DEVELOPMENT OF HIGH YIELDING, DISEASE RESISTANT, YELLOW-SEEDED BRASSICA NAPUS
G. Rakow , J. Relf-Eckstein, J.P. Raney and R. Gugel
Agriculture and Agri-Food Canada, Saskatoon Research Centre,
107 Science Place, Saskatoon, SK, Canada, S7N 0X2
The development of yellow-seeded forms of Brassica napus has been a major focus of breeding research at AAFC Saskatoon for the last 20 years. The original yellow-seeded germplasm was low yielding, highly susceptible to blackleg disease, and the seed had a low oil content. In 1991, a cross was made between the yellow-seeded line YN90-1016 and the black-seeded, blackleg resistant Australian variety Shiralee, followed by a cross to the high oil content breeding lines N89-17 and N89-53. The two crosses were pedigree selected and five near isogenic yellow/black seeded pairs, consisting of 20 F5 derived sublines for each pair, were field tested from 1996 to 1998. Genetically stable, true breeding yellow-seeded lines were identified that had high oil content were resistant to blackleg and had high yield. The results of the field tests indicated that the yellow-seeded line YN90-1016 can successfully be used a source of the yellow seed trait in crosses with black-seeded germplasm to improve the agronomic performance and seed quality of yellow-seeded B. napus. Selected F7 lines of the yellow-seeded F4 line YN94-663, derived from the above cross, are presently used as parents in crosses with various black-seeded B. napus germplasm to produce commercially competitive, high yielding, high oil content, canola quality B. napus varieties for production in western Canada.
KEYWORDS: Oil content, seed quality, blackleg disease.
Research towards the development of yellow-seeded Brassica napus has been conducted for many years by various research groups around the world. The interest is in this work resulted from observations which compared the quality of the seed of yellow and brown-seeded forms of B. rapa (Stringam et al. 1974), B. juncea (Woods 1980) and later also B. carinata (Getinet et al. 1996). In all cases, yellow-seeded forms had significantly higher oil contents than their brown-seeded counterparts and the meal derived from yellow seeds had higher protein and lower crude fibre contents than that of brown seeds. Increases in oil content of Brassica oilseeds are of particular importance since oil is the most valuable component of the crop. However, in B. napus, no yellow-seeded types occur naturally. All yellow-seeded B. napus lines studied have been developed through interspecific hybridizations with yellow-seeded forms of B. rapa, B. juncea and B. carinata in various crossing combinations. Liu and his colleagues in China utilized yellow-seeded B. chinensis in crosses with B. napus to develop yellow-seeded B. napus (Liu 1983), and a first yellow-seeded variety “HUA-yellow No. 1” was registered for commercial production in 1990 (Liu, et al. 1991). The average oil content of this variety was 5-7% higher than that of black seeded varieties during four years of testing from 1983/84 to 1986/87. Shirzadegan and R`bbelen (1985) in Germany crossed a re-synthesized yellow-brown seeded B. napus, derived from an interspecific cross between light yellow-brown seeded B. oleracea ssp. alboglabra and yellow-seeded B. rapa, with the winter rape variety Quinta to develop yellow-seeded winter rape. Selections for yellow-seeded plants segregating from this cross were pedigree selected and the quality of the seed compared with that of black-seeded lines. They found that, on average, yellow seeded lines had lower oil contents than black seeded lines which was attributed to poor embryo development in yellow lines. Early research at AAFC Saskatoon in developing yellow-seeded B. napus also indicated that yellow-seeded lines, derived from interspecific crosses, had low oil contents, were highly susceptible to blackleg disease and were low yielding. The objective of this research was to determine if the yellow-seeded line YN90-1016 could be used as a donor of genes for yellow seed in crosses with black-seeded, blackleg resistant and high oil content lines to develop agronomically improved, high quality, yellow-seeded B. napus lines.
