CO 2 effects on local-lesion production by tobacco mosaic virus and turnip mosaic virus

Abstract

Nicotiana tabacum var. Havana 425 and N. glutinosa plants were inoculated with tobacco mosaic virus (TMV) and those of N. tabacum var. Haranova with turnip mosaic virus (TuMV). After inoculation, plants were kept in normal air or in 1% CO 2, either continuously, only during the light period, or only during the dark period. When plants were exposed to 1% CO 2 during the light period, lesion production in all three hosts was greatly inhibited. In other CO 2 treatments the number of lesions produced was similar to the control (normal air). However, in plants of N. tabacum var. Havana 425 exposed to 1% CO 2, either during the dark period or continuously, lesions were yellow instead of the usual brown. In addition, lesions developed on leaves exposed to 1% CO 2 during dark or light periods were smaller than in the other two treatments. In the yellow lesions there was frequently a new type of particle aggregation, called zipper aggregates, indicating that variation in the environment can cause changes in the structure of the TMV aggregates.