Morphogenesis of edible gall in Zizania latifolia (Griseb.) Turcz. ex Stapf due to Ustilago esculenta Henn. infection in India

The Zizania latifolia Griseb. Turcz. ex Stapf., a perennial wetland wild rice species get infected by a basidiomycetous fungus Ustilago esculenta Henn that produces gall. Here we report the morphogenesis behaviour of this plant during gall transformation. The identity of Z. latifolia and U. esculenta were confirmed by comparing microsatellite and Internal Transcribed Spacer region of nuclear ribosomal DNA sequence with the public database. U. esculenta infection transforms the Z. latifolia into two distinct morphotypes such as gall forming and non-gall forming. The non-gall bearing morphotype exhibited pinkish microporous lamellar discs (15-20 numbers) filled with mycelia in the internodal spaces. Whereas the gall bearing morphotype fuses 3-4 nodes into compact spindle shaped hypertrophic tissue measuring 2.5 cm diameter x 8-10 cm length tapering at the tip end where dark brown coloured teliospores are deposited in linear sori. In vitro culture of lamellar discs and teliospores in Potato Sucrose Agar medium initially develops white colony 2.6- 4.0 cm diameter later turned into yellowish brown after 7 -10 days and subsequent sporulation within 8-12 days. Spherical sporangium of 28 µm diameter developed on long sporangiophore 7 µm diameter filled with large number of spores 1-1.5 µm in diameters. The unsuccessful sporulation of Ustilago even after infection failed to develop gall in the host plants behave normal life cycle and are not consumed. The spore along with hypertrophic soft tissue is consumed as vegetable in the oriental countries.