You decided to investigate the role of c function genes during flower developmen

Question

You decided to investigate the role of c function genes during flower development in the flowers of Mimulus, which is a relative of Antirrhinum. The Mimulusgenome has been sequenced and you have identified at least two c function genes that appear closely related to AGAMOUS.

a) How would you find out where and when these genes are expressed?

b) How would you determine which of these genes is most closely related to
AGAMOUS?

c) Describe an experiment to determine which of these genes has retained the primary homeotic function.

Explanation / Answer

a) The most straightforward way to do this is to carry out an in situ hybridisation using probes from your candidate c-function genes from Mimuluson floral meristems from Mimulusinflorescences. There are alternative strategies that would tell you where and when these genes are expressed and they would also be acceptable answers.

b) You could compare the sequences of the candidate genes from Mimulusand Arabidopsisand identify the sequence most similar to to AGAMOUS. But much better evidence could be provided by comparing the genomes of each species you are comparing. In this way you could use the conservation of gene order (synteny) to confirm which is the closest relative to AGAMOUS

c) The most conclusive way to test whether or not each of the candidate genes has retained the primary homeotic function of the c-function genes is by misexpressing these genes in Arabidopsis. You would need to make
35S constructs to misexpress each gene in all four whorls of the Arabidopsis flower. The 35S promoter is a constitutive promoter. When genes that have retained the homeotic function are misexpressed they will convert whorl 1 organs in carpels and whorl 2 organs in stamens. It might be that the extent to which whorl 1 and 2 organs are converted into alternative structures. but conversion into carpeloid or stamenoid tissues indicates that some of the homeotic function has been retained

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