Over the past two years, we have been stuck in a cycle of the COVID-19 pandemic. While the world focuses on building human immunity against the virus, Associate Professor Miao Yansong from the School of Biological Sciences (SBS) at Nanyang Technological University dedicated his efforts to research on the mechanisms underlying plant immunity during bacterial invasion.
With a better understanding on plants’ immune responses, we could then find ways to improve on their protection against diseases, contributing to the agri-food industry through greater food security and sustainability.
In the two back-to-back publications that the Miao Lab recently published on The Plant Cell [1, 2], Associate Professor Miao described two novel mechanisms underlying plant immunity during bacterial infection. It was found that plant actin cytoskeleton undergoes rapid remodeling when there is an infection. However, how the plant host activates a reorganisation of actin cytoskeleton timely remains unclear.
What is the research about?
To detect and defend themselves against microbial attacks, plants must recognise a wide range of biomolecules that pathogenic microbes produce, such as bacterial surface molecules, quorum sensing signals, and microbe-secreted membrane vesicles. With this, the immune systems of plants could then be activated and trigger serial changes in cellular activities to coordinate defense mechanisms, such as rearrangement of actin cytoskeleton and activate immune regulators.
“In this research, we seek to understand how biomolecule condensation on the plasma membrane regulates plant immune signaling during host-pathogen interactions,” shared Associate Professor Miao. Biomolecule condensation, namely phase separation, is a process that drives multivalent interactions on demand, and thereby leads to macromolecular assembly for functional outputs during cell signaling.
What are the results gathered from the study?
In a study conducted earlier by his lab [3, 4], it was found that the actin nucleator formin proteins respond to immune signaling and undergo phase separation (macromolecular condensation) that activates formin activities in actin polymerisation.
Recent studies by the same group at the Miao Lab have:
- Identified the nanodomain remorin proteins that drive formin condensation into nanometer-scaled clusters on the plant cell surface.
- Deciphered the molecular mechanism of how a heteromeric interaction and consecutive phase separation of formin sense the bacteria-triggered plant innate immunity and then re-organise plant actin cytoskeleton in a spatiotemporal dependent manner.
- Reconstituted such molecular condensation-mediated formin activation on the artificial-lipid-bilayer in vitro to mimic in vivo immune-signaling activated actin remodeling.
The second report by the Miao lab on The Plant Cell has revealed a similar mechanism that has demonstrated the importance of phase separation of plant surface biomolecules during plant-bacteria communication events. It reported that the plants engage the bacterial outer membrane vesicles on the plasma membrane through phase-separated nanodomain, which increase membrane lipid order and thereafter enhance immune responses against bacterial invasion.
These two reports on The Plant Cell were also highlighted by the editorial board (https://academic.oup.com/plcell/article/34/1/6/6425688).
What do the findings imply and how does it affect future research?
The Miao Lab’s research revealed novel fundamental principles regarding the activation of plant immune signaling pathways through surface macromolecular condensation. These principles would shed light on a holistic view of immune signaling and guide their ongoing efforts on synthetic engineering of immune signaling circuits for plant protection and sustainable agriculture.
Related Webinar:
https://plantae.org/plantae-webinar-highlighting-plant-cell-focus-issue-on-cell-biology-jan-13/