Productivity of Indian mustard, an important oilseed crop of India, is affected by several pathogens. Among them, the hemibiotroph Sclerotinia sclerotiorum, which causes sclerotinia rot disease, is the most devastating fungal pathogen causing up to 90% yield losses. The availability of host resistance is the only efficient approach to control and understand the host–pathogen interaction. Therefore, the present investigation was carried out using six Indian mustard genotypes with contrasting behavior towards sclerotinia rot to study the antioxidant resistance mechanism against S. sclerotiorum. The plants at post-flowering stage were inoculated with five-day-old pure culture of S. sclerotiorum using artificial stem inoculation method. Disease evaluation revealed significant genotypic differences for mean lesion length among the tested genotypes, where genotype DRMR 2035 was found highly resistant, while genotypes RH 1569 and RH 1633 were found highly susceptible. The resistant genotypes had more phenolics and higher activities of peroxidase, catalase and polyphenol oxidase which provide them more efficient and strong antioxidant systems as compared with susceptible genotypes. Studies of antioxidative mechanisms validate the results of disease responses.

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Sclerotinia stem rot is one of the utmost important disease of mustard, causing considerable losses in seed yield and oil quality. The study of the genetic and proteomic basis of resistance to this disease is imperative for its effective utilization in developing resistant cultivars. Therefore, the genetic pattern of Sclerotinia stem rot resistance in Indian mustard was studied using six generations (P1, P2, F1, F2, BC1P1, and BC1P2) developed from the crossing of one resistant (RH 1222-28) and two susceptible (EC 766300 and EC 766123) genotypes. Genetic analysis revealed that resistance was governed by duplicate epistasis. Comparative proteome analysis of resistant and susceptible genotypes indicated that peptidyl-prolyl cis-trans isomerase (A0A078IDN6 PPIase) showed high expression in resistant genotype at the early infection stage while its expression was delayed in susceptible genotypes. This study provides important insight to mustard breeders for designing effective breeding programs to develop resistant cultivars against this devastating disease.

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The present investigation was carried out to evaluate the nutritional potential of five different Indian mustard genotypes. Fatty acid composition was determined in the oil, whereas seed meal was analyzed for limiting amino acids (tryptophan and methionine), protein content, glucosinolate content and antioxidant potential (DPPH free radical scavenging activity, total antioxidant activity and iron chelating activity). The monounsaturated fatty acids (MUFA) were found to be maximum in RH 0749 (58.70 %) followed by RH (OE) 0801 (48.91 %), JM 6011 (47.03 %), EC 597328 and EC 597340 (45.77 %). Polyunsaturated fatty acids (PUFA) were observed maximum in EC 597340 (47.45 %).Glucosinolate content ranged from 42.80 (EC 597328) to 79.79 μmole/g defatted seed meal (EC 597340). The methanolic seed meal extract exhibited a concentration dependent elimination of DPPH free radicals. All the five genotypes showed about 50 % inhibition in 3.0 mg of dry seed meal. The highest total antioxidant activity (20.41mg/g) and metal ion chelating activity (32.58 %) was observed in RH 0749. Protein content varied from 33.57 [RH (OE) 0801] to 38.01 % (RH 0749). Maximum methionine and tryptophan content were recorded in RH 0749 (0.99 and 1.01 g/100g protein, respectively). Thus, RH 0749 was observed as a potent variety in terms of total antioxidant activity, metal ion chelating activity, protein content, methionine and tryptophan content.

IntroductionIndian mustard (Brassica juncea) is a naturally autogamous species, yet in this crop frequent out-crossing occur which varies from 5 to 30% depending upon the environmental conditions and random variation of pollinating insects. Cytologically Indian mustard is an amphidiploid (2n=36), derived from interspecific cross of Brassica campestris (2n=20) and Brassica nigra (2n=16) followed by natural chromosome doubling. These relationships have been confirmed by the artificial synthesis of amphidiploids species by hybridizing basic diploid species and also by analysis of chloroplast and mitochondrial DNA restriction pattern of basic and amphidiploids International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 6 Number 5 (2017) pp. 942-953Journal homepage: http://www.ijcmas.comHalf diallel analysis of eight parents was carried out to identify the high heterotic crosses and their relationship in terms of general and specific combining ability (gca & sca) in Brassica juncea L. Czern and Coss. Mean squares due to parent v/s crosses were also significant for all the traits which depicted presence of heterosis for all the traits, except for days to maturity, plant height, siliquae on main shoot, number of seeds/siliqua, siliqua length and oil content in timely sown condition and for plant height, number of primary branches per plant, siliqua on main shoot and 1000 seed weight in late sown condition. The heritability in narrow-sense showed the prevalence of additive variance for siliqua length, days to maturity, number of primary branches per plant in late sown condition, while for other traits an appreciable proportion of total variance was non-additive in both the environments. In the present study, an overall appraisal of GCA effects revealed that RH0735 and BPR349-9 in normal environment and RH0116 and RH0555A in late sown environment were good general combiner for majority of the characters. High GCA effects are related to additive gene effects or additive x additive interaction which represent the fixable genetic component of variation. Hence these parents could be efficiently used for exploiting seed yield. For seed yield the crosses RH8814 x RH0555A, RH0644 x BPR543-3 and BPR349-9 x RH0644 in timely sown condition and crosses RH0555A x RH0644, RH0735 x RH0116 and BPR349-9 x RH0644 were identified as promising on the basis of their high per se performance and with high significant SCA effects. These crosses could be extensively used in breeding programme to develop superior segregants and the parents involved may be converted to well adapted cytoplasmic male sterile or restorer lines in further breeding programmes.

Understanding the mode of gene action that controls seed yield and Sclerotinia stem rot resistance in Indian mustard is critical for boosting yield potential. In a line × tester mating design, ten susceptible lines and four resistant testers were used to conduct genetic analysis. The significance of general combining ability (GCA) and specific combining ability (SCA) variances revealed that both additive and non-additive gene actions were involved in the inheritance of Sclerotinia stem rot resistance and yield attributing traits. In addition to 1000-seed weight and number of primary and secondary branches/plant, the genotypes RH 1569 (line) and DRMR 2035 (tester) appeared to be the strongest general combiners for Sclerotinia stem rot resistance. RH 1657 × EC 597317 was the only cross among several that demonstrated a significant desired SCA value for Sclerotinia rot resistance. Regarding SCA effects for yield and component traits, the cross RH 1658 × EC 597328 performed best, with a non-significant but acceptable negative SCA effect for resistance. DRMR 2035, RH 1222-28, RH 1569, RH 1599-41, RH 1657, RH 1658, and EC 597328 are promising genotypes to use as parents in future heterosis breeding and for obtaining populations with high yield potential and greater resistance to Sclerotinia stem rot disease in Indian mustard, based on GCA effects of parents, per se performance, and SCA effects of hybrids. Days to 50% flowering, number of primary branches/plant, main shoot length, and 1000-seed weight all had a high genotypic coefficient of variability (GCV), broad-sense heritability (h2bs), and genetic advance as percent of the mean (GAM) values, as well as significant and desirable correlations and direct effects on seed yield. As a result, these traits have been recognized as the most critical selection criterion for Indian mustard breeding programs.