Histology of bacterial canker affected Mangifera indica.
Shekhawat G. S., Patel P. N., Rajpal Singh
Author Affiliation: Cent. Potato Res. Inst., Simla-1, Himachal Pradesh, India.
Phytopathologische Zeitschrift 95 : 12-23
Abstract : Pseudomonas mangiferae-indicae entered intact mango leaves through stomata, fruits through stomata and lenticels and twigs through lenticels. The exclusively intercellular parenchymatous pathogen caused separation and collapse of the cells. Host cells surrounding bacterial pockets in leaf and stem were predominantly hypertrophic; the fruit parenchyma showed both hypertrophy and hyperplasia. In fruits of hybrid Neelum X Dusheri, bacterial spread was slow, due to pre-formed lenticel cork and postinfectionally formed cork layers round the bacterial pockets in the mesocarp. In Neelum X Langra and cv. Bangalora, lenticels contained loosely arranged complementary cells and no cork layer. In Neelum X Langra the mesocarp around the bacterial pocket produced elongated, thin-walled cells. Due to increase in host tissue and bacteria, the epidermis ruptured and the lesion protruded on the fruit surface. In Bangalora, mesocarp cells enlarged and rapidly collapsed, large bacterial pockets formed and the bacteria invaded through resin canals into the deeper layers of the mesocarp, producing internal lesions. Tannin increased in diseased tissue. Lignin and wound gum accumulation was profuse in stem and pitted fruit cankers but sparse in raised fruit cankers and leaves.