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OBITUARIES
Hans
Jànos Kende
Hans Jànos
Kende, a university distinguished professor emeritus in the Department
of Energy Plant Research Laboratory (PRL) and the Department of Plant
Biology at Michigan State University, East Lansing, died September 26,
2006, at the age of 69. Hans was widely known for his work on the biosynthesis
and mode of action of plant hormones. In addition to being an excellent
plant scientist, Hans had a strong sense of community and was a vigorous
promoter of plant biology at Michigan State as well as at national and
international levels. He was recognized worldwide as an elder statesman
in plant science.
Jànos was born
in Székesfehérvár, Hungary, in 1937. A happy, comfortable
life was interrupted in 1941, when his father was sent to forced labor
camp as part of the Hungarian army, where he died in February 1943. In
1944, after Germany invaded Hungary, Jànos and his mother were
evicted from their home and sent to a ghetto, then to the local brick
factory to await deportation. When the train of boxcars arrived, 30 people,
including Jànos, his mother, and a few relatives, were called forward
from the group of nearly 3,000 people. This fortunate group of 30 was
taken to Budapest instead of Auschwitz, where the other people were immediately
exterminated. In Budapest, Jànos and his mother became part of
a group that was to be sent to a neutral country as a “good will”
gesture by the Germans to support the rescue negotiations of Rezso Kasztner
and Joel Brandt with Adolf Eichmann. The group, however, was first taken
to Bergen-Belsen, where Jànos and his mother were kept for over
six months until their rescue from almost certain death (due to starvation
and disease). They were finally transported to Switzerland at the end
of December 1944, where Jànos was given the name “Hans.”
His ordeal was not over, for after a few days, the children were separated
from their mothers and sent to children’s homes. This painful separation
lasted almost three years for Hans, until his mother remarried and he
could join her in Zurich. Although he had taught himself to read and write
in Hungary, he had little formal education. One source of delight for
Hans was learning the Odyssey by heart from a scholar at the children’s
home. In Zurich, Hans was enrolled in fourth grade and quickly made up
for the slow start in his formal education, becoming the first student
of that elementary school to pass the entrance exam to the Gymnasium.
When he was 16, Hans
met Gabriele Guggenheim, who was to become his lifelong partner. They
married in 1960 and, over 40 years later, Hans related that not a day
had gone by that he wasn’t happy since they had gotten together.
Hans chose his field
of study with care, as he did so many things in his life. When Hans and
Gaby decided to live on an Israeli kibbutz after their marriage, Hans
contacted the kibbutz and asked what skills were needed. The answer: agriculture
and dietetics. Hans put aside his interest in becoming a brain surgeon
(a decision he never regretted) and delved into plant science, while Gaby
studied dietetics. In fact, they never made it to that kibbutz, which,
fortuitously for the field of plant science, had changed the direction
of this gifted scientist.
Hans earned his PhD
in 1960 from the University of Zürich. His research focused on the
biosynthesis of trigonellin in the coffee plant. His first postdoctoral
work was with A. S. Holt at the National Research Council in Ottawa, Canada,
where he studied chlorophylls in green photosynthetic bacteria. It was
not until he moved to Caltech in 1961 as a postdoctoral research associate
with Anton Lang that he started to work in the area of plant growth and
development, the area in which he would make many major contributions.
Hans made his first
major discovery while working at Caltech with gibberellins. In the 1950s,
a group of chemicals known as growth retardants had been described; these
chemicals caused dwarfing in plants, but their mechanism of action was
unknown at that time. Hans tested the hypothesis that these chemicals
inhibited gibberellin biosynthesis. Gibberellins in green plants were
still poorly understood, so Hans chose to study the fungus Fusarium
moniliforme, which produces copious amounts of gibberellin. His results
demonstrated that growth retardants block gibberellin biosynthesis in
the fungus, and later work showed that this is also the mode of action
of the growth retardants AMO-1618 and CCC in green plants. This example
illustrates Hans’s approach to research throughout his career: He
always asked specific, important questions and then selected the most
suitable biological system in which to look for an answer.
During his two years
(1963–1965) at the Negev Institute for Arid Zone Research, Hans focused
on the role of cytokinin in senescence. He and collaborators showed that
cytokinin is produced in the roots and transported to leaves, where it
prevents leaf senescence. Thus, cytokinin could be assigned the role of
Chibnall’s hypothetical root factor. After joining the PRL in 1965,
Hans continued his studies on the role of cytokinin in delaying senescence.
During a sabbatical leave in Switzerland, he initiated work on the rapid
senescence of morning glory flowers. This work resulted in a series of
publications on the role of ethylene in the fading of flowers. It was
established that ethylene regulates senescence by positive feedback, as
evident from the observation that brief exposure to exogenous ethylene
strongly induces endogenous ethylene production. Ethylene is derived from
methionine, and shortly after the discovery, by Shang Fa Yang’s lab,
that the immediate precursor of ethylene is 1-aminocyclopropane-1-carboxylic
acid (ACC), the Kende lab quickly developed a chemical assay for ACC.
This assay became widely used around the world.
