Alteration in flowering time causes accelerated or decelerated progression through Arabidopsis vegetative phases

2001 ◽  
Vol 79 (6) ◽  
pp. 657-665 ◽  
Author(s):  
Quintin J Steynen ◽  
Dee A Bolokoski ◽  
Elizabeth A Schultz
Keyword(s):  
Arabidopsis Thaliana ◽  
Flowering Time ◽  
Leaf Shape ◽  
Central Mechanism ◽  
Second Phase ◽  
Wild Type ◽  
Low Light ◽  
Terminal Flower ◽  
Vegetative Phases ◽  
Short Days

We have identified three phases within the wild-type Arabidopsis thaliana (L.) Heynh. rosette, based on significant differences in leaf shape, size, vascular pattern, and presence of abaxial trichomes. To test the hypothesis that a single, central mechanism controls the progression through all plant phases and that conditions that alter the time to flowering will also alter the progression through vegetative phases, we analysed the rosette phases under such conditions. In support of our hypothesis, we determined that those conditions (loss of LEAFY activity, short days) that decelerate time to flowering show decelerated progression through the rosette phases, while those conditions (loss of TERMINAL FLOWER, overexpression of LEAFY, low light) that accelerate time to flowering show accelerated progression through the rosette phases. In all conditions except short days, the length of the first phase was unaffected, indicating that this phase is less susceptible to influences of the central mechanism. Progression through the subsequent two rosette phases was accelerated differentially, such that the second phase was affected more strongly than the first. This supports the idea that, in the rosette, as in the inflorescence, the inhibition of phase transition by the central mechanism is gradually decreasing.Key words: phase change, flowering time, Arabidopsis thaliana, LEAFY, TERMINAL FLOWER, heteroblasty.

The early-flowering mutant efs is involved in the autonomous promotion pathway of Arabidopsis thaliana

Development ◽  
1999 ◽  
Vol 126 (21) ◽  
pp. 4763-4770 ◽  
Author(s):  
W.J. Soppe ◽  
L. Bentsink ◽  
M. Koornneef
Keyword(s):  
Arabidopsis Thaliana ◽  
Flowering Time ◽  
Double Mutant ◽  
Plant Size ◽  
Early Flowering ◽  
Wild Type ◽  
Late Flowering ◽  
Long Day ◽  
Short Days ◽  
Transition To Flowering

The transition to flowering is a crucial moment in a plant's life cycle of which the mechanism has only been partly revealed. In a screen for early flowering, after mutagenesis of the late-flowering fwa mutant of Arabidopsis thaliana, the early flowering in short days (efs) mutant was identified. Under long-day light conditions, the recessive monogenic efs mutant flowers at the same time as wild type but, under short-day conditions, the mutant flowers much earlier. In addition to its early-flowering phenotype, efs has several pleiotropic effects such as a reduction in plant size, fertility and apical dominance. Double mutant analysis with several late-flowering mutants from the autonomous promotion (fca and fve) and the photoperiod promotion (co, fwa and gi) pathways of flowering showed that efs reduces the flowering time of all these mutants. However, efs is completely epistatic to fca and fve but additive to co, fwa and gi, indicating that EFS is an inhibitor of flowering specifically involved in the autonomous promotion pathway. A vernalisation treatment does not further reduce the flowering time of the efs mutant, suggesting that vernalisation promotes flowering through EFS. By comparing the length of the juvenile and adult phases of vegetative growth for wild-type, efs and the double mutant plants, it is apparent that efs mainly reduces the length of the adult phase.

scholarly journals Acclimation of Photosynthesis to Changes in the Environment Results in Decreases of Oxidative Stress in Arabidopsis thaliana

2021 ◽  
Vol 12 ◽  
Author(s):  
Mohd Fauzihan Karim ◽  
Giles N. Johnson
Keyword(s):  
Oxidative Stress ◽  
Arabidopsis Thaliana ◽  
Superoxide Dismutase ◽  
Quantum Yields ◽  
Wild Type ◽  
Low Light ◽  
Phosphate Translocator ◽  
Lower Maximum ◽  
Stress Related Genes ◽  
Variable Light

The dynamic acclimation of photosynthesis plays an important role in increasing the fitness of a plant under variable light environments. Since acclimation is partially mediated by a glucose-6-phosphate/phosphate translocator 2 (GPT2), this study examined whether plants lacking GPT2, which consequently have defective acclimation to increases in light, are more susceptible to oxidative stress. To understand this mechanism, we used the model plant Arabidopsis thaliana [accession Wassilewskija-4 (Ws-4)] and compared it with mutants lacking GPT2. The plants were then grown at low light (LL) at 100 μmol m−2 s−1 for 7 weeks. For the acclimation experiments, a set of plants from LL was transferred to 400 μmol m−2 s−1 conditions for 7 days. Biochemical and physiological analyses showed that the gpt2 mutant plants had significantly greater activity for ascorbate peroxidase (APX), guiacol peroxidase (GPOX), and superoxide dismutase (SOD). Furthermore, the mutant plants had significantly lower maximum quantum yields of photosynthesis (Fv/Fm). A microarray analysis also showed that gpt2 plants exhibited a greater induction of stress-related genes relative to wild-type (WT) plants. We then concluded that photosynthetic acclimation to a higher intensity of light protects plants against oxidative stress.

scholarly journals GmFULc Is Induced by Short Days in Soybean and May Accelerate Flowering in Transgenic Arabidopsis thaliana

