China science

Brave new plant world? Chinese scientists smash reproductive barrier between genera for first time, but critics warn of playing god

PUBLISHED : Tuesday, 16 February, 2016, 2:56pm
UPDATED : Monday, 12 June, 2017, 12:53pm

Chinese scientists have come up with a groundbreaking method to remove the reproductive barrier between plants, paving the way for species from separate taxonomic families to mate at will, according to a new paper published in the journal Nature.

By chemically interfering with the plants’ pollen cells, the research team convinced a female plant from one genus to mate with a male from an alien species.

The team said they were able to create a distant-hybrid species using Arabidopsis thaliana and Capsella rubella, two flowering plants as different in biological terms as humans and gorillas.

The experiments were overseen by Professor Yang Weicai from the Institute of Genetics and Developmental Biology in Beijing, which operates under the Chinese Academy of Sciences.

While different plant species can be “fused” using more brutal methods such as cloning or genome editing, this is the first time they have been made to mate in more natural terms.

Such cross-breeding has hitherto only occurred between very close species, for example by combining domestic and wild rice species in China to create hybrid forms of rice and raise crop yields.

READ MORE: Chinese scientists find gene that improves rice yields by 20 per cent

Pollen, the fine powdery substance that produces male gametes (sperm cells), must land on the female sex organ of a flower (the pistil) to germinate, producing a pollen tube that extends to pass sperm into the ovule containing the female gametophyte, where fertilisation can occur.

But the male plant needs guidance from the female to make sure the pollen tube meets its target, and the female will only send the required signal if she recognises the pollen as being from the same genus.

Such restrictions on reproduction have brought order and discipline to the plant kingdom, but they have also made it hard for scientists to cross-breed new species to, for example, boost agricultural production.

Yang’s team partially solved the problem by exploiting this biological “loophole”: they changed the chemical signature of the surface of the pollen cells to trick the female plant into recognising it as belonging to the same plant family.

By modifying the signature of the pollen from Capsella rubella, the team duped the female Arabidopsis thaliana into sending out the correct “attracting signals” to facilitate fertilisation.

This method could be used to “partially break down the reproductive isolation barrier”, the researchers wrote in their paper.

Yet problems remain. First, it could cause the offspring to mutate or be infertile; second, it remains unclear just how effective this procedure would be for other plants, the team said.

“This new technology could trigger a revolution in agriculture. It may lead to the creation of rice that can be grown in the desert, or which can grow as tall and big as a tree, by cross-breeding species in a way that was impossible before,” said a botanist who declined to be named.

“But these kind of tests need to be strictly controlled in a laboratory,” the botanist added.

“Mother Nature has erected reproductive barriers among different species for good reason. Any abuse of this could have unexpected consequences.”