TITLE:
Stem Histopathology of Sesame Seedlings Infected with Alternaria alternata
AUTHORS:
Maryam Ajmal, Abida Akram, Anum Ara, Shaista Akhund, Brian Gagosh Nayyar, Wajiha Seerat
KEYWORDS:
Sesame, Alternaria alternata, Pathogen, Fungus, Light microscopy
JOURNAL NAME:
Microscopy Research,
Vol.4 No.2,
April
1,
2016
ABSTRACT: In the present study, histopathology of three varieties of sesame TS 3, TS 5 and SG 27 infected with Alternaria alternata was carried out to understand the mechanism of fungal infection and penetration in sesame plant as well as to determine the histological manifestation in sesame cells by light microscopy. Fungus was identified in infected tissues as a dark bluish black with toluidine blue O staining. Light microscopic examination of sesame stem showed that the fungus was present in epidermis, hypodermis and cortical parenchyma tissue as the symptoms became visible by naked eye ten days after inoculation (DAI). As the disease progress, the fungus moved from cortical parenchyma to vascular bundle, xylem and phloem. Later on, it completely overlapped the vascular bundle and entered in pith. When necrotic lesion appeared, fungus was present abundantly in epidermis, hypodermis, cortical parenchyma, vascular bundles and in pith. Due to its excessive growth and complete overlapping of cells, disorganization or destruction of cells of sesame took place. It was concluded that the Alternaria alternata was not a tissue limited pathogen instead of this it spread in to all tissues of stem from epidermis to pith.