2021 ◽  
Vol 22 (19) ◽  
pp. 10333
Author(s):  
Jingzhe Sun ◽  
Mengyuan Wang ◽  
Chuanlin Zhao ◽  
Tianmeng Liu ◽  
Zhengya Liu ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Flowering Time ◽  
Transcriptional Activity ◽  
Developmental Process ◽  
Transgenic Arabidopsis ◽  
Mads Box ◽  
Wild Type ◽  
Transcription Factor Family ◽  
Flowering Locus T ◽  
Short Days

Flowering is an important developmental process from vegetative to reproductive growth in plant; thus, it is necessary to analyze the genes involved in the regulation of flowering time. The MADS-box transcription factor family exists widely in plants and plays an important role in the regulation of flowering time. However, the molecular mechanism of GmFULc involved in the regulation of plant flowering is not very clear. In this study, GmFULc protein had a typical MADS domain and it was a member of MADS-box transcription factor family. The expression analysis revealed that GmFULc was induced by short days (SD) and regulated by the circadian clock. Compared to wild type (WT), overexpression of GmFULc in transgenic Arabidopsis caused significantly earlier flowering time, while ful mutants flowered later, and overexpression of GmFULc rescued the late-flowering phenotype of ful mutants. ChIP-seq of GmFULc binding sites identified potential direct targets, including TOPLESS (TPL), and it inhibited the transcriptional activity of TPL. In addition, the transcription levels of FLOWERING LOCUS T (FT), SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) and LEAFY (LFY) in the downstream of TPL were increased in GmFULc- overexpressionArabidopsis, suggesting that the early flowering phenotype was associated with up-regulation of these genes. Our results suggested that GmFULc inhibited the transcriptional activity of TPL and induced expression of FT, SOC1 and LFY to promote flowering.

scholarly journals The New RGA Locus Encodes a Negative Regulator of Gibberellin Response in Arabidopsis thaliana

Genetics ◽  
1997 ◽  
Vol 146 (3) ◽  
pp. 1087-1099 ◽  
Author(s):  
Aron L Silverstone ◽  
Pui Ying Annie Mak ◽  
Eva Casamitjana Martinez ◽  
Tai-ping Sun
Keyword(s):  
Signal Transduction ◽  
Arabidopsis Thaliana ◽  
Flowering Time ◽  
Apical Dominance ◽  
Stem Growth ◽  
Negative Regulator ◽  
Wild Type Plant ◽  
Wild Type ◽  
Hypocotyl Growth ◽  
Separate Branch

We have identified a new locus involved in gibberellin (GA) signal transduction by screening for suppressors of the Arabidopsis thaliana GA biosynthetic mutant ga1-3. The locus is named RGA for repressor of ga1-3. Based on the recessive phenotype of the digenic rga/ga1-3 mutant, the wild-type gene product of RGA is probably a negative regulator of GA responses. Our screen for suppressors of ga1-3 identified 17 mutant alleles of RGA as well as 10 new mutant alleles at the previously identified SPY locus. The digenic (double homozygous) rga/ga1-3 mutants are able to partially repress several defects of ga1-3 including stem growth, leaf abaxial trichome initiation, flowering time, and apical dominance. The phenotype of the trigenic mutant (triple homozygous) rga/spy/ga1-3 shows that rga and spy have additive effects regulating flowering time, abaxial leaf trichome initiation and apical dominance. This trigenic mutant is similar to wild type with respect to each of these developmental events. Because rga/spy/ga1-3 is almost insensitive to GA for hypocotyl growth and its bolting stem is taller than the wild-type plant, the combined effects of the rga and spy mutations appear to allow GA-independent stem growth. Our studies indicate that RGA lies on a separate branch of the GA signal transduction pathway from SPY, which leads us to propose a modified model of the GA response pathway.

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.

scholarly journals Structural and Thermodynamic Analysis of the Resistance Development to Pimodivir (VX-787), the Clinical Inhibitor of Cap Binding to PB2 Subunit of Influenza A Polymerase

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1007
Author(s):  
Jiří Gregor ◽  
Kateřina Radilová ◽  
Jiří Brynda ◽  
Jindřich Fanfrlík ◽  
Jan Konvalinka ◽  
...  
Keyword(s):  
Thermodynamic Analysis ◽  
Influenza A ◽  
Polymerase Activity ◽  
Second Phase ◽  
Missense Mutations ◽  
Wild Type ◽  
Resistance Development ◽  
Third Phase ◽  
Major Mutation ◽  
Control And Prevention

Influenza A virus (IAV) encodes a polymerase composed of three subunits: PA, with endonuclease activity, PB1 with polymerase activity and PB2 with host RNA five-prime cap binding site. Their cooperation and stepwise activation include a process called cap-snatching, which is a crucial step in the IAV life cycle. Reproduction of IAV can be blocked by disrupting the interaction between the PB2 domain and the five-prime cap. An inhibitor of this interaction called pimodivir (VX-787) recently entered the third phase of clinical trial; however, several mutations in PB2 that cause resistance to pimodivir were observed. First major mutation, F404Y, causing resistance was identified during preclinical testing, next the mutation M431I was identified in patients during the second phase of clinical trials. The mutation H357N was identified during testing of IAV strains at Centers for Disease Control and Prevention. We set out to provide a structural and thermodynamic analysis of the interactions between cap-binding domain of PB2 wild-type and PB2 variants bearing these mutations and pimodivir. Here we present four crystal structures of PB2-WT, PB2-F404Y, PB2-M431I and PB2-H357N in complex with pimodivir. We have thermodynamically analysed all PB2 variants and proposed the effect of these mutations on thermodynamic parameters of these interactions and pimodivir resistance development. These data will contribute to understanding the effect of these missense mutations to the resistance development and help to design next generation inhibitors.

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.

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