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In monoecious plants having unisexual flowers (eg Zea Mays, Ricinus Communis etc), there must be some mechanism as to produce two sexually distinct flowers from the same genotype. Since both the type of flowers are placed on the same plant, the genetic constitution of the cells of both the type of flowers will be similar. What is the mechanism by which the development of two sexually distinct flowers is carried out in such plants?

Is the mechanism similar to the mechanism for differential gene expression in case of embryonic development (Homeobox genes)? And moreover, is the genetic constitution of the pollen produced by the male flower similar to that of the egg produced by the female flower, with respect to the composition of autosomes and allosomes (if any)?

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This article might be helpful. It also provides a lot of other references. –  biogirl Mar 18 at 14:19
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There is a whole book on sex determination in plants - Sex Determination in Plants by CC Ainsworth. You can get it on google books. See chapter 12 for maize flower sex determination. It's pretty interesting. –  biogirl Mar 18 at 14:25
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why not try to make an answer out of it @biogirl? –  shigeta Mar 18 at 16:28

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up vote 3 down vote accepted

I will be able to answer only a part of the question.

Sex determination in Zea Mays

Initially, all the flowers in the plant are perfect, ie they have both the male and the female flowers. This is followed by abortion of stamen or pistil resulting in unisexual flowers.

Which part of the flower undergoes abortion is determined according to the location of the flower. The florets in the tassel undergo the suppression of the pistil primordia resulting in staminate flowers, while the florets in the ear undergo suppression of stamen primordia resulting in female flowers.

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The hormone Gibberelic Acid seems to play a role in sex determination.

Source and other useful links :

  1. Sex determination in Plants by CC Ainsworth.

  2. Sex chromsomes in flowering plants

  3. Sex determination in monoecious and dioecious plants

  4. The sex determination process in maize

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This review provides genetics of maize sex determination in (a surprisingly!) simple language. –  biogirl Mar 18 at 17:47
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Thank you for the answer. Just for the sake of aesthetic appeal, can you put all the links quoted in the comments at one place? –  Satwik Pasani Mar 19 at 3:28
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@SatwikPasani I haven't answered the second part of your question but I found some related information in Campbell - Interestingly, maize has a homolog of Hox genes calles KNOTTED-1, but unlike its counterpart in the animal world,KNOTTED1 does not affect the proper number or placement of plant organs. ....an unrelated class of transcription factors called MADS-box proteins play that role in plants. –  biogirl Mar 19 at 14:23
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@SatwikPasani I know that MADS-box plays the role of organ identity genes during flower development but I don't know whether they have a role in the process of sex determination. –  biogirl Mar 19 at 14:25

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