Expert: Dana Krempels, Ph.D. - 9/20/2007

Question
Dr. Krempels:
 I took bio for non-science majors in college and became facinated by genetics.  We learned about incomplete dominance, sex linked traits, etc.  I bought a hibiscus plant and was excited to see it was a mutant--the end of the stamens would grow minature petals (I couldn't find that it was sort of variation on the I.net).  I was all ready to draw/photo the next exciting iteration of blooms, but they were all normal.  A few months later, the mutants were back.  My guess was a phenotypical response to stress, but then I thought that in people with NF, some cells become tumors and others are normal.  So maybe the plant is really a mutant after all.  
Q:  In a person with NF and also this plant, what determines on the cellular level if the mutation will be expressed, is it all environmental at that point?  
Q:  Is there a way to know if this plant is gentically a mutant, could offspring eventually "breed true" so all the blooms are mutated in this way? Thanks!

Answer
Dear Lauren,

These are very interesting questions, and you have the makings of a biologist!  :)

Plant mutations that show up physically and are passed on to offspring are a different situation than in animals.  Unlike animals, plants have special cells in areas known as meristems, and these are essentially the plant equivalent of animal stem cells, which can differentiate into any other type of cells.  The meristems are located at the tips of every root and every shoot, and as they grow, they give rise to the new plant parts: roots, stems, leaves, and flowers.

This means that if there is an unusual mutation that occurs in a meristem cell, it may or may not be expressed, depending on what type of tissue or organ it give rise to, and also what environmental conditions may affect the expression of the gene(s) in question.

So your hibiscus may either be a mutant in all its cells, and be expressing the unusual flower morphology only under certain environmental conditions (it's anyone's guess what that might be; it could be temperature, soil pH, light period, etc.  and you'd have to test these things to find out), or it could be that the meristems are undergoing a particular "easy" mutation at a particular site in response to some environmental condition that promotes that particular mutation.

Almost all hibiscus bushes are highly inbred and selected for mutant traits (large flowers with mutant colors of the leaves and flowers), so who knows what odd things come along for the ride?  :)

So in answer to your first question:  Without doing actual experiments on this particular plant to see what triggers the phenotypic expression of the unusual flower parts, it's not possible to know for sure.  It could be any of dozens of things.

The second question's answer is also necessarily vague.  The only way to know if you could develop a true-breeding strain of this plant would be to try and do so.  I have my doubts, since the unusual phenotype appears to show conditional expression (i.e., only when some unknown environmental factor triggers it).  But if you are truly interested in trying to figure this out, you might want to contact your local Department of Agriculture and find out how to get involved with local hibiscus horticulture groups.

I hope you enjoy this interesting plant, and who knows where it might lead you?  :)

Good luck!

Dana