AUTHOR=Crane Renee A. , Cardénas Valdez Marielle , Castaneda Nelly , Jackson Charidan L. , Riley Ciairra J. , Mostafa Islam , Kong Wenwen , Chhajed Shweta , Chen Sixue , Brusslan Judy A. 

TITLE=Negative Regulation of Age-Related Developmental Leaf Senescence by the IAOx Pathway, PEN1, and PEN3

JOURNAL=Frontiers in Plant Science

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2019.01202

DOI=10.3389/fpls.2019.01202

ISSN=1664-462X

ABSTRACT=<p>Early age-related developmental senescence was observed in Arabidopsis <italic>cyp79B2/cyp79B3</italic> double mutants that cannot produce indole-3-acetaldoxime (IAOx), the precursor to indole glucosinolates (IGs), camalexin and auxin. The early senescence phenotype was not observed when senescence was induced by darkness. The <italic>cyp79B2/cyp79B3</italic> mutants had lower auxin levels, but did not display auxin-deficient phenotypes. Camalexin biosynthesis mutants senesced normally; however, IG transport and exosome-related <italic>pen1/pen3</italic> double mutants displayed early senescence. The early senescence in <italic>pen1/pen3</italic> mutants depended on salicylic acid and was not observed in <italic>pen1</italic> or <italic>pen3</italic> single mutants. Quantitation of IGs showed reduced levels <italic>in cyp79B2/cyp79B3</italic> mutants, but unchanged levels in <italic>pen1/pen3</italic>, even though both of these double mutants display early senescence. We discuss how these genetic data provide evidence that IAOx metabolites are playing a protective role in leaf senescence that is dependent on proper trafficking by PEN1 and PEN3, perhaps <italic>via</italic> the formation of exosomes.</p>