Better anchor roots help crops grow in poor soils
A metabolite in plants has been identified that regulates anchor root growth - essential to support water and nutrient uptake in plants - and could have useful applications in agriculture.
Pigmentary compounds called carotenoids are found in all plants and play a key role in the successful photosynthesis and generation of plant hormones and metabolites. These products are formed when enzymatic activity causes carotenoid molecules to split - a process known as cleavage. Although many carotenoid products are known to play key biological roles, less is known about a group of cleavage molecules called di-apocarotenoids.
"Diapocarotenoids have rarely been characterized because of their instability and low abundance," says KAUST researcher Kunpeng Jia, who worked on the project under the supervision of KAUST's Salim Al-Babili. "Indeed, we are only beginning to understand what their biological significance may be and what their functions are."
KAUST researchers, in collaboration with scientists from the USA and Germany, conducted an in-depth study on the presence and biological activities of di-apocarotenoids in Arabidopsis plants using developmental studies and advanced analytical chemistry techniques. Working with these intrinsically unstable, low molecular weight compounds in plant tissues was a real challenge for Jianing Mi of Al-Babili's team, who perfected laboratory techniques to extract and analyze the molecules without damaging them.
"We have identified the ancene di-apocarotenoid as a metabolite that sends a specific signal to trigger the formation of Arabidopsis anchor roots," says Jia. "Since ancene is a carotenoid product, proper carotenoid biosynthesis is also necessary for the formation of healthy roots. We have confirmed this by using chemical inhibitors and mutants of Arabidopsis".
Further experiments have shown that anchrene modulates the distribution of the plant hormone auxin in the site of anchoring root formation, which stimulates growth. Jia and colleagues found that increasing ancene levels in carotenoid-deficient plants saved the growth of anchor roots, while promoting the growth of normal seedlings. When they altered the structure of the ancene, this resulted in a loss of activity.
"We'd like to further explore the biological importance of ancene and we also hope to understand exactly how plants produce this metabolite," says Jia. "We're also going to look at the biological activity of the ancene in crop plants, as our findings could be relevant to increasing yields. "
"Ancorene modifies root architecture by promoting the formation of anchor roots, which increases root volume and facilitates the absorption of water and nutrients," adds Al-Babili. "Therefore, it may be possible to apply ancorene in nutrient-deficient soils to promote root growth."
