| Abstract Detail
Seed Biology Rijavec, Tomaz [1], Kovac, Maja [2], Dermastia, Marina [3], Chourey, Prem [4]. Cytokinin (CK) levels and expression profiles of CK genes in developing maize caryopsis. Cytokinins are a diverse group of plant hormones that regulate apical dominance, cell divisions, nutrient mobilization, sink strength, leaf senescence, seed germination and pathogen responses. In developing maize kernels, CKs play a critical role during the early stages of development and the highest CK levels coincide with rapid cell divisions. The miniature1 (mn1) seed mutant is of interest because it shows pleiotropic changes due to a loss of the Mn1-encoded cell wall invertase that controls sucrose flux in developing endosperm. Much evidence is available in Arabidopsis to show crosstalk between sugar and hormone signaling. We used the mn1 seed mutant to asses whether CK levels and CK gene transcription profiles are affected by the change in sugar metabolism. Preliminary HPLC analyses showed abundant levels of trans-zeatin and tZRiboside as well as quantitative and qualitative changes in developing kernels of these two genotypes. The most notable changes were in the early stages of kernel development, and we conclude that they result mainly from the impaired sucrose hydrolysis in the mn1 seed mutant. In agreement with our biochemical data, the transcript levels of several CK genes were highest between 8 and 12 DAP. Genes that showed the most changes included isopentenyl transferase (synthesis), cytokinin oxidase (degradation), histidine kinase (receptor) and N-type as well as O-type glucosyl transferase genes (irreversible and reversible conjugation, respectively). Collectively, these results showed that the altered sugar metabolism affected the transcription profiles of CK genes, especially the ones that catalyze glucosyl transfer reactions. Possible significance of these results in relation to sugar and hormone signaling will be discussed in more detail.
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1 - University of Ljubljana, Ljubljana, Slovenia
2 - National Institute of Biology, Ljubljana, Slovenia
3 - University of Ljubljana, Ljubljana, Slovenia and National Institute of
4 - USDA ARS & University of Florida, Chemistry & Plant Pathology, Gainesville, FL, 32611-0680, USA
Keywords:
seed development.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P29011
Abstract ID:804 |
