Genetically modified produce often causes considerable angst for all those interested in the environment but ensuring we maximise our food produce and avoid waste is also an important consideration. Now, researchers at the Plant Molecular and Cellular Biology Institute (IBMCP), in a joint venture between the Universitat Politècnica de València and the Spanish National Research Council (CSIC), have studied how genetically modified tomato plants may have developed improved resistance towards a leaf boring insect called Tuta absoluta .The results are published in BMC Plant Biology.
The insect Tuta absoluta is a major pest of tomatoes grown throughout the world and is now considered a major plague. If unmanaged, it can destroy 80 to 100 per cent of a crop. The scientists have countered this catastrophic problem by introducing genetic material which boost’s the plant’s defence weaponry. To achieve this prospect, genetic engineering was used to introduce defensive genes from other plant species. Barley was selected because it contains genes for protease inhibitors. These are produced by the tomato when the genes are inserted and switched on and prevent the insect from obtaining benefit from the plant material it is ingesting.
To understand whether the inhibitors would be appropriate for the trial by acting on the insects, the researchers looked at 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. The researchers looked at both inhibitors separately and then together in their transgenic tomato plants.
The key feature of the study was that the inhibitors were probably responsible for the larvae feeding on the plants, from suffering severe weight loss. Indeed, 56 per cent of the larvae did not reach their adult stage. The reason is attributed to the ingested proteinase inhibitors acting on the insect’s own digestive enzymes especially trypsin. The proteinase inhibitors from the transgenic tomato plants couild also have attracted more of the lead borer’s predators such as Nesidiocoris tenuis. The inhibitors did not affect the predator’s metabolism.
Tomato has its own defensive mechanisms. The study also checked whether insertion of the genes and activation of production of the protease inhibitors would prevent activation of these defensive mechanisms. The release of barley cystatin benefitted the plant’s defence systems, including the proteinase 2 inhibitor gene (Pin2), endogenous to the tomato, and which is inducible through wounding. These transgenic plants increased their glandular trichome production and their volatile organic compound emission was changed.
Reference
Hamza, R.H., Perez-Hedo, M., Urbaneja, A… et al., (2018) Expression of two barley proteinase inhibitors in tomato promotes endogenous defensive response and enhances resistance to Tuta absoluta. BMC Plant Biology. https://bmcplantbiol.biomedcentral.com/articles/10.1186/s12870-018-1240-6
I am not a fan of GM but I can see the value in this type of research. My biggest worry is whether we can truly feed all the world. Got a strange feeling we might just have to accept GM tomatoes at least.