Some whiteflies use plant genes to neutralize toxins in their diet.Photo credit: Getty
Plant-to-insect gene transfer discovered
A harmful agricultural pest owes part of its success to a gene stolen from its plant host. The finding reported in Cell is the first confirmed example of a natural gene transfer from a plant to an insect (J. Xia et al. Cell https://doi.org/f3k9; 2021). There’s also a reason the whitefly Bemisia tabaci is so adept at eating plants: the gene it pulled from plants allows it to neutralize a toxin that some plants produce to fight insects defend.
Early work suggests that inhibiting this gene can make whiteflies vulnerable to the toxin and is a potential way to control the pest. “This reveals a mechanism by which we can tip the scales back in favor of the plant,” says Andrew Gloss, who studies the interactions between plants and pests at the University of Chicago in Illinois.
The tiny whitefly – a relative of aphids – is causing agricultural havoc around the world. Bemisia tabaci contains sugary juice from hundreds of species of plants and excretes a sticky substance called honeydew that promotes mold. Whiteflies are also vectors for more than 100 pathogenic plant viruses.
Entomologist Youjun Zhang of the Chinese Academy of Agricultural Sciences in Beijing and his colleagues were searching the genome of B. tabaci for stolen genes when they found one that appeared to have evolved in plants. Further studies showed that the gene can transfer a chemical group to defense compounds called phenolic glucosides. Such compounds are made by many plants, including tomatoes, to repel pests. However, the modification caused by the Whitefly gene rendered the compounds harmless.
To test the hypothesis, the team constructed tomato plants to make a double-stranded RNA molecule that can disrupt expression of the Whitefly gene. Most of the whiteflies that fed on these plants died.
Gene transfer between species is difficult to prove, says study co-author Ted Turlings, chemical ecologist at the University of Neuchâtel in Switzerland. The researchers analyzed the sequences of similar genes in plants and showed that the Whitefly gene was their evolutionary relationship. They also performed analysis to show that the gene was integrated into the whitefly genome and not the result of plant DNA contaminating samples.
Bill Nelson.Photo credit: Bill Ingalls / NASA
The former senator will head NASA
US President Joe Biden has named Bill Nelson, a former Democratic Senator from Florida, as the new head of NASA.
Nelson, who has worked in space law for decades, has long defended NASA’s human space flight programs because they create jobs for his state through the launch center in Cape Canaveral on the east coast of Florida. In 1986, on the last flight before the Challenger exploded, he flew aboard the Space Shuttle, the second seated member of the US Congress.
Nelson is a strong proponent of conventional space programs, including the Space Launch System (SLS), NASA’s lengthy attempt to build a heavy-lift rocket to launch astronauts out of orbit. He inherits the Artemis program, which aims to bring astronauts back to the moon, from his predecessor, former NASA administrator Jim Bridenstine.
Nelson, a politician, initially criticized Bridenstine’s appointment, saying the job shouldn’t go to a politician. Nelson is the same age as Biden – 78 years old – and the two worked together in the US Senate. He must be approved by the US Senate before he can take up his new role.
Antonio Ferrari, 92, receives a vaccine against COVID-19 at his Lima home.Photo credit: Ernesto Benavides / AFP / Getty
Older people at higher risk of contracting COVID twice
Analysis of millions of coronavirus test results in Denmark suggests that natural SARS-CoV-2 infection protects most people from re-infection – however, this protection is significantly weaker in those aged 65 and over.
Steen Ethelberg and his colleagues at the State Serum Institute in Copenhagen have obtained data from polymerase chain reaction tests, which are the gold standard method for detecting SARS-CoV-2 infection that has been carried out in Denmark (CH Hansen et al. Lancet https: / / doi.org/gjg8qk; 2021). The researchers focused on people who tested positive for the coronavirus during one or both of the two flare-ups in Denmark – March to May and September to December – in 2020.
They found that around 6 months after the initial infection, protection against repeated infections was around 80%, with no significant difference in reinfection rates between men and women. However, this protection has been reduced to 47% for those aged 65 and over, underscoring the need to prioritize vaccinations for this group.
