scholarly journals A role for GLABRA1 in dark-induced senescence

2019 ◽  
Author(s):  
Aleksandra Eckstein ◽  
Joanna Grzyb ◽  
Paweł Hermanowicz ◽  
Justyna Łabuz ◽  
Agnieszka Katarzyna Banaś
Keyword(s):  
Arabidopsis Thaliana ◽  
Photosynthetic Activity ◽  
Practical Importance ◽  
Wild Type ◽  
Mature Leaves ◽  
Trichome Formation ◽  
Myb Gene ◽  
Black Paper ◽  
In The Wild ◽  
Senescence Associated Genes

The GLABRA (GL1) gene, belonging to the transcription factor-encoding myb gene family, is responsible for trichome formation in Arabidopsis thaliana (L.) Heynh. The leaves and stems of glabra1 mutant plants are devoid of trichomes. Having an easily observable phenotype, the gl1 mutation was one of the first markers established for genetic mapping of Arabidopsis thaliana. Since then, the GL1 gene has been assigned roles in other processes, also related to leaf structure. In this study we present some previously undescribed effects of the gl1 mutation on dark-induced senescence. This process was induced by covering selected mature leaves of Columbia wild-type and gl1 Arabidopsis with black paper for 4 days, while the plants remained growing in a normal photoperiod. While no visible differences in the external symptoms of senescence could be observed in the darkened leaves, the expression of senescence-associated genes was significantly lower in gl1 plants as compared to the wild type. The darkening of leaves led to a decrease in photosynthetic activity and the expression of photosynthesis-associated genes, in comparison to the control leaves. This effect was much less pronounced in gl1 than in the wild type plants. Therefore, gl1 plants seem to be less susceptible to dark-induced aging, suggesting a possible role for the GL1 gene in controlling the onset and progress of senescence. This result is also of practical importance, since gl1 is the genetic background of many other mutants. It may therefore be advisable to revise some of the results obtained with such mutants in light of findings presented here.

scholarly journals cot1: A Regulator of Arabidopsis Trichome Initiation

Genetics ◽  
1998 ◽  
Vol 149 (2) ◽  
pp. 565-577
Author(s):  
Daniel B Szymanski ◽  
Daniel A Klis ◽  
John C Larkin ◽  
M David Marks
Keyword(s):  
Cell Fate ◽  
Gene Dosage ◽  
Signal Transduction Pathway ◽  
Spatial Arrangement ◽  
Complex Signal ◽  
Chromosome 2 ◽  
Wild Type ◽  
Trichome Formation ◽  
In The Wild ◽  
Leaf Trichome

Abstract In Arabidopsis, the timing and spatial arrangement of trichome initiation is tightly regulated and requires the activity of the GLABROUS1 (GL1) gene. The COTYLEDON TRICHOME 1 (COT1) gene affects trichome initiation during late stages of leaf development and is described in this article. In the wild-type background, cot1 has no observable effect on trichome initiation. GL1 overexpression in wild-type plants leads to a modest number of ectopic trichomes and to a decrease in trichome number on the adaxial leaf surface. The cot1 mutation enhances GL1-overexpression-dependent ectopic trichome formation and also induces increased leaf trichome initiation. The expressivity of the cot1 phenotype is sensitive to cot1 and 35S::GL1 gene dosage, and the most severe phenotypes are observed when cot1 and 35S::GL1 are homozygous. The COT1 locus is located on chromosome 2 15.3 cM north of er. Analysis of the interaction between cot1, try, and 35S::GL1 suggests that COT1 is part of a complex signal transduction pathway that regulates GL1-dependent adoption of the trichome cell fate.

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.

A new class of mutations in Arabidopsis thaliana, acaulis1, affecting the development of both inflorescences and leaves

Development ◽  
1993 ◽  
Vol 118 (3) ◽  
pp. 751-764 ◽  
Author(s):  
H. Tsukaya ◽  
S. Naito ◽  
G. P. Redei ◽  
Y. Komeda
Keyword(s):  
Arabidopsis Thaliana ◽  
Apical Meristem ◽  
Developmental Stages ◽  
Temperature Shift ◽  
Wild Type ◽  
New Class ◽  
Group 4 ◽  
Consequent Reduction ◽  
In The Wild ◽  
Specific Temperature

We isolated and analyzed mutants of Arabidopsis thaliana, acaulis, with flower stalks that are almost absent or are much reduced in length. The mutations are divided between two loci, acaulis1 (acl1) and acaulis2 (acl2). The acl1-1 mutation has been assigned to linkage group 4 in the vicinity of locus ap2. The acl1-1 mutant showed premature arrest of the inflorescence meristem after the onset of reproductive development, followed by consequent reduction in the number of flower-bearing phytomers and therefore flowers. The apical meristem of the inflorescences was morphologically normal but its radius was about half that of the wild type. The acl1 mutants are also defective in the development of foliage leaves. Both defects could be rescued by growth at a specific temperature (28°C). The length of the cells in acl1-3 mutant was less than that in the wild type but the numbers of cells in leaves and internodes of acl1 mutants were calculated to be the same as those of the wild type. Thus, the defects in inflorescences and leaves were attributed to defects in the process of elongation (maturation) of these cells. Temperature-shift experiments showed that the Acl1+ product was necessary at all developmental stages. A critical stage was shown to exist for recovery from the cessation of development of inflorescence meristems that was caused by the acl1-1 mutation. Grafting experiments showed that the acl1-1 mutation does not affect diffusible substances. An analysis of double mutants carrying both acl1-1 and one of developmental mutations, ap1, clv1, lfy, or tfl1, showed that ACL1 is a new class of gene.

