This story was originally published by Knowable Magazine.
Plant biologist Pamela Ronald is concerned with the pressing
problem of feeding the world without destroying it. The question of
how to grow enough food for an expanding global population has
grown more urgent in the face of climate change. And it’s only made
harder, she says, by the push-back against the use of the genetic
tools now at scientists’ disposal.
Ronald’s views have emerged from nearly 30 years of research on
how plants resist disease and tolerate stress, work that is ongoing
in her lab at the University of California, Davis. Much of that
work has focused on rice, a staple crop that feeds nearly half the
globe. While she’s an outspoken advocate for using genetic
engineering to modify crops — her TED Talk The Case for Engineering Our Food has
been translated into 26 languages and watched more than 1.7 million
times — she’s also married to an organic farmer, Raoul Adamchak.
Together, they wrote the book Tomorrow’s Table: Organic Farming, Genetics,
and the Future of Food , exploring how the best of both
approaches might be needed for long-term sustainability.
We spoke with Ronald about her research and her views on genetic
modification and its place in the sustainable agriculture toolbox.
This conversation has been edited for length and clarity.
How do genetically modified crops fit into the
sustainable agriculture landscape?
Sustainable agriculture has three pillars: social, economic and
environmental. It creates food that’s nutritious, it allows farmers
to reduce the amount of land and water they use, to foster soil
fertility and genetic diversity, and to reduce toxic inputs. And it
enhances food security for the very poorest farmers and families in
the world. So, for example, if you can breed resistance into a plant, whether through
conventional or genetic engineering, and that means you can reduce
the amount of sprayed chemicals you use, that’s part of sustainable
Any type of agriculture is pretty challenging. Most farmers are
trying to move their farm toward more sustainable approaches.
Unfortunately, there’s no magic bullet because farmers in different
regions of the world face different challenges, grow different
crops and have different markets.
The book you and your husband cowrote is titled
Tomorrow’s Table. What does tomorrow’s table look like to
In the book, we describe what’s on our table and explain how the
foods were developed — the kinds of genetic techniques and organic
farming techniques used to produce that food. We try to give the
reader an idea of what geneticists do and what organic farmers do.
We have a number of recipes.
But the book isn’t about nutrition, it’s about: How do we
produce and provide that nutritious food with minimal environmental
impacts? How do we ensure that farmers and rural communities can
afford the food? How do we address this critical challenge of our
time: to produce sufficient, nourishing food without further
devastating the environment? There are a lot of issues, a lot of
people on the globe right now, and even more in the future. They
all need to eat.
Does your husband have a different view of the future of
It’s a shared view. We both think people should focus on the
challenges and not get distracted by the concept of genes in our
food. We really want to use all the tools that are available and
use scientific-based farming practices, such as those that minimize
pests and disease. There are many organic farming practices that
are very useful, such as crop rotation.
It’s the combination of farming strategies and genetic
strategies that are going to continue to be quite important for
producing our food and moving forward to a sustainable farming
future. Farming is destructive. But, as my husband says, we farm
because we have to eat. Some people say, well, let’s change our
diets, or reduce waste. Those are both important, but we still need
technological change. All these aspects are even more critical as
the population continues to grow.
A lot of your research has focused on rice, a hugely
important staple crop. Did you always want to work on
I was working on peppers and tomatoes as a graduate student at
UC Berkeley and as I was making the transition to a postdoc, I
thought, what do I want to do, because this may last my whole
career. And I decided to work on rice because it feeds half the
world’s people. It’s also a very good genetic system; it’s easy to
do genetic analysis of rice. So I thought if we can make any kind
of incremental advance we could potentially help millions of
One of those advances has been the development of
flood-resistant rice. I’ve seen so many photos of rice paddies
flooded with water, doesn’t rice tolerate flooding?
The rice plants that many of us are familiar with grow well in
standing water. But most rice plants will die if they are
completely submerged for more than three days. When the leaves are
submerged, they can’t carry out photosynthesis. My UC Davis
colleague David Mackill was working with this ancient variety of
rice, discovered at the International Rice Research Institute, that could be
completely submerged in water for two weeks, and then can start to
grow again when the water is removed. So this was very, very
Breeders then tried to use conventional breeding to introduce
this trait from the ancient variety into varieties grown by
farmers. But when you cross-pollinate with another variety, even
though it has a nice trait, you can bring a lot of other traits you
don’t want. So, the result from conventional breeding were rice
varieties that were rejected by farmers because they had traits
that the farmers did not want such as reduced yield, or a change in
the texture of the rice grain.
How did you tackle the problem?
First, we carried out the initial work of isolating the flood-tolerance gene, called
Sub1a, from the ancient variety. Then we introduced the
gene into a model rice plant using genetic engineering. We then
grew up those plants and submerged them, in large tanks in our
greenhouses for two weeks.
The plants that carried the Sub1a gene were very
robust; you could see the difference right away. Plants without
Sub1a turned yellow, had very long leaves and soon died.
