I had the pleasure of interviewing
Pamela Ronald who was recently awarded the 2020 World Agriculture
Prize for her achievements in agricultural research and science education.
Dr. Ronald is a leader in the research field of plant responses to
environmental and pathogen stresses. Additionally, she is an advocate and
educator for sustainable food practices and modern crop breeding strategies.
She has a fabulous TED
talk and has written a book with her husband on modern crop science
and organic farming practices titled Tomorrow’s
Table: Organic Farming, Genetics and the Future of Food.
This Q&A session was designed to learn more about
her accomplishments, understand the challenges humanity faces in food
production, and the ways science has and continues to address these issues.
1. In your own words, can you provide a brief introduction of your
research and interests?
“I have been working on the interaction
between plants and microbes for many years. My interest in this research
started when I was an undergraduate. My plant physiology professor at Reed
College taught me about plant–microbe interactions, and it sparked my interest.
Then, while doing my masters at Stanford, Dr. Brian Staskawicz
came and gave a talk on his lab’s work, and it left an impression on me. After
my Ph.D. work, I decided to work in Dr. Staskawicz’s lab. There I focused on
plant–microbe interactions, where I have now spent a bulk of my career.”
At the helm of her own lab, Dr. Ronald and her
a receptor in rice, using positional cloning. This receptor confers resistance
to the devastating Xanthomonas oryzae pv.
oryzae pathogen. Almost immediately after
publication, “a colleague of mine that I had known for several years, Dr. Dave Mackill,
came by my office and asked if I would help him isolate another gene in rice
that plays a role in stress tolerance. I was immediately interested.” This
turned out to be instrumental for conferring tolerance to submergence. Its
discovery led to an, “exciting international project to create flood-tolerant
rice varieties for farmers in India and Bangladesh.”
2. Can you go a bit more in-depth about the creation and
distribution of Sub1A
“Well this whole process was
started by the International Rice Research Institute (IRRI). The mission of IRRI is to help abolish poverty and hunger in regions that depend on
rice for most of their calories.
Rice fields in India and
Bangladesh were constantly being flooded, resulting in devastating yield
losses, so farmers looked to the scientists at IRRI to help. At the time, IRRI
had built up a large and diverse rice seed collection, which they used to
screen rice varieties for submergence tolerance.
Dave Mackill had worked in South
Asia before working at UC Davis and knew how important this work was.
Researchers at IRRI had identified a rice variety with tolerance to
submergence. Dave then mapped the submergence tolerance (Sub1) trait as a
quantitative trait locus (QTL). This was when Dave came to me and asked if we
could collaborate on isolation of Sub1 using positional cloning. We were
successful and named the key gene Sub1A.
Dave used marker-assisted breeding
to introgress Sub1A
into commonly used rice varieties. This breeding practice is not considered a
genetically modified organism (GMO) and is not regulated. IRRI researchers
collaborated with breeders at breeding stations in India and Bangladesh to test
the performance of the Sub1
varieties.” Last year, 6 million farmers in India and Bangladesh grew Sub1 rice with an
average yield advantage of 60% after flooding.” See
this perspective for more information.
3. If you were to make the argument for GMO products to someone
against it, what would you tell them?
“Well, I would first try to understand
what they were afraid of. The term GMO means something different to everyone.
Interestingly, GMO isn’t even used by the FDA because genetically modified
organism doesn’t accurately describe any breeding process really. Often, a
person who identifies as ‘anti-GMO’ is afraid of large corporations like
Monsanto, or they heard that ‘GMOs’ require more chemicals, and they don’t like
that. This is why it’s really important to understand the root of each person’s
fears of GMOs, so you can narrow the discussion to address individual
When trying to explain to a group
of people why modern genetics is useful in agriculture, I think it’s important
to give specific examples. That’s the one thing that just changes people’s
mind. Two examples I usually give are genetically
engineered papaya that are resistant to the deadly Papaya ringspot virus and Bt
eggplant in Bangladesh that reduces the need to spray
chemical insecticides. Both genetically engineered crop varieties have improved
plant yields and the lives farmers.
