|Marita, Jane - U OF WISCONSIN MADISON|
Submitted to: Plant Physiology
Publication Type: Abstract Only
Publication Acceptance Date: July 15, 2000
Publication Date: N/A
Technical Abstract: Ferulates are thought to have key structural and functional roles in the development of plant cell walls, particularly for plants in the grass family. To broaden our understanding of the molecular roles of ferulates in cell wall (CW) development, we have begun characterization of corn (Zea mays L.) seed tissues including surrounding glumes and silks. Corn plants were grown to maturity in a greenhouse under supplemental light. Plants where allowed to intercross and developing cobs harvested at different stages of maturity. Cell walls were isolated from embryos, endosperm, pericarp-seed coat, glume, and silk tissues and analyzed for sugar and hydroxycinnamate composition. All tissues contained ferulates and p-coumarates (p-CA) that varied with tissue type and stage of development. Typically p-CA was low (0.03 to 0.3% of CW) in all tissues except glumes (0.7 to 2.2% of CW). Ferulates were higher in all tissues (0.2 to5.8% of CW)and increased as tissues matured (e.g., pericarp 1.2 to 5.8% of CW). The proportion of ferulate dimers also varied with tissue type and developmental stage ranging from 15 to 40% of the total ferulates released from the wall. Carbohydrate analysis indicated tissues contained higher concentrations of arabinose and xylose as the major sugar (30 to 32% xylose vs 25 to 28% glucose). Only glume tissues contained appreciable levels of lignin, all others produced less than 3% acid insoluble residue and gave negative responses when stained with phloroglucinol. The high concentrations of ferulates in pericarp-seed coat tissues that do not contain lignin provide a model system to investigate the role of ferulate cross-linkin tin wall structure and function.