title: Lignification of developing maize (Zea mays L.) endosperm transfer cells and starchy endosperm cells.
abstract: Endosperm transfer cells in maize have extensive cell wall ingrowths that play a key role in kernel development. Although the incorporation of lignin would support this process, its presence in these structures has not been reported in previous studies. We used potassium permanganate staining combined with transmission electron microscopy - energy dispersive X-ray spectrometry as well as acriflavine staining combined with confocal laser scanning microscopy to determine whether the most basal endosperm transfer cells (MBETCs) contain lignified cell walls, using starchy endosperm cells for comparison. We investigated the lignin content of ultrathin sections of MBETCs treated with hydrogen peroxide. The lignin content of transfer and starchy cell walls was also determined by the acetyl bromide method. Finally, the relationship between cell wall lignification and MBETC growth/flange ingrowth orientation was evaluated. MBETC walls and ingrowths contained lignin throughout the period of cell growth we monitored. The same was true of the starchy cells, but those underwent an even more extensive growth period than the transfer cells. Both the reticulate and flange ingrowths were also lignified early in development. The significance of the lignification of maize endosperm cell walls is discussed in terms of its impact on cell growth and flange ingrowth orientation.
authors.affiliation: Departamento de Ciências Agrárias, Instituto de Biotecnologia e Bioengenharia - Centro de Biotecnologia dos Açores, Universidade dos Açores Angra do Heroísmo, Portugal.
authors.forename: Sara
authors.initials: S
authors.lastname: Rocha
authors.affiliation: Departamento de Ciências Agrárias, Instituto de Biotecnologia e Bioengenharia - Centro de Biotecnologia dos Açores, Universidade dos Açores Angra do Heroísmo, Portugal.
authors.forename: Paulo
authors.initials: P
authors.lastname: Monjardino
authors.affiliation: Departamento de Ciências Agrárias, Instituto de Biotecnologia e Bioengenharia - Centro de Biotecnologia dos Açores, Universidade dos Açores Angra do Heroísmo, Portugal.
authors.forename: Duarte
authors.initials: D
authors.lastname: Mendonça
authors.affiliation: Departamento de Ciências Agrárias, Instituto de Biotecnologia e Bioengenharia - Centro de Biotecnologia dos Açores, Universidade dos Açores Angra do Heroísmo, Portugal.
authors.forename: Artur
authors.initials: A
authors.lastname: da Câmara Machado
authors.affiliation: Instituto de Biologia Molecular e Celular, Universidade do Porto Porto, Portugal.
authors.forename: Rui
authors.initials: R
authors.lastname: Fernandes
authors.affiliation: Instituto de Biologia Molecular e Celular, Universidade do Porto Porto, Portugal.
authors.forename: Paula
authors.initials: P
authors.lastname: Sampaio
authors.affiliation: Instituto de Biologia Molecular e Celular, Universidade do Porto Porto, Portugal ; Departamento de Biologia, Faculdade de Ciências, Universidade do Porto Porto, Portugal.
authors.forename: Roberto
authors.initials: R
authors.lastname: Salema
keywords: cell growth analysis; flange ingrowths; lignin; maize endosperm; reticulate ingrowths; starchy cells; transfer cells