title: Chalazal seed coat development in Brassica napus.
abstract: The chalazal seed coat (CZSC) is a maternal subregion adjacent to the funiculus which serves as the first point of entry into the developing seed. This subregion is of particular interest in Brassica napus (canola) because of its location within the seed and its putative contribution to seed filling processes. In this study, the CZSC of canola was characterized at an anatomical and molecular level to (i) describe the cellular and subcellular features of the CZSC throughout seed development, (ii) reveal cellular features of the CZSC that relate to transport processes, (iii) study gene activity of transporters and transcriptional regulators in the CZSC subregion over developmental time, and (iv) briefly investigate the contribution of the A and C constituent genomes to B. napus CZSC gene activity. We found that the CZSC contains terminating ends of xylem and phloem as well as a mosaic of endomembrane and plasmodesmatal connections, suggesting that this subregion is likely involved in the transport of material and information from the maternal tissues of the plant to other regions of the seed. Laser microdissection coupled with quantitative RT-PCR identified the relative abundance of sugar, water, auxin and amino acid transporter homologs inherited from the constituent genomes of this complex polyploid. We also studied the expression of three transcription factors that were shown to co-express with these biological processes providing a preliminary framework for the regulatory networks responsible for seed filling in canola and discuss the relationship of the CZSC to other regions and subregions of the seed and its role in seed development.
authors.affiliation: University of Manitoba, Department of Biological Sciences, 50 Sifton Road, Winnipeg, MB R3T 2N2, Canada.
authors.forename: Jenna L
authors.initials: JL
authors.lastname: Millar
authors.affiliation: University of Manitoba, Department of Biological Sciences, 50 Sifton Road, Winnipeg, MB R3T 2N2, Canada.
authors.forename: Deirdre
authors.initials: D
authors.lastname: Khan
authors.affiliation: University of Manitoba, Department of Biological Sciences, 50 Sifton Road, Winnipeg, MB R3T 2N2, Canada.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Becker
authors.affiliation: University of Manitoba, Department of Biological Sciences, 50 Sifton Road, Winnipeg, MB R3T 2N2, Canada.
authors.forename: Ainsley
authors.initials: A
authors.lastname: Chan
authors.affiliation: University of Manitoba, Department of Biological Sciences, 50 Sifton Road, Winnipeg, MB R3T 2N2, Canada.
authors.forename: André
authors.initials: A
authors.lastname: Dufresne
authors.affiliation: University of Manitoba, Department of Biological Sciences, 50 Sifton Road, Winnipeg, MB R3T 2N2, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Sumner
authors.affiliation: University of Manitoba, Department of Biological Sciences, 50 Sifton Road, Winnipeg, MB R3T 2N2, Canada. Electronic address: mark.belmonte@umanitoba.ca.
authors.forename: Mark F
authors.initials: MF
authors.lastname: Belmonte
mesh_terms: D001692:Biological Transport; D029688:Brassica napus / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development* / Q000648:ultrastructure; D018506:Gene Expression Regulation, Plant; D061346:Laser Capture Microdissection; D046529:Microscopy, Electron, Transmission; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D012639:Seeds / Q000033:anatomy & histology / Q000254:growth & development / Q000648:ultrastructure; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D014157:Transcription Factors
keywords: Brassica napus; Chalazal seed coat; Laser microdissection; Seed development; qRT-PCR