Dan Egel, Extension Vegetable Pathologist, SWPAC, Purdue University
A gardener who observed either of the plants in Figures 1 or 2 seen here might wonder if he or she had happened upon a monster of sorts in the garden. In fact, Figures 1 and 2 depict chimeras, a term that comes from a Greek word that describes a monster formed with body parts from different animals. Plant chimeras are part normal and part malformed leaf.
A plant chimera is formed when a mutation occurs in the growing point of a plant. In the case of the two plants shown here, the mutation appears to affect chlorophyll formation. Chlorophyll is the green pigment that helps capture energy from sunlight so that water and carbon dioxide in the air can be combined to form carbohydrates. All mutations are rare and leaves such has shown here are not common. Since the mutation occurred in the growing point of the plant, only a few leaves of the plant are affected. The mutation will not be passed on to the seeds of the plant since the mutation did not occur in the germ cells of the plant.
What will happen to plants with such mutations? The leaves or vines with the mutation will likely not produce much growth. However, the mutation can’t be spread to other plants. The condition isn’t a disease and can’t be treated in any way. So, it is probably best to relax and enjoy the unusual patterns that the chimera has created in your garden.
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Figure 1: Watermelon leaf with a chimera or mutation that causes a pattern of deficiency of the green pigment chlorophyll.
Figure 2: Tomato leaf with a chimera or mutation that causes a pattern of deficiency of the green pigment chlorophyll.