scholarly journals Attachment to Roots and Virulence of a chvB Mutant of Agrobacterium tumefaciens Are Temperature Sensitive

2002 ◽  
Vol 15 (2) ◽  
pp. 160-163 ◽  
Author(s):  
Ryan Bash ◽  
Ann G. Matthysse
Keyword(s):  
Arabidopsis Thaliana ◽  
Agrobacterium Tumefaciens ◽  
Lycopersicon Esculentum ◽  
Daucus Carota ◽  
Room Temperature ◽  
Tagetes Erecta ◽  
Temperature Sensitive ◽  
Wild Type

Agrobacterium tumefaciens chvB mutants are unable to produce β-1,2 glucan. They are nonattaching and avirulent and show reduced motility at room temperature. At lower temperatures (16°C), chvB mutants became virulent on Bryophyllum daigremontiana and Lycopersicon esculentum and were able to attach to L. esculentum, Arabidopsis thaliana, Daucus carota, and Tagetes erecta roots. The mutant bacteria also recovered wild-type motility at lower temperatures. Two other nonattaching mutants of A. tumefaciens, AttR and AtrA, were unaffected by the lowered temperature, remaining nonattaching and avirulent.

scholarly journals Agrobacterium tumefaciens Transformation of the Radiation Hypersensitive Arabidopsis thaliana Mutants uvh1 and rad5

1998 ◽  
Vol 11 (11) ◽  
pp. 1136-1141 ◽  
Author(s):  
Jaesung Nam ◽  
Kirankumar S. Mysore ◽  
Stanton B. Gelvin
Keyword(s):  
Arabidopsis Thaliana ◽  
Agrobacterium Tumefaciens ◽  
Transformation Process ◽  
Stable Transformation ◽  
Wild Type ◽  
Dna Integration ◽  
Agrobacterium Tumefaciens Transformation ◽  
Inoculation Assay

The Arabidopsis thaliana mutants uvh1 and rad5, originally identified as radiation hypersensitive, were reported to be deficient in T-DNA integration based on the relative efficiencies of stable transformation and T-DNA transfer. We reassessed these mutants for susceptibility to transformation by Agrobacterium tumefaciens. The mutant rad5 showed a significant reduction in the efficiency of transient as well as stable transformation, compared with its wild-type progenitor. These data indicate that rad5 is blocked at a step in the transformation process prior to T-DNA integration. We additionally found, using both an in vitro root inoculation and an in vivo flower bolt inoculation assay, that the mutant uvh1 is as susceptible to A. tumefaciens-mediated transformation as is its wild-type progenitor, C10.

Root Morphology Mutants in Arabidopsis thaliana

1992 ◽  
Vol 19 (4) ◽  
pp. 427 ◽  
Author(s):  
TI Baskin ◽  
AS Betzner ◽  
R Hoggart ◽  
A Cork ◽  
RE Williamson
Keyword(s):  
Arabidopsis Thaliana ◽  
Root Growth ◽  
Mutational Analysis ◽  
Root Apex ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Wild Type ◽  
In The Wild ◽  
Root Morphogenesis ◽  
Type Rate

We have begun a mutational analysis of root morphogenesis in Arabidopsis thaliana. We report here the initial genetic and physiological characterisation of six mutations that affect root growth and development. Three of them (rsw1, rsw2, rsw3) cause extensive radial swelling of the root apex. These mutations are recessive at different loci and show temperature-sensitive expression, such that the roots appear wild type when grown at 18�C but express the mutant phenotype when transferred to 31�C. Following transfer to the restrictive temperature, these three mutations have different kinetic and morphological patterns of radial swelling, and grow at different rates with continued time at high temperature. We believe that these mutations represent three different loci active in the wild type in regulating the shape of the root. We have also characterised two mutations that affect only the root epidermis, causing many epidermal cells to bulge (reb1-1, reb1-2). The two mutations are recessive and are alleles. However, rebl-1 is constitutive whereas reb1-2 is temperature sensitive, only expressing at 33�C. Reb1-2 also causes a deviation from the normal straight growth of the root such that the affected roots grow with sharp bends or meanders. The final mutant reported here is a stunted plant (stp1), in which the root growth rate is approximately 25% of the wild type rate. Moreover, root growth steadily accelerates over 5 days following germination in the wild type but remains constant in stp1, which grows at a constant rate over the same interval.

