[초청강연] Weaving the plant forms with PINs

Weaving the plant forms with PINs
Hyung-Taeg Cho

School of Biological Sciences, College of Natural Science, Seoul National University, Seoul, Korea.
It would be unexpected that the hormone concept had been initiated in plants. In 1865, the German
plant physiologist Julius von Sachs established the modern hormone concept, though he did not coin
it with the word ‘hormone’ which was suggested later by Earnest Starling in 1906, by defining
hormones as ‘chemical messengers for formation and growth of organs’ and by suggesting ‘their
distribution changes by stimuli’. And Charles Darwin in 1880 predicted the first plant hormone ‘auxin’
as a ‘moving hormone’ by the observations of photo- and gravi-tropisms of stems and roots. As
Darwin predicted, auxin, by moving directionally, forms a concentration gradient throughout the plant
body and plays a morphogen to initiate axis formation of the embryo, organ formation, vascular
development, asymmetric organ growth, etc., which consists of fundamental plant developmental
processes. The directional auxin movement, so-called Polar Auxin Transport (PAT), can be achieved
by PIN-FORMEDs (PINs) auxin efflux transporters which are asymmetrically localized or polarized in
the plasma membrane (PM). The subcellular localization and polarity of PINs are regulated by their
intracellular membrane trafficking. Therefore, the fundamental question regarding PIN-mediated auxin
responses has been how PIN’s polarity in the PM or its intracellular trafficking is modulated. Our
laboratory has long sought these PIN modulators in a task to find PIN-interacting proteins (PIPs). In
this colloquium, I would like to share our long efforts in this PIN study and recent achievements on
PIPs as PIN modulators.