An American company that supplies premium quality hybrid vegetable seed to commercial growers in the southern part of the US, Mexico, and Central America sought an assessment of the market potential in the Northwest region of Mexico by identifying land area and production concentrations of vegetables by location, crop, and cultivation method, whether open-field, greenhouse, or shade house. Data on the cultivated area of four states in the Northwest region of Mexico was collected for 12 crops of interest for the period of 2003-2012 from secondary sources. Data was entered into a statistical software program to complete frequency distribution charts of each state by crop and cultivation method to determine crop concentrations. Trend data of cultivated area was also analyzed to see changes in cultivation methods over a 10 year period and estimates were made by for NW Mexico through 2017. An analysis of vegetable production in Northwest region of Mexico showed open-field cultivated area was heavily location specific with near monocultures present, especially in the state of Sinaloa. Two-thirds of the crops had a substantial portion of their cultivated area (35-80%) occurring in one place, with bell pepper, onion (green), spinach, and cucumber having a dominant percentage (80-100%) of their cultivation occurring only in Sinaloa. Although it made up a small percentage of overall cultivated area, the majority of protected culture cultivation was also located in Sinaloa, and was shown to have grown rapidly since being introduced or first appearing in government data sources in 2003. With open-field cultivation giving way to more technologically advanced cultivated methods of protected culture, and with the majority of protected culture and open-field export farming taking place in Sinaloa, further input suppliers’ marketing efforts should be concentrated there.

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.

published_or_final_version / abstract / toc / Botany / Doctoral / Doctor of Philosophy

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Canola (Brassica napus) oil has immense economic value due to its use as food. The production of biodiesel has led to the recent increase in the demand for canola oil, and further reinforced the need to improve the oil content and composition of canola seeds. The content and quality of canola oil is dependent on the process of fatty acid biosynthesis and accumulation of triacylglycerols (TAGs) during seed development. The biochemical pathways leading to the synthesis of fatty acids and TAGs are thoroughly understood, and many of the genes encoding the metabolic enzymes involved in this pathway have been isolated and functionally characterized. Despite comprehensive understanding of fatty acid and TAG biosynthesis, alternate factors and genes involved in the modification of seed oil content and composition are being investigated. This has initiated a new sector of research focusing on a series of transcription factors: LEAFY COTYLEDON1 (LEC1), LEAFY COTYLEDON2 (LEC2), FUSCA3 (FUS3) and WRINKLED1 (WRI1), which play a key role during embryo and seed development. Previous studies in Arabidopsis have demonstrated that the noted transcription factors influence the synthesis and accumulation of oil during seed development. These findings have prompted the design of two studies with the objective of further characterizing the role of these genes. In the first study, a homolog of Arabidopsis LEC1 was isolated from Brassica napus (Bn) microspore derived embryos. BnLEC1 contained the same distinct features identified in LEC1 genes from other plant species. BnLEC1 was inserted into an expression vector, which was subsequently used to transform Arabidopsis plants. The transgenic lines were characterized by differences in seed oil composition, and one line showed a reduction in the number of seeds counted per silique. Expression analysis revealed that the transgene was not expressed in the transgenic lines. To account for the discrepant findings, the possibility of endogenous gene silencing mechanisms suppressing transgene expression has been discussed. As an extension of this research, a second study assessed the differential expression of LEC1, LEC2, FUS3 and WRI1 in double haploid Brassica napus lines characterized by different levels of seed oil content. The expression level of the noted genes was determined at 7, 14, 21 and 28 days after pollination. Numerous changes in the transcript level were observed, but the trends were not consistent among high and low oil content lines.

The objective of this research was to determine the relationship between seedling root length and seed yield in spring canola. Field and growth room experiments were conducted using the same eight genotypes. In the field experiment, root length and root area had a strong positive relationship to seed yield with R2 values at the 1-2 leaf stage of 0.90 and 0.93, respectively. Shoot dry weight had a strong positive relationship to seed yield at the cotyledon stage, with an R2 of 0.99. In the growth room, root length was compared to short- and long-term seed yield. The R2 values when root length was compared to short- and long-term seed yield were 0.95 and 0.96, respectively.

The meristem genes SHOOT MERISTEMLESS (STM), CLAVATA1 (CLV1) and ZWILLE (ZLL) are essential for the formation and maintenance of the shoot apical meristem (SAM). As an extension of that work, this thesis examines the function of these genes during seed oil accumulation and microspore-derived embryogenesis. Using a transgenic approach it is demonstrated that only the over-expression of BnSTM increases the percentage of total seed oil and a reduction of glucosinolate (GLS) levels achieved by transcriptional regualtion. The over-expression of BnSTM also affected in vitro embryogenesis by increasing the number and quality of microspore-derived embryos (MDEs) in contrast to the MDEs down-regulating BnSTM. The MDEs with ectopic expression of BnSTM were found to regulate embryonic SAM by altering cytokinin synthesis, catabolism, perception and signaling. Taken together, these findings provide evidence for a novel function of BnSTM in promoting desirable changes in seed oil and GLS levels and enhancing in vitro embryogenesis.

Canola (Brassica napus) oil has immense economic value due to its use as food. The production of biodiesel has led to the recent increase in the demand for canola oil, and further reinforced the need to improve the oil content and composition of canola seeds. The content and quality of canola oil is dependent on the process of fatty acid biosynthesis and accumulation of triacylglycerols (TAGs) during seed development. The biochemical pathways leading to the synthesis of fatty acids and TAGs are thoroughly understood, and many of the genes encoding the metabolic enzymes involved in this pathway have been isolated and functionally characterized. Despite comprehensive understanding of fatty acid and TAG biosynthesis, alternate factors and genes involved in the modification of seed oil content and composition are being investigated. This has initiated a new sector of research focusing on a series of transcription factors: LEAFY COTYLEDON1 (LEC1), LEAFY COTYLEDON2 (LEC2), FUSCA3 (FUS3) and WRINKLED1 (WRI1), which play a key role during embryo and seed development. Previous studies in Arabidopsis have demonstrated that the noted transcription factors influence the synthesis and accumulation of oil during seed development. These findings have prompted the design of two studies with the objective of further characterizing the role of these genes. In the first study, a homolog of Arabidopsis LEC1 was isolated from Brassica napus (Bn) microspore derived embryos. BnLEC1 contained the same distinct features identified in LEC1 genes from other plant species. BnLEC1 was inserted into an expression vector, which was subsequently used to transform Arabidopsis plants. The transgenic lines were characterized by differences in seed oil composition, and one line showed a reduction in the number of seeds counted per silique. Expression analysis revealed that the transgene was not expressed in the transgenic lines. To account for the discrepant findings, the possibility of endogenous gene silencing mechanisms suppressing transgene expression has been discussed. As an extension of this research, a second study assessed the differential expression of LEC1, LEC2, FUS3 and WRI1 in double haploid Brassica napus lines characterized by different levels of seed oil content. The expression level of the noted genes was determined at 7, 14, 21 and 28 days after pollination. Numerous changes in the transcript level were observed, but the trends were not consistent among high and low oil content lines.