A xylan glucuronosyltransferase gene exhibits pleiotropic effects on cellular composition and leaf development in rice

Dawei Gao,Wenqiang Sun,Dianwen Wang,Hualin Dong,Sibin Yu,Ran Zhang

doi:10.1038/s41598-020-60593-3

Abstract

Leaf chlorophyll content is an important physiological indicator of plant growth, metabolism and nutritional status, and it is highly correlated with leaf nitrogen content and photosynthesis. In this study, we report the cloning and identification of a xylan glucuronosyltransferase gene (OsGUX1) that affects relative chlorophyll content in rice leaf. Using a set of chromosomal segment substitution lines derived from a cross of wild rice accession ACC10 and indica variety Zhenshan 97 (ZS97), we identified numerous quantitative trait loci for relative chlorophyll content. One major locus of them for relative chlorophyll content was mapped to a 10.3-kb region that contains OsGUX1. The allele OsGUX1AC from ACC10 significantly decreases nitrogen content and chlorophyll content of leaf compared with OsGUX1ZS from ZS97. The overexpression of OsGUX1 reduced chlorophyll content, and the suppression of this gene increased chlorophyll content of rice leaf. OsGUX1 is located in Golgi apparatus, and highly expressed in seedling leaf and the tissues in which primary cell wall synthesis occurring. Our experimental data indicate that OsGUX1 is responsible for addition of glucuronic acid residues onto xylan and participates in accumulation of cellulose and hemicellulose in the cell wall deposition, thus thickening the primary cell wall of mesophyll cells, which might lead to reduced chlorophyll content in rice leaf. These findings provide insights into the association of cell wall components with leaf nitrogen content in rice.

Highlights

Leaf chlorophyll content is an important physiological indicator of plant growth, metabolism and nutritional status, and it is highly correlated with leaf nitrogen content and photosynthesis
As a first step toward dissecting the genetic bases of such complex www.nature.com/scientificreports trait, we used a Soil-Plant Analysis Development (SPAD) chlorophyll meter to explore the key factors related to relative chlorophyll content in flag leaves in the developed chromosomal segment substitution lines (CSSL) population from the cross of ACC10 and Zhenshan 97 (ZS97) (Fig. S1)
QNC1.1 in our study was found in the same region related to chlorophyll content reported in other studies36,37. qNC7.1 was close to the quantitative trait loci (QTL) detected in the reports38,39. qNC10.1 was mapped to the same location reported previously[36,40]

Summary

Introduction

Leaf chlorophyll content is an important physiological indicator of plant growth, metabolism and nutritional status, and it is highly correlated with leaf nitrogen content and photosynthesis. Our experimental data indicate that OsGUX1 is responsible for addition of glucuronic acid residues onto xylan and participates in accumulation of cellulose and hemicellulose in the cell wall deposition, thickening the primary cell wall of mesophyll cells, which might lead to reduced chlorophyll content in rice leaf. These findings provide insights into the association of cell wall components with leaf nitrogen content in rice. Another thorough study revealed that the absence of GlcA xylan in cell wall had no impact on plant growth in the gux1/2/3 triple mutant[20] Further investigation of this discrepancy is required. Transgenic experiments revealed that OsGUX1 affects primary cell wall components corresponding to the QTL for relative chlorophyll content

Methods

Results

Conclusion