Astract

Rapeseed-mustard is the second most important group of oilseed crops in India after groundnut. These crops account for 27.5% of the total oilseed production and the 13% of the gross cropped area in the country. Anti-nutritional factors in the oil and oilcake have limited its use and export. Reducing erucic acid in oil and glucosinolates in oilcake (00) is the prime breeding objectives in rapeseed-mustard improvement program in India. None of the available varieties have '00' character. Induced mutation studies at BARC has resulted in 13 stable lines having zero erucic acid and low glucosinolates. These lines were studied in M₆ and M₇ generations. These are early maturing and better yielding than the parent. Fatty acid profile showed that zero erucic acid lead to the increase in the content of desirable fatty acids like oleic (18:1) and linoleic acid (18:2). In addition, there is concomitant decrease in the linolenic acid (18:3). The glucosinolates level also decreased to low or zero. In this report, results on fatty acid profile, glucosinolate content along with yield and its contributing characters of the 13 lines will be presented.

Introduction

Rapeseed-mustard is the second most important group of oilseed crops in India after groundnut. It contributes nearly 27% of the total oilseed production and the 13% of the gross cropped area in the country. Antinutritional factors like erucic acid in oil and glucosinolate in oilcake restricted the use of oil and oilcake in meal and poultry respectively. A present released variety does not have the desired quality characters. Erucic acid content in the Indian cultivars is high averaging 49% compared to 25% in the European cultivars (Kirk and Hurlstone,1983). The amount of glucosinolate varies from 150-240 μmole/g of defatted meal (Bhadouria, 1990). Therefore reducing erucic acid in oil and glucosinolate in oilcake to zero (00) is the prime-breeding objective in repeseed-mustard improvement programme in India. Besides classical breeding, mutation breeding has demonstrated the plasticity of seed oil quality with significant alteration in fatty acid composition and no apparent detrimental effects on the crop agronomics (Robbelen,1990). Similar approach of the mutation breeding has resulted in the isolation of zero erucic acid and low glucosinolate mutant in B.napus (Jambhulkar er al 1998). In the present paper, studies on these lines in advance generation is presented.

Material and methods

Based on double zero nature, eighty-three single plants were selected in M₅ generation. Their plant to row progenies were advanced to M₆ generation. Their breeding behavior was recorded during crop growth. At maturity, data on yield and its contributing character was recorded on 10-15 plants each. Paper chromatography and Tes-tape method determined erucic acid and glucosinolate content respectively. Quantitative analysis of fatty acids was determined by Gas liquid Chromatography (Garces and Mancha, 1993).

Results

Out of 83 plant progenies, 40 were found to be true breeding for morphology. Remaining progenies were rejected. Near about 500 single plants were analysed for erucic acid and glucosinolate content. Erucic acid was absent in all the plants but segregation was observed for glucosinolate content. Among 40 lines, only 13 lines found to be true breeding for both zero erucic acid and zero glucosinolate. Data on only 7 line is presented in Table 1. Average single plant yield of these lines does not show significant difference over parent except line no. 96, 111, 393, 541 (Table 1). Their yield potentiality will be confirmed in next generation. The quantitative analysis of fatty acid composition in 13 lines confirmed zero erucic acid content. The level of oleic acid content was doubled and linoleic acid content was also increased. However, linolenic acid was reduced to approximately one third in most of the lines.

Discussion

Fatty acid composition of vegetable oil plays an important role to decide its quality. Rapeseed-mustard oil differ from most other vegetable oils in containing significant amount of long chain monoenoic fatty acids with 20 and 22 carbon atoms called eicosenoic and erucic respectively. High amount of erucic acid has industrial use while low content of the same makes it nutritious edible oil. Downey et al (1969) reported on the development of zero erucic acid varieties in B.napus. Kirk and Hurlstone (1983) isolated erucic acid line in B. juncea. as a potential oilseed crop for Australia.

All the plants in 13 lines in M₆ generation were devoid of erucic acid and glucosinolate indicated stability for the characters. This would be tested in the subsequent generation. In parent line, high amount of erucic acid is accompanied with low levels of oleic acid and linoleic acid. However, zero erucic acid in the mutant line has double oleic acid high linoleic acid content. This is expected results of alteration in the biosynthetic pathways of the main fatty acids which follows two directions from oleic acid, one towards erucic acid and other towards linoleic and linolenic acid (Jonsson aand Uppstrom,1980). Such alteration by induced mutation has also been reported in B.napus (Landge and Khalatkar,1996 )

Rapeseed-mustard meal, the remains left after oil has been extracted from the seed, contains about 40% protein on dry matter basis. But the high level of glucosinolate and their degradation product creat antinitritional and toxicity problem (Eggum et al, 1985a). Development of low or zero level varieties is one of the major objectives in quality improvement programme. In the present study, induced mutant with zero or trace amount of glucosinoltae could be isolated using gamma ray induce muatgenesis. Similar mutants with low level of glucosinolate wre isolated in B. napus (Landge and Khalatkar,1996).

References

1. Bhadouria S.S. 1996 Brief note on progress of research work at J.N.K.V.V. Morena for development of ‘0’ and ‘00’ varieties of rapeseed-mustard. Presented at ICAR-NDDB Meeting on ‘00’ mustrad Dec.2-3 1996 Anand.

2. Eggum B.O., Olsen O. and Sorenson H. 1985a Effect of glucosinolates on the nutritive value of rapeseed. In Advances in the production and utilization of cruciferous crops (ed. H.Sorenson), Martinus Nijhoft Publ. Dordrecht.pp.55-60.

3. Downey R.K., Craig B.M. and Young C.G.1969 Breeding rapeseed for oil and meal quality. J. Am. Oil Chem.Soc. 46 : 121-123

4. Garces R.and Mancha M. 1993 One-step lipid extraction and fatty acid methyl esters preparation from fresh plant tissues. Anal. Bioch. 211 : 139-143

5. Jonsson R. and Uppstrom B. 1986 Quality breeding in repeseed. In Svulof 1886-1986 Research and Results in Plant Breeding (ed. G.olsson) LTS Forlag, Stockholm, Sweden. pp 173-184

6. Jambhulkar, S.J., Kotwal, S.A., Vaidya, U.J., and Joshua, D.C. 1998 Development of early maturing '00' lines in Brassica napus using induced mutations. In DAE symposium on Induced mutations and molecular techniques in improving crop productivity and quality. Chennai. pp 14.

7. Landge S.P. and Khalatkar A.S. 1996 Induced mutations in Brassica Napus cv. Westar In Proc.2^nd International Crop Science Congress, Nov. 17-24 New Delhi India. pp 183

Table 1. Fatty acid composition of 7 B. napus selections and their single plant yield