Transcriptome Analysis Reveals a Potential Role of Benzoxazinoid in Regulating Stem Elongation in the Wheat Mutant qd.

Daxing Xu,Huijun Guo,Luxiang Liu,Weiwei Zeng,Linshu Zhao,Hongchun Xiong,Yuping Ding,Jiayu Gu,Shirong Zhao,Yongdun Xie

doi:10.3389/fgene.2021.623861

Daxing Xu, Huijun Guo + Show 8 more

Open Access

https://doi.org/10.3389/fgene.2021.623861

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Abstract

The stems of cereal crops provide both mechanical support for lodging resistance and a nutrient supply for reproductive organs. Elongation, which is considered a critical phase for yield determination in winter wheat (Triticum aestivum L.), begins from the first node detectable to anthesis. Previously, we characterized a heavy ion beam triggered wheat mutant qd, which exhibited an altered stem elongation pattern without affecting mature plant height. In this study, we further analyzed mutant stem developmental characteristics by using transcriptome data. More than 40.87 Mb of clean reads including at least 36.61 Mb of unique mapped reads were obtained for each biological sample in this project. We utilized our transcriptome data to identify 124,971 genes. Among these genes, 4,340 differentially expressed genes (DEG) were identified between the qd and wild-type (WT) plants. Compared to their WT counterparts, qd plants expressed 2,462 DEGs with downregulated expression levels and 1878 DEGs with upregulated expression levels. Using DEXSeq, we identified 2,391 counting bins corresponding to 1,148 genes, and 289 of them were also found in the DEG analysis, demonstrating differences between qd and WT. The 5,199 differentially expressed genes between qd and WT were employed for GO and KEGG analyses. Biological processes, including protein-DNA complex subunit organization, protein-DNA complex assembly, nucleosome organization, nucleosome assembly, and chromatin assembly, were significantly enriched by GO analysis. However, only benzoxazinoid biosynthesis pathway-associated genes were enriched by KEGG analysis. Genes encoding the benzoxazinoid biosynthesis enzymes Bx1, Bx3, Bx4, Bx5, and Bx8_9 were confirmed to be differentially expressed between qd and WT. Our results suggest that benzoxazinoids could play critical roles in regulating the stem elongation phenotype of qd.

Highlights

Sessile plants produce a wide variety of chemical compounds to regulate their growth, stress resistance, and environmental response
Benzoxazinoids represent a predominant family produced by numerous Poaceae family species including maize, rye, and wheat (Frey et al, 2009; Sue et al, 2011), and those compounds can account for 1% or more of the dry weight of crop seedlings (Zhou et al, 2018)
Through transcriptome analysis methods, we demonstrated that benzoxazinoids may play roles in regulating the stem elongation progress

Summary

Introduction

Sessile plants produce a wide variety of chemical compounds to regulate their growth, stress resistance, and environmental response. Benzoxazinoids represent a predominant family produced by numerous Poaceae family species including maize, rye, and wheat (Frey et al, 2009; Sue et al, 2011), and those compounds can account for 1% or more of the dry weight of crop seedlings (Zhou et al, 2018). The biochemical process of benzoxazinoid synthesis in plants is catalyzed by enzymes encoded by the Bx genes Bx1-Bx9, while all the identified genes in this process have been mapped in maize, rye, and wheat (Makowska et al, 2015). Among the Bx genes, Bx1 is considered to be responsible for the first committed step of benzoxazinoid biosynthesis in chloroplasts (Tzin et al, 2017). The expression of the Bx1-Bx5 genes was considered to be co-regulated in hexaploid wheat (Nomura et al, 2005)

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