scholarly journals Sucrose synthase activity is not required for cellulose biosynthesis in Arabidopsis

2021 ◽  
Author(s):  
Wei Wang ◽  
Sonja Viljamaa ◽  
Ondrej Hodek ◽  
Thomas Moritz ◽  
Totte Niittylä
Keyword(s):  
Sucrose Synthase ◽  
Cell Walls ◽  
Vascular Tissue ◽  
Tissue Cell ◽  
Cellulose Content ◽  
Cellulose Biosynthesis ◽  
Plant Cell Walls ◽  
Wild Type ◽  
Glucose Content

AbstractBiosynthesis of plant cell walls requires UDP-glucose as the substrate for cellulose biosynthesis, and as an intermediate for the synthesis of other matrix polysaccharides. The sucrose cleaving enzyme sucrose synthase (SUS) is thought to have a central role in UDP-glucose biosynthesis, and a long held and much debated hypothesis postulates that SUS is required to supply UDP-glucose to cellulose biosynthesis. To investigate the role of SUS in cellulose biosynthesis of Arabidopsis thaliana we characterized mutants in which four, or all six Arabidopsis SUS genes were disrupted. These sus mutants showed no growth phenotypes, vascular tissue cell wall defects or changes in cellulose content. Moreover, the UDP-glucose content of rosette leaves of the sextuple sus mutants was increased by approximately 20% compared to wild type. It can thus be concluded that cellulose biosynthesis is able to employ alternative UDP-glucose biosynthesis pathway(s), and thereby the model of SUS requirement for cellulose biosynthesis in Arabidopsis can be refuted.

scholarly journals Arabidopsis cell wall composition determines disease resistance specificity and fitness

2021 ◽  
Vol 118 (5) ◽  
pp. e2010243118 ◽  
Author(s):  
Antonio Molina ◽  
Eva Miedes ◽  
Laura Bacete ◽  
Tinguaro Rodríguez ◽  
Hugo Mélida ◽  
...  
Keyword(s):  
Cell Wall ◽  
Disease Resistance ◽  
Plant Cell ◽  
Cell Walls ◽  
Plant Cell Walls ◽  
Wild Type ◽  
Glycome Profiling ◽  
Enhanced Resistance ◽  
Trade Offs ◽  
Resistance Specificity

Plant cell walls are complex structures subject to dynamic remodeling in response to developmental and environmental cues and play essential functions in disease resistance responses. We tested the specific contribution of plant cell walls to immunity by determining the susceptibility of a set of Arabidopsis cell wall mutants (cwm) to pathogens with different parasitic styles: a vascular bacterium, a necrotrophic fungus, and a biotrophic oomycete. Remarkably, most cwm mutants tested (29/34; 85.3%) showed alterations in their resistance responses to at least one of these pathogens in comparison to wild-type plants, illustrating the relevance of wall composition in determining disease-resistance phenotypes. We found that the enhanced resistance of cwm plants to the necrotrophic and vascular pathogens negatively impacted cwm fitness traits, such as biomass and seed yield. Enhanced resistance of cwm plants is not only mediated by canonical immune pathways, like those modulated by phytohormones or microbe-associated molecular patterns, which are not deregulated in the cwm tested. Pectin-enriched wall fractions isolated from cwm plants triggered immune responses in wild-type plants, suggesting that wall-mediated defensive pathways might contribute to cwm resistance. Cell walls of cwm plants show a high diversity of composition alterations as revealed by glycome profiling that detect specific wall carbohydrate moieties. Mathematical analysis of glycome profiling data identified correlations between the amounts of specific wall carbohydrate moieties and disease resistance phenotypes of cwm plants. These data support the relevant and specific function of plant wall composition in plant immune response modulation and in balancing disease resistance/development trade-offs.

Role of Dectin-2 in the phagocytosis of Cryptococcus neoformans by dendritic cells

2021 ◽  
Author(s):  
Yuki Kitai ◽  
Ko Sato ◽  
Daiki Tanno ◽  
Xiaoliang Yuan ◽  
Aya Umeki ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Cryptococcus Neoformans ◽  
Conformational Changes ◽  
Cell Walls ◽  
Actin Polymerization ◽  
Similar Degree ◽  
Wild Type ◽  
Lectin Receptor ◽  
Adapter Molecule

The cell walls and capsules of Cryptococcus neoformans , a yeast-type fungal pathogen, are rich in polysaccharides. Dectin-2 is a C-type lectin receptor (CLR) that recognizes high-mannose polysaccharides. Previously, we demonstrated that Dectin-2 is involved in cytokine production by bone marrow-derived dendritic cells (BM-DCs) in response to stimulation with C. neoformans . In the present study, we analyzed the role of Dectin-2 in the phagocytosis of C. neoformans by BM-DCs. The engulfment of this fungus by BM-DCs was significantly decreased in mice lacking Dectin-2 (Dectin-2KO) or caspase recruitment domain-containing protein 9 (CARD9KO), a common adapter molecule that delivers signals triggered by CLRs, compared to wild-type (WT) mice. Phagocytosis was likewise inhibited, to a similar degree, by the inhibition of Syk, a signaling molecule involved in CLR-triggered activation. A PI3K inhibitor, in contrast, completely abrogated the phagocytosis of C. neoformans . Actin polymerization, i.e., conformational changes in cytoskeletons detected at sites of contact with C. neoformans , was also decreased in BM-DCs of Dectin-2KO and CARD9KO mice. Finally, the engulfment of C. neoformans by macrophages was significantly decreased in the lungs of Dectin-2KO mice compared to WT mice. These results suggest that Dectin-2 may play an important role in the actin polymerization and phagocytosis of C. neoformans by DCs, possibly through signaling via CARD9 and a signaling pathway mediated by Syk and PI3K.

