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The wild relatives of crops represent a rich reservoir of genes for introducing resilience to climate change into cultivated crops. To introgress genes from Sinapis alba, a wild relative of Brassicaceae, into Brassica juncea, a cultivated member of this family, we initially produced somatic hybrids between the two species and then produced a large number of backcross populations involving the two somatic hybrids (H1 and H2) with Brassica juncea. BC1 progeny were morphologically very similar. However, when they were challenge inoculated with a highly virulent Alternaria brassicae (ITCC No. 2542) culture under in vivo and in vitro conditions in two growing seasons, they showed wide variations in their disease reaction. Of the 40 BC1 lines tested in one season, 36 showed a resistant reaction. BC1F2 progenies derived from these resistant BC1 plants also showed resistance to Alternaria brassicae, indicating stable inheritance of the resistant phenotype. However, BC1F2 progenies showed a wide variation in morphological traits, including plant height, basal branching, leaf thickness, trichome density on leaves and stem. BC1 plants were examined by genomic in-situ hybridization (GISH) to determine their chromosome constitution. All five plants were found to possess 12 strong hybridization signals upon hybridization with a FITC-labeled S. alba-specific probe. GISH studies on BC1F2 plants indicated localized signals in addition to 12 full chromosome hybridization signals, suggesting alien introgressions into B. juncea that requires further validation. The BC2 generation was found to possess half of the haploid set of alien chromosomes. The BC1F2 and BC2 generations were further screened against A. Brassiceae and found to be resistant/tolerant. [ABSTRACT FROM AUTHOR]

Alternaria black leaf spot disease of oilseed mustard is a primary cause of yield penalty not only in India but also throughout the world. To assess the degree of tolerance, 47 Indian mustard (Brassica juncea) genotypes were evaluated based on the performance against the causal pathogen Alternaria brassicicola. Genotypes were divided into six tolerance groups including resistant, highly tolerant, moderately tolerant, moderately susceptible, susceptible, and highly susceptible, keeping the nonhost resistant Sinapis alba as resistant control. Genotypes EC399312 and PAB-9511 were found to be the most tolerant. Fourteen morphological traits were evaluated which revealed considerable morphological variability among the genotypes. A number of seeds/siliqua and 1000 seed weight were positively correlated with yield per plant. Insignificant negative correlations had been found among plant height, days to maturity, and disease resistance with yield per plant. Correlation data indicate that seeds/siliqua and siliqua on the main shoot can be highly effective for higher grain yield. Genetic diversity of all genotypes was evaluated using simple sequence repeats (SSR) markers. The genotypes were evaluated for polymorphisms after amplification with 41 SSR primer pairs. Nineteen SSR markers in total were found to be highly informative with a polymorphic information content value > 0.50. The evaluation of genetic similarity and cluster analysis together with disease resistance provides some useful guides for assisting plant breeders in selecting suitable genetically diverse parents for the crossing program as well as for the development of mapping population. [ABSTRACT FROM AUTHOR]

Sinapis alba possesses a number of desirable traits that can be employed to broaden genetic variability in Brassica oleracea or B. napus. Using transgenic B. oleracea (CC, 2n = 18) as paternal plants and non-transgenic S. alba (SS, 2n = 24) as maternal plants, 11 hybrid plants were successfully obtained by using a combination of ovary culture and embryo rescue, while 2 seedlings of the reciprocal cross were generated but lost during the propagation. The hybridity of these plants was confirmed by flower color and other agronomic characteristics, chromosome counting, and pollen viability. Most of the intergeneric F1 plants showed only one set each of S and C chromosome (SC, 2n = 21) and were male sterile, while a few plants were semi-fertile and had one set of S chromosomes but two sets of C chromosomes (CCS, 2n = 30). PCR, genomic Southern blotting and qRT-PCR for bar gene revealed that among the F1 hybrid plants only 9.1% was bar positive and could be forwarded to F2 and F3 generation. The majority of F3 plants obtained sufficient resistance to Alternaria brassicae. Thus, the generation of disease (A. brassicae) and herbicide (Bastar) resistant intergeneric hybrids was of importance for breeding program. The existence of bar gene in these intermediate materials will facilitate the identification of hybridity and transfer of S.alba traits into target genetic background. [ABSTRACT FROM AUTHOR]

In the last decade, the cabbage seedpod weevil ( Ceutorhynchus obstrictus (Marsham)) has become a major insect pest of canola ( Brassica napus L.) in Canada reducing seed yields up to 35%. Therefore, the benefits of developing weevil resistant germplasm to canola breeders and the industry would reduce input costs, pesticide use, environmental degradation and increase yield. Yellow mustard ( Sinapis alba L.) is resistant to C. obstrictus (CSPW), although the exact mechanism is not known (McCaffrey et al. ). A unique canola population was generated at the University of Guelph from a cross between B. napus and S. alba through embryo rescue and backcrossed to canola several times prior to double haploid (DH) production. Approximately one-half of this DH population had canola quality glucosinolate concentration (<16 μmol/g) and was used for further breeding. The hypothesis was that some DH progeny from this cross inherited resistance to CSPW from S. alba. Weevil infestation levels were assessed for the B. napus × S. alba BC2 and BC3 DH populations in the field over 7 years in Alberta where weevil pressure is strong to establish the resistant or susceptible status of these lines. The basic objectives for this study were to confirm field resistance in the B. napus × S. alba germplasm in Ontario and to identify any biochemical markers associated with resistance/susceptibility. Canola doubled haploid lines derived from BC2 or BC3 families were field screened for resistance (R) followed by chemical analysis of glucosinolates to detect biochemical polymorphisms correlated with CSPW resistance using High Performance Liquid Chromatography (HPLC). Two polymorphic peaks were found, one each, from extracts of upper cauline leaves and Stage 3 pod seed, with retention times of ~23 and 19 min, respectively. These HPLC peaks consistently correlated with larval infestation data and the peak differences between R and S DH lines were significant. Therefore, these two peaks can be considered as biochemical markers in this breeding germplasm and may play a role in rapid and early detection of CSPW resistance. [ABSTRACT FROM AUTHOR]

Researchers have conclusively shown that Sinapis alba (commonly known as yellow mustard) has many agronomic traits which would be beneficial if transferred to rapeseed ( Brassica napus L.). S. alba is resistant or tolerant to all major insect pests of Brassica crops in the Pacific Northwest region of the United States of America. It is also tolerant of high temperatures and drought stress, is shatter resistant and capable of high seed yield without the need for insecticides and herbicides. However, S. alba is considerably lower in oil content and lacks the high oil quality and seed meal quality of rapeseed (i.e. canola). This paper describes a combination of ovary culture and embryo rescue techniques used to develop fertile hybrid plants from the intergeneric cross between S. alba and B. napus . The hybrids were intermediate between both parents for presence of trichomes, leaf shape and color, seed size, pod shape, and seed oil content; showing expression of traits from both parental species. Hybrid plant tissue and seed contained all types of glucosinolate that exists in either B. napus or S. alba, at the same or higher level to the parental species. These hybrid crosses offer the potential for combining the desirable oil and glucosinolate qualities of B. napus with insect and disease resistance characters of S. alba. [ABSTRACT FROM AUTHOR]