Free amino acids of sunflower hypocotyl tissue during crown gall tumor development

Abstract

The concentration of each free amino acid present in hypocotyl tissue of sunflower seedlings was determined during the period following both sterile wounding and inoculation with either tumorigenic (strain 1025) or non-tumorigenic (strain IIBNV6) Agrobacterium tumefaciens. The concentration of the total free amino acids of hypocotyl tissue reached a maximum 68 hours after infection with strain 1025 and this level was 50% greater than that found in plants treated with strain IIBNV6. The total content of free basic amino acids increased to a peak value at 20 hours after infection by strain 1025 and this represented 1.4 to 3 times the level found in strain IIBNV6 inoculated seedlings at 20 hours.The amount of free proline decreased with time and it was essentially absent 164 hours after infection with strain 1025. At 2 months the concentration of free proline in the tumor tissue was greatly increased with 75% of the total free amino acids accounted for as proline.The free amino acid content of strain 1025 growing in either the presence or absence of an extract from wounded seedlings was measured and the results indicated no significant relationship between the plant and bacterial systems with regard to their free amino acid pools.