Fenugreek (Trigonella foenum-graecum L.) is an annual legume mainly used as a spice crop in many parts of the world. "Tristar" is a new forage cultivar that requires - 120 days to produce mature seed in western Canada where only - 100 frost-free days are available. The goal for this study was to reduce maturity duration for the crop through a series of studies on the genetics and agronomic aspects of fenugreek. This two year study suggests that: 1)mutation breeding using Tristar seed as a base population could be successfull; 2)multi-location trials using world accessions exhibited genotype X environment interaction; 3)swathing of plants before freezing temperatures set in; 4)application of phosphate fertilizer increased seed yield and; 5)foliar sprays of chemicals can be used for production of high quality seed. In this study some short duration, high yielding and determine lines of fenugreek were produced improving the potential for use of fenugreek and the economics of beef production in western Canada. / xix, 184 leaves : ill. (some col.) ; 29 cm.

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Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 126-136). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 126-136). Also available on the Internet.

O tomateiro (Solanum lycopersicum) tornou-se importante ferramenta para estudos de genética e fisiologia nos últimos anos, devido à disponibilidade de mutantes, incluindo aqueles com alterações hormonais. Nesta cultura, a cultivar ornamental miniatura de tomateiro Micro-Tom (MT) tem sido utilizada como modelo genético em vários estudos, visto que produz frutos e sementes viáveis em vasos de apenas 50-100 ml de substrato, completando o ciclo em setenta a noventa dias. Este trabalho foi feito com o intuito de gerar informações que possam colaborar para a compreensão dos mecanismos que determinam a sensibilidade das raízes ao estresse hídrico. Para tal, foram criados duplos mutantes hormonais homozigóticos da cultivar MT, sendo posteriormente usados para verificar o papel das interações hormonais ABA-Etileno no controle do crescimento da raiz sob condições de estresse osmótico. O estudo é relevante pelo fato de que o entendimento dos mecanismos de controle hormonal no crescimento radicular poderá auxiliar a pesquisa de melhoramento genético para a obtenção de plantas tolerantes à seca, o que representaria avanço na agricultura, principalmente para regiões de clima árido e semiárido. Os experimentos foram realizados no Laboratório de Controle Hormonal do Desenvolvimento Vegetal da ESALQ-USP, onde foram produzidos genótipos de cinco duplos mutantes: diagetropica/sitiens (dgt/sit), diagetropica/epinastic (dgt/epi), diagetropica/Never ripe (dgt/Nr), sitiens/epinastic (sit/epi) e Never ripe/sitiens (Nr/epi) em homozigose em BC6Fn. Sementes germinadas de (MT) e de mutantes de sitiens (sit), Never ripe (Nr) e o duplo mutante Nrsit foram colocadas em tratamento com PEG 6000 em diferentes potenciais osmóticos. Também foram realizados experimentos com ácido cloro-2-etil fosfônico (CEPA), um liberador de etileno (Ethrel), e o inibidor da síntese do mesmo, o aminoetoxivinil glicina (AVG), sendo avaliados os parâmetros como crescimento radicular, caulinar, razão raiz/hipocótilo e conteúdo relativo de água (CRA). Observouse que baixos potencias osmóticos inibem mais o caule que a raiz, e que o estresse osmótico moderado (-0.6 MPa) favoreceu o crescimento da raiz e da razão raiz/hipocótilo em MT, principalmente em sit e, em menor extensão, na raiz de Nr/sit. Esse crescimento não foi observado em Nr. No mutante sit, em -1.1 MPa, observou-se inchaço radicular semelhante ao provocado pela presença de etileno. Em menor extensão, esse inchaço também foi observado no duplo mutante Nr/sit. Quando adicionado Ethrel, houve inibição do crescimento radicular em sit e MT, sendo também observado um pouco de inibição no mutante insensível a etileno, Nr. Em estresse moderado (-0.6 MPa), a inibição foi mais severa do que em água para MT, mas não para sit, até a dose de 1 µM. A inibição do etileno causada pelo AVG resultou em uma maior diferença entre água e -0.6 MPa, sendo o último mais inibido. Pode-se concluir que, em condições de déficit hídrico moderado, há aumento radicular e da razão/hipocótilo quando comparados a condições normais de suprimento de água. Tais constatações são importantes porque podem ajudar no desenho de práticas agronômicas que podem levar a maior economia de água, bem como aumento da eficiência de uso de água pelas plantas. / Tomato (Solanum lycopersicum) has become a very important model for genetic and physiological studies in the last years, due to the presence of various mutants, including those with hormonal alterations. The ornamental dwarf tomato cv. Micro-Tom (MT) has been largely used because of its ability to produce viable fruits and seeds in pots of just 50-100 ml, completing its life cycle in seventy to ninety days. In an attempt to gain insights on the mechanisms that regulate plant growth under physiologic stress, homozygote hormonal double mutants of the MT were created and later on screened for the role of hormonal interactions in the control of root growth under osmotic stress. The experiment was conducted at ESALQ-USP Hormonal Control of Plant Development Laboratory, where genotypes of five double mutants namely diagetropica/sitiens (dgt/sit), diagetropica/epinastic (dgt/epi), diagetropica/Never ripe (dgt/Nr), sitiens/epinastic (sit/epi) and Never ripe/sitiens (Nr/epi) were produced in BC6Fn homozygosis. Germinated seeds of MT and the mutants sitiens (sit), Never ripe (Nr) and the double mutant Nr/sit were treated with PEG 6000 at different osmotic potentials. There were also experiments with chloro-2-ethyl phosphonic acid (CEPA), an ethylenereleaser (Ethrel) and the inhibitor of ethylene synthesis aminoethyoxyvinyl glycine (AVG). The parameters evaluated were radicle and hypocotyls growth, root/hypocotyl ratio and relative water content (RWC). The stem was more inhibited than the root at moderate osmotic stress (-0.6 MPa), which resulted in elevated root/hypocotyl ratio for MT, sit and, in lesser extent, Nr/sit. This pattern was not observed in Nr. A root swelling similar to that caused by ethylene was observed in sit at -1.1 MPa. This swelling was less evident in the double mutant Nr/sit. When added Ethrel, there was inhibition of root growth in sit and MT. A discrete root inhibition was also observed in the ethyleneinsensitive Nr mutant. In moderate osmotic stress (-0.6 MPa), root inhibition was more severe than in water for MT, but not for sit, until 1 µM Ethrel. The AVG application increased this difference between water and PEG 6000 treatments. It can be concluded that, in moderate water deficit, the root growth and root/hypocotyl ratio were increased, when compared to normal water supply. These findings are important, since they can provide for the better design of agronomic practices and crop improvement aiming at the enhancement of water use efficiency.

