PT  - JOURNAL ARTICLE
AU  - Coenen, Catharina
AU  - Lomax, Terri L.
TI  - The <em>Diageotropica</em> Gene Differentially Affects Auxin and Cytokinin Responses throughout Development in Tomato
AID  - 10.1104/pp.117.1.63
DP  - 1998 May 01
TA  - Plant Physiology
PG  - 63--72
VI  - 117
IP  - 1
4099  - http://www.plantphysiol.org/content/117/1/63.short
4100  - http://www.plantphysiol.org/content/117/1/63.full
SO  - Plant Physiol.1998 May 01; 117
AB  - The interactions between the plant hormones auxin and cytokinin throughout plant development are complex, and genetic investigations of the interdependency of auxin and cytokinin signaling have been limited. We have characterized the cytokinin sensitivity of the auxin-resistantdiageotropica (dgt) mutant of tomato (Lycopersicon esculentum Mill.) in a range of auxin- and cytokinin-regulated responses. Intact, etiolated dgtseedlings showed cross-resistance to cytokinin with respect to root elongation, but cytokinin effects on hypocotyl growth and ethylene synthesis in these seedlings were not impaired by thedgt mutation. Seven-week-old, green wild-type anddgt plants were also equally sensitive to cytokinin with respect to shoot growth and hypocotyl and internode elongation. The effects of cytokinin and the dgt mutation on these processes appeared additive. In tissue culture organ regeneration fromdgt hypocotyl explants showed reduced sensitivity to auxin but normal sensitivity to cytokinin, and the effects of cytokinin and the mutation were again additive. However, although callus induction from dgt hypocotyl explants required auxin and cytokinin, dgt calli did not show the typical concentration-dependent stimulation of growth by either auxin or cytokinin observed in wild-type calli. Cross-resistance of thedgt mutant to cytokinin thus was found to be limited to a small subset of auxin- and cytokinin-regulated growth processes affected by the dgt mutation, indicating that auxin and cytokinin regulate plant growth through both shared and separate signaling pathways.