Morphological and Biochemical Changes in Ginseng Seedling Roots Affected with Stripe Symptoms

Zamir K Punja,Mahfuzur Rahman

doi:10.4236/ajps.2015.616257

Zamir K Punja, Mahfuzur Rahman

Open Access

https://doi.org/10.4236/ajps.2015.616257

Copy DOI

Abstract

A unique symptom of longitudinal red stripes on the surface of one-year-old ginseng roots was studied to determine the morphological and biochemical changes taking place. Light and scanning electron microscopy, measurements of phenolic and mineral element content, and enzyme activity, were compared between healthy and stripe-affected root tissues. Light microscopy revealed that the root epidermis had ruptured and fissures extended for 3 - 4 cell layers into the cortex. Phenolic compounds accumulated in the epidermal cells which stained with Toluidine blue 0. Total phenolic content was higher in tissues from striped roots compared to healthy roots and HPLC profiles showed increases in a number of specific phenolic compounds. Analysis of epidermal tissues by SEM-EDX for mineral element content showed a marked increase in levels of iron, silicon and aluminum and a decline in potassium in striped root tissues. The activity of the enzymes phenylalanine ammonia lyase and peroxidase were also found to be higher in striped root tissues. Striping of ginseng roots is a physiological condition caused by a rupture of the epidermis due to rapid growth of underlying cells, which results in phenolic accumulation and sequestration of several minerals. Further oxidation causes a visible red striping on the root surface.

Highlights

Ginseng (Panax species, Family Araliaceae) is a medicinal plant which is cultivated in various parts of NorthHow to cite this paper: Punja, Z.K. and Rahman, M. (2015) Morphological and Biochemical Changes in Ginseng Seedling Roots Affected with Stripe Symptoms
Reddish-brown to orange-brown discolored regions near the crown of the root were shown to be due to infection by fungi that included Fusarium spp. [8], Cylindrocarpon destructans [9], and Rhexocercosporidium sp. [10]
Ginseng roots with stripe symptoms were distinctly different from healthy roots that showed no external discoloration (Figure 1(a))

Summary

Introduction

Ginseng (Panax species, Family Araliaceae) is a medicinal plant which is cultivated in various parts of NorthHow to cite this paper: Punja, Z.K. and Rahman, M. (2015) Morphological and Biochemical Changes in Ginseng Seedling Roots Affected with Stripe Symptoms. How to cite this paper: Punja, Z.K. and Rahman, M. In Canada, American ginseng (Panax quinquefolius L.) is cultivated in regions of British Columbia and Ontario and the root is harvested, dried, trimmed, and shipped for export to Asia. During the four-year growth cycle, ginseng plants can be affected by a number of fungal diseases and abiotic stress factors which can affect root quality [2] [3]. Previous studies have shown that physiological (abiotic) and biotic factors can cause root discoloration of the ginseng root surface and distortion of root growth. Reddish-brown to orange-brown discolored regions near the crown of the root were shown to be due to infection by fungi that included Fusarium spp. These fungi caused root rot as well as extensive distortion and discoloration of the root

Objectives

Methods

Results

Conclusion