Developmental and Structural Section
Rodrigues, Maria Aurineide , Freschi, Luciano , Ceccantini, Gregório Cardoso Tápias , Kerbauy, Gilberto Barbante .
Root growth and apical meristem pattern are related with competence acquisition to conversion of Catasetum fimbriatum root tips into buds.
The roots of most species become determinate on aging, and root determination is communly preceded by activation of quiescent center (QC) cells, resulting in a change from closed to open in root apical meristem (RAM) architecture. Root apices isolated from orchids of the genera Catasetum represent an interesting model for studying RAM structure, since they are able to convert into buds in vitro. Recently, it was noticed that competence acquisition for this process was related to plant ageing. This work aimed at studying the connection among Catasetum fimbriatum root growth, RAM organization and its competence to convert into buds. To achieve this, the root growth rate of young plants of C. fimbriatum was measured weekly during their development. Aditionally, histological modifications and RAM competence to convert into buds were analysed in root tips isolated from 30, 60, 120 and 240-day-old-plants. The results disclosed that root growth was accelerated until the age of 50 days, and RAMs from 30 and 60-day-old-plants showed a typically closed organization. 30-day-old-RAMs did not display competence to convert into buds, and only 6% of those from 60-day-old-plants presented the aforesaid competence. By 80 days the root determinate length was reached, and the pattern of 120-day-old-RAMs had changed to an intermediate open organization. At this point 70% of the RAMs were competent to convert into buds, this event increasing to 81% among 240-day-old-RAMs, when they presented remarkable meristematic differentiation, total loss of root cap and lack of quiescence of QC cells. The present results indicate that competence acquisition of C. fimbriatum RAMs to convert into buds is coupled with root determinate growth and modifications in the RAM pattern during ageing.(FAPESP)
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Plant Development Research
1 - Universidade de São Paulo, Botany Department, Rua do Matão, nº 277 - Cidade Universitária, São Paulo, São Paulo, 05508-090, Brazil
determinate root growth
root apical meristem
Presentation Type: Poster:Posters for Sections
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM