PMID- 31862648 OWN - NLM STAT- MEDLINE DCOM- 20200702 LR - 20200930 IS - 1618-1328 (Electronic) IS - 0176-1617 (Linking) VI - 245 DP - 2020 Feb TI - Biosynthesis pathway of indole-3-acetyl-myo-inositol during development of maize (Zea mays L.) seeds. PG - 153082 LID - S0176-1617(19)30211-1 [pii] LID - 10.1016/j.jplph.2019.153082 [doi] AB - Indole-3-acetic acid (IAA) conjugation is one of the mechanisms responsible for auxin homeostasis. IAA ester conjugates biosynthesis has been studied during development of maize seeds where IAA-inositol (IAInos) and its glycosidic forms make up about 50 % of its ester conjugates pool. 1-O-indole-3-acetyl-beta-d-glucose (IAGlc) synthase and indole-3-acetyl transferase (IAInos synthase) are key enzymes in a two-step pathway of IAInos synthesis. In the first reaction, IAA is glucosylated to a high energy acetal, 1-O-indole-3-acetyl-beta-d-glucose by IAGlc synthase, whereas in the second step, IAInos synthase transfers IAA moiety to myo-inositol forming a stable auxin ester, indole-3-acetyl-myo-inositol (IAInos). It should be mentioned that IAGlc synthase catalyzes a reversible reaction with unfavourable equilibrium that delivers IAGlc for favourable transacylation to IAInos. This is the first study where IAGlc synthase and IAInos synthase are simultaneously analyzed by enzymatic activity assay and quantitative RT-PCR in maize seeds at four stages of development (13, 26, 39 and 52 Days After Flowering). Activity of IAGlc/IAInos synthases as well as their expression profiles during seed development were different. While both enzymatic activities and ZmIAIn expression were the highest in seeds at 26 DAF, the highest expression of ZmIAGlc was observed at 13 DAF. Protein gel blot analysis showed that IAInos synthase exists as a mixture of several isoforms at a similar protein level at particular stages of seed development. Neither of other ester conjugates of IAA (IAA-mannose) nor IAA-amino acids were detected at the stages studied. Catalytic activity of l-tryptophan aminotransferase involved in IAA biosynthesis as well as UDPG pyrophosphorylase, synthesizing UDPG as a substrate for IAGlc synthase, were also analyzed. l-tryptophan aminotransferase activity was the highest at 26 DAF. Changes in enzyme activity of UDPG pyrophosphorylase are difficult to interpret. Expression levels of ZmIPS and ZmIPP encoding two enzymes of myo-inositol biosynthesis pathway: inositol-x-phosphate synthase (IPS) and inositol-x-phosphate phosphatase (IPP), respectively, were analyzed. 26 DAF seeds displayed the highest expression level of ZmIPS, whereas transcription of ZmIPP was the highest at 13 DAF. CI - Copyright (c) 2019 Elsevier GmbH. All rights reserved. FAU - Ostrowski, Maciej AU - Ostrowski M AD - Nicolaus Copernicus University in Torun, Department of Biochemistry, Lwowska 1 St, 87-100 Torun, Poland. Electronic address: maciejost@umk.pl. FAU - Ciarkowska, Anna AU - Ciarkowska A AD - Nicolaus Copernicus University in Torun, Department of Biochemistry, Lwowska 1 St, 87-100 Torun, Poland. FAU - Dalka, Agata AU - Dalka A AD - Nicolaus Copernicus University in Torun, Department of Biochemistry, Lwowska 1 St, 87-100 Torun, Poland. FAU - Wilmowicz, Emilia AU - Wilmowicz E AD - Nicolaus Copernicus University in Torun, Department of Plant Physiology and Biotechnology, Lwowska 1 St, 87-100 Torun, Poland. FAU - Jakubowska, Anna AU - Jakubowska A AD - Nicolaus Copernicus University in Torun, Department of Biochemistry, Lwowska 1 St, 87-100 Torun, Poland. LA - eng PT - Journal Article DEP - 20191216 PL - Germany TA - J Plant Physiol JT - Journal of plant physiology JID - 9882059 RN - 0 (Indoleacetic Acids) RN - 0 (Indoles) RN - 0 (Plant Growth Regulators) RN - 0 (Protein Isoforms) RN - 23784-11-4 (indol-3-ylacetylinositol) RN - 4L6452S749 (Inositol) RN - 6U1S09C61L (indoleacetic acid) RN - EC 2.4.1.- (Glucosyltransferases) RN - EC 2.4.1.121 (indole-3-acetate beta-glucosyltransferase) RN - EC 2.6.1.27 (Tryptophan Transaminase) RN - EC 2.7.7.9 (UTP-Glucose-1-Phosphate Uridylyltransferase) RN - EC 3.1.3.56 (Inositol Polyphosphate 5-Phosphatases) RN - EC 5.5.- (Intramolecular Lyases) RN - EC 5.5.1.- (D-myo-inositol-3-phosphate synthase) RN - V50K1D7P4Y (Uridine Diphosphate Glucose) SB - IM MH - Biosynthetic Pathways/genetics/physiology MH - Catalysis MH - Glucosyltransferases/genetics/*metabolism MH - Homeostasis/genetics/physiology MH - Indoleacetic Acids/*metabolism MH - Indoles/metabolism MH - Inositol/metabolism MH - Inositol Polyphosphate 5-Phosphatases/metabolism MH - Intramolecular Lyases/metabolism MH - Plant Growth Regulators/metabolism MH - Protein Isoforms/chemistry/genetics/metabolism MH - Seeds/*enzymology/*growth & development MH - Tryptophan Transaminase/metabolism MH - UTP-Glucose-1-Phosphate Uridylyltransferase/metabolism MH - Uridine Diphosphate Glucose/metabolism MH - Zea mays/*enzymology/*growth & development/metabolism OTO - NOTNLM OT - Auxin conjugate OT - Uridine diphosphate glucose OT - Zea mays OT - indole-3-acetyl-glucose OT - indole-3-acetyl-myo-inositol COIS- Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. EDAT- 2019/12/22 06:00 MHDA- 2020/07/03 06:00 CRDT- 2019/12/22 06:00 PHST- 2019/06/11 00:00 [received] PHST- 2019/10/03 00:00 [revised] PHST- 2019/10/06 00:00 [accepted] PHST- 2019/12/22 06:00 [pubmed] PHST- 2020/07/03 06:00 [medline] PHST- 2019/12/22 06:00 [entrez] AID - S0176-1617(19)30211-1 [pii] AID - 10.1016/j.jplph.2019.153082 [doi] PST - ppublish SO - J Plant Physiol. 2020 Feb;245:153082. doi: 10.1016/j.jplph.2019.153082. Epub 2019 Dec 16.