Hans’s group
was the first to purify ACC synthase from tomato fruit tissue and to generate
monoclonal antibodies specific for ACC synthase. Wound-induced ACC synthase
proved to be synthesized de novo and to be the rate-controlling enzyme
for ethylene synthesis. When molecular biology techniques came on the
scene, Hans’s lab quickly adopted them to isolate a cDNA clone encoding
ACC synthase. They then used this clone to demonstrate that ACC synthase
is encoded by a small gene family whose members are differentially expressed
during wounding. Hans and his colleagues continually adapted their approaches
as new techniques became available; his work on ethylene shows a remarkable
transition from physiological to biochemical to molecular approaches.
As a postdoc, Hans
had found that dark-grown dwarf peas were much more responsive to applied
gibberellin than light-grown seedlings. This kindled Hans’s lifelong
interest in plant hormone receptors. During his early years at the PRL,
he synthesized cytokinin and gibberellin of high specific activities,
but failed to detect specific binding by classical biochemical methods.
Much later, Hans saw the possibility that hormone receptors might be found
in Arabidopsis by isolation of hormone-insensitive mutants. In collaboration
with Chris Somerville’s lab, a screen for ethylene response mutants
was designed. The picture of the ethylene-insensitive etr mutant seedling
towering above a canopy of dwarfed seedlings, whose growth is suppressed
by ethylene, is a classic one that has been widely reproduced. This work
led in turn to isolation of the ETR gene (in Elliot Meyerowitz’s
lab). Subsequent work demonstrated that the ETR gene encodes an
ethylene receptor, the first plant hormone receptor to be identified.
Hans’s lab initiated
pioneering work with the semi-aquatic plant deepwater rice, in which ethylene
has a growth-promoting effect—quite the reverse of its effect in
terrestrial plants, where it inhibits growth. Hans’s group unraveled
the chain of events that leads from submergence to accelerated growth.
Three hormones—ethylene, abscisic acid, and gibberellin—participate
in response to changes in the internal gas composition. Low oxygen tension
promotes ethylene synthesis, which reduces the level of abscisic acid
and stimulates synthesis of gibberellin, the immediate growth-promoting
hormone. Elongation of internodes is based on increased cell division
in the intercalary meristem and subsequent elongation of these newly formed
cells. Cell expansion is made possible by relaxation of the cell wall,
and this cell-wall loosening is at least partially mediated by expansins.
Further evidence in support of the role of expansins in growth and development
was obtained with transgenic plants over-expressing EXPANSIN genes. Such
transgenic plants grew taller, whereas antisense plants were shorter than
control plants. Another important finding in the work with deepwater rice
was made by Hans’s graduate student Ilya Raskin, who showed in elegant
experiments that aeration of partially submerged leaves takes place by
mass flow through air layers along the leaves. Until this seminal work,
aeration had been thought to occur through internal air spaces.
Hans received numerous
honors for his outstanding contributions to science, including election
to the German Academy of Natural Sciences, Leopoldina (1985), Fellow of
the American Association for the Advancement of Science (1990), and the
U.S. National Academy of Sciences (1992). He was awarded a university
distinguished professorship at Michigan State University (1990) and the
Stephen Hales Prize from the American Society of Plant Physiologists (1998).
Hans was a dedicated
advocate for plant biology. For example, when in 1998 the Nobel Prize
for Physiology or Medicine was awarded for “nitric oxide as a signalling
molecule in the cardiovascular system,” representing a new principle—signaling
by a gaseous molecule—Hans was quick to point out in a letter to
Science that plant biologists had discovered ethylene as a gaseous
signaling molecule much earlier.
Hans served the plant
sciences, and science in general, in many different ways: as a member
of grant review panels and journal editorial boards and on many committees
for the National Academy of Sciences and the National Research Council.
He served ASPB in many different capacities. He was an effective member
of the Board of Trustees during the critical period when the Society was
in transition from a semi-volunteer to a professional organization. He
also chaired the Membership Committee of the Society, and his work led
to a significant increase in membership. He further promoted the plant
sciences during the early 1990s when funding was dismal: He took the initiative
in organizing groups of plant biologists to meet in Washington, DC, with
congressional delegations to request increased funding for agencies that
supported plant biology.
Hans is survived by
his wife Gaby, sons Benny (Pamela) and Michael (Caroline), daughter Judi
(Rael Mazansky), and seven grandchildren. Hans was a kind and giving person
with high professional standards and a keen sense of humor. Few of his
colleagues would be unable to recall an occasion that was made memorable
by Hans’s sparkling wit. He was always generous in giving credit
to his associates. His altruism in helping and promoting others, especially
younger colleagues, is legendary.
More than anything,
Hans enjoyed spending time with his family. He and Gaby often traveled
to Switzerland, their “other home,” for hiking or skiing in
the Alps and for visiting friends and family. A passionate fan of classical
music, he often scheduled his vacations to take greatest advantage of
Europe’s summer music festivals. Hans put much effort into taking
care of his health, taking care of his family, and planning for a full
and active retirement. It is unfortunate that he wasn’t given more
time to enjoy it. He is greatly missed by his family, friends, and colleagues,
but his legacy lives on through his published work and through the careers
of the associates and students he mentored.
Karen Bird
Jan Zeevaart
Michigan State University
The account of
Hans’s early life was provided by Gaby Kende.
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