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Seedling developmental defects upon blocking CINNAMATEU+20104U+2010HYDROXYLASE are caused by perturbations in auxin transport

Journal Contribution - Journal Article

U+2022 The phenylpropanoid pathway serves a central role in plant metabolism, providing numerous compounds involved in diverse physiological processes. Most carbon entering the pathway is incorporated into lignin. Although several phenylpropanoid pathway mutants show seedling growth arrest, the role for lignin in seedling growth and development is unexplored.U+2022 We use complementary pharmacological and genetic approaches to block CINNAMATEU+20104U+2010HYDROXYLASE (C4H) functionality in Arabidopsis seedlings and a set of molecular and biochemical techniques to investigate the underlying phenotypes.U+2022 Blocking C4H resulted in reduced lateral rooting and increased adventitious rooting apically in the hypocotyl. These phenotypes coincided with an inhibition in auxin transport. The upstream accumulation in cisU+2010cinnamic acid was found to likely cause polar auxin transport inhibition. Conversely, a downstream depletion in lignin perturbed phloemU+2010mediated auxin transport. Restoring lignin deposition effectively reestablished phloem transport and, accordingly, auxin homeostasis.U+2022 Our results show that the accumulation of bioactive intermediates and depletion in lignin jointly cause the aberrant phenotypes upon blocking C4H, and demonstrate that proper deposition of lignin is essential for the establishment of auxin distribution in seedlings. Our data position the phenylpropanoid pathway and lignin in a new physiological framework, consolidating their importance in plant growth and development.
Journal: New Phytologist
ISSN: 0028-646X
Issue: 6
Volume: 230
Pages: 2275 - 2291
Publication year:2021
Keywords:Plant sciences, Plant sciences