Plant Hormones to Help Prevent Striga Invasion

As part of a multipronged approach to prevent infestations by the parasitic plant Striga hermonthica, researchers are unraveling the role of plant hormones, known as strigolactones (SLs). Their latest research is published in Science Advances.

Cereal crops release SLs that regulate plant architecture and play a role in other processes related to plant development and stress response. The SLs released by plant roots attract mycorrhizal fungi, which provide plant nutrients. But strigolactones also induce germination and invasion by the parasitic plant Striga, with severe impacts on agricultural production, particularly on cereal yields in Africa.

In an important discovery, the team has recently shown that canonical SLs do not affect plant architecture in rice.

The researchers employed CRISPR/Cas9 technology to generate rice lines without canonical SLs and compared them to wild-type plants. The shoot and root phenotypes did not differ significantly between the mutants and the wild type, indicating that canonical SLs are not major regulators of rice architecture.

"Knowing which SLs regulate plant architecture and other functions, such as establishing symbiosis with beneficial mycorrhizal fungi or enabling invasion by root parasitic plants, will allow us to optimize and engineer one trait without affecting others," explains Jian You Wang, a postdoc in Al-Babili's lab.

The research showed that canonical SLs do contribute to a symbiosis with mycorrhizal fungi and play a major role in stimulating seed germination in root parasitic weeds.

"Decreasing their level, or even completely knocking out their biosynthesis, can significantly reduce the damage caused by Striga and other root parasitic plants without causing severe plant architectural changes or having a large negative impact on plant mycorrhization," says Wang.