TUMOROUS CROWN GALL RESPONSE TO IRON-DEFICIENCY STRESS IN FE-EFFICIENT T3238FER AND FE-INEFFICIENT T3238FER TOMATOES

Although sunflower (Helianthus annus L.) is an Fe efficient plant, tum orous crown gall tissue development and tissue ability to reduce Fe3to Fe2+ were both diminished by Fe-deficiency stress. Crown gall also develops readily on Fe-efficient and Fe-inefficient tomato cultivars ( Lycopersicon esculentum Mill.). The objective of this study was to det ermine if the effect of a limited Fe supply on the growth, nutrition a nd reduction of Fe3+ to Fe2+ by tumorous crown gall would differ betwe en Fe-efficient T3238FER and Fe-inefficient T3238fer tomato. Healthy g reen 25-day-old plants were either stem-inoculated with Agrobacterium tumefaciens to induce tumorous crown gall tissue development or were l eft uninoculated for comparison. Plants were grown in modified Hoaglan d nutrient solutions containing 0.0, 0.15, 0.6 and 2.0 mg Fe L-1. Yiel d of tumorous crown gall tissue was not diminished by low solution Fe in T3238FER, but was in T3238FER. This was attributed to inability of the T3238fer tomato to make Fe available to itself. Tumor tissue from both cultivars contained more Fe, Cu and P than normal stem tissues, w hich confirms a modified metabolism in these tissues previously observ ed in sunflower. An abundant supply of Fe enhances the development and growth of the tumorous crown gall tissue, but a deficient supply of F e retards its growth.