Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/27/2008
Publication Date: N/A
Technical Abstract: The two major hormones, auxins and cytokinins, essential for normal cell division and development are present in high amounts in developing maize kernels. They are presumed to be involved in sink strength formation, either directly by affecting cell divisions, or indirectly through sugar-hormone signaling. The maize mn1 seed mutant is of much interest because it shows pleiotropic changes both at cellular and metabolic levels due to a loss of the Mn1-encoded cell wall invertase (CWI) that controls the flux of sucrose in developing endosperm during seed development. In this study, we used previously described mn1 alleles that show gene-dose dependence for the levels of CWI activity, sink strength and seed mass to check transcription profiles of hormone metabolism related genes. Using real-time quantitative PCR (qPCR) we obtained expression profiles of five CK metabolism related genes, isopentenyl transferase (Ipt), cytokinin oxidase (Ckx), N-glucosyl transferase (Cngt), histidine kinase (Hk) and cis-zeatin glucosyl-transferase (Czog) and an auxin biosynthesis gene YUCCA on developing kernels during the 6 to 28 DAP (days after pollination) period. Of these six genes, Ipt, Cngt and Yucca, showed peak levels of expression that coincided with the expression of the Mn1 gene during cell division and elongation phase, whereas, Ckx, Hk and Czog genes showed a rather uniform pattern of expression throughout seed development. Overall, the developmental profiles of expression of the genes studied here were similar between mn1 and Mn1 but the absolute levels in terms of number of transcripts for each gene varied widely between the two genotypes. Significance of these results in relation to CWI activity and seed mass will be discussed.