The family Brassicaceae includes a number of important species used as vegetables, oilseeds and medicine. The Brassica B-genome is significantly diverged from the A- and C-genomes, and species containing the B-genome possess many valuable agronomic and disease resistance traits. In this thesis, two populations of interspecific crosses between Brassica napus (AACC) and Brassica carinata (BBCC) were studied, and microsatellite (SSR) markers and genomic in situ hybridization (GISH) techniques were applied to characterize the B-genome chromosome introgressions in the advanced backcross populations and their effect on disease resistance, morphological and seed quality traits. A BC2S3 derived doubled haploid (DH) population was genotyped with 184 SSR markers and DH lines carrying stable B-genome chromosomal segments were identified. The GISH assay demonstrated that three of the 60 DHs were substitution lines in which the B-genome chromosome J13 was common to all. The lines with B-genome chromosomes, B+, were significantly different (P <0.01) from the lines without B-genome chromosomes, B- for some morphological and seed quality traits, such as days to flowering, days to maturity and erucic acid content. Further study revealed that resistance to Sclerotinia stem rot (caused by Sclerotinia sclerotiorum) has been inherited from the B or C genomes of B. carinata in some of the DH lines. Several BC3S1 families of another cross, derived from well-characterized BC3 plants containing introgressed B-genome chromosomes, were analyzed using SSR markers and the GISH assay to study the inheritance of the B-genome chromosome(s) and their association with morphological traits. This study revealed that the B-genome chromosomes tend to transfer through generations, either as whole chromosome(s) or as chromosomes without small terminal segments, as evidenced by low recombination frequencies (~ 0%) between the B and A/C-genome chromosomes. These results were supported by the GISH assay and chromosomes counts, and revealed that many of the BC3S1 lines were addition lines carrying extra B-genome chromosomes. / Plant Science

Oilseed crops are being widely evaluated for potential biodiesel production. Seed meal (SM) remaining after extracting oil may have use as a bioherbicide or organic fertilizer. Brassicaceae SM often contains glucosinolates that can hydrolyze into biologically active compounds. Jatropha curcas SM does not contain glucosinolates but contains curcin, a known phytotoxin (toxalbumin). A 14-d greenhouse study was conducted to determine how Sinapis alba (white mustard, WM), Brassica juncea (Indian mustard, IM), Camelina sativa (camelina) and Jatropha curcas (jatropha) applied to soil at varying application rates and incubation times affected seed germination and seedling survival of cotton [Gossypium hirsutum (L.)], sorghum [Sorghum bicolor (L.) Moench], Johnsongrass (Sorghum halepense), and redroot pigweed (Amaranthus retroflexus). Seed meals were analyzed for the presence of glucosinolates, and were applied at 0, 0.5, 1.0 or 2.5 percent (w/w) to Darco fine sand soil and incubated for 1, 7 or 14 d prior to planting. With the weed species, germination and survival was most reduced by 2.5 percent WM SM incubated 1d for Johnsongrass and 14 d for redroot pigweed. Cotton and sorghum seedlings showed strong negative responses to WM SM applications of 2.5 percent at any incubation time. All crops and weed species were most inhibited by 2.5 percent application with any SM, but incubation days varied. Seed meals of each species showed negative results dependent on the incubation day, but overall, WM and camelina SMs were most detrimental compared to IM and jatropha. A second greenhouse study was conducted to determine the availability of nutrients in SMs (WM and IM) to cotton and sorghum compared to inorganic fertilization. Seed meals were applied at 1.0 and 2.5 percent (w/w) and initially incubated for 35 days prior to planting. Emergence of both species was so poor that treatments were incubated for an additional 21 d and replanted. Application rates of 2.5 percent WM and IM SMs reduced sorghum heights and biomass, but only WM had a negative effect on cotton yield. However, the higher of the SM application rates provided greater levels of nutrients compared to the fertilized treatment and control. Results suggested that the type, rate, and timing of SM applications should be considered before land-applying SMs in organic cropping systems in order to successfully manage weeds while producing a profitable crop.

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Magistrantūros studijų darbu siekta nustatyti Leptosphaeria maculans ir L. biglobosa rūšių paplitimą ir pasiskirstymą ant įvairių rūšių bastutinių šeimos augalų (Brassica napus var. biennis, Brassica napus var. annua, Brassica oleracea var. capitata, Brassica oleracea var. italica) bei grybo surinkto iš skirtingų augalų rūšių augimo specifiką in vitro sąlygomis. / The master work was aimed to identify the occurrence and distribution of Leptosphaeria maculans and Leptosphaeria biglobosa species on the plants of various Brassica species (Brassica napus var. biennis, Brassica napus var. annua, Brassica oleracea var. capitata, Brassica oleracea var. italica) determine growth specificity of fungi on agar media, collected from different plant species, in in vitro conditions.