Plant discovery could lead to wider use of bee-friendly pesticides

Certain plant families, such as citrus and mahogany, naturally produce organic chemicals known as limonoids. These substances help protect the plants from pest insects, while not harming bees.

One limonoid – called azadirachtin – is already used in both traditional and commercial farming operations, as a natural-source, fast-acting, bee-friendly pesticide. Like other limonoids, it has to be extracted directly from the plant which produces it … in limited amounts. Because it hasn’t been possible to inexpensively produce the chemical in large quantities, it’s not nearly as widely used as it could be.

That may be about to change, though, thanks to an international research project.

Scientists from Britain’s John Innes Centre mapped the genome of the Chinaberry (Melia azedarach) – which is a member of the mahogany family – and used molecular analysis to identify the enzymes in the biosynthetic pathway which the plant uses to produce azadirone. Meanwhile, colleagues at Stanford University in the US used the same technique to reveal the enzymes that citrus plants use to produce kihadalactone A, another limonoid.

Armed with this knowledge, the researchers were able to create genetically engineered Nicotiana benthamiana plants (a close relative of tobacco) which produced large quantities of the two limonoids. Processing commonly farmed plants like Nicotiana benthamiana would reportedly yield much greater amounts of liminoids than is currently possible, plus it would be considerably more sustainable.

“By finding the enzymes required to make limonoids, we have opened the door to an alternate production source of these valuable chemicals,” said the John Innes Center’s Dr. Hannah Hodgson, co-first author of a paper on the research.

That paper was recently published in the journal Science.

Source: John Innes Centre
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