New Zealand Journal of Botany abstracts
Levels of apomictic and amphimictic seed formation in a natural population of Coprosma robusta (Rubiaceae) in Riccarton Bush, Christchurch, New Zealand
P. B. Heenan
B. P. J. Molloy
Allan Herbarium
Landcare Research
P.O. Box 69
Lincoln 8152, New Zealand
R. A. Bicknell
Crop & Food Research
Private Bag 4704
Christchurch, New Zealand
C. Luo
Landcare Research
P.O. Box 69
Lincoln, New Zealand
Abstract Facultative autonomous apomictic seed formation has been identified in Coprosma robusta by flow cytometry. Twenty-one (84%) of the plants sampled produced some seeds with an embryo-to-endosperm ploidy ratio (2:4) consistent with autonomous embryo development from a single unreduced egg nucleus, and autonomous endosperm development from two unreduced polar nuclei. The average number of apomictic seeds produced in the population was about 15%. Remaining seeds have an embryo-to-endosperm ploidy ratio of 2:3, consistent with sexual reproduction. Dissections of individual apomictic seeds confirmed that the 4C peak occurs in the endosperm, the 2C peak in the embryo. In sexually derived seeds the embryo has a 2C peak and the endosperm is multiploid with 3C and 6C. In both apomictic and sexual seeds the woody endocarp has 2C and 4C peaks.
Keywords Rubiaceae; Coprosma; C. robusta; apomixis; flow cytometry; New Zealand flora
B02043 Received 30 May 2002; accepted 16 December 2002; published 11 June 2003
New Zealand Journal of Botany, 2003, Vol. 41: 287-291
0028-825X/03/4102-0287 $7.00 © The Royal Society of New Zealand 2003
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