Different Influence of Mutant Alleles of the APETALA1 Gene on the Development of Reproductive Organs in abruptus Mutant Flowers of the of Arabidopsis thaliana (L.) Heynh.

The APETALA1 (AP1) gene of A. thaliana codes type II MADS protein with domains MADS, I, K, and C. The role of K-and C-domains in the functioning of AP1 protein is poorly investigated. The analysis of phenotypic manifestation of mutations disrupting the activity of various domains of the protein product allows one to obtain information on the function of domains and, thereby, on the structural-functional organization of the gene. We investigated the action of mutant alleles of the AP1 gene whose protein products are probably lacking the functionally active domains K (ap1-20), K-and C-domains (ap1-1 and ap1-6), and C-domain (ap1-3) on the flower morphology in abr mutant (the ABRUPTUS/ PINOID gene allele). It was detected that, unlike the ap1-20 allele, the presence of ap1-3, ap1-6, and ap1-1 alleles results in reduction of a number of the generative organs in the flowers of the double mutants abr ap1-3, abr ap1-6, and abr ap1-1. It was suggested that C-domain of the AP1 protein prevents the alteration of determination of the type of reproductive organs when the AP1 gene ectropically expressed in the inner whorls of a flower in the abr mutant.