Beschreibung:
<jats:title>Abstract</jats:title><jats:p><jats:styled-content style="fixed-case"><jats:italic>pPLA‐I</jats:italic></jats:styled-content> is the evolutionarily oldest patatin‐related phospholipase <jats:styled-content style="fixed-case">A</jats:styled-content> (<jats:styled-content style="fixed-case">pPLA</jats:styled-content>) in plants, which have previously been implicated to function in auxin and defence signalling. Molecular and physiological analysis of two allelic null mutants for <jats:italic>pPLA‐I</jats:italic> [<jats:styled-content style="fixed-case"><jats:italic>ppla‐I‐1</jats:italic></jats:styled-content> in <jats:styled-content style="fixed-case">W</jats:styled-content>assilewskija (<jats:styled-content style="fixed-case">W</jats:styled-content>s) and <jats:styled-content style="fixed-case"><jats:italic>ppla‐I‐3</jats:italic></jats:styled-content> in <jats:styled-content style="fixed-case">C</jats:styled-content>olumbia (<jats:styled-content style="fixed-case">C</jats:styled-content>ol) ] revealed <jats:styled-content style="fixed-case"><jats:italic>pPLA‐I</jats:italic></jats:styled-content> functions in auxin and light signalling. The enzyme is localized in the cytosol and to membranes. After auxin application expression of early auxin‐induced genes is significantly slower compared with wild type and both alleles show a slower gravitropic response of hypocotyls, indicating compromised auxin signalling. Additionally, phytochrome‐modulated responses like abrogation of gravitropism, enhancement of phototropism and growth in far red‐enriched light are decreased in both alleles. While early flowering, root coils and delayed phototropism are only observed in the Ws mutant devoid of <jats:styled-content style="fixed-case">phyD</jats:styled-content>, the light‐related phenotypes observed in both alleles point to an involvement of <jats:styled-content style="fixed-case">pPLA‐I</jats:styled-content> in phytochrome signalling.</jats:p>