Trianthema portulacastrum — Local lesion host for brinjal mosaic and tobacco mosaic viruses

Abstract

This paper deals with the first record of virus infections (brinjal mosaic virus and tobacco mosaic virus) on Trianthema portulacastrum L., a common weed in India. Trianthema portulacastrwn L., locally known as “Bishkhapra”, is a common weed with medicinal properties, and grows extensively in summer everywhere. It is a succulent, prostrate, glabrous or slightly pubescent herb with many branched, angular stems, leaves broader towards the tip, fruits small like flowers, concealed in the base of the leaf stalk. Experiments were carried out to determine the utility of T. portulacastrum as a local lesion host. The culture of mosaic disease of brinjal (Seth et al. 1967) and SK strain of tobacco mosaic virus (Verma et al. 1972) were maintained on Nicotiana glutinosa L. and N. tabacum cv. White Burley, respectively. The test plants of T. portulacastrum were raised in 4 inch pots, filled with sterilized soil, and kept inside the insect-proof glasshouse. For inoculations, the conventional method of macerating the infected leaf material in a mortar and pestle and rubbing the test seedlings by means of a cotton wool swab was employed. The plants were maintained on glasshouse benches at a temperature of 29 to 30°C. Within 6”7 days of inoculation, distinct countable chlorotic local lesions appeared which turned necrotic with a yellow halo over a period of 10”12 days. The lesions produced by both these viruses on T. portulacastrum were slightly different in their size and necrotic reaction on this host. Leaves of T. portulacastrum developed at first a few local lesions, followed by mosaic mottling of the newly emerging leaves in case of brinjal mosaic virus. Systemic infection, however, does not occur by tobacco mosaic virus in this host. A perusal of literature suggested that this constitutes the only record of a virus infection on Φ in India and is the first record as a local lesion host for brinjal mosaic virus and tobacco mosaic virus SK strain. Kristensen (1955) reported T. portulacastrum a systemic host of Beet yellows virus from Denmark. Die Mitteilung berichtet über Virusinfektionen (brinjal mosaic virus und Tabakmosaik-Virus) bei Trianthema portulacastrum , einem weitverbreiteten Unkraut in Indien.