Mixotrophy: an uncharted carbon flux in the plant world

Introduction

Plants need light to grow. They use energy from sunlight to produce organic carbon. However, new findings – including my own work – now hint that up to 35% of all plant species can also obtain carbon from root-associated fungi when light availability is insufficient for growth. This calls into question much of what we thought we knew about how plants survive in the understory.

Project Goal

The goal of this project is to determine the frequency and magnitude of this newly discovered form of ‘mixotrophy’ in our terrestrial ecosystems. I will achieve this exciting goal by working at the intersection of physiology, ecology, evolutionary, and molecular biology.

Background

The vast majority of land plants transfer part of the organic carbon they produce by photosynthesis to root-associated ‘arbuscular mycorrhizal’ (AM) fungi, which help plants to take up nutrients and water from the soil. My previous findings demonstrate that this carbon can be subsequently taken up by rare non-green plants that tap into the same fungal network. This paved the way for the discovery of AM mixotrophy, in which common green plants take up carbon from AM fungi.

Research Gaps

However, the plant and fungal diversity involved in AM mixotrophy are unknown. Likewise, the environmental drivers that influence carbon uptake have never been measured, nor do we know about its evolution and geographic distribution. This is problematic because we are unable to quantify or understand the role of AM mixotrophy in our natural world.

Methodology

With field studies, laboratory experiments, and genetic screening of natural history collections, I will:

1. Identify AM mixotrophic plants and their habitats.
2. Reveal environmental drivers that regulate carbon uptake.
3. Expose fungal networks that sustain AM mixotrophs.
4. Measure the magnitude of AM mixotrophy across evolutionary and geographic scales.

Expected Outcomes

This will lead to a fundamental shift in our understanding of carbon uptake by plants, with profound effects for carbon cycling models and conservation.