Regeneration of zygotic-like microspore-derived embryos suggests an important role for the suspensor in early embryo patterning.
The inaccessibility of the zygote and proembryos of angiosperms within the surrounding maternal and filial tissues has hampered studies on early plant embryogenesis. Somatic and gametophytic embryo cultures are often used as alternative systems for molecular and biochemical studies on early embryogenesis, but are not widely used in developmental studies due to differences in the early cell division patterns with seed embryos. A new Brassica napus microspore embryo culture system, wherein embryogenesis highly mimics zygotic embryo development, is reported here. In this new system, the donor microspore first divides transversely to form a filamentous structure, from which the distal cell forms the embryo proper, while the lower part resembles the suspensor. In conventional microspore embryogenesis, the microspore divides randomly to form an embryonic mass that after a while establishes a protoderm and subsequently shows delayed histodifferentiation. In contrast, the embryo proper of filament-bearing microspore-derived embryos undergoes the same ordered pattern of cell division and early histodifferentiation as in the zygotic embryo. This observation suggests an important role for the suspensor in early zygotic embryo patterning and histodifferentiation. This is the first in vitro system wherein single differentiated cells in culture can efficiently regenerate embryos that are morphologically comparable to zygotic embryos. The system provides a powerful in vitro tool for studying the diverse developmental processes that take place during the early stages of plant embryogenesis.
Supena
Ence Darmo Jaya
ED
Plant Research International, Wageningen University and Research Centre, PO Box 16, 6700 AA Wageningen, The Netherlands.
Winarto
Budi
B
Riksen
Tjitske
T
Dubas
Ewa
E
van Lammeren
André
A
Offringa
Remko
R
Boutilier
Kim
K
Custers
Jan
J
D019521:Body Patterning; D029688:Brassica napus / Q000196:embryology*; D047108:Embryonic Development; D010940:Plant Proteins; D021381:Protein Transport; D012639:Seeds / Q000378:metabolism*; D046509:Tissue Culture Techniques; D015053:Zygote / Q000378:metabolism*
D010940:Plant Proteins