Histopatholgy of Sorghum Leaf Infected by Phyllachora sorghi

Abstract

A microscopic study was made of leaf tissue infected by Phyllachora sorghi, the causal organism of tar spot disease in sorghum. Cross sections of infected tissue were stained using safranin and fast green for study. Mature ascospores germinated on both the upper and lower leaf surfaces and gained penetration of the leaf through the stomata. The perfect stage of the organism develops below the epidermis of teh leaf; the perithecium consists of a unique stalk ascus with eight ascospores. Dikary oticism occurs in the leaf tissue. Under favourable environmental conditions the ascospores are released to initiate the cyle of infection again. the study demonstrated Phyllachora sorghi infects the mesophyIi of the sorghum leaf but not the vascular bundle. The organism interferes with photosynthesis through is destruction of the chloroplasts in teh mesophyII.