The angiosperms evolution is associated with innovations in floral architecture. The field of plant developmental evolution seeks to understand the generation of this diversity using comparative genetic approaches that build on work done in model species such as Arabidopsis thaliana and Antirrhinum majus. Studies of Arabidopsis thaliana, have been fundamental in advancing the structural and molecular understanding of flower development. Plants have many differences, like protoandry, protogyny, etc. however, all angiosperms have a common mechanism of flowering i.e., they all form sepals, petals, stamen and carpel in normal conditions.

          Different models have explained the mechanism of flowering but the most outstanding and authentic explanation has been provided by the ABC model proposed by Coen and Meyerowitz in 1991. Based on these models various steps have been proposed for flower development process. Independently of the sexual reproduction strategy, in many plants, floral size seems to be controlled by several genetic programs that are to some extent independent of vegetative growth. Also floral symmetry is controlled by different genes. Change in the floral symmetry may lead to drastic change in breeding behavior of different crops. Different steps in floral induction, floral initiation, identification of organ primordial and organ specificity are governed by a series of genes, which if present in recessive form lead to the development of mutant forms.

        Various mutants have been identified based on experiments with Arabidopsis thaliana. These genetic structures may be exploited in crop improvement programmes through several modifications. The floral development mechanism may have various commercial applications like early heading in Oryza sativa (Zuhua He, Qun Zhu, Tsegaye Dabi, Debao Li, Detlef Weigel & Chris Lamb), double flower, palealess spikelet in Oryza sativa (Qiong Luo etal) etc. The coordination of the direction of cell division and expansion by unknown mechanisms poses a challenge for future research.

 

References:

Meyerowitz, Elliot M., Bowman, J.L., Brockman, L.L., Drews, G.N., Jack, T.(1991). A genetic and molecular model for flower development in Arabidopsis thaliana. Development Supplement 1, Great Britain, 157-167.

Parimalan, R., Giridhar, P., Joel, A.J., Jagdeesan, S.(2005). Molecular basis of flower initiation-A review. Indian Journal of Biotechnology 4:455-465.

Hong Ma(1994). The unfolding drama of flower development: recent results from genetic and molecular analysis. Genes and Development, Cold Spring Harbor Laboratory, New York. 8:745-756.

Kramer, Elena M.(2007). Understanding the Genetic Basis of Floral Diversity. Bioscience 56(6): 479-487.

Krizek, B.A. and Fletcher, J.C. Molecular Mechanism of Flower Development: An armchair guide. Nature 2005, (6) 688-698.

Zuhua He etal. Transformation of rice with the Arabidopsis floral regulator LEAFY causes early heading. Transgenic Research, 2000, 9: 223–227.