Arabidopsis has been a model system for studying plant development for decades and its morphology has been extensively described. Now, however, Sarah Assmann and Timothy Gookin describe an aerial organ that forms during inflorescence development. Named ‘cantils’ after their cantilever function, these conditional structures initiate from the stem and terminate at a junction that holds up the pedicel (the flower-bearing stalk) at an angle. Cantils can be observed in many wild-type Arabidopsis strains (e.g. Columbia) when flowering is delayed by short day lengths. Conversely, the popular Landsberg erecta strain, which carries a mutation in the receptor-like kinase encoding ERECTA gene, does not produce cantils. The researchers show that cantils are also lost when ERECTA is knocked out in the Columbia background, indicating that ERECTA positively regulates their formation. They also find that the long-day photoperiod suppression of cantil production is lost in mutants of FLOWERING LOCUS T, which exhibit delayed flowering. Through genetic experiments, the authors determine that cantil production is repressed by heterotrimeric G proteins, and specifically by the GPA1-AGB1-AGG3 Gαβγ complex. Together, these data reveal that cantil development is dependent on delayed flowering and controlled by a distinct genetic program.
