94 P.A. Sabelli · B.A. Larkins
cell cycle genes, coupled to the identification of mutants affecting endoredupli-
cation patterns and the ability to perturb gene expression in transgenic plants,
has resulted in substantial progress being made in recent years. Although sev-
eral fundamental mechanisms controlling the endoreduplication cell cycle are
evolutionarily conserved, the identities of the specific factors and pathways in-
volved vary considerably, particularly in relation to the biological context in
which they operate. This, of course, is an indication of the remarkable plastic-
ity of cell cycle regulation in plants, which suits well the necessity of sessile
organisms to respond to rapidly changing environmental conditions. Many
studies have been based on increasing or decreasing expression of certain cell
cycle regulators constitutively, but it is becoming increasingly apparent that in
thefutureinvestigatorswillhavetodesignmorepreciseapproachestocon-
trol gene expression in specific cell types and in a timely manner. Fortunately,
the necessary molecular tools to do this are already available or are being de-
veloped, and there is little doubt that exciting advancements will be made in
unraveling the endoreduplication cell cycle in the near future.
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