Abstract:

Analysis of dynamic distributions of cytokinin and auxin response signals in tomato plants is of great significance for clarifying the regulatory roles and functional mechanisms of these two hormones at the cytological level. A green fluorescent reporter gene TCSn1::GFP（GFP）with a cytokinin-responsive promoter TCSn1，and a red fluorescent reporter gene DR5v2::tdTomato（tdTomato）with an auxin-responsive promoter DR5v2，were used to perform real-time in-situ analyses of the signals of cytokinin and auxin responses in tomato roots，stems，leaves，flowers，and fruits. It is found that the two types of fluorescence distributed in the tissues/organs including：lateral root cap and columella in root cap，as well as the procambium，ground meristerm and protoderm in root elongation zone at three to seven days after germination，the shoot apical meristem at five to ten days after germination，vascular tissues in stems of plants at 23 and 37 days after planting，young leaves of plants at 32 days after planting，petals and fruit peduncles at anthesis，ovules，the placenta，columella and pericarp of fruits at two to six days after anthesis. Intensities of the two types of fluorescence were both highest in the shoot apical meristem and ovules in fruits，and had a similar variation trend：first decreased and then recovered in the root cap and elongation zone during three to seven days of germination；were weaker in stem segments at 37 days than 23 days after planting；continuously rose in the shoot apical meristem at five to ten days after germination and in the fruits at zero to six days after anthesis. This study provides a sensitive and robust visualization tool for analyzing cytokinin and auxin responses in tomato，and has analyzed their distribution and intensity in different organs of tomato.

Key words: Solanum lycopersicum, cytokinin response, auxin response, visible fluorescence, microimaging