus availability, dissect the cellular mechanism of root hair growth in response to exogenous phosphorus nutrition, and determine the ecological importance of the root hair response in a populated environment. Controlled phosphorus treatments were applied through plant culture, solution culture, and soil-based culture on three Arabidopsis genotypes that differed in root hair growth and development. Growth analysis showed that root hairs are beneficial to shoot growth under phosphorus limiting conditions. Cost-benefit analysis showed that the stimulation of root hair elongation under phosphorus stress is an efficient strategy for phosphorus acquisition. Quantitative fluorescence microscopy was used to show that the root hair response to low phosphorus availability may be mediated through cytoplasmic pH. Finally, plants that have the root hair response are competitively more aggressive at acquiring phosphorus under phosphorus stress than plants that do not have normal root hair growth. The results from this research show that differential root hair growth is an important plant strategy in maximizing phosphorus acquisition under phosphorus limiting conditions. |
