Gene Splice Helps Fight Crop Disease, Say Researchers

Biologists on Sunday said they had found a potential super weapon in a long-running arms race with bacteria that threaten essential crops.

Tested in a lab, their technique entails inserting a gene kit into a plant so that its immune system recognizes and fights germ invaders, they reported in the journal Nature Biotechnology.

Bacteria cause huge losses to crops each year. Farmers usually tackle the foe by dousing their fields with chemicals, but these are expensive and can damage soil biodiversity.

Another way is to shore up the plant’s defences by a gene introduced through cross-breeding with a hardier strain.

Yet this technique is rarely able to give a plant resistance against a wide range of germs — and in any case a bacterium may swiftly evolve to sneak around the new defence.

Phytobiologists led by Cyril Zipfel at the Sainsbury Laboratory at Norwich, eastern England, took a novel tack.

They delved into plants’ innate defence system, hunting for watchdog genes able to spot a pattern of telltale proteins exuded by a microbial invader.

Like bones and skin in humans, these proteins are essential for the bacteria’s core functions and so are less likely to mutate, for to do so could harm the pathogen’s survival.

The watchdog genes govern so-called pattern recognition receptors, or PRRs.

PRRs were first discovered 15 years ago, although only a few have been discovered to date, and much is unclear.

It was known that a PRR can spot essential proteins from quite a wide a range of bacteria. But it was uncertain whether the defence is unique to a given family of plants or can be transferred to another.

Exploring this avenue, Zipfel’s team took a PRR that was specific to the Brassica family — the plant group that includes mustard, Brussels sprouts and cabbage — and slotted it into two plants from the Solanaceae family, which includes tomatoes, potatoes, aubergines (US: eggplants), tobacco and other valuable crops.

By having the PRR added to their arsenal, the Solanaceae plants showed “drastically enhanced” resistance to many different bacteria, including Ralstonia solanacearum, a major cause of crop wilt.

“The strength of this resistance is because it has come from a different plant family, which the pathogen has not had any chance to adapt to,” Zipfel said in a press release.

“Through genetic modification, we can now transfer this resistance across plant species boundaries in a way traditional breeding cannot.”

The work is proof of principle and there is a long way to go before the technique may enter the public domain.

Zipfel said that in the “constant evolutionary arms race” between plant and pathogen, the possibility that a germ could mutate and thus bypass the new weapon will be smaller, although it cannot be discounted.

Genetically-modified crops are widely grown and consumed in North America and other parts of the world but are strongly resisted in Europe, where a powerful green lobby says it is too soon to know whether the technology is safe for the environment and health.

The head of the Sainsbury Laboratory, Sophien Kamoun, said the research was exciting, given the challenge to boost food production to feed the world’s growing millions while meet demands for biofuels and the impact from climate change.

“Cyril’s work indicates that transfer of genes that contribute to this basic innate immunity from one plant to another can enhance pathogen resistance,” said Kamoun.

“The implications for engineering crop plants with enhanced resistance to infectious diseases are very promising.” Breitbart