Temperature-sensitive expression of auxin-autotrophy by crown-gall teratoma cells of tobacco.

Crown-gall teratoma tissues of tobacco (Nicotiana tabacum L.) grow in culture at 25° in the absence of added auxin or cell-division factors. The capacity of these tissues to grow without added auxin is temperature sensitive. At 35° auxin provided as α-naphthalene acetic acid or 2,4-dichlorophenoxyacetic acid is required for continued exponential growth. Moreover at 35° the auxin dose response of teratoma tissues shifts from the pattern characteristic of autonomous tumor tissues at 25° to the pattern characteristic of auxin-requiring normal tissues. Incubation of the tissues at 35° also appears to induce lasting changes in teratoma phenotype. Using relative growth of tissues with and without added auxin as a criterion, pretreatment with auxin induces a stable increase in auxin-autotrophy, while pretreatment without auxin induces a stable decrease in auxin-autotrophy. These results are consistent with a positive feedback mechanism for stable changes in auxin-autotrophy.