Interspecific hybridization between diploid Fagopyrum
esculentum and tetraploid F. homotropicum
Yingjie Wang1, Rachael Scarth2, and Clayton Campbell1
1Kade Research Ltd., 135 13
Street, Morden, Manitoba, Canada R6M 1E9; and 2Department of Plant Science, University of
Manitoba, Winnipeg, Manitoba, Canada R3T 2N2.
Can. J. Plant Sci. 85: 41-48
The wild diploid species Fagopyrum homotropicum (2n
= 2x = 16) has been used for buckwheat improvement, but, prior to
this study, the tetraploid form (2n = 4x = 32) had not been
hybridized with the cultivated species F. esculentum. The objective of
this study was to hybridize F. esculentum with tetraploid F.
homotropicum to increase the genetic variability. Forty-one interspecific F1 hybrids were obtained through ovule rescue in vitro,
with hybridity confirmed using morphological characters, chromosome numbers (2n
= 3x = 24) and DNA analysis. The F1 plants were mainly sterile. However, seven seeds were set spontaneously
on two hybrid plants, and a large number of seeds were obtained after
colchicine treatment. The F2 plants were
divided into two groups based on chromosome numbers and morphology. The first
group was hexaploid plants (2n = 6x = 48) or hypohexaploid plants
(2n = 44-46), partially fertile with “gigas” features including
increased height, dark green leaves, and large seeds with thick seed hulls. The
second group of plants was diploid (2n = 2x = 16) (one plant had
17 chromosomes), with normal growth and fertility, and a combination of
characters from both parents, indicating that genetic recombination had occurred
during chromosome elimination. The diploid group was superior to the hexaploid
group for use in buckwheat breeding programs due to the desirable characters
and the ease of crossing. This is the first report of interspecific
hybridization using different ploidy levels in the Fagopyrum genus.
Key words:
Buckwheat (F. esculentum; F. homotropicum), interspecific
hybridization, breeding, tetraploid, diploid, hexaploid, fertility
© 2005 Agricultural Institute of Canada