APETALA2 antagonizes the transcriptional activity of AGAMOUS in regulating floral stem cells in Arabidopsis thaliana

Abstract

Summary APETALA2 (AP2) is best known for its function in the outer two floral whorls where it specifies the identities of sepals and petals by restricting the expression of AGAMOUS (AG) to the inner two whorls in Arabidopsis thaliana. Here, we describe a role of AP2 in promoting the maintenance of floral stem cell fate, not by repressing AG transcription, but by antagonizing AG activity in the center of the flower.We performed a genetic screen with ag-10 plants, which exhibit a weak floral determinacy defect, and isolated a mutant with a strong floral determinacy defect. This mutant was found to harbor another mutation in AG and was named ag-11. We performed a genetic screen in the ag-11 background to isolate mutations that suppress the floral determinacy defect. Two suppressor mutants were found to harbor mutations in AP2.While AG is known to shut down the expression of the stem cell maintenance gene WUSCHEL (WUS) to terminate floral stem cell fate, AP2 promotes the expression of WUS.AP2 does not repress the transcription of AG in the inner two whorls, but instead counteracts AG activity.

microRNAs involved in auxin signalling modulate male sterility under high‐temperature stress in cotton (Gossypium hirsutum)

“…From our degradome sequencing data, the major two types of AP2 (RAP2.7 and AP2) were identified. AP2, a key factor during the differentiation of floral organs, is necessary for anther formation and development (Huang et al ., ). RAP2.7 (also known as TARGET OF EAT1, TOE1) was reported to interact with a subset of JAZ proteins and repress the transcription of FLOWERING LOCUS T , resulting in delayed flowering time in Arabidopsis (Zhai et al ., ).…”

Same Actor in Different Stages: Genes in Shoot Apical Meristem Maintenance and Floral Meristem Determinacy in Arabidopsis

“…Transgenic lines expressing miR172-resistant versions of AP2 and TOE3 were found to exhibit floral organ identity defects and severe FM indeterminacy phenotypes (Zhao et al, 2007;Jung et al, 2014). In addition, AP2 physically interacts with TOE3 in vivo, and it inhibits both KNU and AG expression to promote WUS expression and FM activity (Zhao et al, 2007;Yant et al, 2010;Huang et al, 2017). At the same time, AP2 also directly represses the expression of AUXIN RESPONSE FACTOR3 (ARF3) to regulate WUS expression (see below) (Liu et al, 2014; Figure 2B).…”

Comparative transcriptomic analysis provides an insight into floral organ petaloid in lotus (Nelumbo nucifera)

“…The role of AP3/PI genes is specification in 'petaloid' identity under the sliding borders or fading borders models, which are different from the earlier models [2]. C and A function genes have antagonism regulation with each other [7]. Loss of C class genes functions results in substitution of petals for stamens and sepals for carpels [8]..…”