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Genomic instability underlies diseases of unregulated cell growth that result in cancers and developmental abnormalities in humans. Similar genome destabilizing mechanisms are used to create genetic variety in crops for use in breeding and trait development. Errors that occur during DNA replication may cause mutations if they are not corrected before further cell divisions. DNA mismatch repair (MMR) corrects misinsertions and insertion/deletion DNA loop-outs that arise during DNA replication in plants, animals, prokaryotes, and some archaea, all of which incur mutations at rates 100 to 1,000-fold greater when subjected to inherited or somatic-mismatch repair deficiencies. An understanding of the effects of mismatch repair on somatic and germ-line cells in Arabidopsis thaliana is critical to the development of this plant as a model system for the study of genomic instability. Insertions and deletions of multiples of two base pairs in dinucleotide repeat sequences (microsatellites) occur more frequently in the absence of mismatch repair, and the mismatch-repair status of an individual, tissue, or cell may be inferred on the basis of microsatellite mutation frequency. Single-template PCR analysis measured microsatellite mutation frequencies in leaves and shoot-apical-meristem stem cells, and allowed me to address for the first time an important question: Do plants relax mismatch repair in vegetative tissues relative to meristematic germ-line and floral tissue? Analyses of four microsatellite loci in mismatch repair-deficient and wild type plants surprisingly suggest that there is little difference in mismatch repair activity between leaves and seeds. Mismatch-repair-deficient leaves displayed only two-fold higher microsatellite mutation frequency compared to wild type, and wild-type leaves also displayed a two-fold higher microsatellite mutation frequency compared to shoot-apical- meristems. The high frequency of microsatellite mutation in these wildtype tissues is unexpected, and it suggests that plants relax mismatch repair in differentiated tissues while maintaining genetic fidelity in a small set of stem cells in the shoot apical meristem (SAM). Genome sequencing of msh2⁻/⁻ mutation accumulation A. thaliana lines provides an estimated germ-line mutation rate of 3.9 × 10⁻⁷ in the absence of mismatch repair. Comparison of the rates of base substitution mutation per chromosome in mismatch repair-deficient plants with rates reported for wild-type plants suggests mismatch repair is more efficient on chromosome 5 than on chromosomes 1-4. Bias towards G:C → A:T mutations among transitions is maintained but increased nearly 100-fold in the absence of mismatch repair. / Graduation date: 2012

Fenugreek (Trigonella foenum-graecum L.) was recently introduced to western Canada as a forage crop. To reach its full potential, high yielding, early maturing fenugreek cultivars that produce good seed yield and quality within 100 frost free days need to be developed. In this study, mutation breeding approach was used on five locally adapted fenugreek genotypes to generate variants showing improved seed yield and yield attributing traits that can be used for cultivar development. Mutant generations of these plants were evaluated in multi-location, multi-year trials, and individual plants were selected for high seed and biomass yield. Seeds from a tetraploid fenugreek line and its diploid parent Tristar were grown under multiple environments to understand effect of environment on seed oil content. In addition, mold resistant fenugreek genotypes were identified by screening a collection of fenugreek accessions against a destructive fungal pathogen Cercospora traversiana. / xv, 179 leaves : ill. ; 29 cm