Auxins are hormones that regulate growth and development in plants. Besides plants, various microorganisms also produce auxins. Here we investigate whether and how the phytopathogenic fungus Leptosphaeria maculans biosynthesizes auxins. We characterized the auxin profile of in vitro grown L. maculans. The culture was further supplied with the auxin biosynthetic-precursors tryptophan and tryptamine and gene expression and phytohormone content was analyzed. L. maculans in vitro produced IAA (indole-3-acetic acid) as the predominant auxin metabolite. IAA production could be further stimulated by supplying precursors. Expression of indole-3-pyruvate decarboxylase LmIPDC2, tryptophan aminotransferase LmTAM1 and nitrilase LmNIT1 genes was mainly upregulated after adding tryptophan and correlated with IAA production, suggesting that these genes are the key components of auxin biosynthesis in L. maculans. Tryptamine acted as a potent inducer of IAA production, though a pathway independent of LmIPDC2/LmTAM1 may be involved. Despite L. maculans being a rich source of bioactive IAA, the auxin metabolic profile of host plant Brassica napus was not altered upon infection. Exogenous IAA inhibited the growth of L. maculans in vitro when supplied in high concentration. Altogether, we showed that L. maculans is capable of IAA production and we have identified biosynthetic genes that were responsive to tryptophan treatment.
- MeSH
- aminohydrolasy genetika MeSH
- biosyntetické dráhy MeSH
- Brassica napus mikrobiologie MeSH
- fylogeneze MeSH
- genetická transkripce MeSH
- houby klasifikace genetika metabolismus MeSH
- karboxylyasy genetika metabolismus MeSH
- kyseliny indoloctové metabolismus farmakologie MeSH
- Leptosphaeria enzymologie genetika růst a vývoj metabolismus MeSH
- regulace genové exprese u hub MeSH
- regulátory růstu rostlin metabolismus MeSH
- tryptaminy metabolismus farmakologie MeSH
- tryptofan metabolismus farmakologie MeSH
- tryptofantransaminasa genetika metabolismus MeSH
- upregulace MeSH
- Publikační typ
- časopisecké články MeSH
The mode of action of auxin is based on its non-uniform distribution within tissues and organs. Despite the wide use of several auxin analogues in research and agriculture, little is known about the specificity of different auxin-related transport and signalling processes towards these compounds. Using seedlings of Arabidopsis thaliana and suspension-cultured cells of Nicotiana tabacum (BY-2), the physiological activity of several auxin analogues was investigated, together with their capacity to induce auxin-dependent gene expression, to inhibit endocytosis and to be transported across the plasma membrane. This study shows that the specificity criteria for different auxin-related processes vary widely. Notably, the special behaviour of some synthetic auxin analogues suggests that they might be useful tools in investigations of the molecular mechanism of auxin action. Thus, due to their differential stimulatory effects on DR5 expression, indole-3-propionic (IPA) and 2,4,5-trichlorophenoxy acetic (2,4,5-T) acids can serve in studies of TRANSPORT INHIBITOR RESPONSE 1/AUXIN SIGNALLING F-BOX (TIR1/AFB)-mediated auxin signalling, and 5-fluoroindole-3-acetic acid (5-F-IAA) can help to discriminate between transcriptional and non-transcriptional pathways of auxin signalling. The results demonstrate that the major determinants for the auxin-like physiological potential of a particular compound are very complex and involve its chemical and metabolic stability, its ability to distribute in tissues in a polar manner and its activity towards auxin signalling machinery.
- MeSH
- aktivní transport účinky léků MeSH
- Arabidopsis účinky léků genetika metabolismus MeSH
- buněčná membrána účinky léků metabolismus MeSH
- buněčné dělení účinky léků MeSH
- endocytóza účinky léků genetika MeSH
- kořeny rostlin účinky léků růst a vývoj MeSH
- kyseliny indoloctové farmakologie MeSH
- mutace genetika MeSH
- promotorové oblasti (genetika) genetika MeSH
- proteiny huseníčku genetika metabolismus MeSH
- regulace genové exprese u rostlin účinky léků MeSH
- rostlinné buňky účinky léků metabolismus MeSH
- semenáček účinky léků růst a vývoj MeSH
- suspenze MeSH
- tabák cytologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
