New light on protein and hormone signalling in plant growth

14 May 2019

A team of researchers at the Chinese University of Hong Kong (CUHK) and South China Normal University has discovered an important and novel function of a plant vesicular transport regulatory protein in processes that affect plant growth.

The team, led by Professor Liwen Jiang (Croucher Senior Research Fellowship 2015 and 2009) of CUHK and Dr Caiji Gao of South China Normal University, has revealed the relationship between the protein FREE1 and plant abscisic acid (ABA), with FREE1 found to affect the modulation of ABA signalling in the nucleus.

ABA is one of the most important plant hormones involved in plant developmental processes. Unlike animals, plants cannot move around to different locations to find food and water, or choose the optimal environment for living. However, they have the ability to suppress their growth to increase their chances of survival. For example, seed germination will only happen with the presence of water, while the size of the stomatal opening is regulated to prevent dehydration. These essential functions are controlled by ABA.

Jiang’s team has focused on exploring the molecular mechanisms of protein transport and organelle biogenesis for 20 years. In recent studies, the researchers discovered the unique plant vesicular transport regulator, known as FREE1, and illustrated its functions in regulating membrane protein transport and autophagic degradation – the orderly disassembly and recycling of cellular components.

In the new study, the collaborative team further demonstrated that ABA regulated the phosphorylation and nuclear shuttling of FREE1, which inhibited the transcriptional activation of downstream transcription factors of the ABA signalling pathway in the nucleus.

The research showed that plant vesicle transport regulators are involved in the regulation of gene expression in the nucleus, and vesicular transport regulators, such as FREE1 proteins, can participate in ABA signalling, not only in the cytoplasm by regulating the transport of ABA receptors to vacuolar degradation, but also in the nucleus to directly regulate ABA signalling at the transcriptional level. These results indicate that the vesicle trafficking pathway and plant environmental response signals have crosstalk at both gene expression and protein transport levels.

The latest discovery, published in Nature Plant, provides a theoretical basis for improving crop tolerance to environmental stresses through genetic engineering.

Professor Liwen Jiang is Choh-Ming Li Professor of Life Sciences and Director of the Centre for Cell and Developmental Biology at the Chinese University of Hong Kong. He is an editorial board member of several internationally renowned journals. He received Croucher Senior Research Fellowships in 2009 and 2015.

To view Professor Jiang’s Croucher profile, please click here.