Understanding plants: making adaptations for climate change

27 October 2016

Agriculture is one of the biggest casualties of extreme weather events and increasing levels of carbon dioxide. So severe is the effect of increasing temperatures on crop production that malnutrition and food insecurity has become a frequent occurrence around the world.

Learning to adapt to this global climate change is a priority of the highest order. Dr On Sun Lau’s (Croucher Fellowship 2010) research in understanding the mechanisms of environmental signalling in the growth and development of plants at the cellular level using stomatal guard cells aims to do exactly that.

Lau was first inspired to work in this field after seeing the dedication and passion of one of his mentors, Professor Samuel Sun, during his undergrad years at the Chinese University of Hong Kong.

“To me being a scientist means that if you feel passionate about your work, you work on interesting problems with the potential to help people and make world a better place and contribute with scientific knowledge,” said Lau. “Although this is what initially inspired me, as I went on working in this field I realised every plant scientist has some role sand responsibilities in contributing to society through plant research.”

Stomata

Stomata are tiny pores on the surfaces of leaves that help in gas exchange during photosynthesis, allowing intake of carbon dioxide and release of oxygen. These essential cellular “vents” are also important for regulating water loss; without them, plants couldn’t survive in dry habitats.

“My interest is understanding how different environment signals, such as higher temperatures, impact the production of stomata. Plants need to regulate their number on leaves in order to adapt to the environment. This means the production of these pores is dynamic and highly responsive to the environment,” explained Lau.

“Besides being an important structure for the growth and development of plants, it is an excellent and accessible model system for us to understand how different environmental signals can affect cell type production or cell specification processes in general.”

Research works and implications in climate change

The focus of Lau’s research has been on stomatal development, understanding how the environment affects their production and their interaction with the environment in a continuous effort to breed crop plants that will ultimately respond better to climate change.

During his postdoctoral study at Stanford, Lau studied the early stages of the stomata developmental process. Stomatal development is very similar to other general cell specification type process, like the production of muscle cells in humans, which also begins with undifferentiated cells leading up to a mature stage. 

Specifically, he studied the master regulator responsible for making precursor stem cells and revealed the genetic makeup of this early cell stage when an undifferentiated cell commits and enters the stomatal cell lineage.

Dr On Sun Lau

“We found that this master regulator can influence thousands of genes, meaning the initial specification process of a cell type or cell lineage probably involves the rewiring of the whole genome,” said Lau. “And, particularly relevant to my current work, I found from that study that master regulators also bind to a lot of genes involved in environmental and hormone responses. This seems to reflect that there is heavy regulation or interaction or interplay with environmental signalling pathways in these stomatal precursor cells.”

One of the most challenging problems of our time is climate change. Due to extreme changes in weather, crop plants already need to deal with a lot more stress factors, and we also expect them to cope with heat stroke and increasing levels of carbon dioxide. 

But stomata on the surface of leaves are highly responsive to the environment. The increase in temperature and carbon dioxide leads to a decline in the number of stomata.

This response coupled with higher temperatures make plants more prone to heat damage because stomata are a way for plants to cool through evaporation, much like how humans sweat. So higher temperatures and fewer pores mean that there might be overheating in plants which could be detrimental to agricultural production.

“We want to understand in detail the underlying signalling mechanisms, that is how plants perceive and send signals to control the development of guard cells,” explained Lau. “This will allow us to engineer crop plants that will be better prepared for the future climate.”

Another potential benefit could be in growing plants indoors or urban farming where light and water are can be controlled.

“We can use what we understand about stomatal development to make plants that are particularly suited to urban farming. For example, if light and water are plentiful, plants with more stomata would likely offer better yield.” said Lau.

Interdisciplinary approach

It’s not new for scientists to incorporate different approaches in their research to understand underlying mechanisms and solve them.

“Genetic approaches have been instrumental in the study of stomatal development. For example, the master regulator that I focus on was first identified through a genetic screen, where its mutant completely lacks stomata on its surface,” said Lau, “With the advances in genomic tools and the adoption of cell sorting techniques used in animal studies, researchers in the field are now able to study gene expression programs during stomatal development at the genome-wide level and in a cell type-specific manner, providing unprecedented insights into the process.”

“Also, as stomata are on the surface of leaves, we can label proteins that function in the stomata lineage with fluorescence markers and easily study and visualise them using fluorescence microscopy,” Lau goes on.

But studying guard cells is just one way of addressing the problem of climate change in agriculture. Many scientists are also focusing on drought-resistant crops as extreme climate is frequently linked with water stress.

Although stomata play a role in drought resistance among plants, there are researchers looking at both the whole organism and specifically at the root system of crops; how they develop and respond to water. At the same time, there are also people using traditional breeding or phenotyping, trying to select plants that are more tolerant to water deficiency.

But more than anything, the field also needs more collaboration between scientists working on basic science and those working on crops.

“Traditionally, these two are different fields but in dealing with climate change these two groups of scientists need to work together in other to generate a better solution. There are more initiatives from different governments and private foundations that encourage this kind of research, which is promising,” said Lau.

Singapore and Hong Kong as research hubs of the region

Many might question the significance of crop research in places like Singapore and Hong Kong, which do not have much agricultural production at all. But Lau explained that because of the level of science and technology, these countries could act as a hub for higher-level crop research in the region.

Several Southeast Asian countries like Indonesia, the Philippines, and Thailand are all major crop producers. Researchers at the National University of Singapore had previously collaborated with International Rice Research Institute in the Philippines to work on rice improvement.

“If agriculture in the surrounding countries is suffering, we’ll all suffer. Of course, Singapore will not be directly affected because we have no crop production but in a way it is contributing to the region and regional food security,” said Lau. “Countries and places like Singapore and Hong Kong could play a role by undertaking higher-level research and collaboration in the region to improve agricultural production.”

Challenges

Funding is one of the biggest drivers for plant research but the level of support depends heavily location. There are plenty of resources in countries like the U.S. with vast agriculture sectors. Yet the biggest issue is trying to convince people of the importance of studying crop plants.

“Unlike the medical field where you can easily justify your research by developing cures for diseases, in this field, we study rice, which is not as attractive to funding agencies, and the problems associated with climate change are long-term, not immediate enough,” explained Lau. “It is also difficult to get people involved in this field for the same reason. But even with a limited amount of money, we are trying to focus on more crop research.”

Apart from public awareness about the significance of plant research, international collaboration between the agencies concerned can also generate more support for the field.

“Scientists can also play a role by communicating the importance of plant research to the general public so that governments, funding agencies, as well as individuals will better understand and support this type of research.”

Through collaboration between high-level researchers and crop producing countries, breakthroughs in breeding and genetic engineering techniques will lead to crop plants able to tolerate and thrive in our changing world.

Dr On Sun Lau obtained both his B.Sc. and M.Phil. in Molecular Biotechnology from the Chinese University of Hong Kong in 2001 and 2004 respectively. He completed his Ph.D. in Molecular, Cellular, and Developmental Biology at Yale University in 2010 under Professor Xing Wang Deng. The same year he was awarded the John S. Nicholas Prize for his doctoral work. He carried out his postdoctoral research in the lab of Professor Dominique Bergmann at Stanford University. He’s currently an Assistant Professor in the Department of Biological Sciences at the National University of Singapore. Lau received a Croucher Scholarship in 2003 and a Croucher Fellowship in 2010.

To view Lau’s personal Croucher profile, please click here.