How to help plants with their defence

---

How to help plants with their defence

Aphids are one of the many insects that are a pest to plants. They eat by sucking up plant juices. In the process they can transfer plant pathogens. On top of that, they also reproduce supper quickly. Making them a real pest. One, farmers don’t like to have on their crops. A farmer can use pesticides in their fight against aphids, but he can also help the plant to induce its own defence system.

Plants have their own ways to deal with hungry insects. They make sure they are not tasty. They produce substances that make those insects less successful, or even kill them. And they sent out volatiles, fragrances, to attract insect eating insects, for example predatory wasps.

Researchers like to know how to use the plant defence system to protect crops against insects. Studies on this using the model plant Arabidopsis showed that plants treated with the defence inducer cis-jasmone are avoided by aphids and attract predatory insects. Researchers from the UK now tested if this also holds for 5 brassica species.

The brassica plants treated with cis-jasmone attracted less aphids, and these aphids produced less offspring. Moreover, plants treated with cis-jasmone also attracted more predatory wasps. These predatory wasps use aphids as food for their offspring. Together this keeps the aphid population in control and so limit the damage to the plants.

The researchers also analysed if cis-jasmone affects the volatiles excreted by the plant. They noticed that all studied brassica species excrete more volatiles after being treated with cis-jasmone. And that the composition of those volatiles was different between treated and untreated plants. With aphids preferring the volatiles of untreated plants.

Treatment of brassicas with cis-jasmone induces the type of plant defence mechanism needed to treat an aphid plague. The researchers showed that cis-jasmone can be a useful tool in the war against aphids. It is, however, still essential to find out the best way how a farmer can use this tool for protecting crops against aphids.

Literature

Ali, J., Covaci, A.D., Roberts, J.M., Sobhy, I.S., Kirk, W.D. and Bruce, T.J. (2021) Effects of cis-jasmone treatment of Brassicas on interactions with Myzus persicae aphids and their parasitoid Diaeretiella rapae. Frontiers in Plant Science, 12, p.711896. doi: 10.3389/fpls.2021.711896