Disease relevance of AP2

• An ERF/AP2-type transcription factor (CaPF1) was isolated by differential-display reverse transcription-PCR, following inoculation of the soybean pustule pathogen Xanthomonas axonopodis pv glycines 8ra, which induces hypersensitive response in pepper (Capsicum annuum) leaves [1].
• The Arabidopsis CBF gene family is composed of three genes encoding AP2 domain-containing proteins whose expression Is regulated by low temperature but not by abscisic acid or dehydration [2].
• We generated transgenic N. benthamiana lines expressing Arabidopsis wild type AP2 (35S::AP2), miR172-resistant AP2 mutant (35S::AP2m3) and MIR172a-1 (35S::MIR172) under the control of the cauliflower mosaic virus 35S promoter [3].

High impact information on AP2

• On the basis of these observations, it has been proposed that AG and AP2 act in an antagonistic fashion [4].
• In contrast, mutations in another floral homeotic gene, APETALA2 (AP2), result in the replacement of the perianth organs by the reproductive organs [4].
• The Gl15 gene encodes a putative transcription factor with significant sequence similarity to the Arabidopsis regulatory genes APETALA2 and AINTEGUMENTA, which act primarily to regulate floral organ identity and ovule development [5].
• The pattern of PI expression also depends on the activity of the floral development genes APETALA2 and SUPERMAN and on the activity of PI itself [6].
• Genetic analysis shows that termination of the primary shoot meristem in l28 mutants requires an active CLV signaling pathway, indicating that AP2 functions in stem cell maintenance by modifying the WUS-CLV3 feedback loop [7].

Biological context of AP2

• AP2 is known to regulate expression of several floral-specific homeotic genes such as AGAMOUS [8].
• The aim of this study was to clarify the relationship between AP2 and AtEBP in gene expression [8].
• Over-expression of AtEBP caused upregulation of AP2 expression in leaves [8].
• This result suggests that the N-terminal region is not required to produce the ap2-like phenotype [9].
• In addition to the most highly conserved APETALA2/ERF DNA-binding domain, the encoded protein contained an N-terminal MCGGAIL signature sequence, a putative nuclear localization sequence, and a C-terminal acidic transcription activation domain containing a novel mammalian hemopexin domain signature-like sequence [10].

Associations of AP2 with chemical compounds

• AP2 expression was affected by EIN2 but was not regulated by ethylene treatment [8].
• Twenty TF genes were induced by both the pathogen and methyl JA and these included 10 members of the AP2/ERF TF family, primarily from the B1a and B3 subclusters [11].
• We show further that ap2 mutations cause changes in the ratio of hexose to sucrose during seed development, opening the possibility that AP2 may control seed mass through its effects on sugar metabolism [12].
• The maize dehydration-responsive element (DRE)-binding factor, DBF1, is a member of the Apetala 2/Ethylene Response Factor transcription factors family and is involved in the regulation of the ABA-responsive gene rab17 through the DRE in an ABA-dependent pathway [13].
• A subset of Arabidopsis AP2 transcription factors mediates cytokinin responses in concert with a two-component pathway [14].

Physical interactions of AP2

• Like AP2, ANT contains two AP2 domains homologous with the DNA binding domain of ethylene response element binding proteins [15].
• Transcription factors of the DREBP subgroup and the EREBP subgroup contain conserved DNA-binding domains called AP2/EREBP domains, which specifically bind to DRE cis-element and GCC-box, respectively [16].

Regulatory relationships of AP2

• AP2 expression was suppressed by the null-function of ethylene-insensitive2 (EIN2), although AP2 expression was not affected by ethylene treatment [8].
• MUCILAGE-MODIFIED4 encodes a putative pectin biosynthetic enzyme developmentally regulated by APETALA2, TRANSPARENT TESTA GLABRA1, and GLABRA2 in the Arabidopsis seed coat [17].

Other interactions of AP2

• AP2 seems to keep the AG gene inactive in the two outer whorls while the converse is likely in the two inner whorls [18].
• Therefore, HEN1, like the A function gene AP2, plays multiple roles in plant development as well as acting in organ identity specification in the flower [19].
• While the activities of the MADS domain proteins are essentially confined to the flower or to the inflorescence, several genes, such as APETALA2, HUA1 and HUA2, also act outside the flower in addition to their organ identity functions inside the flower [19].
• Based on these results, we suggest that the AP1 and the apetala 2 (AP2) genes may encode similar functions that are required to define the pattern of where floral organs arise, as well as for determinate development of the floral meristem [20].
• In addition to homeotic changes, mutations at the APETALA2, APETALA3 and PISTILLATA loci may lead to reduced numbers of organs, or even their absence, in specific whorls [18].

Analytical, diagnostic and therapeutic context of AP2

• An annotation update via cDNA sequence analysis and comprehensive profiling of developmental, hormonal or environmental responsiveness of the Arabidopsis AP2/EREBP transcription factor gene family [21].
• Gel mobility shift assay using mutant DREB proteins showed that the two amino acids, valine and glutamic acid conserved in the ERF/AP2 domains, especially valine, have important roles in DNA-binding specificity [22].
• This protocol coupling with single-cell reverse transcriptase-polymerase chain reaction (SC-RT-PCR) has been used to monitor LFY and AP2 expression in individual cells from the shoot apical meristem, leaf, root, and stem of Arabidopsis, simultaneously [23].
• We have isolated three Apetala2 (Ap2)-like genes from petunia and studied their expression patterns by in situ hybridization [24].

References