Photosynthesis

For the first time, RIPE researchers have proven that multigene bioengineering of photosynthesis increases the yield of a major food crop in field trials. After more than a decade of working toward this goal, a collaborative team led by the University of Illinois has transgenically altered soybean plants to increase the efficiency of photosynthesis, resulting in greater yields without loss of quality.

In honor of the IGB's anniversary, we're revisiting some of the history of our institute over the past 15 years with a series of articles highlighting IGB people, projects, and research.

Improving crop yields in collaboration with RIPE

Scientists having been breeding plants for over a century with the goal of feeding hungry people across the world. To that end, the Green Revolution in the 1960s used new technologies to increase food production in scale with the population growth. Unfortunately, these increases will not be enough in a few decades.

The world is warming quickly with no indication of slowing down. This could be catastrophic for the production of food crops, particularly in already warm areas. Today, research from The University of Illinois and the US Department of Agriculture Agricultural Research Service show that bypassing a photosynthetic glitch common to crops like soybean, rice, and wheat, can confer thermal protection under heat stress in the field.  

Millions of people in Asia are dependent on rice as a food source. Believed to have been domesticated as early as 6000 BCE, rice is an important source of calories globally. In a new study, researchers compared domesticated rice to its wild counterparts to understand the differences in their photosynthetic capabilities. The results can help improve future rice productivity.

Agricultural scientists who study climate change often focus on how increasing atmospheric carbon dioxide levels will affect crop yields. But rising temperatures are likely to complicate the picture, researchers report in a new review of the topic.

The flag leaf is the last to emerge, indicating the transition from crop growth to grain production. Photosynthesis in this leaf provides the majority of the carbohydrates needed for grain filling--so it is the most important leaf for yield potential. A team from the University of Illinois and the International Rice Research Institute (IRRI) found that some flag leaves of different varieties of rice transform light and carbon dioxide into carbohydrates better than others. This finding could potentially open new opportunities for breeding higher yielding rice varieties. 

An international effort called Realizing Increased Photosynthetic Efficiency (RIPE) aims to transform crops' ability to turn sunlight and carbon dioxide into higher yields. To achieve this, scientists are analyzing thousands of plants to find out what tweaks to the plant's structure or its cellular machinery could increase production.

Crops grow dense canopies that consist of several layers of leaves--the upper layers with younger sun leaves and the lower layers with older shaded leaves that may have difficulty intercepting sunlight trickling down from the top layers.

The crops we grow in the field often form dense canopies with many overlapping leaves, such that young “sun leaves” at the top of the canopy are exposed to full sunlight with older “shade leaves” at the bottom. In order to maximize photosynthesis, resource-use efficiency, and yield, sun leaves typically maximize photosynthetic efficiency at high light, while shade leaves maximize efficiency at low light. 

Rice is a direct source of calories for more people than any other crop and serves as the main staple for 560 million chronically hungry people in Asia. With over 120,000 varieties of cultivated rice (Oryza sativa) across the globe, there is a wealth of natural diversity to be mined by plant scientists to increase yields.