Bacterial leaf spot is a destructive disease in Rajasthan caused by Xanthomonas axonopodis pv. vesicatoria (Doidge) Dye. A field and market survey was conducted for the study of incidence and location. Dry seed examination of 103 seed samples of chilli (Capsicum spp.) belonging to 16 districts of Rajasthan that revealed a 10–100% incidence of Xanthomonas axonopodis pv. vesicatoria (XAV) on Tween-80 medium. Two naturally infected seed samples of chilli carrying a 100% incidence of XAV were selected and categorized into asymptomatic (06.25–94.25%), moderately discolored (01.75–42%), and heavily discolored (01.25–27.75%) seeds. The heavily discolored seeds showed shriveled, water-soaked symptoms on their surface, and on bisecting such types of infected seeds, the embryo and endosperm showed necrosis and browning. The pathogen was found confined to the outer seed coat layer, particularly at the ramnent of funiculus in a few asymptomatic seeds. In moderately discolored seeds, the pathogen was found in the seed coat and the space in between the seed coat and the endosperm. It colonized all the seed components, including embryo and endosperm, in heavily discolored seeds. The pathogen caused necrosis, the formation of lytic cavities, a reduction in cell contents, and aggregation of the bacterial cells. The pathogen was found to be extra-as well as intra-embryonic.
Keywords: Chilli, Bacterial leaf spot, Seed discolorations, Xanthomonas axonopodis pv. vesicatoria, Seed-borne bacterial disease, histopathology.
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