Transcript Poster CSSA Mukhlesur Rahman

Inheritance of seed coat color of Ethiopian mustard
(Brassica carinata A. Braun)
Mukhlesur Rahman, Muhammad Tahir1
Department of Plant Science, North Dakota State University, Fargo, ND 58105, USA
1 Department of Plant Science, University of Manitoba, Winnipeg, Manitoba, Canada
INTRODUCTION
RESULTS & DISCUSSION
Brassica carinata A. Braun, known as Ethiopian mustard is an
amphidiploid (2n=34, BBCC) originated from natural hybridization
between two diploid species, Brassica nigra (L.) Koch (2n=16, BB) and
Brassica oleracea L. (2n=18, CC) (U, 1935). This species is more
compatible with the disease-, pest- and drought-tolerant in nature
(Getinet et al., 1996) and could be grown where cultivated rapeseed (e.g.
B. napus) is not well adapted. Moreover, B. carinata is resistant to
blackleg, white rust and alternaria leaf spot which are major diseases
for B. napus (Warwick et al. 2006).
Yellow seeded Brassica have an advantage over the dark-seeded
ones since them resulting in higher oil content in the seed. The meal
from yellow seeds contains lower dietary fiber, lower antinutritional
compound and higher protein content (Bell, 1993). Cultivated varieties
of B. carinata are mostly brown seeded, however, yellow seeded
germplasm are also available which could be used for agronomical
improvement in breeding program. Therefore, B. carinata could be
improved by the development high yielding yellow seeded germplasm.
Seed coat color in B. carinata displayed primarily maternal
inheritance. Seed coat color varied from yellow to yellow-brown and
brown (Figure 1). The yellow-brown color is darker than the parental
yellow, is the result of incomplete dominance of the yellow over brown
in heterozygous condition. Monogenic inheritance was found for seed
coat color gene, with yellow color trait was dominant over brown color
trait. The dominant nature of yellow seed coat color of B. carinata is in
contrast to many previous reports in B. napus, B. juncea, B. rapa where
the yellow seed was being identified as a recessive trait. The dominant
nature of the yellow seed trait in B. carinata has been explained as an
interaction between seed coat color gene and dominant repressor (Rp)
gene. The Rp gene repress the function of seed coat color gene
resulted translucent and colorless seed coat i.e. yellow seed in B.
carinata (Getinet et al., 1997). Absence of the repressor gene will allow
the seed coat color gene to be functioned for synthesis of seed coat
pigments in the brown seed of B. carinata. The development of
molecular marker for seed coat color gene/or repressor gene is in
progress (Figure 2).
OBJECTIVES
The objectives of this study were to describe the seed coat color
inheritance and to develop high seed yield yellow seeded B. carinata
germplasm. An attempt has been taken to develop molecular marker for
seed coat color gene to facilitate marker assisted selection for seed coat
color in B. carinata breeding programs.
Brown parent
MATERIALS AND METHODS
Plant materials
The pure breeding brown seeded cultivar ‘ACC-8’ and the pure
breeding yellow seeded cultivar ‘ACC-9’ of B. carinata were collected
from Dr. M.A. Malek, Bangladesh Institute of Nuclear Agriculture,
Mymensingh, Bangladesh and were selfed for three generations.
Crosses and reciprocal crosses were made between the brown and the
yellow seeded lines. The F1, F2 and F3 plants were grown in the green
house of the Department of Plant Science, University of Manitoba,
Canada, and Department of Plant Science, North Dakota State
University, USA. Backcross progeny were produced by crossing the F1
plant with the respective yellow seeded and brown seeded parental
lines. The seed coat colors were classified into three groups, such as
yellow, yellow-brown and brown (Figure 1). Chi-square (χ2) goodness of
fit tests was used to check expected versus observed phenotypic
segregation ratios for F2 and BC1 data.
RESULTS
F2 Populations
ACC-8 x ACC-9
ACC-9 x ACC-8
Total
Segregation ratio
Yellow/
Brown
3:1
Yellow-brown seed
χ2
df
110
69
179
42
26
68
BC1 Populations
(ACC-8xACC-9)xACC-8
(ACC-8xACC-9)xACC-9
Total
53
85
129
F1 seed
F2 seed
F3 seed
F3 seed
F3 seed
Figure 1. Seed coat color segregation in different F2 [(ACC-8 x ACC-9)] and BC1
[(ACC-8 x ACC-9) x ACC-8] populations of B. carinata crosses.
Figure 2. Development of SSR marker for seed coat color gene (in progress).
Table 1: Segregation ratio and Chi-square tests for seed coat color in the F2
and BC1 populations of crosses and reciprocal crosses of brown seeded and
yellow seeded B. carinata cultivars.
Populations
Yellow parent
44
0
53
0.561
0.284
1
1
P
0.3-0.5
0.5-0.7
1:1
χ2
df
P
0.844
1 0.3-0.5
CONCLUSIONS
Monogenic inheritance with yellow seed color dominant over brown
seed color in B. carinata has been identified in this research. A dominant
repressor gene is present in the yellow seeded parent which blocked the
function of seed coat color synthesis genes.
REFERENCES
Bell, J.M. 1993. Factors affecting the nutritional value of canola meal: A review. Can. J.
Anim. Sci. 73:679-697.
Getinet, A., Rakow, G. and Downey, R.K. 1996. Agronomic performance and seed quality
of Ethiopian mustard in Saskatchewan. Can. J. Plant Sci. 76: 387–392.
Getinet A. and Rakow G. 1997. Repression of seed coat pigmentation in Ethiopian
mustard. Can. J. Plant Sci. 77: 501–505.
U, N. 1935. Genome-analysis in Brassica with special reference to the experimental
formation of B. napus and its peculiar mode of fertilization. Japan J. Bot. 7:389–452.
Warwick, S.I., Gugel, R.K., McDonald, T. and Falk, K.C. 2006. Genetic variation of
Ethiopian mustard (Brassica carinata A. Braun) germplasm in western Canada.
Genet. Resour. Crop Evol. 53: 297–312.