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.

Characterisation of three shoot apical meristem mutants of Arabidopsis thaliana

Development ◽  
1992 ◽  
Vol 116 (2) ◽  
pp. 397-403 ◽  
Author(s):  
H. M. Ottoline Leyser ◽  
I. J. Furner
Keyword(s):  
Arabidopsis Thaliana ◽  
Root Growth ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Floral Development ◽  
Wild Type ◽  
Recessive Mutations ◽  
Phenotypic Characterisation ◽  
Dicotyledonous Plants ◽  
And Function

The shoot apical meristem of dicotyledonous plants is highly regulated both structurally and functionally, but little is known about the mechanisms involved in this regulation. Here we describe the genetic and phenotypic characterisation of recessive mutations at three loci of Arabidopsis thaliana in which meristem structure and function are disrupted. The loci are Clavata1 (Clv1), Fasciata1 (Fas1) and Fasciata2 (Fas2). Plants mutant at these loci are fasciated having broad, flat stems and disrupted phyllotaxy. In all cases, the fasciations are associated with shoot apical meristem enlargement and altered floral development. While all the mutants share some phenotypic features they can be divided into two classes. The pleiotropic fas1 and fas2 mutants are unable to initiate wild- type organs, show major alterations in meristem structure and have reduced root growth. In contrast, clv1 mutant plants show near wild-type organ phenotypes, more subtle changes in shoot apical meristem structure and wild-type root growth.

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.

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.

scholarly journals Mutations That Reduce Sinapoylmalate Accumulation in Arabidopsis thaliana Define Loci With Diverse Roles in Phenylpropanoid Metabolism

Genetics ◽  
2001 ◽  
Vol 159 (4) ◽  
pp. 1741-1749
Author(s):  
Max Ruegger ◽  
Clint Chapple
Keyword(s):  
Arabidopsis Thaliana ◽  
Secondary Metabolites ◽  
Plant Development ◽  
Phenylpropanoid Metabolism ◽  
Normal Plant ◽  
Wild Type ◽  
Developmentally Regulated ◽  
Recessive Mutations ◽  
Uv Illumination ◽  
Cell Specificity

Abstract The products of phenylpropanoid metabolism in Arabidopsis include the three fluorescent sinapate esters sinapoylglucose, sinapoylmalate, and sinapoylcholine. The sinapoylmalate that accumulates in cotyledons and leaves causes these organs to appear blue-green under ultraviolet (UV) illumination. To find novel genes acting in phenylpropanoid metabolism, Arabidopsis seedlings were screened under UV for altered fluorescence phenotypes caused by changes in sinapoylmalate content. This screen identified recessive mutations at four Reduced Epidermal Fluorescence (REF) loci that reduced leaf sinapoylmalate content. Further analyses showed that the ref mutations affected other aspects of phenylpropanoid metabolism and some led to perturbations in normal plant development. A second class of mutations at the Bright Trichomes 1 (BRT1) locus leads to modest reductions in sinapate ester content; however, the most notable phenotype of brt1 mutants is the development of hyperfluorescent trichomes that appear to contain elevated levels of sinapate esters when compared to the wild type. These results indicate that at least five new loci affecting the developmentally regulated accumulation of phenylpropanoid secondary metabolites in Arabidopsis, and the cell specificity of their distribution, have been identified by screening for altered UV fluorescence phenotypes.

Elements present in mineral nutrient reserves in dry Arabidopsis thaliana seeds of wild type and pho1, pho2, and man1 mutants

2001 ◽  
Vol 79 (11) ◽  
pp. 1292-1296 ◽  
Author(s):  
John NA Lott ◽  
M Marcia West
Keyword(s):  
Arabidopsis Thaliana ◽  
P Uptake ◽  
Mineral Nutrient ◽  
Wild Type ◽  
Nutrient Storage ◽  
X Ray ◽  
Spherical Inclusions ◽  
Nutrient Reserves ◽  
Total P ◽  
Different Tissues

Comparison of wild type and mutants of Arabidopsis thaliana offers an opportunity to study the genetic control of nutrient storage in seeds. We used energy dispersive X-ray analysis to determine the elements present and their relative amounts in globoids of dry wild-type seeds, as well as seeds of a reduced total P uptake mutant (pho1), a phosphate accumulator (pho2), and a metal accumulator (man1). Globoids are spherical inclusions, rich in phytate that function as a store for inositol, P, K, Mg, Ca, Fe, and Zn. Key findings of this study were the following: (i) globoids in protein bodies from nine different tissues and (or) organs in dry Arabidopsis thaliana seeds contained P, K, Mg, and Ca, and sometimes traces of Fe and Zn; (ii) globoids contained higher Ca and lower Mg amounts than occur in globoids in seeds of most other plant species; (iii) globoids in comparable tissue and (or) organ regions of seeds were very similar in elemental composition for wild type and all mutant plants.Key words: Arabidopsis, dry seeds, phytate, mineral nutrient mutants, phosphorus, globoids.

