Fine-tuning photosynthesis

Dhruv Patel

2019-2022 FFAR Fellow

University of California, Berkeley

  • Soil Health

The dimmer switch is one of the most underrated inventions. Whether you are in the mood for a cozy setting or facing an action-packed day of Zoom meetings, with the dimmer switch you can adjust the light setting freely. Having a finer level of control can add something extra to your life. My research hopes to do the same, but by fine-tuning the genes in the foods we eat.

Agriculture thus far has done a great job running at maximum wattage. From disease resistance to yield, plant breeding has carefully selected for traits that maximize yield per acre. This success often relies on an array of inputs on limited, fertile land to manufacture an optimal growth environment. However, we can only leave the lights on full blast for so long before we risk burning out the bulb. As the climate changes and resources become growingly scarce, we need to build crops that are productive, resilient and efficient to feed our world sustainably.

In my work on the Foundation for Food & Agriculture Research’s (FFAR) RIPE (Realizing Improved Photosynthetic Efficiency) Project, I strive for this goal by fine-tuning how plants capture light. Plants often get much more sunlight than they can use, and while that sounds convenient, trying to harness all that energy is incredibly damaging. Doing so can slow the important machinery needed for photosynthesis—taking that sunlight and turning it into food. To account for this, photosynthetic organisms of all kinds throw away that extra energy in a photoprotective process known as non-photochemical quenching (NPQ).

However, our research has shown that crops like to play it safe. Plants have evolved to turn up the NPQ dial very quickly but are much slower at turning back down that dial when light is limited, such as when sun flecks shine through dense canopies on a clear day. And the more time crops spend on NPQ, the less time they are using to photosynthesize. Computational modeling shows this could result in 10-30 percent losses in crop and farm productivity!

Our group and collaborators in the RIPE Project have shown that we can increase the expression of specific photoprotection genes to help plants more quickly turn down NPQ. This small change can improve how plants photosynthesize under fluctuating light conditions, leading to an almost 15 percent increase in biomass in the field. But this work relied on the use of transgenics—taking the genes we have studied in our lab organism, Arabidopsis, and putting them into our model crop plant, tobacco. We know these photoprotective genes are already found in all photosynthetic organisms. My work asks, can we fine-tune the expression of the genes that are already there?

CRISPR-Cas9 has revolutionized how quickly and specifically we can modify a plant’s genome. Zachary Lippman’s group at the Cold Spring Harbor Lab has used this gene editing system to modify regions around tomato genes to attenuate their expression. Their outstanding work shows we can super-charge genetic change at important loci to produce variation that may normally take many years of domestication and evolution. By using a similar approach, I hope to generate gene-edited, but transgene-free, plants with finer control of their photoprotective dimmer switch. By exerting this additional layer of control, we hope to increase how efficiently our first target crop, rice, uses water, and some day optimize its photosynthetic yield per acre of land.

As a FFAR Fellow, I am grateful for the support from FFAR, the U.K. Foreign, Commonwealth, & Development Office, and my fellowship sponsor the Bill and Melinda Gates Foundation for supporting my work. Their support has made our high-risk, high-reward research on photosynthetic efficiency possible. By generating these tools and having pipelines in place to work towards placing them into the hands of smallholder farmers that can use it, we hope to build both food resiliency and equity in the global food system. Through innovations like these, we can develop relevant crops that are better adapted to the challenges facing agriculture in the years to come.

To learn more about the exciting work going on within the RIPE project, please visit our grant website. RIPE is an international research project that is improving photosynthesis to equip farmers worldwide with higher-yielding crops needed to ensure everyone has enough food to lead a healthy, productive life. RIPE is sponsored by the Bill & Melinda Gates Foundation, the U.S. Foundation for Food and Agriculture Research, and the U.K. Foreign, Commonwealth & Development Office.

RIPE is led by the University of Illinois in partnership with The Australian National University (ANU), Chinese Academy of Sciences (CAS), Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lancaster UniversityLouisiana State University (LSU), University of California, BerkeleyUniversity of Essex, and U.S. Department of Agriculture, Agricultural Research Service (USDA-ARS).