Defense mechanisms in Solanum virginianum against brinjal shoot and fruit borer -a comparative study

A study was taken up to morphologically characterize Solanum virginianum accessions to identify suitable lines for resistance breeding. Four accessions of S. virginianum were evaluated along with S. melongena  varieties ‘Ponni’ and ‘Surya’. Plants belonging to S. virginianum were prostrate growing and weedy in nature with strongly lobed leaves and small fruits bearing prickles. The plants of ‘Ponni’ and ‘Surya’ were erect growing with weakly lobed leaves and large sized fruits and were devoid of prickles. The accessions were screened for brinjal shoot and fruit borer infestation during August-November 2018 and March-July 2019 along with ‘Ponni’ and ‘Surya’. Shoot damage was not observed in the wild accessions during both the seasons. Variety ‘Ponni’ was highly susceptible as the shoot and fruit damage ranged from 13.33 to 54.16 per cent and 15.87 to 45.56 per cent, respectively. ‘Surya’ was more prone to damage by borer as the shoot and fruit damage ranged from 15.55 per cent to 54.17 per cent, and 16.58 per cent to 67.25 per cent, respectively. The plants belonging to S. virginianum were distinctly characterized by thick walled epidermis, thick cuticle and cortex wall, numerous trichomes, large number of well developed vascular bundles and small pith size. The susceptible varieties ‘Ponni’ and ‘Surya’ were characterized by thin walled epidermis, thin cuticle and cortex wall, very few trichomes, small number of poorly developed vascular bundles and large pith size. Hence, anatomical parameters viz., thickness of epidermis and cortex, trichome intensity, number and size of vascular bundles and pith size may serve as morphological markers, and S. virginianum  could be a promising wild species in pre-breeding programmes as a suitable donor for fruit and shoot borer resistance.