scholarly journals LETHALS, STERILES AND DEFICIENCIES IN A REGION OF THE X CHROMOSOME OF CAENORHABDITIS ELEGANS

Genetics ◽  
1979 ◽  
Vol 92 (1) ◽  
pp. 99-115 ◽  
Author(s):  
Philip M Meneely ◽  
Robert K Herman
Keyword(s):  
Caenorhabditis Elegans ◽  
X Chromosome ◽  
Maternal Effect ◽  
Mutant Allele ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Nematode Caenorhabditis Elegans ◽  
X Chromosomes ◽  
X Ray ◽  
Chromosome Duplication

ABSTRACT Twenty-one X-linked recessive lethal and sterile mutations balanced by an unlinked X-chromosome duplication have been identified following EMS treatment of the small nematode, Caenorhabditis elegans. The mutations have been assigned by complementation analysis to 14 genes, four of which have more than one mutant allele. Four mutants, all alleles, are temperature-sensitive embryonic lethals. Twelve mutants, in ten genes, are early larval lethals. TWO mutants are late larval lethals, and the expression of one of these is influenced by the number of X chromosomes in the genotype. Two mutants are maternal-effect lethals; for both, oocytes made by mutant hermaphrodites are rescuable by wild-type sperm. One of the maternal-effect lethals and two larval lethals are allelic. One mutant makes defective sperm. The lethals and steriles have been mapped by recombination and by complementation testing against 19 deficiencies identified after X-ray treatment. The deficiencies divide the region, about 15% of the X-chromosome linkage map, into at least nine segments. The deficiencies have also been used to check the phenotypes of hemizygous lethal and sterile hermaphrodites.

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).

Non-destructive X-ray analysis of Arabidopsis embryo mutants

1993 ◽  
Vol 3 (3) ◽  
pp. 167-170 ◽  
Author(s):  
R. J. Bino ◽  
J. W. Aartse ◽  
W. J. van der Burg
Keyword(s):  
Arabidopsis Thaliana ◽  
Double Mutant ◽  
Embryo Morphology ◽  
Wild Type ◽  
X Ray ◽  
Non Destructive ◽  
Mature Seeds

AbstractX-radiography is a simple, rapid and non-destructive method for analysing the morphology of embryos in dry, mature seeds of Arabidopsis thaliana. In wild type seeds, the cotyledons, hypocotyl and radicle tip can be readily distinguished. In seeds of the mutant types knolle, keule, and the double mutant keulelgnom, aberrations in embryo morphology can be visualized. X-radiography may therefore be useful in the isolation of embryo mutants from Arabidopsis seed samples.

scholarly journals Suppressors of the organ-specific differentiation gene pha-1 of Caenorhabditis elegans.

Genetics ◽  
1991 ◽  
Vol 129 (1) ◽  
pp. 69-77 ◽  
Author(s):  
H Schnabel ◽  
G Bauer ◽  
R Schnabel
Keyword(s):  
Caenorhabditis Elegans ◽  
Temperature Sensitive ◽  
Lethal Gene ◽  
Wild Type ◽  
Nematode Caenorhabditis Elegans ◽  
X Ray ◽  
Organ Specific ◽  
Complementation Groups ◽  
Differentiation Gene ◽  
Two Temperature

Abstract The embryonic lethal gene pha-1 of the nematode Caenorhabditis elegans is required for late differentiation and morphogenesis of the pharynx in the developing embryo. Revertants of two temperature-sensitive alleles of pha-1 were isolated with the aim of obtaining mutations in genes that interact with pha-1. By various methods of mutagenesis, chemical, X-ray, transposon, or by spontaneous reversion, 220 recessive revertants were obtained, defining three complementation groups. The largest, sup-35 on linkage group (LG) III, maps close to but is separable from pha-1. This suppressor can exert its effect either maternally or zygotically to allow survival of pha-1(ts) embryos. The other two, sup-36 and sup-37, are required zygotically and map on LGIV and LGV, respectively. We have not noted a phenotype distinguishing any of the suppressors from wild type except for suppression of pha-1. That suppression is the null phenotype of at least sup-35 is indicated by the high frequency of mutation and by the fact that heterozygotes carrying sup-35 and a deficiency spanning the locus are also able to suppress. Five spontaneous mutations in sup-35 were found to be associated with recombination.

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