MADS domain factors AGL15 and AGL18 act redundantly as repressors of the floral transition in Arabidopsis

• Published in: The Plant journal : for cell and molecular biology Vol. 50; no. 6; pp. 1007 - 1019
• Main Authors: Adamczyk, Benjamin J, Lehti-Shiu, Melissa D, Fernandez, Donna E
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.06.2007; Blackwell Publishing Ltd; Blackwell Science
• Subjects: AGAMOUS-like 15; AGAMOUS-like 18; Arabidopsis; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Biological and medical sciences; Biology and morphogenesis of the reproductive apparatus. Photoperiodism, vernalisation; Botany; FLOWERING LOCUS T; flowering time; Flowers & plants; Flowers - growth & development; Fundamental and applied biological sciences. Psychology; Gene Expression; Gene Expression Regulation, Plant; MADS box; MADS Domain Proteins - genetics; MADS Domain Proteins - metabolism; Mutation; Photoperiod; Plant physiology and development; Signal Transduction - physiology; Time Factors; Vegetative and sexual reproduction, floral biology, fructification; Flower; Arabidopsis; Photoperiod; Gene; MADS box; Cruciferae; flowering time; Dicotyledones; Angiospermae; AGAMOUS-like 18; Flowering; Spermatophyta; Transgenic plant; Mutation; FLOWERING LOCUS T; AGAMOUS-like 15
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/j.1365-313x.2007.03105.x

The developmental roles of AGL15 and AGL18, members of the AGL15-like clade of MADS domain regulatory factors, have not been defined previously. Analysis of transgenic Arabidopsis plants showed that overexpression of AGL18 produces the same phenotypic changes as overexpression of AGL15, and the two genes have partially overlapping expression patterns. Functional redundancy was confirmed through analysis of loss-of-function mutants. agl15 agl18 double mutants, but not single mutants, flower early under non-inductive conditions, indicating that AGL15 and AGL18 act in a redundant fashion as repressors of the floral transition. Further genetic analyses and expression studies were used to examine the relationship between AGL15 and AGL18 activity and other regulators of the floral transition. AGL15 and AGL18 act upstream of the floral integrator FT, and a combination of agl15 and agl18 mutations partially suppresses defects in the photoperiod pathway. agl15 agl18 mutations show an additive relationship with mutations in genes encoding other MADS domain floral repressors, and further acceleration of flowering is seen in triple and quadruple mutants under both inductive and non-inductive conditions. Thus, flowering time is determined by the additive effect of multiple MADS domain floral repressors, with important contributions from AGL15 and AGL18.