MATERIALS AND METHODS
The yellow-seeded B. napus line YN90-1016 was developed at the Saskatoon Research Centre from a complex cross involving the black-seeded, canola quality B. napus variety Regent, yellow-seeded B. rapa yellow sarson, yellow-seeded B. carinata and yellow-seeded B. juncea. Pedigree selection was used to isolate yellow-seeded plants in segregating generations after crosses which resulted in the identification of the true breeding, yellow-seeded line YN90-1016. In comparison to the black-seeded variety AC Excel, line YN90-1016 had 4.4% lower oil content, and its yield was only 75% of AC Excel (average of two yield tests, Saskatoon and Scott, Sask., 1996). In 1991, the yellow-seeded line YN90-1016 was crossed with the highly blackleg resistant Australian canola-quality B. napus variety Shiralee. The F1 was then crossed, as the male, with two canola-quality F4 lines, N89-17 and N89-53, selected for high oil content and derived from the cross between the Canadian B. napus varieties Midas and Westar. The oil contents of N89-17 and N89-53 were 3% absolute higher than that of the B. napus canola variety Legend in three years of multilocation co-operative tests in western Canada from 1993 to 1995. The F1 generation of the 3-way cross, consisting of 320 plants, was grown in the greenhouse and F2 seed produced. A total of 300 F2 progeny were grown in the field in a single row, 3-replicate nursery in 1993. Twenty nine “yellow-seeded” F2 progeny were selected and grown as F3 lines in a double row, 2-replicate nursery in 1994; and nine highest oil content progeny selected. The seed colour of these nine lines was a mixture of yellow and black seeds. Approximately 1000 yellow seeds were selected by hand from each of the nine bulk seed samples, and only these were further tested as F4 lines in 1995. Five hundred plants were individually harvested from each of the nine F4 lines, a total of 4,500 plants. Seven of the nine families segregated yellow and black seeded plants. Twenty yellow-seeded (hand selected for yellow seed) and 20 black-seeded plants were selected from each of the seven families, and progeny tested as F5 lines in a double-row, 2-replicate nursery in 1996, for a total of 280 progeny. A third replicate was planted for the production of 20 single plants (selfed) for further pedigree selection from each line. The nine F5 lines were also included in a 3-location yield test in 1996 to assess their agronomic potential. The row nursery was combine harvested, and the seed rated for colour and analyzed for oil and protein content. Five F5 families were selected based on overall family performance (colour, oil and protein). Five highest oil and five highest protein F5 lines were selected from both the yellow and black seeded sublines of each family. Seed of 20 single F5 plants produced in the third replicate of the 1996 nursery was then used for planting on F6 double-row, 2-replicate nursery in 1997. The 1997 nursery consisted of 18x5=90 highest oil lines and 18x5=90 highest protein lines for a total of 180 F6 lines each from the yellow-seeded as well as the black-seeded near isogenic sublines of each family for a total of 1800 lines, excluding checks. The nursery rows were combine harvested and the seed analyzed for seed colour, oil and protein. A 5% selection was applied to each group (oil and protein, yellow and black) to reduce the total number of lines to 100 which were tested in five, 4-replicate yield tests at three locations in 1998.
We present here the results of the 1997 and 1998 field tests for seed colour, oil content and yield of near-isogenic yellow/black seeded lines and compare their performance with that of the yellow-seeded parent line YN90-1016 and the average of the high oil content parents N89-17 and N89-53 (Table 1). The seed colour of the yellow-seeded lines ranged from –14 for YN94-669 to –23 for YN94-660 and YN94-670 in 1997. There was some improvement in seed colour as the result of selection for yellow
Table 1. Average seed colour, oil content and yield of near-isogenic yellow/black seeded lines of Brassica napus canola, Saskatchewan, Canada, 1997-98
