Use of Transcriptomic Analyses to Elucidate the Mechanism Governing Nodal Root Development in Eremochloa ophiuroides (Munro) Hack.

Rui Wang,Haoran Wang,Haoyan Zhao,Jianjian Li,Junqin Zong,Jianxiu Liu,Jingjing Wang,Hailin Guo

doi:10.3389/fpls.2021.659830

Abstract

Centipedegrass [Eremochloa ophiuroides (Munro) Hack.] is a perennial warm-season grass that originated in China, and its speed of nodal rooting is important for lawn establishment. In our study, centipedegrass nodal rooting ability was limited by node aging. Transcriptome sequencing of nodal roots after 0, 2, 4, and 8 days of water culture was performed to investigate the molecular mechanisms of root development. GO enrichment and KEGG pathway analyses of DEGs indicated that plant hormone signal transduction and transcription factors might play important roles in centipedegrass nodal root growth. Among them, E3 ubiquitin-protein ligases participated in multiple hormone signal transduction pathways and interacted with transcription factors. Furthermore, an E3 ubiquitin protein ligase EoSINAT5 overexpressed in rice resulted in longer roots and more numerous root tips, while knockout of LOC_Os07g46560 (the homologous gene of EoSINAT5 in rice) resulted in shorter roots and fewer root tips. These results indicated that EoSINAT5 and its homologous gene are able to promote nodal root development. This research presents the transcriptomic analyses of centipedegrass nodal roots, and may contribute to elucidating the mechanism governing the development of nodal roots and facilitates the use of molecular breeding in improving rooting ability.

Highlights

Adventitious roots develop post-embryonically from non-root tissues in the majority of monocotyledon fibrous root systems (Atkinson et al, 2014)
These results indicated that the young nodes of centipedegrass rooted more while the old nodes rooted with greater difficulty
The rest of the differentially expressed genes (DEGs) belonged to the basic leucine zipper transcription factor (TF) family, GATA TF family, heat stress TF family, homeodomain TF family, lysine-specific demethylase (LSD) TF family, sigma factor TF, and zinc finger proteins (Supplementary Table 1 and Figure 4C). These results showed that auxin signal transduction, E3 ubiquitin-protein ligases, the APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) TF family, and the WRKY TF family may have significant roles in regulating centipedegrass nodal root development

Summary

Introduction

Adventitious roots develop post-embryonically from non-root tissues in the majority of monocotyledon fibrous root systems (Atkinson et al, 2014). Centipedegrass Nodal Root Development (L.) Pers., Zoysia japonica Steud, Eremochloa ophiuroides (Munro) Hack., and Paspalum vaginatum Sw.] have specialized stolons and adventitious roots produced by stem nodes, which are known as nodal adventitious roots; as a result, these plants can propagate rapidly. The research works of nodal roots are mostly focused on maize, sorghum, and other food crops with erect stems. The growth angle of nodal roots strongly influences the spatial distribution of soil profile to impact drought adaptation (Joshi et al, 2017). For nodal roots of stolon, the research works were mostly focused on white clover indicating that nodal roots influence branch development (Thomas et al, 2003). The molecular mechanism of stolon nodal roots largely remains unknown

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Conclusion