The genetics behind miniature plants

How do organisms maintain their size and shape despite varying environmental conditions? Unlike animals, plants are sessile and cannot maintain their internal body temperatures during ambient temperature changes. Thus, plants have evolved complex genetic pathways to maintain normal growth patterns during temperature changes.

Scientists from the Whitehead Institute have discovered a new mechanism of plant growth homeostasis. Dr. Gerald Fink and colleagues at have discovered that the gene, BONZAI1, or BON1 for short, is a central player in a novel growth homeostasis pathway in the fully-sequenced genome of the model plant Arabidopsis.

Arabidopsis plants grow normally anywhere between 16 and 33 degrees Celcius. However, as the name suggests, plants deficient in BONZAI1 are perfectly miniature at 22 degrees, but grow to a normal size at 28 degrees. Using electron microscopy, Dr. Fink determined that BON1 mutant cells fail to achieve a normal size at cooler temperatures.

Dr. Fink and colleagues also identified a BON1 interacting protein, BAP1. BON1 and BAP1 localize to the plasma membrane, and are both more highly expressed at lower temperatures. Dr. Fink and colleagues have determined that BON1 is a member of the copine gene family, a group of prevalent and highly conserved genes found in plants and animals whose function is largely unknown. This work is of particular interest because it suggests that the copine gene family may function in membrane trafficking and be regulated by the environmental conditions to which they respond.

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