Anatomy and cell wall ultrastructure of sunflower stalk rind

Lizhen Wang,Shengcheng Zhai,Huamin Zhai,Hao Ren

doi:10.1186/s10086-021-02001-6

Lizhen Wang, Shengcheng Zhai + Show 2 more

Open Access

https://doi.org/10.1186/s10086-021-02001-6

Copy DOI

Abstract

The anatomy and ultrastructure of sunflower stalk rind are closely related to its conversion and utilization. We studied systematically the anatomy and ultrastructure of the stalk rind using light, scanning electron, transmission electron and fluorescence microscopy. The results showed that the stalk rind consisted of phloem fibers (PF), xylem fibers (XF), vessel elements (V), ground parenchyma cells (GPC), axial parenchyma cells (APC), xylem ray parenchyma cells (XRPC), and pith ray parenchyma cells (PRPC). These cell walls were divided into the middle lamella, primary wall, and secondary wall (S). It was found that the S of PF, XF and V was further divided into three layers (S1–S3), while the S of APC, GPC, XRPC and PRPC showed a non-layered cell wall organization or differentiated two (S1, S2) to seven layers (S1–S7). Our research revealed the plasmodesmata characteristics in the pit membranes (PMs) between parenchyma cells (inter-GPCs, inter-XRPCs, and inter-PRPCs). The morphology of the plasmodesmata varied with the types of parenchyma cells. The thickness and diameter of PMs between the cells (inter-Vs, V–XF, V–APC, and V–XRPC) were greater than that of PMs between parenchyma cells. The cell corners among parenchyma cells were intercellular space. The lignification degree of vessels was higher than that of parenchyma cells and fibers. The results will provide useful insights into the biological structure, conversion and utilization of sunflower stalk rind.

Highlights

The ultrastructure of plant cell walls is important for plant biology, and for the conversion and utilization of mature plants [1]
We analyzed the anatomy of stalk rind using light microscopy (LM), the cell pits characteristics using scanning electron microscopy (SEM), the ultrastructure of cell wall layers and Pit membrane (PM) using transmission electron microscopy (TEM), and lignin distribution using fluorescence microscopy (FM) and scanning electron microscopy with energy dispersive X-ray analysis (SEM–EDXA), and measured cell wall layer thickness, the PMs thickness and diameter using a combination of TEM images and ImageJ software
The Ep was composed of epidermal membrane and epidermal cells, was located in the outermost layer of the stalk rind

Summary

Introduction

The ultrastructure of plant cell walls is important for plant biology, and for the conversion and utilization of mature plants [1]. The anatomy and cell wall ultrastructure of lignocellulosic materials are closely related to their conversion and utilization [4]. The anatomy of sunflower stalk rind is not detailed, and the ultrastructure of its fibers, vessel elements (V), and parenchyma cells has not been reported. We analyzed the anatomy of stalk rind using light microscopy (LM), the cell pits characteristics using scanning electron microscopy (SEM), the ultrastructure of cell wall layers and PMs using transmission electron microscopy (TEM), and lignin distribution using fluorescence microscopy (FM) and scanning electron microscopy with energy dispersive X-ray analysis (SEM–EDXA), and measured cell wall layer thickness, the PMs thickness and diameter using a combination of TEM images and ImageJ software. This study aimed to reveal the anatomy and cell wall ultrastructure of sunflower stalk rind and to provide the basis for its conversion and utilization

Objectives

Methods

Results