HKU Bulletin December 2014 (Vol. 16 No.1)

freezing stress on rosette leaves which comprise the vegetative tissues of the Arabidopsis plant, but unfortunately research had to cease because we did not have enough funding to continue.” “We were able to re-start the research in 2011 using the endowed professorship funding, plus a small grant from the Committee on Research and Conference Grants. In addition, the arrival of an intern from Germany, Linda Chi (Free University of Berlin), gave the laboratory the extra manpower it needed that autumn to photograph flowers after the freezing stress treatment.” Previous studies had shown Arabidopsis to be one of several plants that can adapt when pre-exposed to low temperatures – that is, cold acclimation. Changes in gene expression, critical components in food webs and food chains on planet Earth. “If, after further research, we are able to extend this technology to food crops, we hope to be able to ensure that flower development progresses to fruit and seed yield, thereby improving food production in areas susceptible to freezing.” Further, if the technology can be used to protect cultivated flowers from freezing, it will also have major implications for the floral industry, which regularly suffers major losses through cold conditions. The laboratory has filed a patent on its research findings and is now seeking funding to go to the next research stage – to carry out similar tests on Brassica (oilseed), a close relative of Arabidopsis thaliana . Professor Chye established her laboratory at HKU in 1993. Its main focus is to understand how stress-induced plant proteins, particularly acyl-CoA-binding proteins, function. The intention is to use these proteins to generate transgenic plants that can better withstand both abiotic and biotic stresses, which between them currently account for 40 per cent of crop losses. Her team will continue to promote sustainability and optimum use of resources to feed the growing global population, an aim which aligns with two of HKU’s emerging Strategic Research Themes – ’Earth as a Habitable Planet’ and ’Food’– as well as with the aspirations of Dr Wilson and Mrs Amelia Wong in the use of plant biotechnology to ensure the supply of food for a sustainable future. Key research by the School of Biological Sciences has found a way to protect flowers of the model plant Arabidopsis thaliana from freezing that could have major implications for protecting them from low temperature injury. Flowers are the forbears to fruit and seed formation, which make up a large percentage of agricultural harvests that feed people and livestock. This technology has potential to improve yield, by cutting the percentage of harvests lost to cold conditions. The research team was led by Professor Chye Mee-len, Wilson and Amelia Wong Professor in Plant Biotechnology, working with two PhD students, Chen Qinfang and Liao Pan. “The original research findings were published by Chen et al ( Plant Physiology ) in 2008,” said Professor Chye. “That initial work analysed tolerance – including ours in 2008 – have utilised Arabidopsis seedlings and rosettes which represent the vegetative stages, but flowers comprising the reproductive stage have seldom been tested. “Liao Pan, who harvested flowers and treated them at subzero temperatures, was aided by Linda who took myriad photos. Liao Pan followed up with lipid profiling and analysis of gene expression on treated and non-treated flowers to better understand the mechanism of freezing tolerance conferred by ACBP6 over-expression in transgenic flowers.” The team discovered that when ACBP6 was over-expressed in the plant, it protects transgenic flowers against freezing; at -7ºC for one hour only 54 per cent of wild-type flowers remained intact after treatment, while 86 per cent of the transgenic flowers survived the stress. As ACBP6 is a lipid-binding protein, it can bind phosphatidylcholine, an important component of membrane lipids, and their interaction conferred freezing tolerance in ACBP6-over-expressing flowers. Professor Chye said: “Finding ways to protect plants from environmental stress is an important research area given that plants form metabolism and remodelling of lipids occur as the plant responds. Therefore identifying genes and transcription factors that enhance freezing tolerance gives a first step towards developing potential applications in agriculture. The research came out of the knowledge that the gene that encodes lipid-binding protein ACBP6 (acyl-CoA-binding protein 6) is cold inducible, which gave rise to the question: Could ACBP6 have a role when a plant is under cold stress? Challenging methodology “This time the research focusses on the flowers of the transgenic Arabidopsis lines generated by Chen Qinfang – requiring more challenging methodology since the flowers are tiny,” said Professor Chye. “Many studies on freezing Strategy to protect flowers from freezing has major implications for improving food production. More power to the flower Arabidopsis thaliana – the model plant used in this study. Finding ways to protect plants from environmental stress is an important research area given that plants form critical components in food webs and food chains on planet Earth. Professor Chye Mee-len Transformed Arabidopsis flower over-expressing acyl-CoA-binding protein 6 (ACBP6) shows intact petals (right) while the control succumbs to freezing stress (left). Professor Chye Mee-len (left) and PhD student Liao Pan (right). 16 | 17 The University of Hong Kong Bulletin | December 2014 Research