New Zealand Journal of Botany abstracts

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Spontaneous hybrids between naturalised populations of pak choi (Brassica rapa var. chinensis) and wild turnip (B. rapa var. oleifera) from near Ashburton, Canterbury, New Zealand

P. B. Heenan
M. I. Dawson

Allan Herbarium
Landcare Research
P.O. Box 69
Lincoln 8152, New Zealand

Abstract  Natural intraspecific hybrids between Brassica rapa var. chinensis and B. rapa var. oleifera are documented and analysed from a single wild population near Ashburton, Canterbury, New Zealand. Principal Component Analysis of 13 leaf morphological characters identified putative F₁ hybrids that are intermediate between the parents. A second group of plants that are highly variable probably represent F₂ and/or backcross hybrids. The putative parents and the hybrid plants all had high percentages of pollen stainability, indicative of normal meiosis. Flow cytometry data are consistent with the hybrid plants being derived from intraspecific B. rapa crosses. This study has shown that closely related intraspecific taxa in Brassica can form natural hybrid populations in New Zealand and, therefore, gene flow between such closely related taxa can readily occur.

Keywords  Brassicaceae; Brassica; B. rapa var. chinensis; B. rapa var. oleifera; hybrids; gene flow; morphology; phenetics; flow cytometry; pollen viability; naturalised flora

B05021; Received 16 May 2005; accepted 1 August 2005; Online publication date 26 September 2005
New Zealand Journal of Botany, 2005, Vol. 43: 817–824
0028–825X/05/4304–0817 © The Royal Society of New Zealand 2005

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