Chinese scientists find plant breeding loophole that could reshape food security – South China Morning Post

Efforts to breed for ideal genes that can be detrimental to their plants have been limited by the classical principles of Mendelian inheritance and Darwinian natural selection, the team from the Chinese Academy of Sciences and Peking University said in their paper.

07:58

Why is the Chinese government so concerned about food security?

Why is the Chinese government so concerned about food security?

Mendelian inheritance is a principle that describes how genetic traits are passed from one generation to another, and states that the two alleles contained within a single gene each have a 50 per cent chance of passing on to offspring through reproduction.

Synthetic gene drives, inspired by natural selfish genetic elements and transmitted to progeny at super-Mendelian (greater than 50 per cent) frequencies, present transformative potential for disseminating traits that benefit humans throughout wild populations, even facing potential fitness costs, the team said.

A gene drive is a genetic engineering technique that allows genes to be modified in a way that discourages them from following the usual rules of heredity, thereby increasing the likelihood that a particular suite of genes will be passed onto the next generation and spread through a population.

The synthetic toxin in this case, a guide RNA Cas9 cassette was used to disrupt the No Pollen Germination 1 (NPG1) gene limiting pollen germination. A CRISPR-resistant antidote copy of NPG1 is then used to rescue pollen cells that carry the desired gene drive.

A red fluorescent seed marker was added to CAIN to track the progress of the gene drive.

CAIN transmission rates greatly exceeded the expected Mendelian inheritance of 50 per cent in heterozygous male parents, reaching 88 to 99 per cent within two successive generations, the team wrote.

We established CAIN as a state-of-the-art tool to efficiently modify entire plant populations.

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CRISPR/Cas9: a gene-editing tool with promise and peril

CRISPR/Cas9: a gene-editing tool with promise and peril

CAIN has advantages over other gene drive systems, which can develop a higher amount of resistance alleles that limit their efficacy. Compared to other systems, the team said they also chose to target the male germline over the female germline, since toxin-antidote gene drives targeting the female germline can compromise fertility and limit efficiency.

CAIN could be used in a variety of plants, as NPG1 is conserved across many species. One potential use of the system would be to target herbicide resistant genes in weeds to help reduce the need for excessive herbicide spraying, according to the researchers.

This gene drive-based approach thus seeks to balance crop protection and environmental considerations to minimise the loss of biodiversity while optimising productivity, the researchers wrote.

The team acknowledged that even if gene drive technologies are biosafe and self-containment strategies are implemented, the strategies may not be feasible in cases of intentional misuse of gene drive technology, targeting domestic crops or wild plants.

One method to safeguard against misuse could be the intentional creation and if necessary, release of suppressor lines. Editing the native NPG1 allele to resist Cas9 cleavage is a particularly straightforward and efficient method, the team said.

As we venture into this new frontier in genetic engineering, [CAIN] and other gene drive systems could reshape ecological management and agricultural practices.

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Chinese scientists find plant breeding loophole that could reshape food security - South China Morning Post