How plants help make their kids stronger

Inactivating a single gene can induce a form of “stress memory” in plants that is then inherited by some progeny, making them more resilient, according to US geneticists.

This could allow for advances in plant breeding without the controversy surrounding genetic modification, they suggest, because the technique is epigenetic: it involves the expression of existing genes not the introduction of new genetic material from another plant.

The gene, known as MSH1, provides access to “what is controlling a broad array of plant resiliency networks”, says Sally Mackenzie from Penn State University, lead author of a paper in the journal Nature Communications. 

There are many ways to inactivate MSH1, the researchers add, and in this context they all work. 

The research to date has focused on the small flowering plant rockcress (Arabidopsis), a relative of cabbage and mustard in the Brassica family. It is one of the model organisms used for studying plant biology and is the first plant to have its entire genome sequenced. 

Arabidopsis is useful for genetic experiments because of its short generation time and prolific seed production through self-pollination. Mackenzie and colleagues grew five generations of Arabidopsis to study “memory” and “non-memory” plants.

They found that by adjusting the epigenetic architecture of a plant they were able to access its resiliency network. They identified pathways that enhance root growth and plant vigour, increasing yield. 

When an MSH1-modified plant was crossed or grafted, this enhanced plant vigour became quite pronounced.

The researchers contend that plants can be “reprogrammed” epigenetically to express genes differently without altering genotype, which constitutes a non-traditional approach to breeding. 

And because they can now identify gene networks that appear to be targeted by this manipulation, they suggest that plants have mechanisms designed to address stress or alter growth, and these can be accessed.

“In our research, we show that this memory condition is heritable by progeny but occurs in only a proportion of the progeny, so that there are memory and non-memory full siblings,” Mackenzie says. “That results in definable gene expression changes that impact a plant’s phenotypic ‘plasticity’. 

“We suggest that all plants have this capacity, and that the condition that we describe is likely to be an important part of how plants transmit memory of their environment to precondition progeny.”

In follow-up research, the researchers have suppressed MSH1 genes in tomato and soybean plants and grafting experiments have been field tested. A large-scale experiment growing MSH1-modified canola is now planned.