Scientists Explain the Bonsai Effect

Plants exposed to unfavorable conditions, such as cold, drought, salinity and herbivory, are usually smaller than those growing in stress-free conditions. The basis of stress growth-inhibition is not well understood, even though it reduces plant growth and crop yield by approximately 22 percent worldwide. Wound-induced stunting is exemplified in ornamental bonsai plants, with their height, girth, and leaf sizes uniformly reduced to as little as 5 percent of their untreated sister trees.

Scientists at the University of East Anglia in the United Kingdom found that when leaves of the model plant Arabidopsis are repeatedly wounded, cell division in the plant’s apical meristems is reduced and the growth of the plant is arrested within days. They also found a seven-fold increase in the concentration of the phytohormone jasmonate (JA) in wounded plants.

Growth of mutant Arabidopsis plants unable to synthesize JA or unable to respond to the hormone, is not affected by wounding stress. The scientists noted that the primary function of wound-induced JA is to stunt growth through the suppression of cell division. The finding opens the possibility of improving crop growth through the manipulation of the jasmonate signal pathway.

The open access paper published PLoS ONE is available at http://dx.doi.org/10.1371/journal.pone.0003699