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Production and roles of IAA and ABA during development of superior and inferior rice grains
Journal article   Peer reviewed

Production and roles of IAA and ABA during development of superior and inferior rice grains

Heather M. Nonhebel and Karina Griffin
Functional plant biology: FPB, Vol.47(8), pp.716-726
07/2020
DOI: https://doi.org/10.1071/FP19291
PMID: 32438973

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Abstract

cereal grain fill dorsal aleurone endosperm MRP-1 Oryza sativa OsNF-YC RISBZ1
Current understanding of the role of plant hormones during cereal grain filling is confounded by contradictory reports on hormone production that is based on poor methodology. We report here on the accurate measurement of indole-3-acetic acid (IAA) and abscisic acid (ABA) by combined liquid chromatography-tandem mass spectrometry in multiple reaction-monitoring mode with heavy isotope labelled internal standards. ABA and IAA contents of superior versus inferior rice grains (ABA maxima 159 ng g(-1)FW and 109 ng g(-1)FW, IAA maxima 2 mu g g(-1)FW and 1.7 mu g g(-1)FW respectively) correlated with the expression of biosynthetic genes and with grain fill. Results confirm that grain ABA is produced primarily by OsNCED2(5), but suggest that ABA import and metabolism also play important roles in ABA regulation. The IAA content of grains is primarily influenced byOsYUC9andOsYUC11. However, the distinct expression profile ofOsYUC12suggests a specific role for IAA produced by this enzyme. Co-expression ofOsYUC12withOsIAA29indicates their involvement in a common signalling pathway. Co-expression andcis-element analysis identified several aleurone-specific transcriptional regulators as well as glutelin as strong candidates for detailed investigation for direct regulation by the auxin-signalling pathway.

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