Molecular basis of flower initiation—A review

Plants have many differences, like protandry, protogyny, etc. However, amidst these differences, all angiosperms have a common mechanism of flowering, i.e. concentric pattern of flowering (sepal, petal, stamen and carpel). The mechanism or the genes thorough which plants maintain boundaries between the four, sepal-petal-stamen-carpel, are also given due importance. Once a plant attains competence, flowers may be produced through the reorganization of SAM directly to floral meristem, or through the inflorescence or co-inflorescence meristem, in response of exogenous and endogenous signals. Initiation, determination and differentiation are classed into four stages and this is the region which is studied here in detail. Some organ specificity genes, like MALE STERILITY (MS) and BICAUDAL (BIC), move us towards a better understanding of the mechanism like male sterility and self-incompatibility in plants. Models like ABC, biophysical, MCDK, etc., help in explaining the mechanism of flowering on a molecular basis. However, in general, the path towards flowering is laid when the floral repressor genes are down regulated. Recently identified miRNAs in plants authenticate them and also give out the mechanism by which they down regulate. It has also been found out that MADS-box gene family and CArG-box genes (where those MADS domain protein binds) are highly conserved. Their role in flower development is also touched upon.