Molecules Boosting Plant Immunity Identified

Two studies published in the journal Science by researchers at the Max Planck Institute for Plant Breeding Research in Cologne, Germany in collaboration with colleagues in China have discovered natural cellular molecules that drive critical plant immune responses. These compounds have all the hallmarks of being small messengers tailored by plants to turn on key defense-control hubs. Harnessing these insights may allow scientists and plant breeders to design molecules that make plants, including many important crop species, more resistant to disease.

World food production must double by 2050 in order to feed the anticipated extra 2 billion people living on Earth by then. Boosting food production requires increases in the yields of many of our staple crops. To do so, strategies need to be in place to ensure that we can make plants more resistant to microscopic infectious agents, whilst also ensuring that food production is environmentally safe. Achieving this, in turn, requires a detailed understanding of the plant immune system—the defenses that plants mount when confronted with invading microorganisms.

Now, in two studies, scientists led by Jijie Chai and Jane Parker from the Max Planck Institute for Plant Breeding Research in Cologne and the University of Cologne, Germany, collaborating with Junbiao Chang's group at Zhengzhou University in Zhengzhou and Zhifu Han and colleagues at Tsinghua University in Beijing, China, have identified two classes of molecules and determined their modes of action in mediating immune responses inside plant cells. Their findings pave the way for the design of bioactive small molecules that could allow researchers and plant growers to manipulate—and thereby boost—plant resistance against harmful microbes.

At a molecular level, a main immune strategy employed by plants involves proteins called nucleotide-binding leucine-rich repeat receptors, or NLRs for short. NLRs are activated by invading microorganisms and set in motion protective immune responses. These immune responses culminate in the so-called hypersensitive response, which involves restriction of pathogen growth and often strictly demarcated death of cells at the site of infection—akin to amputating a toe to ensure survival of the body.