Plant Biotechnology and Genetics: Principles, Techniques and Applications

posttranslational regulation is becoming increasingly valuable as we engineer some plants
to be protein production factories, accumulating high levels of desirable, functional proteins
for numerous applications ranging from industrial to medical.

LIFE BOX 6.1. MAARTEN CHRISPEELS

Maarten Chrispeels, Professor of Biology and Director, Center for

Molecular Agriculture, University of California San Diego; Member,

National Academy of Science

Maarten Chrispeelsgiving a public

lecture on molecular agriculture (2002).

I was born in a small Flemish town not

far from Brussels, Belgium, and after

an uneventful youth and a solid classical

education with three foreign languages

and six years of Latin, I enrolled in the

College of Agriculture in Ghent. I

wanted to become a biochemist. In the

fall of 1960, after graduation at the age

of 22, I found myself on the

Mauretania, sailing for America with a

Fulbright travel fellowship and a fellow-

ship from the University of Illinois to

start graduate studies in the Department

of Agronomy. My Ph.D. research and

postdoctoral work (with Joe Varner)

were in plant cell biology. A couple of

papers inPlant Physiologylanded me

a job as assistant professor of biology

at the then newly founded University

of California San Diego (UCSD).

Upon arriving there I switched from

studyinga-amylase secretion by barley

aleurone cells to the biosynthesis and

secretion of hydroxyproline-rich glyco-

proteins, which had just been discovered

but were little studied. We discovered

that these proteins move from the ER

to the Golgi apparatus where glycosyla-

tion of hydroxyproline residues takes

place. After a sabbatical leave in

England I switched to study the syn-

thesis and intracellular transport of pro-

teases to the protein storage vacuoles

(PSVs) in cotyledons during germina-

tion. We made use of antibodies—

quite a novelty at the time—to demon-

strate by immuno-electrton microscopy

that the protease that digests storage pro-

teins is in the ER before it arrives in the

PSVs. It then occurred to me that if I

wanted to study protein transport to

PSVs I should be looking at developing

seeds and not at germinating seeds,

because seed development is character-

ized by massive protein synthesis and

transport to vacuoles. So, I switched

again and started working on the syn-

thesis, posttranslational modification

and transport of storage glycoproteins

and lectins in developing bean seeds.

About that time others invented gene

cloning and plant transformation and

soon we had bean storage protein and

lectin genes and were expressing them

in tobacco seeds to identify vacuolar tar-

geting domains.

LIFE BOX 6.1. MAARTEN CHRISPEELS 153