Question: Research Preamble: It Is Largely Unknown How The Glyceollin Biosynthetic Genes Are Turned On (i.e. Regulated) And Made In Soybean. Since Glyceollins And Related Phytoalexins Appear To Be Of Major Pharmaceutical Value, There Is Interest In Determining How Plants Turn On These Genes. Dr. Kovinich’s Research Group Has Identified Several Candidate Transcription…
It is largely unknown how the glyceollin biosynthetic genes areturned on (i.e. regulated) and made in soybean. Since glyceollinsand related phytoalexins appear to be of major pharmaceuticalvalue, there is interest in determining how plants turn on thesegenes. Dr. Kovinich’s research group has identified severalcandidate transcription factors that may be responsible for this,but whether these transcription factors truly do (and if they do,which specific gene promoters they bind to and activate) iscurrently unknown.
Over the course of the past several weeks, you have gone throughthe process of generating a construct that fuses the GmMYB103 gene(one of the identified candidate transcription factors) to theGAL4-AD for use in a yeast-1-hybrid assay. To conduct the assay,Dr. Kovinich provides you a strain of yeast that possesses thepromoter from the IFS2 gene (one of the genes that encode an enzymein the glyceollin biosynthesis pathway). This promoter has beenengineered into the yeast genome to direct the transcription of agene that gives yeast the ability to grow on histidine-deficientmedia.
Before doing the experiment, Dr. Kovinich asks you in a labmeeting to think about
potential experimental outcomes and what they may mean. Considerthe following scenario:
Imagine that you see growth of cells on histidine-deficient mediain the yeast-1-hybrid assay. Assume you know that this is a falsepositive result. Provide a mechanistic explanation for this falsepositive result that does not rely on experimental error. Yourexplanation can be anything, but you will be heavily penalized ifyour reasoning is not plausible, logically sound, or if you
invoke the presence of other molecules that are not required forthe assay to work. You may
assume the yeast cells you are using are normal. Provide youranswer in four sentences max.