Development of asparagus microspores in vivo and in vitro is influenced by gametogenic stage and cold treatment |
| |
Authors: | Mingsheng Peng Asma Ziauddin David J Wolyn |
| |
Institution: | (1) Department of Horticultural Science, University of Guelph, N1G 2W1 Guelph, Ontario, Canada |
| |
Abstract: | Summary Development of asparagus microspores in cold-treated buds of varying sizes and shed microspores from these buds in in vitro culture were observed cytologically for the G459 genotype. Before cold pretreatment, more than 75% of the microspores in
flower buds of the 1.4–1.6, 1.7–1.9, 2.0–2.2, 2.3–2.5, and 2.6–2.8 mm size classes were at the early-, mid-, late-uninucleate,
early-, and late-binucleate stages, respectively. After 7 d in cold treatment, percentages of microspores at different stages
changed in all flower buds. Most notable was the appearance of binucleate microspores resulting from symmetric rather than
asymmetric division. For flower buds of 1.7–1.9, 2.0–2.2, and 2.3–2.5 mm size classes, 4.9%, 27.2%, and 11.4% of the microspores
had divided symmetrically, respectively. When microspores from buds of each size category were cultured in androgenesis induction
medium, only microspores completing symmetric pollen mitosis I during cold treatment were observed to divide further, and
calluses were only obtained from microspores of flower bud size classes where symmetric divisions were observed after several
days of cold treatment. Significant correlations existed among microspore callus yield, the percentage of late-uninucleate
microspores in vivo before cold treatment, and the frequency of symmetric pollen mitosis I after 7 d of cold treatment. Consequently, asparagus
microspore androgenesis may occur through one developmental pathway, where a symmetric first mitotic division is a prerequisite
for continued development. |
| |
Keywords: | asparagus microspore androgenesis microspore development pollen mitosis I microspore callus |
本文献已被 SpringerLink 等数据库收录! |
|