|
|
Seed colour1 |
Oil content (%) |
Yield (rel.)6 |
||||||
|
Family |
1997 |
1998 |
Av. of lines 1997 1998 |
Dif. to YN90-10162 1997 1998 |
Dif. to N89-17/533 1997 1998 |
1998 |
|||
|
YN94-660 |
|
|
|
|
|
|
|
|
|
|
Yellow |
-234 |
-255 |
42.9 |
39.2 |
-0.1 |
-0.1 |
-5.1 |
-4.0 |
74 |
|
Black |
-2 |
-6 |
48.9 |
44.2 |
+5.9 |
+4.9 |
+0.6 |
+1.0 |
94 |
|
Difference |
|
|
-6.0 |
-5.0 |
|
|
|
|
-20 |
|
|
|
|
|
|
|
|
|
|
|
|
YN94-663 |
|
|
|
|
|
|
|
|
|
|
Yellow |
-19 |
-30 |
49.5 |
43.3 |
+4.2 |
+4.3 |
-1.1 |
+1.0 |
101 |
|
Black |
-2 |
-6 |
49.8 |
43.1 |
+4.5 |
+4.1 |
-0.8 |
+0.8 |
100 |
|
Difference |
|
|
-0.3 |
+0.2 |
|
|
|
|
+1 |
|
|
|
|
|
|
|
|
|
|
|
|
YN94-669 |
|
|
|
|
|
|
|
|
|
|
Yellow |
-14 |
-24 |
49.9 |
42.2 |
+4.1 |
+3.3 |
-0.8 |
-0.2 |
84 |
|
Black |
-4 |
-8 |
50.1 |
41.8 |
+4.4 |
+2.8 |
-0.6 |
-0.7 |
99 |
|
Difference |
|
|
-0.2 |
+0.4 |
|
|
|
|
-15 |
|
|
|
|
|
|
|
|
|
|
|
|
YN94-670 |
|
|
|
|
|
|
|
|
|
|
Yellow |
-23 |
-24 |
45.2 |
39.1 |
-0.7 |
+0.1 |
-5.5 |
-2.8 |
73 |
|
Black |
-1 |
-5 |
48.8 |
42.4 |
+2.9 |
+3.5 |
-1.9 |
+0.5 |
101 |
|
Difference |
|
|
-3.6 |
-3.3 |
|
|
|
|
-28 |
|
|
|
|
|
|
|
|
|
|
|
|
YN94-679 |
|
|
|
|
|
|
|
|
|
|
Yellow |
-15 |
-20 |
48.6 |
41.6 |
+2.6 |
+2.7 |
-1.5 |
-1.2 |
72 |
|
Black |
-2 |
-6 |
49.1 |
42.2 |
+3.1 |
+3.3 |
-1.0 |
-0.6 |
86 |
|
Difference |
|
|
-0.5 |
-0.6 |
|
|
|
|
-14 |
1 HunterLab reflectance colour measurements, high negative values indicate light coloured seed.
2 YN90-1016 = yellow-seeded parent
3 N89-17/53 = high oil content parents
4 Average of 180 lines, of which 90 were selected for high oil and 90 for high protein
5 Average of 10 lines, 3-location yield tests
6 Yield relative to standard check varieties AC Excel, Legacy, Defender
seed, particularly in YN94-663 with colour ratings of -19 in 1997 and –30 in 1998. Colour ratings of –25 to –30 represent bright yellow seeds. Oil contents of near-isogenic yellow/black pairs were variable. Yellow-seeded sublines of family YN94-660 had 6.0% (1997) and 5.0% (1998) lower oil
content than their black-seeded counterparts; and these oil contents were the same as those of the yellow-seeded parent YN90-1016. On the other hand, oil contents of yellow-seeded sublines of family YN94-663 were identical to those of their black-seeded counterparts, and similar to those of the high oil content parents N89-17/53. These results clearly indicated that the yellow seed trait of YN90-1016 is not associated with a lower oil content, and that YN90-1016 can therefore be used as a source of the yellow seed trait in crosses with black-seeded, high oil content B. napus lines to develop high oil content, yellow-seeded B. napus.
Seed yields of yellow-seeded lines were, on average, lower than those of their black-seeded near-isogenic counterparts in four of the five families studied. The average yield of yellow-seeded lines of family YN94-663 were, however, identical to those of black seeded sublines and to standard check varieties of B. napus canola used in official variety tests. This result indicated that the yellow seed colour in B. napus can be successfully combined with high oil contents and high seed yields which is a highly significant finding.
The yellow-seed characteristic in Brassica seed is of particular importance for the improvement of meal quality in canola (Simbaya et al. 1995). We initiated selection for protein content, and will also conduct meal fibre determinations and selections in this material. The results of these studies will be reported elsewhere.
This project was financially supported, in part, by grants from Canodev Inc., a subsidiary of the Saskatchewan Canola Development Commission, Saskatoon, Canada, and by the Matching Investment Initiative of the Government of Canada. The technical assistance of D. Rode,
D. Hennigan and G. Serblowski is greatly acknowledged.
Getinet, A., Rakow, G. and Downey, R.K. 1996. Agronomic performance and seed quality of Ethiopian mustard in Saskatchewan. Canadian Journal of Plant Science, 76:387-392.
Liu, H.L. 1983. Studies on the breeding of yellow seeded Brassica napus L. Proceedings of the 6th International Rapeseed Congress, Paris, France, Vol. 1: 637-641.
Liu, H.L., Han, J.X. and Hu, X.J. 1991. Studies on the inheritance of seed coat colour and other related characteristics of yellow seeded Brassica napus. Proceedings of the 8th International Rapeseed Congress, Saskatoon, Canada, Vol. 5: 1438-1444.
Shirzadegan, M. and R`bbelen, G. 1985. Influence of seed colour and hull proportions on quality properties of seeds in Brassica napus L. Fette, Seifen, Anstrichmittel, 87: 235-237.
Simbaya, J., Slominski, B.A., Rakow, G., Campbell, L.D., Downey, R.K. and Bell, J.M. 1995. Quality characteristics of yellow-seeded Brassica seed meals: protein, carbohydrates and dietary fibre components. Journal of Agricultural and Food Chemistry, 43: 2062-2066.
Stringam, G.R., McGregor, D.I. and Pawlowski, H.S. 1974. Chemical and morphological characteristics associated with seed coat colour in rapeseed. Proceedings of the 4th International Rapeseed Congress, Giessen, Germany, pp. 99-108.
Woods, D.L. 1980. Association of yellow seed coat colour with other characteristics in mustard (Brassica juncea). Eucarpia Cruciferae Newsletter, 5: 23-34.