Spatially-controlled expression of a zinc-finger and HMG-related gene of Arabidopsis, FILAMENTOUS FLOWER, in formation of leaf and floral organ primordia

Abstract

Summary: filamentous flower(fil)mutant of Arabidopsis thaliana generates clusters of filamentous structures and of flowers with floral organs of altered number and shape. The FIL gene is involved in the fate determination of the floral meristem, because a homeotic conversion from a flower to an inflorescence was observed in fil ap1double mutants. In double mutants with leafy(lfy), filamentous structures are formed, but very few or no flowers with floral organs are formed, showing that FIL gene is required for the formation and development of the floral meristem. The enhanced phenotype in the fil ap1and the fil lfy double mutants suggests that FIL protein may work coordinately with AP1and LFY proteins. We cloned a gene, FIL, that regulates the maintenance and growth of inflorescence and floral meristems, and of floral organs of Arabidopsis thaliana. FIL encodes a protein that carries a HMG-related domain and is localized in the nucleus. Expression of FIL was detected in the abaxial side of young primordia of leaves and floral organs. The spatially-controlled expression indicates that cells at the abaxial side of the lateral organs may be responsible for the normal development of the organs as well as for maintaining the activity of the meristems.