Ultrastructural Studies of Root Swelling in Mutants of Arabidopsis Thaliana

2001 ◽  
Vol 7 (S2) ◽  
pp. 64-65
Author(s):  
Y. Naidoo ◽  
T.I. Baskin ◽  
G. Naidoo
Keyword(s):  
Arabidopsis Thaliana ◽  
Primary Root ◽  
Root Apex ◽  
Cellulose Microfibrils ◽  
Cellulose Synthesis ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Root Tips ◽  
Ultrastructural Studies ◽  
Essentially Normal

Growth is “anisotropic” when growth rates in different directions are not equal. Anisotropic elongation is controlled by cortical microtubules and cellulose microfibrils of the cell wall. Distorted anisotropic growth results when there are aberrations in either the cellulose network or microtubule cytoskeleton. in this ultrastructural study, the roots of wild type (control) and mutants of Arabidopsis thaliana (L.) Heynh, ecotype Columbia, were compared to determine the role of microtubule organisation, cellulose synthesis and cytokinesis on root expansion.Three mutations, obtained by treating seeds of A. thaliana with ethane-methylsulfonate and backcrossing once to wild type after four selfed generations, were isolated and designated as rsw (radially swollen). These phenotypes are all temperature sensitive, growing and appearing as wild type at 19°C but expressing the mutant phenotype at or above 30°C. Segments of intact root tips from the three mutants and wild type were prepared and examined for TEM with a Jeol 1200EX. The overall appearance of rsw seedlings at 19°C is the same as wild type. At 30°C these phenotypes lead to extensive swelling of the root apex. Despite considerable alteration in the morphology of the root apex, the appearance of the root cap and root hairs seems essentially normal. When mutant roots expressing these phenotypes at 30°C are returned to 19°C, a wild type appearance of the root apex and elongation gradually returns.The primary root of the wild type has a remarkably uniform cellular organisation with regularly arranged dense cytoplasmic cells (Fig. 1). At 19°C, rsw4, rsw6 and rsw7 were indistinguishable from wild type; however, at 30°C, the well-defined anatomy was distorted in all tissues by additional cell walls in unusual positions (Fig. 2).

scholarly journals Temperature-Sensitive, Vitamin-Requiring Mutants of Arabidopsis Thaliana

1965 ◽  
Vol 18 (2) ◽  
pp. 311 ◽  
Author(s):  
J Langridge
Keyword(s):  
Arabidopsis Thaliana ◽  
High Temperatures ◽  
Temperature Sensitive ◽  
Wild Type ◽  
X Ray ◽  
Recessive Mutations ◽  
Naturally Occurring ◽  
Induced Mutant

Three mutants of Arabidopsi8 requiring specific vitamins for growth at certain temperatures are described. All are due to recessive mutations of single wild-type genes. One X-ray-induced mutant is unable to synthesize thiamine at low tempera-tures because of a block in the phosphorylation or coupling of the immediate precursors. Two mutants which require biotin for growth at high temperatures are determined by recessive alleles of the same gene. These mutants comprise naturally occurring ecotypes in Spain and Austria. Experiments indicate that an inability to make biotin at high temperatures may be adaptively advantageous. The consequent cessation in growth is a balanced one, readily reversible by a lowering of temperature, which allows the plant to escape the irreversible sterilizing effect of heat.

Effects of an Autoregulatory Senescence-inhibitor Gene Construct on Nicotiana alata Link and Otto.

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 519d-519 ◽  
Author(s):  
Kenneth R. Schroeder ◽  
Dennis P. Stimart
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Plant Height ◽  
Dry Weight ◽  
Nicotiana Alata ◽  
Wild Type ◽  
Gene Encoding ◽  
Delayed Senescence ◽  
Gene Construct ◽  
Shoot Dry Weight ◽  
Inhibitor System

Nicotiana alata Link and Otto. was transformed via Agrobacterium tumefaciens encoding a senescence-specific promoter SAG12 cloned from Arabidopsis thaliana fused to a Agrobacterium tumefaciens gene encoding isopentenyl transferase (IPT) that catalyzes cytokinin synthesis. This was considered an autoregulatory senescence-inhibitor system. In 1996, we reported delayed senescence of intact flowers by 2 to 6 d and delayed leaf senescence of transgenic vs. wild-type N. alata. Further evaluations in 1997 revealed several other interesting effects of the SAG12-IPT gene construct. Measurement of chlorophyll content of mature leaves showed higher levels of both chlorophyll a and b in transgenic material under normal fertilization and truncated fertilization regimes. At 4 to 5 months of age transgenic plants expressed differences in plant height, branching, and dry weight. Plant height was reduced by 3 to 13 cm; branch counts increased 2 to 3 fold; and shoot dry weight increased up to 11 g over wild-type N. alata. These observations indicate the system is not tightly autoregulated and may prove useful to the floriculture industry for producing compact and more floriferous plants.

scholarly journals Inhibition of cell expansion enhances cortical microtubule stability in the root apex of Arabidopsis thaliana

2021 ◽  
Vol 28 (1) ◽  
Author(s):  
Veronica Giourieva ◽  
Emmanuel Panteris
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Cell Expansion ◽  
Cortical Microtubule ◽  
Root Apex ◽  
Cellulose Synthase ◽  
Cellulose Biosynthesis ◽  
Cortical Microtubules ◽  
Wild Type ◽  
Microtubule Stability

Abstract Background Cortical microtubules regulate cell expansion by determining cellulose microfibril orientation in the root apex of Arabidopsis thaliana. While the regulation of cell wall properties by cortical microtubules is well studied, the data on the influence of cell wall to cortical microtubule organization and stability remain scarce. Studies on cellulose biosynthesis mutants revealed that cortical microtubules depend on Cellulose Synthase A (CESA) function and/or cell expansion. Furthermore, it has been reported that cortical microtubules in cellulose-deficient mutants are hypersensitive to oryzalin. In this work, the persistence of cortical microtubules against anti-microtubule treatment was thoroughly studied in the roots of several cesa mutants, namely thanatos, mre1, any1, prc1-1 and rsw1, and the Cellulose Synthase Interacting 1 protein (csi1) mutant pom2-4. In addition, various treatments with drugs affecting cell expansion were performed on wild-type roots. Whole mount tubulin immunolabeling was applied in the above roots and observations were performed by confocal microscopy. Results Cortical microtubules in all mutants showed statistically significant increased persistence against anti-microtubule drugs, compared to those of the wild-type. Furthermore, to examine if the enhanced stability of cortical microtubules was due to reduced cellulose biosynthesis or to suppression of cell expansion, treatments of wild-type roots with 2,6-dichlorobenzonitrile (DCB) and Congo red were performed. After these treatments, cortical microtubules appeared more resistant to oryzalin, than in the control. Conclusions According to these findings, it may be concluded that inhibition of cell expansion, irrespective of the cause, results in increased microtubule stability in A. thaliana root. In addition, cell expansion does not only rely on cortical microtubule orientation but also plays a regulatory role in microtubule dynamics, as well. Various hypotheses may explain the increased cortical microtubule stability under decreased cell expansion such as the role of cell wall sensors and the presence of less dynamic cortical microtubules.

Caffeoyl Shikimate Esterase (CSE) Is an Enzyme in the Lignin Biosynthetic Pathway in Arabidopsis

Science ◽  
2013 ◽  
Vol 341 (6150) ◽  
pp. 1103-1106 ◽  
Author(s):  
Ruben Vanholme ◽  
Igor Cesarino ◽  
Katarzyna Rataj ◽  
Yuguo Xiao ◽  
Lisa Sundin ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Walls ◽  
Metabolite Profiling ◽  
Biosynthetic Pathway ◽  
Wild Type ◽  
Secondary Cell Walls ◽  
Phenolic Metabolite ◽  
In The Wild ◽  
Lignin Biosynthetic Pathway

Lignin is a major component of plant secondary cell walls. Here we describe caffeoyl shikimate esterase (CSE) as an enzyme central to the lignin biosynthetic pathway. Arabidopsis thaliana cse mutants deposit less lignin than do wild-type plants, and the remaining lignin is enriched in p-hydroxyphenyl units. Phenolic metabolite profiling identified accumulation of the lignin pathway intermediate caffeoyl shikimate in cse mutants as compared to caffeoyl shikimate levels in the wild type, suggesting caffeoyl shikimate as a substrate for CSE. Accordingly, recombinant CSE hydrolyzed caffeoyl shikimate into caffeate. Associated with the changes in lignin, the conversion of cellulose to glucose in cse mutants increased up to fourfold as compared to that in the wild type upon saccharification without pretreatment. Collectively, these data necessitate the revision of currently accepted models of the lignin biosynthetic pathway.

scholarly journals Role of SpoVA Proteins in Release of Dipicolinic Acid during Germination of Bacillus subtilis Spores Triggered by Dodecylamine or Lysozyme

2006 ◽  
Vol 189 (5) ◽  
pp. 1565-1572 ◽  
Author(s):  
Venkata Ramana Vepachedu ◽  
Peter Setlow
Keyword(s):  
Bacillus Subtilis ◽  
Small Molecules ◽  
Spore Germination ◽  
Dipicolinic Acid ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Ph Optimum ◽  
Inner Membrane ◽  
Temperature Sensitive Mutants

ABSTRACT The release of dipicolinic acid (DPA) during the germination of Bacillus subtilis spores by the cationic surfactant dodecylamine exhibited a pH optimum of ∼9 and a temperature optimum of 60°C. DPA release during dodecylamine germination of B. subtilis spores with fourfold-elevated levels of the SpoVA proteins that have been suggested to be involved in the release of DPA during nutrient germination was about fourfold faster than DPA release during dodecylamine germination of wild-type spores and was inhibited by HgCl2. Spores carrying temperature-sensitive mutants in the spoVA operon were also temperature sensitive in DPA release during dodecylamine germination as well as in lysozyme germination of decoated spores. In addition to DPA, dodecylamine triggered the release of amounts of Ca2+ almost equivalent to those of DPA, and at least one other abundant spore small molecule, glutamic acid, was released in parallel with Ca2+ and DPA. These data indicate that (i) dodecylamine triggers spore germination by opening a channel in the inner membrane for Ca2+-DPA and other small molecules, (ii) this channel is composed at least in part of proteins, and (iii) SpoVA proteins are involved in the release of Ca2+-DPA and other small molecules during spore germination, perhaps by being a part of a channel in the spore's inner membrane.

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