A somatic hybrid between Solanum integrifolium and Solanum violaceum that is resistant to bacterial wilt caused by Ralstonia solanacearum

Abstract.

Protoplast fusion was performed between a commercial rootstock variety of Solanum integrifolium that is widely used in the cultivation of edible eggplant, and Solanum violaceum, a wild eggplant species tolerant to bacterial wilt. One of the somatic hybrid lines (27–14) obtained showed morphological traits intermediate between those of its parents. Its hybrid nature was confirmed by analysis of random amplified polymorphic DNA and restriction fragment length polymorphism patterns. Microscopic observation revealed that the line was amphidiploid. The hybrid line and both parent species were infected with a virulent strain of Ralstonia solanacearum by the root cutting method. Line 27–14 developed much less severe symptoms of bacterial wilt than the susceptible S. integrifolium. Twenty days after inoculation, the bacterial density in the shoot apex tissue was significantly lower in the hybrid than in S. integrifolium, suggesting that the multiplication of bacteria was inhibited in line 27–14.