<i>ALP1</i> is required to activate PcG target gene expression.

<p>(A) T1 plants transformed with <i>35S</i>::<i>AG</i> transgene. The <i>alp1-1</i> mutation did not suppress the characteristic phenotype of small, early flowering plants with narrow, curled leaves. (B) Real time RT-PCR analysis of <i>SEP3</i>, <i>FT</i>, <i>FLC</i> and <i>AG</i> expression in seedlings of 12 day old short day grown plants. Relative expression was first normalised relative to the <i>EiF4A</i> reference gene and then calculated relative to the wild type value. Error bars indicate the standard error of the mean of three biological replicates. All four genes are upregulated in <i>clf-50</i> but show reduced expression in <i>clf-50 alp1-4</i> double mutants. One way ANOVA tests indicate that the differences are significant (p<0.05) between <i>clf-50</i> and <i>clf-50 alp1-4</i> for <i>SEP3</i>, <i>FT</i> and <i>FLC</i> but not <i>AG</i>. (C) Venn diagram comparing the number of genes mis-regulated relative to wild type (Ws) in 12 day old seedlings. Misregulated genes showed Log₂(FoldChange)>2 and False Discovery Rate <0.05. (D) Bar charts comparing the number of genes downregulated (blue) and up-regulated (red) relative to wild-type. Numbers above the bars indicate the proportion of up-regulated genes. (E) Pie chart showing that the bulk of genes mis-expressed in <i>clf-50</i> relative to wild-type are no longer mis-expressed (restored) in <i>clf-50 alp1-4</i> relative to wild-type. (F-G) Inflorescences (F) and flowers (G) illustrating the enhancement of the weak <i>lfy-5</i> phenotype by <i>alp1-3</i>. In <i>lfy-5</i> flowers, fewer petals and stamens are produced than in wild-type whereas <i>lfy-5 alp1-3</i> flowers from similar position on the inflorescence had much more severe phenotype with petals and stamens usually lacking and replaced with sepals and carpels, respectively (G). (H) Real time RT-PCR analysis of <i>AP3</i> and <i>PI</i> expression in inflorescences shows reduced expression of both genes in <i>lfy-5</i> compared to wild type and a more severe reduction in <i>lfy-5 alp1-3</i> consistent with the enhanced phenotype. Expression is normalised relative to the reference gene <i>EIF4A</i>. Error bars indicate standard error of mean of three biological replicates. Scale bars are 5mm in A and F, 500μm in G.