Now in the world of COVID-19, more
people are familiar with viruses and their infective nature. This is a good
example, because some people may be interested to know that viruses also infect
plants. This allows you to then engage people by using their knowledge about
the vaccine for COVID-19 to explain the techniques used by plant scientists to
ward off pathogens. Also, something I realized while writing my book was, why
would the average American know a lot about farming? And, how much would they
actually know about it? This is also a really important thing to keep in mind
when talking about GMOs with people. Many people may not understand or know the
farming practices used today and what challenges farmers face.”
4. In your point of view, what are some of the toughest challenges
facing agriculture right now? And, how might agriculture look in 2040 to
address these problems?
“I think problems associated with
climate change, like increased flooding, which I’m now more aware of, droughts,
and unpredictable insect infestations, like the
fall armyworm sweeping through Africa, are going to be tough. There are
scientists and modelers trying to predict new infestation events, but it is
proving very difficult. The work we do now is similar to what breeders have
been doing for 100 years or so, but we now have to work smarter and faster to
keep up with all of the changes occurring around the world.
Additionally, we will have to
start growing more food, while reducing emissions. This is something that
wasn’t really being talked about when I first entered the field. It was more
about reducing chemical inputs. So, now we have to also think about enhancing
soil fertility, reducing greenhouse gas emissions, and using water more
This is seemingly a daunting task;
however, Dr. Ronald is optimistic that scientists can work toward solutions.
“The field is rapidly advancing, and new technologies are now starting to be
developed and tested to address these problems.”
5. In your mind, what are some of the most intriguing questions
concerning pattern recognition receptors and their role in plant immunity?
“Well, I think an emerging topic
that is still sort of a black box is the relationship between development and
immunity. There is great work from Dr. Joanne Chory
and others on the SERK receptors that are involved in both immunity and
development. When this relationship was discovered years ago it was pretty
surprising, and now there are many great examples of the relationship between
development and immunity.
I think the other complicated
aspect of this area is that immunity has been traditionally thought of as a
linear concept—immunogen interacts with receptor, and this induces a linear
pathway that results in a response. However, we now know that the responses to immunogens
are much more complex than this. For instance, there are receptor complexes and
receptors that can double dip into immunity and development. I think trying to
sort out the balance and inner workings of this is really fascinating and will
be studied for a long time.”
6. For pattern recognition receptors (PRRs) and resistance (R)
genes, what needs to be done to increase their use and efficacy against
“There are examples where
different resistance genes have been stacked [placing multiple R genes into a
plant], and this provided additive and, hopefully, more durable resistance. I
think some steps to improve the process will be trying to predict how resistant
and durable these added genes will be in a crop plant. This involves doing
epidemiological studies where you think about the population diversity of the
pathogen in the field. This allows you to predict the types of mechanisms the
pathogen has to overcome and the methods being placed into plants to confer
durable resistance. You really need to know the effector repertoire of a
pathogen population and the interactions they have with the receptors of
interest. This allows you to answer the question, ‘Are there pathogen strains
in the field that can already overcome the R gene(s) or PRR(s) being added?’
There really is no shortcut to the process of engineering durable resistance.
We are still learning a lot about
utilizing plant immune components to increase pathogen resistance. For example,
being able to introduce many R genes at a single time in a cassette of genes
would be a great step forward. Currently, it takes a long time to breed many R
genes into a population. If people become more accepting of genetic
engineering, this could decrease the time needed to introduce resistance genes
into plants, which is exciting.
For a long time, there has been the hypothesis
that PRRs that recognize conserved virulence factors or immunogens would be
more durable in the field than R genes. However, I don’t think this has been
very well validated or tested in the field. One reason may be because much of
the research on PRRs, like FLS2, is carried out on non-crops. So there are very
few studies that examine if these theories hold up in the field. Even for Xa21, where plants
carrying this gene have been grown in the field for years now, there really
hasn’t been any thorough epidemiological studies to determine if this
resistance is indeed more durable than the resistance provided by other types
of resistance genes such as NBS-LRR genes. Researchers have discovered
bacterial strains that evade Xa21 in the field; however, to my knowledge it is not known
if they become problematic to farmers. So, what does that mean? Does the
evolution of the ability to evade Xa21-mediated immunity result in strains that are
compromised in virulence somehow? You really can’t determine this unless you do
large-scale field trials that look at the pathogen population over time.”