Nature & Animals

Plant–insect gene transfer, NASA chief and COVID reinfections

Two whiteflies and an egg on leaf, at 5x magnification.

Some whiteflies use plant genes to render toxins in their food harmless.Credit: Getty

Gene transfer from plant to insect spotted

A pernicious agricultural pest owes some of its success to a gene pilfered 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; 2021). It also provides one reason why the whitefly Bemisia tabaci is so adept at munching on crops: the gene that it swiped from plants enables it to neutralize a toxin that some plants produce to defend against insects.

Early work suggests that inhibiting this gene can render the whiteflies vulnerable to the toxin, providing a potential route to combating the pest. “This exposes a mechanism through which we can tip the scales back in the plant’s favour,” says Andrew Gloss, who studies plant–pest interactions at the University of Chicago in Illinois.

The diminutive whitefly — a relative of aphids — wreaks agricultural havoc globally. Bemisia tabaci sups sugary sap from hundreds of types of plant and excretes a sticky substance called honeydew that encourages mould. Whiteflies are also vectors for more than 100 pathogenic plant viruses.

Entomologist Youjun Zhang at the Chinese Academy of Agricultural Sciences in Beijing and his colleagues were scouring the B. tabaci genome for stolen genes, when they found one that seemed to have evolved in plants. Further study showed that the gene can transfer a chemical group on to defensive compounds called phenolic glucosides. Such compounds are made by many plants, including tomatoes, to ward off pests. But the modification caused by the whitefly gene rendered the compounds harmless.

To test the hypothesis, the team engineered tomato plants to produce a double-stranded RNA molecule capable of shutting down expression of the whitefly gene. Most whiteflies that fed on these plants died.

Gene transfer between species is hard to prove, says study co-author Ted Turlings, a chemical ecologist at the University of Neuchâtel in Switzerland. The researchers analysed the sequences of similar genes in plants, and showed that the whitefly gene was their evolutionary kin. They also ran analyses to show the gene was integrated into the whitefly genome, and was not the result of plant DNA contaminating samples.

Bill Nelson

Bill Nelson.Credit: Bill Ingalls/NASA

Former Senator will lead NASA

US President Joe Biden has appointed Bill Nelson, a former Democratic senator from Florida, as the new head of NASA.

Involved in space legislation for decades, Nelson has long defended NASA’s human-space-flight programmes because of the jobs they bring to his state through the launch centre at Cape Canaveral on Florida’s east coast. In 1986, he flew aboard the space shuttle, the second sitting member of the US Congress to do so, on the last flight before Challenger exploded.

Nelson is a strong supporter of conventional space-flight programmes, including the Space Launch System (SLS), NASA’s long-delayed effort to build a heavy-lift rocket to carry astronauts beyond Earth orbit. He inherits the Artemis programme, which aims to return astronauts to the Moon, from his predecessor, former NASA administrator, Jim Bridenstine.

Nelson, a politician, initially criticized Bridenstine’s appointment, saying that the job should not go to a politician. Nelson is the same age as Biden — 78 years old — and the two worked together in the US Senate. He will have to be confirmed by the US Senate before he can begin his new role.

A health worker gives an older man a dose of the Pfizer–BioNTech COVID-19 vaccine

Antonio Ferrari, 92, receives a vaccine against COVID-19 at his house in Lima.Credit: Ernesto Benavides/AFP/Getty

Older people at higher risk of getting COVID twice

An analysis of millions of coronavirus test results in Denmark suggests that natural infection with SARS-CoV-2 protects against reinfection in most people — but that this protection is significantly weaker in those aged 65 years or older.

Steen Ethelberg and his colleagues at the State Serum Institute in Copenhagen mined data from polymerase chain reaction tests, which are the gold-standard method for detecting SARS-CoV-2 infection, conducted in Denmark (C. H. Hansen et al. Lancet; 2021). The researchers focused on people who tested positive for the coronavirus during one or both of Denmark’s two surges of infection — from March to May and from September to December — in 2020.

They found that, at about 6 months after initial infection, protection against repeat infection was approximately 80%, with no significant difference in reinfection rates between men and women. But this protection was reduced to 47% for those aged 65 or older, emphasizing the need to prioritize vaccinations for this group.

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