Professor Sun’s research has centred on plant gene structure and function and the genetic improvement of crops. In 1980, he isolated and cloned the phaseolin seed-storage protein gene of common bean, and in 1981 reported in Nature the discovery that plant genes contain introns. His subsequent work included the cloning of the arcelin gene for insect resistance and the genetic engineering of seed proteins to increase their methionine content. His research on transferring a methionine-rich Brazil nut protein gene into soybean also contributed to early scientific work on assessing the allergenic risks associated with genetically modified foods. Since returning to Hong Kong, he has collaborated with researchers in mainland China on improving the yield and nutritional quality of hybrid rice, including an international programme supported by the Bill & Melinda Gates Foundation to develop lysine-rich rice. He has also developed seed-based bioreactor systems for producing functional proteins for medical and industrial applications. Professor Sun has published more than 130 SCI-indexed papers, including articles in Nature, Science, and The Lancet, holds 17 international patents, and has supervised more than 80 postgraduate and postdoctoral researchers. Through sustained research, international collaboration, and academic mentorship, Professor Sun has contributed to the development of plant molecular biology and agricultural biotechnology and to research addressing crop nutritional quality and global food security.