Effect of the ABRUPTUS/PINOID gene on expression of the LEAFY gene in Arabidopsis thaliana

The nucleotide sequence was analyzed for the temperature-sensitive allele abruptus (abr), which distorts polar auxin transport (PAT) in the inflorescence. The mutation C → T was found in the second exon and led to an amino acid substitution (glycin → glutamic acid) in the conserved domain of protein kinase encoded by the ABRUPTUS/PINOID (ABR/PID) gene. QRT-PCR revealed a 100-fold decrease in transcription of the LEAFY (LFY) gene in the abr mutant with high expressivity of the mutant character; transcription of the fused LFY::GUS gene was also low in the mutant. The results agree with data of the phenotypic analysis of the abr lfy double mutant and testify to an important role of auxin gradients in regulating the expression pattern of the LFY gene.