The location of Fe3+reduction in tumorous and normal stem tissue of sunflower and tomato

Abstract

Abstract An agar embedding technique used to identify the location of Fe3+ reduction on roots was adapted to study the site of Fe 3+ reduction in normal and tumorous crown gall stem tissues. Crown gall tissue was induced on the stems of sunflower (Helianthus annus L.) and tomato (Lycopersicon esculentum Mill.) by carefully inoculating injured stems with the soil bacterium Agrobacterium tumefaciens. Slices of normal and crown gall tissue were embedded in agar containing Fe 3+ and BPDS, an Fe 2+ indicator. In infected sunflower stem tissue, Fe 3+ was strongly reduced to Fe 2+ throughout the gall tissue as evidenced by the formation of Fe 2+ BPDS complex, but there was practically no reduction in the normal tissue. In tomato stem tissue, Fe 3+ was reduced at the outer edge of the stem of both normal and tumorous tissues. Although not quantitative, the technique was effective in locating actively reducing tissues.