The ectopic expression of Arabidopsis glucosyltransferase UGT74D1 affects leaf positioning through modulating indole-3-acetic acid homeostasis

Shanghui Jin,Guizhi Zhang,Bingkai Hou

doi:10.1038/s41598-021-81016-x

Shanghui Jin, Guizhi Zhang + Show 1 more

Open Access

https://doi.org/10.1038/s41598-021-81016-x

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Abstract

Leaf angle is an important agronomic trait affecting photosynthesis efficiency and crop yield. Although the mechanisms involved in the leaf angle control are intensively studied in monocots, factors contribute to the leaf angle in dicots are largely unknown. In this article, we explored the physiological roles of an Arabidopsis glucosyltransferase, UGT74D1, which have been proved to be indole-3-acetic acid (IAA) glucosyltransferase in vitro. We found that UGT74D1 possessed the enzymatic activity toward IAA glucosylation in vivo and its expression was induced by auxins. The ectopically expressed UGT74D1 obviously reduced the leaf angle with an altered IAA level, auxin distribution and cell size in leaf tissues. The expression of several key genes involved in the leaf shaping and leaf positioning, including PHYTOCHROME KINASE SUBSTRATE (PKS) genes and TEOSINTE BRANCHED1, CYCLOIDEA, and PCF (TCP) genes, were dramatically changed by ectopic expression of UGT74D1. In addition, clear transcription changes of YUCCA genes and other auxin related genes can be observed in overexpression lines. Taken together, our data indicate that glucosyltransferase UGT74D1 could affect leaf positioning through modulating auxin homeostasis and regulating transcription of PKS and TCP genes, suggesting a potential new role of UGT74D1 in regulation of leaf angle in dicot Arabidopsis.

Highlights

Auxin, primarily indole-3-acetic acid (IAA), is an endogenous plant hormone that plays a crucial role in plant growth and development
The Arabidopsis PHYTOCHROME KINASE SUBSTRATE (PKS) family and TEOSINTE BRANCHED1/CYCLOIDEA/PCF (TCP) family were demonstrated to be required for the regulation of leaf development and leaf p ositioning[26,27,28]
The results of qRT-PCR analysis indicated that both IAA and indole-3-butyric acid (IBA) could induce the expression of UGT74D1 within different treatment duration from 1 to 24 h (Fig. 1), suggesting that UGT74D1 might function in the auxin homeostasis

Summary

Introduction

Primarily indole-3-acetic acid (IAA), is an endogenous plant hormone that plays a crucial role in plant growth and development. It was indicated that UGT84B1 has high in vitro catalytic specificity to both IAA and IBA, and by contrast, UGT74E2 prefers IBA to IAA13–15 Transgenic plants overexpressing these genes in Arabidopsis showed obvious growth deficiency phenotypes. Overexpression of UGT84B1 resulted in the curly leaves in contrast to wild t ype[14] Another Arabidopsis gene UGT84A2 was an indole-3-butyric acid glucosyltransferase and involved in delayed flowering[16], suggesting that the auxin glucosylation might play a significant role in the regulation of plant reproductive development. It was found that the increased UGT74D1 activity substantially altered auxin distribution in leaf primordial and resulted in accumulation of free IAA in leaves, which dramatically stimulated cell elongation and led to BR independent change of leaf positioning, possibly by a feedback transcription regulation of PKS and TCP factors. Our work provides evidences for the link between auxin glucosylation, auxin homeostasis and leaf positioning in dicots, highlighting a distinct role of UGT74D1 from other auxin glycosyltransferases identified so far

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