Genetically engineered tomatoes may be plague resistant

Researchers at the Plant Molecular and Cellular Biology Institute (IBMCP), a joint venture of the Universitat Politècnica de València and the Spanish National Research Council (CSIC), have performed a study showing how genetically modified tomato plants may have increased resistance towards Tuta absoluta insect plagues. The results are published in BMC Plant Biology.

“The miner insect Tuta absoluta has become one of the main plagues that threaten tomato plantations across the world, and without the appropriate management it can cause losses of between 80% and 100% of their production,” explained Luis Cañas, researcher of the CSIC at the IBMCP. “To face this threat, we have to fortify the plant’s defense arsenal, and one of the alternatives being studied is giving the plants, through genetic engineering, defensive genes from phylogenetically distant species such as the protease inhibitors present in barley.”

The researchers investigated the in vivo effect of a serine proteinase inhibitor (BTI-CMe) and a cysteine proteinase inhibitor (Hv-CPI2)—isolated from the barley plant—on the Tuta absoluta insect. To do that, the researchers tested both inhibitors separately as well as together in transgenic tomato plants.

The researchers found that the Tuta absoluta larvae that were fed the double transgenic plants showed noticeable weight loss, and only 56% of the larvae reached their adult stage. When the researchers studied the effect of ingesting proteinase inhibitors on the insect’s digestive enzymes, they found a decrease in larvae trypsin activity. Proteinase inhibitors in transgenic tomato plants attracted species of the Tuta absoluta predatory insects such as the Nesidiocoris tenuis, but did not have an effect on them.

Finally, the researchers also studied whether the defensive mechanisms of the plants would activate on transgenic tomatoes. Interestingly, the release of barley cystatin benefitted the plant’s defense, including the proteinase 2 inhibitor gene (Pin2), endogenous to the tomato, and which is inducible through wounding. Furthermore, transgenic plants increased their glandular trichome production and their volatile organic compound emission was altered.

Study