scholarly journals Arabidopsis thaliana cbp80, c2h2, and flk Knockout Mutants Accumulate Increased Amounts of Circular RNAs

Cells ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1937
Author(s):  
Anna Philips ◽  
Katarzyna Nowis ◽  
Michal Stelmaszczuk ◽  
Jan Podkowiński ◽  
Luiza Handschuh ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Circular Rnas ◽  
Wild Type ◽  
Proper Order ◽  
Knockout Mutants ◽  
In The Wild ◽  
And Function

Circular RNAs (circRNAs) are the products of the non-canonical splicing of pre-mRNAs. In contrast to humans and animals, our knowledge of the biogenesis and function of circRNAs in plants is very scarce. To identify proteins involved in plant circRNA generation, we characterized the transcriptomes of 18 Arabidopsis thaliana knockout mutants for genes related to splicing. The vast majority (>90%) of circRNAs were formed in more than one variant; only a small fraction of circRNAs was mutant-specific. Five times more circRNA types were identified in cbp80 and three times more in c2h2 mutants than in the wild-type. We also discovered that in cbp80, c2h2 and flk mutants, the accumulation of circRNAs was significantly increased. The increased accumulation of circular transcripts was not accompanied by corresponding changes in the accumulation of linear transcripts. Our results indicate that one of the roles of CBP80, C2H2 and FLK in splicing is to ensure the proper order of the exons. In the absence of one of the above-mentioned factors, the process might be altered, leading to the production of circular transcripts. This suggests that the transition toward circRNA production can be triggered by factors sequestering these proteins. Consequently, the expression of linear transcripts might be regulated through circRNA production.

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 Cytokinesis in fra2 Arabidopsis thaliana p60-katanin Mutant: Defects in Cell Plate/Daughter Wall Formation

2021 ◽  
Author(s):  
Emmanuel Panteris ◽  
Anna Kouskouveli ◽  
Dimitris Pappas ◽  
Ioannis-Dimosthenis S. Adamakis
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Cell Walls ◽  
Higher Plants ◽  
Cell Plate ◽  
Wild Type ◽  
Microtubule Organization ◽  
Root Cells ◽  
Wall Formation ◽  
In The Wild

Cytokinesis is accomplished in higher plants by the phragmoplast, creating and conducting the cell plate, to separate daughter nuclei by a new cell wall. The microtubule-severing enzyme p60-katanin plays an important role in the centrifugal expansion and timely disappearance of phragmoplast microtubules. Consequently, aberrant structure and delayed expansion rate of the phragmoplast occur in p60-katanin mutants. Here, the consequences of p60-katanin malfunction in cell plate/daughter wall formation were investigated by transmission electron microscopy (TEM), while deviations in the chemical composition of cell plate/new cell wall were identified by immunolabeling and confocal microscopy, in root cells of the fra2 Arabidopsis thaliana mutant. It was found that, apart from defective phragmoplast microtubule organization, cell plates/new cell walls appeared also faulty in structure, being unevenly thick and perforated by large gaps. In addition, demethylesterified homogalacturonans were prematurely present in fra2 cell plates, while callose content was significantly lower than in the wild-type. Furthermore, KNOLLE syntaxin disappeared from newly formed cell walls in fra2 earlier than in the wild-type. Taken together, these observations indicate that delayed cytokinesis, due to faulty phragmoplast organization and expansion, results in a loss of synchronization between cell plate growth and its chemical maturation.

scholarly journals Arabidopsis Phototropins Participate in the Regulation of Dark-Induced Leaf Senescence

2021 ◽  
Vol 22 (4) ◽  
pp. 1836
Author(s):  
Aleksandra Eckstein ◽  
Joanna Grzyb ◽  
Paweł Hermanowicz ◽  
Piotr Zgłobicki ◽  
Justyna Łabuz ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Dominant Role ◽  
Photosynthetic Pigment ◽  
Photochemical Activity ◽  
Wild Type ◽  
Delayed Senescence ◽  
Photosynthetic Genes ◽  
Cellular Components ◽  
Senescence Associated Genes

Senescence is the final stage of plant development, affecting individual organs or the whole organism, and it can be induced by several environmental factors, including shading or darkness. Although inevitable, senescence is a complex and tightly regulated process, ensuring optimal remobilization of nutrients and cellular components from senescing organs. Photoreceptors such as phytochromes and cryptochromes are known to participate in the process of senescence, but the involvement of phototropins has not been studied to date. We investigated the role of these blue light photoreceptors in the senescence of individually darkened Arabidopsis thaliana leaves. We compared several physiological and molecular senescence markers in darkened leaves of wild-type plants and phototropin mutants (phot1, phot2, and phot1phot2). In general, all the symptoms of senescence (lower photochemical activity of photosystem II, photosynthetic pigment degradation, down-regulation of photosynthetic genes, and up-regulation of senescence-associated genes) were less pronounced in phot1phot2, as compared to the wild type, and some also in one of the single mutants, indicating delayed senescence. This points to different mechanisms of phototropin operation in the regulation of senescence-associated processes, either with both photoreceptors acting redundantly, or only one of them, phot1, playing a dominant role.

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