CUHK Passions and Pursuits

13 c c A new model of vacuole biogenesis c c The whole cell tomography of vacuole biogenesis (Cui Y et al., (2018)) Jiang explained with a metaphor: ‘We are given a more powerful zoom lens now. What used to appear as a house in the hazy distance can now be seen in sharper focus. We can see the details inside the house such as the furniture, the persons and their relative positions to each other and at different times. We understand better what’s happening inside the house.’ The team also came upon the discovery that the SVs are formed from the fusion of multivesicular bodies (MVBs) measuring 100–400 nm in diameter. Because of their similarity in appearance (both have a number of vesicles or pockets enclosed by a membrane wall), SVs and MVBs can easily be mistaken for each other. But Professor Jiang concludes from their sizes, membrane composition, and distribution at different developmental stages that the latter indeed fuse and mature into the former. Based on their findings from whole- cell tomography and experimenting with different gene mutants, the team has proposed a new model of vacuole biogenesis: vacuoles are mainly derived from the fusion and maturation of MVBs with each phase of the process regulated by a specific molecular regulator. Professor Jiang said, ‘This work has redefined the concept of vacuole nature and vacuole formation in plants in textbooks which will certainly have a significant impact on applied plant biology.’ He further pointed out its implications for further research on how to improve crop quality to overcome an adverse environment or pathogen infection as well as how to use and manipulate seed protein storage vacuoles in plant bioreactors for manufacturing pharmaceutical proteins.