Global warming could cause key culinary crops to release seeds prematurely

Climate change is threatening crop yields worldwide, yet little is known about how global warming will confuse normal plant physiology. Researchers in the UK now show that higher temperatures accelerate seed dispersal in crop species belonging to the cabbage and mustard plant family, limiting reproductive success, and this effect is mediated by a gene called INDEHISCENT. The findings appear February 12 in the journal Molecular Plant.

This photograph shows oilseed rape pods that are opening and spreading the seeds. - Credit: Andrew Davies / John Innes Centre

"In many crops, such as oilseed rape, premature seed dispersal is one of the major causes of crop loss. In the context of climate change, this could become increasingly severe," says co-senior author Vinod Kumar, a plant developmental biologist at the John Innes Centre in Norwich, England. "This study exposes the potential vulnerabilities of crop production in the warming world and paves the way for addressing this problem."

Plants have an extraordinary ability to adjust their life cycle to suit a range of environmental conditions. For example, despite day-to-day changes in weather and temperature, the release of seeds stays in tune with prevailing seasonal conditions.

"Seed dispersal is also a key trait that must be controlled when domesticating plants for food production," says co-senior author Lars Østergaard, a plant geneticist at the John Innes Centre. "With the prospect of climate change affecting crop performance, we wanted to understand how environmental signals such as temperature affect seed dispersal."

One clue came from the observation that Arabidopsis plants, which belong to the Brassicaceae (mustard or cabbage) family, mature and open their seed pods faster when grown at elevated temperatures. Inspired by this observation, Xin-Ran Li, a postdoctoral researcher with Kumar and Østergaard and first author of the study, set out to investigate.

They found that a rise in temperature, from 22ºC to 27ºC, accelerated pod shattering and seed dispersal in Arabidopsis plants and important Brassicaceae crops such as oilseed rape, a key ingredient in vegetable oil. Moreover, elevated temperatures accelerated seed dispersal by enhancing the expression of the INDEHISCENT gene, which is known to regulate the development of seed pod tissue and promote fruit opening.

"We speculate that such mechanisms have evolved to facilitate proper seasonal timing of dispersal to ensure that seeds are released under conditions that are both timely and climatically optimal for germination," Li says. "There could perhaps be a selective advantage in early maturation and dispersal in the wild."

Beyond the evolutionary implications, the findings could have broad relevance for maintaining yields of important crops. Oilseed rape is one of the largest sources of vegetable oil in the world and is also used for biofuel and animal feed. More generally, the Brassicaceae family includes many economically valuable agricultural crops, including cabbage, mustard, broccoli, cauliflower, collard greens, Brussels sprouts, bok choy, kale, turnip, radish, and rutabaga.

"We were excited by the discovery that what we found in the model plant Arabidopsis also holds true for both crop plants, such as oilseed rape, as well as non-domesticated species from the Brassicaceae family," Kumar says. "This highlights the significance of our findings both in the wild as well as in the field."

Based on their study, the research team suggests new strategies for preparing crops for global warming. For example, plant breeding efforts could focus on developing temperature-resilient varieties capable of coping with climate change. In addition, gene-editing tools, such as the CRISPR/Cas system, could be used to reduce the expression of the INDEHISCENT gene, thereby delaying seed release and reducing crop loss.

For their own part, Kumar and Østergaard plan to further investigate the molecular mechanisms underlying temperature-induced changes in seed dispersal. "We are hopeful that by understanding this in detail, we will be better equipped to devise strategies to breed for crop resilience to climate change," Østergaard says.

This work was supported by the FACCE ERA-NET+, the Biotechnological and Biological Sciences Research Council, and Institute Strategic Programme grants to the John Innes Centre.

Molecular Plant, Li et al.: "Temperature modulates tissue-specification program to control fruit dehiscence in Brassicaceae" http://www.cell.com/molecular-plant/fulltext/S1674-2052(18)30023-6

Molecular Plant, published by Cell Press for the Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, and Chinese Society of Plant Biology, is a monthly journal that focuses broadly on plant science, including cellular biology, physiology, biochemistry, molecular biology, genetics, development, plant-microbe interaction, genomics, bioinformatics, and molecular evolution. All contents are freely available starting 12 months after publication. Visit: http://www.cell.com/molecular-plant.