Auxin Input Pathway Disruptions Are Mitigated by Changes in Auxin Biosynthetic Gene Expression in Arabidopsis

    June 2014 in “ PLANT PHYSIOLOGY ”
    Gretchen M. Spiess, Amanda Hausman, Peng Yu, Jerry D. Cohen, Rebekah A. Rampey, Bethany K. Zolman
    TLDR Arabidopsis plants adjust gene expression to maintain balance when auxin pathways are disrupted.
    The study investigated how Arabidopsis thaliana maintained auxin homeostasis despite disruptions in auxin input pathways, specifically focusing on indole-3-acetic acid (IAA) and its conjugates. Researchers created mutants with impaired IBA metabolism and IAA-conjugate hydrolase, resulting in phenotypes indicative of low auxin levels, such as delayed germination and abnormal root development. Despite reduced IAA levels, the plant compensated by up-regulating auxin biosynthetic genes, particularly in the YUCCA/Tryptophan Aminotransferase of Arabidopsis1 pathway, suggesting a feedback mechanism to maintain cellular homeostasis. The study highlighted the importance of storage forms of IAA and identified specific genes like YUC2 and YUC4 that were up-regulated in response to low auxin levels, underscoring the complexity of auxin regulation and the redundancy and specialization of input pathways.
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