AGL24 acts as a promoter of flowering in Arabidopsis and is positively regulated by vernalization

MADS-domain-containing transcription factors comprise a large family of regulators that have diverse roles in plant development, including the regulation of flowering time. AGAMOUS-LIKE 20/SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) and FRUITFUL act to promote flowering, whereas FLOWERING LOCUS C (FLC) , FLOWERING LOCUS M/MADS AFFECTING FLOWERING1 , and SHORT VEGETATIVE PHASE are inhibitors of flowering. Here we report that AGAMOUS-LIKE 24 (AGL24) also plays a role in the regulation of flowering time. agl24 mutants are late flowering and overexpression of AGL24 causes early flowering in wild-type and late-flowering-mutant backgrounds. The effect of AGL24 overexpression is most pronounced in autonomous-pathway-mutant and FRIGIDA -containing backgrounds. The behavior of AGL24 is most similar to that of SOC1 . Like SOC1 , AGL24 mRNA levels are upregulated by vernalization. Unlike SOC1 , however, AGL24 mRNA levels are not affected by FLC , and therefore AGL24 may represent an FLC -independent target of the vernalization pathway. There is also evidence for cross-talk between AGL24 and SOC1 . When overexpressed, SOC1 and AGL24 are able to upregulate each other's expression. Thus, AGL24 represents another component in a network of MADS-domain-containing transcription factors that regulate flowering time.