CROSS APPLICABILITY OF RAPD MARKERS FOR LINOLENIC ACID CONTENT IN DOUBLED HAPLOID POPULATIONS OF RAPESEED (BRASSICA NAPUS)
Department of Plant Science, University of Manitoba, Winnipeg MB, CANADA
Although molecular markers for linolenic acid content have been identified by several research groups, the cross applicability of these makers has not been established. In order to provide optimal flexibility in MAS or a breeding program, a marker that is effective in lines derived from different crosses would be most useful. The objective of this research is to test the applicability of 4 RAPD markers in 4 different doubled haploid populations of B. napus.
The quality of the oil derived from rapeseed (Brassica napus and Brassica rapa) is determined by its fatty acid composition. Although, rapeseed oil is considered superior due to its low levels of saturated fatty acids, its relatively high level of linolenic acid is a drawback. Oil containing high levels of linolenic acid (18:3), a polyunsaturated fatty acid, is prone to oxidative rancidity and requires partial hydrogenation if used for commercial frying. Given this instability and the health risks associated with hydrogenated oils, it would be beneficial to breed for rapeseed cultivars with low linolenic acid levels. Breeding for low linolenic acid rapeseed is, however, complicated by the fact that the trait has complex genetic inheritance and is highly influenced by the environment. Molecular markers that tag for the trait appear to hold potential as an accurate and environmentally insensitive tool for use in breeding for low linolenic acid rapeseed.
While several research groups have identified various markers for linolenic acid content, the cross applicability of these markers has not been established. Clearly, markers that are effective in lines derived from different crosses would be ideal. A cross-applicable marker would provide a breeder with greater flexibility in a MAS (Marker Assisted Selection) breeding program. RAPD (Random Amplified Polymorphic DNA) markers identified by 2 research groups will be tested in 4 different DH derived populations of rapeseed (B. napus).
Doubled haploid (DH) populations
1. University of Guelph – LL09 x Reston
2. University of Wisconsin – Stellar (derived line) x Major
3. University of Manitoba – 94LL57 x Jewel
4. University of Manitoba – 94LL65 x Quantum
Lines within each population will be classified according to linolenic acid content - low (<3.5%), intermediate (3.5 – 7%), high (>7%).
RAPD primer sequences (5’ -> 3’)
1. RM350 - TGA CGC GCT C (Rajcan et al., 1999)
2. RM574 - GCC AGA CAA G
3. D081310 – GTG TGC CCC A (Jourdren et al., 1996)
4. L131150 - ACC GCC TGC T
These primers, previously identified as markers for linolenic acid content, will be individually tested in select high, intermediate and low lines from each population to determine cross applicability. Standard PCR and RAPD protocols will be used.
RESULTS & DISCUSSION
Research is currently underway. Results for the four DH populations will be presented.
-Dr. Istvan Rajcan (University of Guelph) and Dr. Tom Osborn (University of Wisconsin) for the use of their DH germplasm
-NSERC for project funding
1. Jourdren, C. et al. 1996 Euphytica 90: 351-357
2. Rajcan, I et al. 1999 Euphytica 105: 173 - 181