AgBioResearch

Beans are an important legume crop in Zambia, where 60 percent of the population lives in poverty and more than 350,000 suffer from food insecurity. Unfortunately, bean production in this African country is severely limited by diseases, insects, low soil fertility and drought. And national bean harvests of 300 to 500 kilograms per hectare each year fall short by more than 2 million pounds.

David Kramer, Michigan State University (MSU) Hannah Distinguished Professor in Photosynthesis and Bioenergetics, and the 2016 Charles F. Kettering Award recipient for excellence in the field of photosynthesis, said countries like Zambia (ranked 164 out of 184 countries on the Human Poverty Index), cannot wait years for traditional plant breeding.

“There is an urgent need to develop highly productive, robust and sustainable bean crops — and the urgency is only increasing as climate change continues to impact farming systems and plant production negatively each successive season,” he said. “In short, we need to think about improving beans in new ways, and we need the tools to dramatically accelerate the processes.”

Kramer and colleague Kelvin Kamfwa at the University of Zambia have teamed up in a three-year project funded by the MSU-managed Feed the Future Legume Innovation Lab to accelerate improvements in the robustness and efficiency of photosynthesis. They started by identifying hurdles that limit plant improvement in Africa and working with the MSU Center for Advanced Algal and Plant Phenotyping (CAAPP, which is run by Kramer) to develop new technologies to overcome them.

One factor limiting crop productivity is photosynthesis—the process by which plants capture solar energy to generate food and energy for growth and development. Ultimately, any increases in yield depend—directly or indirectly—on photosynthesis. Low photosynthetic efficiency in Zambia, which is highly sensitive to biotic and abiotic stresses, severely constrains grain legume production.

“Plant breeders have been really effective at targeting certain kinds of traits, like disease resistance or plant architecture, but we really haven’t touched the core processes of photosynthesis,” said Kamfwa.

This means that the solar energy input into the plant has remained constant or, in some cases, even decreased, over the past century. But there are additional reasons for improving photosynthesis.

“In addition to its importance for plant energy, photosynthesis is an excellent way to probe plant health,” said Kramer. “Photosynthesis must be extremely well controlled to avoid toxic byproducts, especially when the plant is under environmental stresses. Consequently, a lot of information about the health of a plant can be learned measuring photosynthetic reactions. It’s like a window into the workings of plant.”

Kramer’s lab has developed a series of new tools that gauge living plants in the field and measure photosynthesis in real time. Using these tools, they found signals that could be used to indicate how efficient photosynthesis is, whether the plant is productive or if it’s under stress, losing energy or being damaged.

But Kramer believes this emerging technology could be made even better.

“To really map genes so we can breed better plants,” said Kramer. “We need to observe photosynthesis on many plants, under varying conditions—and then analyze the data. Plants, which are particularly sensitive to their environments, must be measured under the conditions in which they are actually grown. It’s a massive undertaking.”

The photosynthesis project is harnessing two new phenotyping technologies developed at MSU. One of these, the PhotosynQ platform, allows researchers, farmers and extension agents throughout the world access to sophisticated yet very inexpensive and easy-to-use instruments to measure reactions related to photosynthesis. This field-deployable network of handheld sensors and associated online communication and analysis tools enable researchers and farmers to conduct plant phenotyping experiments, analyze data and share results, and allow improvements in breeding and management on local and global scales.

“With these tools, we are now able to monitor many photosynthesis reactions in crops in multiple environments under natural conditions,” said Dan TerAvest, a post-doc in Kramer’s plant research lab. “Among the measurements we need to obtain in developing a stronger germplasm is photosynthesis regulation.”

The second platform called Dynamic Environmental Phenotyping Imager (DEPI) simulates field conditions in special chambers so that sophisticated imaging sensors from Kramer’s lab can probe myriad plant processes and properties. For example, DEPI can measure how sensitive photosynthesis, growth, etc. are to specific weather conditions.

Developing DEPI and the PhotosynQ platform has been a major part of this project. With these technologies now available, distribution along with training and use of them has now shifted to the forefront. The goal of improving the robustness and efficiency of photosynthesis to accelerate the breeding efforts to improve grain legumes and germplasm can soon be explored.

Kramer’s team has provided six handheld PhotosynQ MultispeQ units to Kamfwa’s team to initiate the project’s first field trials. They will study a gene platform in common bean plants that confer better performance under Zambian environmental stresses, looking for more resilient and productive traits.

“The key limiting factor of plant breeding is determining phenotypes, that is, the performance levels of particular traits in the field,” said Kramer. “The technology we’ve developed determines which phenotypes are contributing to good or bad yield outcomes. We can map genes, but we don’t know what the genes do. The MultiSpeQ and PhotosynQ can tell us that—and Kelvin is using the technology to that end in Zambia as part of his work to improve bean germplasm for better yields.”

Using the MultispeQ and PhotosynQ, Kamfwa and his team in Zambia are beginning to develop rapid bean phenotyping protocols. Kamfwa’s undergraduate and graduate students are using the PhotosynQ platform to find genes that let photosynthesis work more efficiently under combinations of agricultural limitations experienced in the region, including drought (and lack of irrigation), low soil nutrients (and the high cost of fertilizers in Africa) and various diseases.

Meanwhile in East Lansing, MSU graduate students Isaac Osei-Bonsu and DongHee Hoh are using both the DEPI and PhotosynQ platforms to identify factors that allow beans and cowpeas to perform better under extreme temperature changes, a major hindrance worldwide of these crops.

Ultimately, the technological results will determine which cowpea and bean lines are most promising for breeding germplasm to achieve optimal grain legume yields in Zambia.

Kramer has just recently expanded this technology network into Malawi at three different research stations, where six researchers from Malawi’s Department of Agricultural Research Services are collecting data for 15 different projects on various plants and cropping systems studies.