Insects that feed on starch can find abundant resources in crops such as corn, peas, and beans, as well as in stored grains. It is no coincidence that the wild ancestors of these commercial plants evolved α-amylase inhibitor proteins, which render the starch in their seeds indigestible to pests and help prevent significant damage. However, human-driven domestication aimed at improving yield and digestibility has likely reduced the levels of these natural inhibitors.
In a recent Biotechnology Journal article, an international team of scientists reviews two decades of progress in this field and highlights the promise of gene editing to boost the production of these inhibitors in crop plants as a strategy against insect pests. At the same time, they emphasize the importance of ensuring that enhanced inhibitor levels do not compromise digestibility for humans or other non-target organisms, such as livestock.
The study was led by researchers from the Brazilian Agricultural Research Corporation (EMBRAPA) and the Genomics for Climate Change Research Center (GCCRC), an Applied Research Center supported by FAPESP at the State University of Campinas (UNICAMP), according to a press release.
“In the early 2000s, there were many advances in this area, such as the prospecting of genes encoding alpha-amylase inhibitors in different plant species, the evaluation of the specificity of these molecules against alpha-amylase enzymes in insect pests and non-target organisms, and the development of transgenic plants that overexpress these molecules. Advances were also made in protecting intellectual property through patents filed and granted,” says Marcos Fernando Basso, a researcher at the GCCRC with a scholarship from FAPESP and first author of the article.
However, the use of classical transgenic approaches—in which genes from unrelated species are inserted into crop genomes—has discouraged biotechnology and food companies from fully developing or commercializing such products. Transgenic organisms intended for human consumption face the dual challenge of low consumer acceptance and high regulatory costs.
Potential
Common agricultural pests such as bedbugs, beetles, weevils, and woodworms produce amylase enzymes that break down the starch stored in the leaves and seeds of major crops into sugars. Whether as larvae or adults, these insects can damage seeds both in the field and in storage, leading to economic losses and reduced food quality.
Bruchids, including weevils and woodworms, were among the first pests targeted by inhibitor-based strategies due to the severe damage they inflict, especially on long-stored grains. In these nutrient-rich environments, they reproduce quickly. Infestations can begin during pod development and continue throughout storage and even during commercialization.
Alpha-amylase inhibitors have also shown efficacy against other pests. The boll weevil (Anthonomus grandis), for example, feeds on sugars produced and stored in cotton flower buds, while the coffee berry borer (Hypothenemus hampei) has larvae that feed on the seeds of coffee berries.
The authors emphasize that breeding or engineering crop varieties with increased production of alpha-amylase inhibitors—so long as these inhibitors do not interfere with amylase activity in humans or non-target organisms—holds strong potential when combined with gene-editing approaches.
Gene editing can be used to boost the expression or fine-tune the DNA sequence of a plant’s native genes. In some cases, this may result in plants that are not classified as transgenic by Brazil’s National Technical Commission on Biosafety (CTNBio), the technical-scientific agency responsible for developing and implementing national biosafety policies for genetically modified organisms (GMOs). As a result, crops developed through gene editing could face lower regulatory barriers and greater market acceptance, increasing their appeal for agribusiness development and commercialization.
“Gene editing using the technique known as CRISPR [a tool that allows precise and specific genetic modifications to be made to DNA chains or genomic rearrangements to be generated] and its variations gives us the possibility of increasing the production of these inhibitors or making them more active in plants of interest to act specifically against insect pests, without the molecules being a problem for humans and animals that consume the plants or seeds. Therefore, it may be a promising path in the coming years,” concludes Basso (read more about CRISPR at revistapesquisa.fapesp.br/en/a-tool-to-edit-dna/).
