Suspensor Development in the Nun Orchid, Phaius tankervilliae

Publisher Website
Google Scholar
Abstract
The suspensor of the Nun orchid (Phuiur trtnkenilliae) consists of a single cell, which originates as follows: after fertilization, the zygote divides once, unequally, giving rise to a smaller terminal cell and a larger basal cell. At the two-celled stage, a prominent cortical array of microtubules is present in the basal cell. The actin filaments are more centrally located within the cell having a perinuclear arrangement, and some actin material is also present at the micropylar end of the basal cell. After the basal cell divides one more time, the cell near the micropyle enlarges and differentiates into the suspensor cell. The enlargement of the suspensor results primarily from vacuolation. Characteristic organization of the cytoskeletal elements can be found at the time of cell enlargement. The actin filaments are localized in the cortical region of the cell, while the microtubules become internalized, forming a perinuclear array with exten- sions toward the poles of the cell. The final structural event in the development of the suspensor is the extension of the suspensor cell through the inner integument into the outer integument. At this stage, a cortical array of microtubules once again reappears. The cortical microtlibules of the suspensor near the embryo proper are arranged transversely while those near the tip portion of the suspensor are aligned parallel to the long axis of the cell. The actin filaments remain unchanged and appear as a netlike framework located in the cell cortex. As the embryo matures, the cytoskeletal elements become disorganized and defined structures cannot be discerned. Material and methods Although the structural characteristics of suspensors from different species have been detailed, little infor- mation is available about the cytoskeleton of the sus- Developing fruits of Phai~is tankewilliae (Banks ex pensor during its development. As the suspensor is 1'Herit) B1. were collected from greenhouse-grown plants normally firmly embedded within the seed coat, it is maintained at the South China Institute of Botany at Guang- difficult to isolate it from the seed. This might have zhou, China. Fruits were collected from May to August over limited the study of the suspensor to conventional mi- a 2-yr period. Approximately 50 developing fruits were gath- croscopy only. With the improvement in isolation tech- ered for this study. Seeds from freshly collected fruits were niques in conjunction with the use of confocal laser utilized for histological and immunological studies. About 60 seeds were processed from each fruit for microtubule and scanning microscopy, the study of the cytoskeleton of actin staining.

This publication has 0 references indexed in Scilit: