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Molecular cloning and characterization of the diageotropica gene in tomato (Lycopersicon esculentum Mill.)Oh, KwangChul 15 July 2003 (has links)
The auxin-resistant diageotropica (dgt) mutant of tomato (Lycopersicon
esculentum Mill.) has a pleiotropic phenotype including a lack of lateral roots and
reduced gravitropic response, apical dominance, vascular development, and fruit
growth. The dgt mutation reduces the auxin sensitivity of only a subset of auxin
responses while levels, metabolism, and transport of auxin appear normal,
suggesting that the Dgt gene encodes a component in an auxin-signaling pathway.
This dissertation reports isolation and characterization of the Dgt gene.
Delineation of three microsyntenic regions in the Arabidopsis genome containing
genes homeologous to genetic markers near the Dgt gene allowed isolation of
additional ESTs from the corresponding tomato region, significantly reducing the
mapping distance to the dgt locus. Further analysis determined that the Dgt gene
encodes a cyclophilin (LeCYP1), a previously unidentified component of auxin
signaling. Each known dgt allele contains a unique mutation in the coding
sequence of LeCyp1. In addition, the wild-type Dgt gene can complement dgt
mutant plants. Cyclophilins characteristically have peptidylprolyl cis-trans
isomerase (PPIase) activity, but it is unclear whether that activity is necessary for
all of their biological functions. Each allelic dgt mutation reduces or nullifies PPIase
activity of LeCYP1 fusion proteins in vitro. Immunoblot analysis indicates that all
three dgt mutations are null mutations. Phylogenetic comparisons of tomato and
Arabidopsis cytosolic-type cyclophilins could not identify any single Arabidopsis
member as orthologous to LeCYP1/DGT. Five T-DNA insertion mutants were
analyzed to determine if mutations in Arabidopsis cytosolic-type cyclophilins
phenocopy the pleiotropic dgt phenotype. Overall seedling growth and morphology
appear normal in the mutants, however, their gravitropic response is slow. The
lack of exact phenocopy may be due to the redundant nature of Cyp genes in
Arabidopsis, which has over twice as many Cyp genes as tomato. In tomato, the
cyclophilin inhibitor cyclosporin A (CsA) inhibits auxin-induced adventitious root
initiation and expression of two early auxin response genes, LeIAA10 and 11, that
are also affected by the dgt mutation. Taken together, these results suggest that
the cyclophilin encoded by the Dgt gene plays an important role in auxin signal
transduction. / Graduation date: 2004
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The characterization of tomato plants transformed with various anti-sense ACC synthase genes麥文馨, Mak, Man-hing. January 2001 (has links)
published_or_final_version / Botany / Master / Master of Philosophy
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Genetic studies of earliness and growth stages of Lycopersicon esculentum Mill.Li, Shin-Chai January 1975 (has links)
It is desirable to develop tomato (Lycopersicon esculentum Mill.) cultivars which have the characteristics of earliness to fit the relatively short and cool growing season in Canada. Earliness was studied by parti-tioning the life cycle of the tomato plant into 7 component growth stages and using these as a basis for attempts to recombine quantitative genes which control the earliness of different stages from different parents to obtain progeny earlier than both parents.
The mode of inheritance of the earliness in the 7 growth component stages was studied with 3 approaches. First, a complete diallel cross experiments used 3 parental cultivars: Bonny Best, Immur Prior Beta and Cold Set. The progenies were grown under 2 temperature regimes (17.0-21.0°C and 10.0-13.0°C). The data for days required for each stage were analyzed first by the Hayman and Jinks method which estimated the following 4 genetic parameters; variation due to differences in additive and dominant gene action; asymmetry of positive and negative effects of genes; relative frequencies of dominant and recessive alleles; and 5 genetic estimators: average degree of dominance; proportion of dominant and recessive alleles; ratio of the total numbers of dominant to recessive genes in the parents; number of effective factors which exhibit some degree of dominance and the heritability.
The calculated genetic parameters and estimators differed in the 2 temperature regimes indicating there could be differences in gene action such as overdominant instead of partial dominant gene action depending on the temperature conditions. There were differences in heritabilities for the component stages, and some of the longer stages had potentially useful high heritabilities.
The data were also analyzed by the Griffing method which estimated the general combining ability and specific combining ability. The analyses showed that both the additive and dominant gene action had significant effects in most of the component stages, and in most cases, the additive variance was larger than the dominant variance.
The second approach employed reciprocal cross experiments with 2 parental cultivars, Bonny Best and Immur Prior Beta, and their reciprocal hybrids under the 2 temperature regimes in greenhouses and growth chambers. The nuclear and/or cytoplasmic effect on the 7 growth component stages, net photosynthesis rate and leaf area were studied. There was some evidence that cytoplasmic effects were relatively important for some of these characteristics, and these effects were more noticeable in the cool regime.
In the third approach, field selection experiments on the earliness of 2 major stages were commenced in the F₃ of Bonny Best and Immur Prior Beta reciprocal cross populations. The mean values for both stages in the F₅ reciprocal populations were earlier than the 2 original parents indicating recombination of genes for earliness from parental cultivars. These results indicate that the methods which were used in these studies are a feasible way to increase the quantitative characteristic of earliness in the tomato. / Land and Food Systems, Faculty of / Graduate
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Cytogenetical effects of seed treatments with maleic hydrazide on tomato plants of the first and second generation.Harney, Patricia M. January 1959 (has links)
No description available.
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Factors affecting shoot regeneration and genetic transformation of a self-compatible accession of Lycopersicon peruvianum /Liang, Wenqing 01 January 1994 (has links) (PDF)
No description available.
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Characterization of the LeIAA family of auxin-regulated genes in tomato (Lycopericon esculentum, Mill.)Nebenfuhr, Andreas 05 September 1997 (has links)
The plant hormone auxin regulates many aspects of plant growth and
development. At the cellular level, auxin can stimulate cell division, cell elongation, and
cell differentiation. Little is known about the molecular mechanisms that mediate auxin
action at this level, although changes in gene expression have been implicated in each of
them. An important step in elucidating the signal transduction steps involved in these
responses is the identification of intermediates that respond to auxin treatment within a
physiologically relevant range, and can be functionally linked to specific response(s).
The Aux/IAA family of auxin-regulated genes, which has been identified in several
species, may constitute such a group of signalling intermediates.
This dissertation reports on the isolation and characterization of eleven tomato
genes, LeIAA1 - 11, which are homologous to these Aux/IAA genes. Expression
characteristics in response to exogenously-applied auxin were determined in segments of
etiolated hypocotyls. The LeIAA genes fell into three kinetic classes and displayed
differential responsiveness to the treatment. Comparison of auxin-induced expression in
wild-type and the auxin-insensitive diageotropica (dgt) mutant revealed that induction of
only a subset of genes was affected by the mutation while the other genes retained wild-type response levels in the mutant. This finding indicates that at least two signal
transduction chains lead to auxin-induced gene expression, and the dgt gene product acts
on only one of them.
The expression pattern of nine LeIAA genes was determined in a wide variety of
tissue samples in order to link individual LeIAA genes with specific physiological
responses. To that end, a qualitative multiplex RT-PCR method was developed that
allowed quick assessment of relative expression levels in a large number of small RNA
samples. It was found that LeIAA10 expression was highest in tissues undergoing rapid
growth, suggesting a role for this gene in the process of cell expansion. The expression
of LeIAA1 1 was also variable during development, while LeIAA2 was strongly down-regulated
after light treatment. These experiments demonstrated organ-preferential
expression of LeIAA genes under the control of environmental factors and depending on
developmental stages. The LeIAA genes may thus act as integrators of several other
signals with the auxin stimulus. / Graduation date: 1998
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The roles of 1-aminocyclopropane-1-carboxylate synthase isogenes in the flower and fruit development in tomatoesFan, Rong, 樊榮 January 2008 (has links)
published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy
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Genetic and physiological analysis of a light-regulated gravitropic mutant of tomatoGaiser, J. Christopher 10 August 1993 (has links)
Graduation date: 1994
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Molecular cloning and characterization of SNF1 related protein kinasesin tomato (lycopersicon esculentum)Lam, Pui-Yi., 林佩儀. January 2003 (has links)
published_or_final_version / abstract / toc / Botany / Master / Master of Philosophy
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Characterization of two auxin-induced ACC synthase genes in tomatoesLeung, Ching-man., 梁靜雯. January 2005 (has links)
published_or_final_version / abstract / Botany / Master / Master of Philosophy
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