ER Microsome Preparation and Subsequent IAA Quantification in Maize Coleoptile and Primary Root Tissue.
Auxin is a major growth hormone in plants and the first plant hormone to be discovered and studied (Darwin and Darwin, 1880). The auxin molecule in plants was first identified as indole-3-acetic acid (IAA) by Köglet al.(1934). Active research over nearly a decade has shed light on many of the molecular mechanisms of its action but the complexity and redundancy of the auxin biosynthetic network raises questions about control of this system. We have shown that some enzymes involved in the YUCCA-route of auxin biosynthesis are not cytosolic but localised to the endoplasmic reticulum (ER) in bothArabidopsis thaliana(YUCCA4.2) (Kriechbaumeret al., 2012) as well asZea mays(ZmTAR1 andZmSPI) (Kriechbaumeret al., 2015). This is raising the intriguing possibility of subcellular compartmentation of auxin biosynthesis. To show that maize auxin biosynthesis indeed can take place in microsomal as well as cytosolic cellular fractions from maize seedlings we applied the protocol described here: Microsomes are being isolated from maize coleoptile and primary root tissue, enzyme assays with microsomal and cytosolic fractions using either tryptophan (Trp) or indole- -3pyruvic acid (IPyA) as a substrate are carried out and the auxin IAA is extracted and quantified.
Plant Cell Biology, Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Headington, Oxford, UK.
Verena
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Kriechbaumer