🧬 Rapeseed-Mustard — Breeding Objectives

This lesson explains Brassica species relationships and the breeding path toward high-oil, canola-quality, and stress-resilient mustard cultivars.

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Origin and Species

The rapeseed-mustard group comprises several cultivated Brassica species of the family Brassicaceae. Indian mustard (Brassica juncea, 2n = 4x = 36, genome AABB) is the predominant oilseed Brassica in India, accounting for about 80% of the rapeseed-mustard area. Rapeseed (B. napus, 2n = 4x = 38, genome AACC) is widely grown in Europe and Canada. Other species include toria (B. rapa var. toria, 2n = 20, genome AA), yellow sarson (B. rapa var. yellow sarson), and black mustard (B. nigra, 2n = 16, genome BB). The genomic relationships among these species are described by the Triangle of U (U, 1935), which shows that the three amphidiploid species (B. juncea, B. napus, B. carinata) originated from hybridization between pairs of the three diploid species (B. rapa, B. nigra, B. oleracea). India is the third largest rapeseed-mustard producer after Canada and China, with Rajasthan being the leading state.

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Breeding Objectives

The primary breeding objectives include high oil content (target >44% in B. juncea), as current Indian mustard varieties average 38-42% oil content. Low erucic acid (<2%) and low glucosinolate (<30 micromoles/g seed) content are quality targets for producing canola-quality oil and meal, respectively. Erucic acid (a C22:1 fatty acid) is considered undesirable for human consumption as it is associated with cardiac lipidosis. Development of double-zero (00) or canola quality varieties with both low erucic acid and low glucosinolates is a major objective. Yellow seeded types are preferred as they have thinner seed coats, higher oil content, better meal quality, and more protein compared to brown/black seeded types. Disease resistance targets include Alternaria blight (Alternaria brassicae), white rust (Albugo candida), downy mildew (Hyaloperonospora parasitica), and Sclerotinia stem rot (Sclerotinia sclerotiorum). Aphid tolerance (Lipaphis erysimi) through antixenosis and non-preference mechanisms is important.

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Breeding Methods and Achievements

Indian mustard is predominantly self-pollinated, while B. napus exhibits variable outcrossing (20-30%). Breeding methods include pedigree selection, backcross breeding (especially for quality trait introgression), and mutation breeding. Hybrid development using CMS systems (Ogu-INRA, Mori, and tour cytoplasms) and self-incompatibility is a major thrust area. The first CMS-based mustard hybrid NRCHB 506 was developed at DRMR, Bharatpur. Notable varieties include Pusa Mustard 25 (early, high yielding), Pusa Bold (bold seeded), RH 749 (Rajasthan), and Pusa Double Zero Mustard 31 (canola quality B. juncea). The Directorate of Rapeseed-Mustard Research (DRMR), Bharatpur, Rajasthan, coordinates the national programme. Marker-assisted introgression of low erucic acid genes (from zero-erucic B. juncea lines) and disease resistance QTLs is accelerating varietal development.

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Summary Cheat Sheet

Quick Recall Points

• Indian mustard is B. juncea (AABB, 2n=36).
• Canola quality requires low erucic acid and low glucosinolates.
• Triangle of U is central for Brassica genomic relationships.

Exam Traps

• High oil % alone does not mean canola quality.
• Species identity (B. juncea vs B. napus) must be matched with genome formula.

References

2 sources • [1] [2]

[1]

Breeding Oilseed Brassicas

Book

[2]

ICAR rapeseed-mustard research updates

Official