This is because when the leaves try to grow out of the water, they
deplete their chlorophyll content and energy reserves. But the
plants that carry the Sub1a gene just stay kind of
metabolically inert — they don’t grow very fast, they just kind of
wait out the flood. And when the flood’s gone, they start to
regrow. The Sub1 plants remained green and healthy, indicating we
had indeed isolated the correct gene.
Is Sub1 rice now being grown by farmers?
Yes. As I described we used genetic engineering tools to isolate
and validate the submergence-tolerance gene in the greenhouse. That
genetic knowledge was then used to develop a flood-tolerant variety through a
different approach called marker-assisted breeding. That work
was done by the International Rice Research Institute. The ancient,
flood-tolerant variety was cross-pollinated with a modern variety
that farmers like because of its flavor and high yields. Seeds
derived from those hybrids were planted, and tested for the
preferred genetic fingerprint that included Sub1a but did
not carry genes from the ancient variety that affected traits
important to the farmers.
Marker-assisted breeding is very focused, you don’t drag in
genes that you don’t want, you can just drag in a very small region
of a chromosome. And because the genetic fingerprint can be
determined at the seedling stage, it saves a lot of time and labor
that would normally be spent on submerging hundreds of plants.
Farmers have now been growing Sub1 varieties for several years.
In 2017, more than 5 million farmers grew it. Sub1 rice is
disproportionately benefiting the poorest farmers in the world, who often have the
most flood-prone land. Compared with conventional rice varieties,
farmers growing Sub1 rice are able to harvest three- to fivefold
more grain after floods. The Intergovernmental Panel on Climate
Change predicts that flooding will become more
frequent and last longer as the climate changes.
These various breeding approaches underscore the
difficulty in defining “genetically modified” crops. How do you
The term “genetically modified” is scientifically meaningless,
and so it’s not useful. The FDA does not use the term.
With Sub1 rice, for example, scientists can introduce the
Sub1a gene with either genetic engineering or
marker-assisted breeding. In each of these cases, the genetic
region that’s introduced is smaller than the huge number of genes
that you bring in with conventional breeding, in which you are
mixing two genomes together.
Grafting is another kind of conventional breeding that mixes two
genomes. There are a lot of grafted varieties on farms in
California. The walnuts harvested in California are actually a
graft of two different species where the rootstock is a different
species than the top part of the plant. Then there are foods that
we eat that have been developed through radiation and chemical
mutagenesis, like grapefruit. Those approaches create many random
uncharacterized changes in the genome and are not regulated. They
can also be sold as “certified organic.”
What do you think most consumers mean when they say
genetically modified organism or GMO?
I think some consumers are concerned only about plants
engineered to contain genes from another species, like the
bacterial Bt gene. It sounds a little strange to put
bacterial genes into a plant, but it is important to consider the
risks versus the benefits. Organic farmers spray Bt to prevent
insect damage to their crops. It is safe to use. But spraying Bt is
not always effective. In Bangladesh, for example, there is an
insect that can destroy an entire eggplant crop and spraying
doesn’t keep the insect from getting into the plant. And the Bt
sprays are expensive and difficult to get. So Bangladeshi and
Cornell scientists engineered eggplants with the bacterial gene
so that the plants produce the Bt organic
insecticide in the crop. And it’s been tremendously successful
over the last five years, allowing farmers to reduce their
insecticide sprays dramatically.
One reason that the FDA and many scientists don’t find the term
“GMO” useful is because it means different things to different
people. You can’t really compare an eggplant engineered for farmers
in Bangladesh that has allowed them to reduce insecticide use to,
say, the “Golden Rice” plants engineered to have higher amounts of
provitamin A to help save the lives of children in developing
countries, or herbicide-tolerant canola grown in developed
countries. These are different traits, different crops, and
different people benefit.
Why do you think there is so much distrust of modern
I think part of the issue is that less than 2 percent of people
in the US are farmers and are somewhat removed from food
production. Many people aren’t familiar with the challenges faced
by farmers and may not understand that Bt crops have massively
reduced the use of insecticides in the US and globally. The World
Health Organization estimates that 200,000 people die every year
from misuse or overuse of insecticides, primarily in less developed
The use of genetic technologies has become very politicized like
several other issues in science — vaccines, climate change. The
major scientific organizations have concluded that the climate is
changing, that vaccines can save lives, and that genetically
engineered crops are safe to eat and safe for the environment.
I think most of us know someone who has been very sick and we
would do anything to help them. Often that means using a
genetically engineered drug. Or maybe we know someone with diabetes
who uses genetically engineered insulin. We accept that use of the
technology, most consumers accept it, because they have some
understanding of it in their own world. But I think very few
Americans have seen a malnourished Bangladeshi kid, so it’s not in
their world. It’s not that they aren’t compassionate, it’s that at
some level they don’t understand or see it. They don’t really
understand why farmers need genetically improved crops.
I think people understand with computer technology that there
are different applications of that single technology. People
wouldn’t say “computers are bad.” But somehow it gets confusing to
people when it comes to agriculture, maybe because so many of us
are so removed from actual farming.