C3-C4 Intermediates: relics from the past useful for the future

GAIN4CROPS has a focus on a specific type of plant: the C3-C4 intermediates. According to our project coordinator, Prof. Weber, “they are relics of past evolutionary stages, which, in time, lead to C4 plants.” The C4 plants indeed evolved from C3 ancestors – the only option at that time – but they show so many biochemical, anatomical and physiological differences that the C3-C4 transition is very unlikely to have happened in one step.

Instead, the trajectory from C3 to C4 plants is the consequence of many little changes, each representing a step toward C3-C4 intermediacy. Many of them have disappeared with time, probably evolving towards a C4 plant, yet few of them have survived up to now.

“The study of C3-C4 intermediates help us to understand the link between C3 and C4 metabolism, informing us on the changes necessary to make a C3 system evolve towards a C4 system.“

Andreas Weber, Project Coordinator

C4 plants are a highly desirable system to increase carbon fixation efficiency and enhance crop yield: although they account for only 3% of the vascular plants on earth, they contribute to 25% of the terrestrial photosynthesis (Westhoff and Gowik, 2010). They do so by more efficient use of resources like water and nitrogen, proving to be a more sustainable alternative to C3 plants. Furthermore, C4 plants might better resist rough environments: they can resist long-term droughts and demand less fertiliser per unit yield.

They are not the most common plants because the conditions in which they evolved were different from the ones of today. In the past, the planet was covered mostly with dense forest and the C4 plants didn’t find their way in this environment. C4 plants prefer to grow in grasslands or fields, where they can receive a lot of light, and in warm climates. In today’s changing conditions and increasing temperatures, they likely are beneficial for sustainable agriculture.