Emily Chan
Researchers from Michigan State University have discovered something surprising about tomatoes. Apparently, the roots of tomato plants produce a special class of metabolites known as acylsugars.
Previously, these compounds were thought only to be found in the fuzzy hairs, which are called trichomes, that grow on tomato leaves and stems.
Acylsugars consist of sugar cores made up of fatty acid chains. They help defend against pests in tomato trichomes. The acylsugars in the roots are different from the ones found within the trichomes.
After conducting advanced analyses, the scientists determined that the predominant acylsugar in tomato roots featured a sugar core composed of glucose linked to inositol, as opposed to the sucrose core present in trichome acylsugars.
“What’s so remarkable about these specialized metabolites is that they’re typically synthesized in highly precise cells and tissues,” Rachel Kerwin, one of the authors of the study and a postdoctoral researcher at MSU, said.
To find out more about how root and trichome acylsugars are made, the researchers identified genes in tomato roots that closely resembled the known trichome acylsugar genes.
Then, they used CRISPR gene editing to remove the genes ASAT1 and a particular gene from the tomato roots, dubbed ASAT1-L. It was the cousin of the trichome gene ASAT1.
Tomato plants without ASAT1-L did not produce any detectable acylsugars in their roots, while the acylsugar levels of trichomes remained unaffected.
When ASAT1 was knocked out, the opposite was true. These results suggest that, over time, tomatoes developed to have two separate acylsugar metabolic pathways. One of the pathways was for the trichomes, and the other was for the roots.
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