PULLMAN, Wash. — Genes that control flowering time are fine-tuned to help plants avoid heat during the summer and freezing temperatures during the fall, according to new research from scientists at Washington State University, USDA, and other institutions.
Published in the journal Cell, the findings have potential implications for conservation and the production of biofuels.
The study combined genetic data from switchgrass field experiments with nature lovers’ photos of flowering warm-season, perennial grasses to help researchers explore flowering-time differences and determine how switchgrass adapts to environmental factors like temperature.
“The goal of this research is to understand what’s happening in the native habitats of these grasses,” said corresponding author Xianran Li, a scientist with the USDA Agricultural Research Service and an adjunct professor in WSU’s Department of Crop and Soil Sciences. “We identified the major genes and environmental conditions, then modeled how they interact with each other to see the whole picture.”
Switchgrass is one of four dominant perennial grass species in the United States. A stress-tolerant plant that can accumulate substantial biomass annually, it’s an ideal species for generating bioeconomy products like alternative fuels and chemicals. The paper’s findings could eventually help improve switchgrass breeding to fit local environmental conditions, Li said.
“Further development of the bioeconomy could mean finding new products for U.S. agriculture and less reliance on fossil fuels,” said study co-author Laura Bartley, an associate professor in WSU’s Institute of Biological Chemistry. “Studying bioeconomy species like switchgrass could be one key to reducing human impact on Earth.”
Unfortunately, many North American tallgrass prairies have been destroyed.
“That makes these species conservation priorities as well,” Bartley said. “Because our environment is changing so much, it’s also useful to understand how these grasses are responding.”
Switchgrass has a wide geographical distribution, ranging from Mexico to the southern Canadian prairies. The researchers found that the species has different versions of the same flowering-time regulatory genes that respond to environmental conditions differently.
“Our goal is to understand the genes that are important for flowering,” Li said. “If we can control those genes, then we can encourage the plant to keep growing throughout more of the season.”
Southern switchgrass has the gene version that helps it avoid high temperatures by delaying flowering until after summer heat.
At higher latitudes, the opposite occurs: The plant’s gene version helps it flower and complete its life cycle early to avoid the harsh, potentially fatal cold temperatures of fall and winter.
Because it’s neither practical nor cost-effective for researchers to travel the country gathering observations, the study highlights how “citizen science” can help scientists see patterns and understand what’s happening in nature, said Li.
To record the observable characteristics of switchgrass in different regions, the scientists used photos uploaded by the public to iNaturalist, a community science database. In addition to showing whether the grass was flowering, the photos included data such as a time stamp and GPS coordinates.
“Our lab didn’t need to organize or coordinate this activity,” Li said. “The citizen science observations are already online, so we could extract information from them. That opened a lot of possibilities. All we needed to do was download and mine the pictures for useful information.”
Bartley agrees.
“It’s impossible for scientists to make all the observations,” she said. “iNaturalist offers information at a much larger scale than we can imagine doing anytime soon. Even with satellite photos, the resolution isn’t high enough to determine if a plant is flowering or not. Having this resource offers exciting future opportunities for preserving genetic diversity and preventing the loss of more species.”
The researchers trained an AI tool, cleverly named FLORIST (short for Flowering Labeler for Open-source Research-grade Images via Self-supervised Transformer), to scour the database and differentiate between photos of flowering and non-flowering plants.
The paper’s co-authors included scientists from Oak Ridge National Laboratory, the University of Delaware, the HudsonAlpha Institute for Biotechnology, the University of Georgia, the University of Texas, Iowa State University, Stanford University, and South Dakota State University.
“This study is a perfect example of what can be accomplished when researchers from a variety of backgrounds come together,” said Raj Khosla, Cashup Davis Family Endowed Dean of WSU’s College of Agricultural, Human, and Natural Resource Sciences. “I look forward to witnessing how our faculty utilize citizen science in the future to advance research in plant genetics and other fields that benefit the planet.”
Media Contacts
Xianran Li, USDA Agricultural Research Service; xianran.li@usda.gov
Laura Bartley, WSU Institute of Biological Chemistry; laura.bartley@wsu.edu
Angela Sams, WSU College of Agricultural, Human, and Natural Resource Sciences; alsams@wsu.edu