Arabinogalactan proteins mark stigmatic receptivity in the protogynous flowers of Magnolia virginiana (Magnoliaceae)

Abstract

These results show that the period of stigmatic receptivity is finely coordinated with the secretion of two arabinogalactan proteins on stigmas of flowers of M. virginiana. This first report of AGP presence in stigmatic tissues in a member of the magnoliids, together with recently described similar patterns in eudicots, monocots, and members of early-divergent lineages of flowering plants, suggests an ancient and widespread role for AGPs on stigmatic receptivity in angiosperms.

Temporal Petal Closure Benefits Reproductive Development of Magnolia denudata (Magnoliaceae) in Early Spring

“…It is intriguing to note that there is vast variation of flower opening types within the Magnolia genus. Magnolia sprengeri , like M. denudata in the current study, flowers in daytime (Wang et al, 2014), while M. ovata and M. virginiana in night (Gottsberger et al, 2012; Losada et al, 2014). Some Magnolia species, such as M. praecocissima, M. schiedeana , and M. tamaulipana have a single flower opening (Dieringer and Espinosa, 1994; Ishida, 1996; Dieringer et al, 1999), while others show repetitive opening, such as M. denudata, M. sprengeri, M. ovata , and M. virginiana (Wang et al, 2010, 2014; Gottsberger et al, 2012; Losada et al, 2014).…”

“…Magnolia sprengeri , like M. denudata in the current study, flowers in daytime (Wang et al, 2014), while M. ovata and M. virginiana in night (Gottsberger et al, 2012; Losada et al, 2014). Some Magnolia species, such as M. praecocissima, M. schiedeana , and M. tamaulipana have a single flower opening (Dieringer and Espinosa, 1994; Ishida, 1996; Dieringer et al, 1999), while others show repetitive opening, such as M. denudata, M. sprengeri, M. ovata , and M. virginiana (Wang et al, 2010, 2014; Gottsberger et al, 2012; Losada et al, 2014). Considering that these Magnolia species are living in different habitats and pollination was mediated by different insects (Dieringer et al, 1999; Gottsberger et al, 2012; Wang et al, 2014), the vast variance in flowering types might be an adaptation to their pollinators with distinct activity rhythms.…”

The role of the integuments in pollen tube guidance in flowering plants

“…AGPs have been suggested to play a key role in pollen tube growth (Clarke et al ., ; Gleeson & Clarke, ; Prychid et al ., ; Losada & Herrero, , ; Suárez et al ., ; Losada et al ., ; Pereira et al ., ). AGPs detected by JIM8 and JIM13 are present in ovules of pollinated and unpollinated flowers of A. cherimola and Arabidopsis , indicating that their production is independent of pollination.…”

Pollen–pistil interaction in pawpaw (Asimina triloba), the northernmost species of the mainly tropical family Annonaceae

“…To confirm the presence and nature of these glycoproteins on the stigmas, we immunodetected two AGP epitopes in stigmatic sections throughout development. From among the monoclonal antibodies available to detect various AGPs, we chose JIM8 and JIM13 that have been used to reveal secretory patterns in the stigma of other angiosperms (Losada and Herrero, 2012; Losada et al, 2014). Immunolocalizations of AGP epitopes recognized by both antibodies showed their presence in the cell walls of the papillae of stigmas of A. triloba at very early developmental stages of the flowers, when they just start to open and their petals are green (15 d before anther dehiscence) (Fig.…”

“…Additionally, the secretion of AGPs correlates with the temporal window in which interactions between pollen tubes and the carpel tissues occur (Losada and Herrero, 2012, 2014, 2017; Pereira et al, 2015; Mizukami et al, 2016). However, the involvement of AGPs in the interaction between the carpel, germinating pollen grains, and growing pollen tubes has only been explored in a handful of species in the magnoliid clade (Mollet et al, 2002; Losada et al, 2014).…”