Superior photosynthesis abilities of some plants could hold key to climate-resilient crops

CO2 is not pollution

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We’re told that C3 photosynthesis (used by 95% of plants) has two major shortcomings, one of which is that ‘20% of the time, oxygen is accidentally used instead of carbon dioxide and must be recycled, which slows down the process and wastes energy’. Conversion of some plants e.g. rice to C4 type might be possible. Researcher: “The ultimate goal is to try to switch C4 photosynthesis on and, in turn, create more productive and resilient crops for the future.” Summary here.
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More than 3 billion years ago, on an Earth entirely covered with water, photosynthesis first evolved in little ancient bacteria, says ScienceDaily.

In the following many millions of years, those bacteria evolved into plants, optimizing themselves along the way for various environmental changes.

This evolution was punctuated around 30 million years ago with the emergence of a newer, better way to photosynthesize.

While plants like rice continued using an old form of photosynthesis known as C3, others like corn and sorghum developed a newer and more efficient version called C4.

There are now more than 8,000 different C4 plant species, which grow particularly well in hot, dry climates and are some of the most productive crop species in the world. However, the vast majority of plants still run on C3 photosynthesis. So how did C4 plants come to be, and could C3 plants ever get a similar update?

Now, for the first time ever, Salk scientists and collaborators at the University of Cambridge discovered a key step C4 plants like sorghum needed to take to evolve to become so efficient at photosynthesizing — and how we could use this information to make crops like rice, wheat, and soybeans more productive and resilient against our warming climate.

The findings were published in Nature on November 20, 2024.

“Asking what makes C3 and C4 plants different is not just important from the basic biological perspective of wanting to know why something evolved and how it functions on the molecular level,” says Professor Joseph Ecker, senior author of the study, Salk International Council Chair in Genetics, and Howard Hughes Medical Institute investigator.

“Answering this question is a huge step toward understanding how we can make the most robust and productive crops possible in the face of climate change and a growing global population.”

Around 95% of plants use C3 photosynthesis, in which mesophyll cells — green spongy cells that live inside leaves — turn light, water, and carbon dioxide into plant-powering sugars.

Despite its high prevalence, C3 photosynthesis has two major shortcomings: 1) 20% of the time, oxygen is accidentally used instead of carbon dioxide and must be recycled, which slows down the process and wastes energy, and 2) pores on the leaf surface are open too frequently while waiting for carbon dioxide to enter, causing the plant to lose water and become more vulnerable to drought and heat.

Full article here.