The first HGT (Horizontal Gene Transfer) between an animal and a plant has been found. A common insect called Silverleaf whitefly, Bemisia tabaci obtained a gene from one of the different plants it feeds on, according to the report by researchers in Cell on March 25h, 2021. The gene (BtPMaT1) defends the pest from toxins known as phenolic glycosides that several plants generate to protect themselves against such insects, hence enabling the Silverleaf whiteflies to feast.
Charles Davis, Harvard University’s evolutionary biologist who did not participate in the study stated that this study is really interesting. It depicts yet another good instance of how HGT between eukaryotes presents evolutionary novelty.
HGT is the nonsexual interchange of genes among species. It is been reported before among unicellular organisms and even among few eukaryotes like beetles and fungi. There are various means by which HGT can happen. Genetic matter can be swapped through viruses or phages, and few organisms might absorb free DNA from the surrounding.
Ted Turlings, co-writer, and chemical environmentalist, Université de Neuchâtel claimed that the research team really didn’t start looking for evidence of cross-species gene swapping involving whiteflies. Turling’s teammate Youjun Zhang and his team at the Chinese Academy of Agricultural Sciences initially started to understand the escape mechanism of these pests from various plants. Turlings added that Silverleaf whiteflies cause diseases in plants. They can ruin crops. Hence, they are economical very significant across the whole world.
Zhang’s lab started by exploring the genome of Silverleaf whiteflies to find the genetics that gives protection from all-natural toxins produced by plants. After analyzing its genetic makeup with comparable insects that can’t protect themselves from these plant toxins, they focused on BtPMaT1. They uncovered that this genetics codes for a protein that nullifies the effect of phenolic glycosides. Then, the research group explored the evolutionary source of the gene with NCBI (National Center for Biotechnology Information) databases of genomes. No other insect shared the gene or maybe one similar to it. It needed to have indeed appeared from elsewhere.
Eventually, they discovered the evidence of similar genes in one of the data sources, however, they remained within plants and not different pests. The group thinks that 35 million years ago, a plant infection occupied the gene, and later whitefly fed on the infected plant. The virus integrated the gene into the insect’s genome and later was spread to the population.
Turlings mentioned that it demonstrates that progress can consist of genes from other microbes that can aid you to survive efficiently.
Immediately after the identification of the gene, researchers also found that it had appeared from plants and turned their aim towards deactivating the gene. They genetically engineered tomato plants with the toxic chemical to express RNA that obstructed the genetics. When the insects fed on these plants, the protective genetics of the insect was deactivated and died. When another pest, Myzus persicae, devoid of the BtPMaT1 gene was allowed to feed on the same genetically modified tomato plants, their death rates were unchanged, suggesting that scientists might be able to develop whitefly resistant crops but these plants won’t result in any harm to the rest of the species.
Pamela Soltis, plant biologist, College of Florida who didn’t participate in the research asserted in a mail to The Scientist that interesting questions have arisen about the research, like how and when the gene swapping occurred and how often has this process been occurring in creating resistance in insects against plant chemicals.
The study is published in the Cell journal with the title ‘Whitefly pirates a plant detoxification genetics that counteracts plant toxins’.
Plant to Insect Gene Transfer, First Plant To Animal Gene Transfer, Horizontal Gene Transfer, Plant to Insect Gene Transfer