Characterization of rhizome transcriptome and identification of a rhizomatous ER body in the clonal plant Cardamine leucantha

Kiwako S Araki,Shuji Shigenobu,Atsushi J Nagano,Ryohei Thomas Nakano,Tatsuya Kitazume,Ikuko Hara-Nishimura,Katsushi Yamaguchi,Hiroshi Kudoh

doi:10.1038/s41598-020-69941-9

Abstract

The rhizome is a plant organ that develops from a shoot apical meristem but penetrates into belowground environments. To characterize the gene expression profile of rhizomes, we compared the rhizome transcriptome with those of the leaves, shoots and roots of a rhizomatous Brassicaceae plant, Cardamine leucantha. Overall, rhizome transcriptomes were characterized by the absence of genes that show rhizome-specific expression and expression profiles intermediate between those of shoots and roots. Our results suggest that both endogenous developmental factors and external environmental factors are important for controlling the rhizome transcriptome. Genes that showed relatively high expression in the rhizome compared to shoots and roots included those related to belowground defense, control of reactive oxygen species and cell elongation under dark conditions. A comparison of transcriptomes further allowed us to identify the presence of an ER body, a defense-related belowground organelle, in epidermal cells of the C. leucantha rhizome, which is the first report of ER bodies in rhizome tissue.

Highlights

The rhizome is a plant organ that develops from a shoot apical meristem but penetrates into belowground environments
The rhizome remained beneath the ground surface, when leaves and inflorescences had already formed at its tip
Previous studies investigating rhizome transcriptomes have reported a clear difference in gene expression pattern between the rhizome and aerial shoots/leaves in bamboo[15], Oryza[16], Sorghum[7,52] and Atractylodes[18], its relationship to the transcriptome of belowground organs such as roots remained unclear

Summary

Introduction

The rhizome is a plant organ that develops from a shoot apical meristem but penetrates into belowground environments. A comparison of transcriptomes further allowed us to identify the presence of an ER body, a defenserelated belowground organelle, in epidermal cells of the C. leucantha rhizome, which is the first report of ER bodies in rhizome tissue. Terrestrial plants spread their organs into two distinct spaces, i.e. above- and belowground. During the initial stage of plant growth after germination, two sets of organs, shoot and root systems, grow into the opposite directions to penetrate into aerial and soil spaces, respectively Their growth and morphogenesis are distinctly determined by the shoot and root meristems. The development of rhizomes and the controls that regulate this process have been extensively studied in rhizomatous crops and wild p lants[7,9,10]

Objectives

Methods

Results

Conclusion