Assistant Professor Michigan State University East Lansing, Michigan
Changes in ongoing climate are bound to bring in radical shifts in atmospheric gases (for example, CO2 – an anthropogenic pollutant), which can jeopardize the nutritional quality and food production. While the photosynthetic rate is enhanced by elevated atmospheric CO2, resulting in increased biomass production2 high CO2 catalyzes a general drop in the accumulation of essential plant nutrients, including phosphorus (P). Despite a decline in nutritional status, better plant growth is baffling and counterintuitive, leading to the following poignant question: how do plants grow better in spite of meager nutritional status? To discover fundamental processes underpinning plant growth response to an elevated CO2, we first used Arabidopsis as a model system and explored natural variation of the responsiveness of P accumulation in chloroplast to high CO2. Notably, studying the natural variation of nutrient accumulation in organelles like chloroplasts has never been investigated to the extent reported in our study, primarily owing to the difficulty of phenotyping this trait at high throughput. We bypassed technical challenges and used the chloroplastic P levels at high CO2 to run genome-wide association analysis, which in combination with molecular genetics, and microscopy allowed us to discover a Phosphate transporter, PHT4;3, that mediates the inhibition of chloroplastic P by high CO2. Furthermore, we demonstrate that a decrease in chloroplastic P is vital to control the production of an antinutrient, phytic acid, to sustain growth at high CO2 levels. We extended our research from the model plant (Arabidopsis) and confirmed our discovery in the primary staple for more than half the world's population, rice (monocots). Our results establish a mechanistic framework to improve the nutritional status of crops under elevated CO2 without compromising the final yield.