LEAFY controls floral meristem identity in Arabidopsis

Abstract

The first step in flower development is the generation of a floral meristem by the inflorescence meristem. We have analyzed how this process is affected by mutant alleles of the Arabidopsis gene LEAFY. We show that LEAFY interacts with another floral control gene, APETALA1, to promote the transition from inflorescence to floral meristem. We have cloned the LEAFY gene, and, consistent with the mutant phenotype, we find that LEAFY RNA is expressed strongly in young flower primordia. LEAFY expression procedes expression of the homeotic genes AGAMOUS and APETALA3, which specify organ identify within the flower. Furthermore, we demonstrate that LEAFY is the Arabidopsis homolog of the FLORICAULA gene, which controls floral meristem identity in the distantly related species Antirrhinum majus.

Repression of AGAMOUS-LIKE 24 is a crucial step in promoting flower development

“…The floral organ defects in lfy-6 mutants were not rescued in the lfy-6 agl24 double mutant, which indicates that LFY and AP1 function through distinct mechanisms in the regulation of floral organ identity. lfy-6 ap1-1 double mutants showed enhanced inflorescence phenotypes as compared with single mutants 4 , and these were rescued in an agl24 background, as in the single mutants (data not shown). These genetic data indicate that AGL24 contributes much of the inflorescence character of lfy and ap1 mutants, supporting the possibility that LFY and AP1 act to repress AGL24 in wild-type plants.…”

“…Floral meristem identity genes LEAFY (LFY) and APETALA1 (AP1) promote establishment and maintenance of floral identity in newly formed floral primordia [1][2][3][4][5][6][7][8][9] . Without their activity, the floral primordia develop with inflorescence characteristics.…”

Antimutagenic specificities of two plant glycosylases, oxoguanine glycosylase and formamidopyrimidine glycosylase, assayed in vivo

“…Plasmids. cDNAs were produced from mRNA templates of FPG variants in a flower mRNA library of Arabidopsis thaliana [7] as described [2]. Sequences of fpg-1 and fpg-2 cDNAs are registered as NCBI ID: AF099970 and AF099971, respectively.…”

Relaxed Selection Among Duplicate Floral Regulatory Genes in Lamiales

“…However, because these hypotheses predict retention of paralogs in an undifferentiated state and we see divergence between functional domains of DEFA/B, it is unlikely that they have contributed significantly to their preservation in Lamiales. Similarly, although dosage effects are seen for transcription factors (Birchler et al 2001), dosage seems an unlikely explanation for LFY/FLO, which can regulate floral induction at very low levels (Coen et al 1990;Weigel et al 1992), because of partial redundancy with another floral regulatory gene (SQUA/ AP1 [Zik and Irish 2003]) and because of divergence within the DNA binding domain.…”

“…These include co-orthologs of the floral meristem identity gene FLO (Coen et al 1990) and floral homeotic MADS box gene DEF (Sommer et al 1990) from the model Lamiales species Antirrhinum majus. Orthologs of FLO and DEF from A. thaliana (LFY and AP3, respectively [Weigel et al 1992;Jack et al 1992]) carry out similar functions in the floral regulatory pathway as in A. majus, where LFY/FLO positively regulates the expression of the downstream gene AP3/DEF (Ingram et al 1997;Weigel and Meyerowitz 1993). Duplication of the A. majus genes FLO and DEF in Lamiales is thought to be the result of a whole-genome duplication (polyploidization) which occurred after the split between the ancestor of A. majus (Veronicaceae) and the lineage leading to many of the other families of Lamiales including Verbenaceae, Paulowniaceae, Phrymaceae, and Orobanchaceae .…”