scholarly journals Necrotizing Activity of Verticillium dahliae and Fusarium oxysporum f. sp. vasinfectum Endopolygalacturonases in Cotton

Plant Disease ◽  
2017 ◽  
Vol 101 (7) ◽  
pp. 1128-1138 ◽  
Author(s):  
Nana Liu ◽  
Xiaowen Ma ◽  
Yun Sun ◽  
Yuxia Hou ◽  
Xueyan Zhang ◽  
...  
Keyword(s):  
Fusarium Oxysporum ◽  
Verticillium Dahliae ◽  
Cell Walls ◽  
Gene Expression Analysis ◽  
Susceptible Cultivar ◽  
Plant Cell Walls ◽  
Glucose Medium ◽  
Symptom Development ◽  
Hydroxyproline Content

Polygalacturonase (PG), which digests the pectin of plant cell walls, contributes to pathogenicity of fungi in plants. To explore the role of PG in pathogenicity of the fungal cotton pathogens Verticillium dahliae and Fusarium oxysporum f. sp. vasinfectum, VDPG1 and FOVPG1 were cloned and their expression in different cotton (Gossypium hirsutum) cultivars and media was analyzed. VDPG1 and FOVPG1 were strongly upregulated during infection. Purified VDPG1 and FOVPG1 play important roles in the symptom development of both resistant and susceptible cotton. Moreover, after inoculation with purified PGs, the hydroxyproline content of the cell walls increased in cotton seedlings, with resistant cultivar seedlings showing significantly higher hydroxyproline content than seedlings of the susceptible cultivar. PG gene expression analysis in different media showed that both PG genes were induced in pectin medium but not in glucose medium. This study highlighted the role of VDPG1 and FOVPG1 in pathogenicity and virulence, which were detected in fungus-inoculated cotton, suggesting that PGs play an important role in the pathogenicity of V. dahliae and F. oxysporum f. sp. vasinfectum.

Characterization and expression analysis of the expansin gene NnEXPA1 in lotus Nelumbo nucifera

Biologia ◽  
2016 ◽  
Vol 71 (1) ◽  
Author(s):  
Neng Cheng ◽  
Xiao-Fei Zeng ◽  
Zheng Xing-Fei ◽  
Diao Ying ◽  
Wang You-Wei ◽  
...  
Keyword(s):  
Plant Cell ◽  
Expression Analysis ◽  
Cell Walls ◽  
Physiological Role ◽  
Nelumbo Nucifera ◽  
Plant Cell Walls ◽  
Expansin Gene

AbstractExpansin proteins play a key role in inducing the extension and relaxation of plant cell walls. To understand the physiological role of expansins in lotus crop,

scholarly journals Paradoxical conservation of a set of three cellulose-targeting genes in Mycobacterium tuberculosis complex organisms

Microbiology ◽  
2010 ◽  
Vol 156 (5) ◽  
pp. 1468-1475 ◽  
Author(s):  
Felix Mba Medie ◽  
Iskandar Ben Salah ◽  
Michel Drancourt ◽  
Bernard Henrissat
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Cell Walls ◽  
Pcr Amplification ◽  
Plant Cell Walls ◽  
Rt Pcr ◽  
Bacterial Genomes ◽  
Tuberculosis Complex ◽  
Transcription Analysis ◽  
Cellulose Binding

The genome of the tuberculosis agent Mycobacterium tuberculosis encodes a putative cellulose-binding protein (CBD2), one candidate cellulase (Cel12), and one fully active cellulase (Cel6). This observation is puzzling, because cellulose is a major component of plant cell walls, whereas M. tuberculosis is a human pathogen without known contact with plants. In order to investigate the biological role of such cellulose-targeting genes in M. tuberculosis we report here the search for and transcription analysis of this set of genes in the genus Mycobacterium. An in silico search for cellulose-targeting orthologues found that only 2.5 % of the sequenced bacterial genomes encode the Cel6, Cel12 and CBD2 gene set simultaneously, including those of the M. tuberculosis complex (MTC) members. PCR amplification and sequencing further demonstrated the presence of these three genes in five non-sequenced MTC bacteria. Among mycobacteria, the combination of Cel6, Cel12 and CBD2 was unique to MTC members, with the exception of Mycobacterium bovis BCG Pasteur, which lacked CBD2. RT-PCR in M. tuberculosis H37Rv indicated that the three cellulose-targeting genes were transcribed into mRNA. The present work shows that MTC organisms are the sole mycobacteria among very few organisms to encode the three cellulose-targeting genes CBD2, Cel6 and Cel12. Our data point toward a unique, yet unknown, relationship with non-plant cellulose-producing hosts such as amoebae.

scholarly journals Jasmonate biosynthesis arising from altered cell walls is prompted by turgor-driven mechanical compression

2021 ◽  
Vol 7 (7) ◽  
pp. eabf0356
Author(s):  
Stefan Mielke ◽  
Marlene Zimmer ◽  
Mukesh Kumar Meena ◽  
René Dreos ◽  
Hagen Stellmach ◽  
...  
Keyword(s):  
Cell Walls ◽  
Turgor Pressure ◽  
Mechanical Compression ◽  
Wild Type ◽  
Cell Type ◽  
Cortex Cell ◽  
Seedling Roots ◽  
Cell Type Specific ◽  
Altered Cell

Despite the vital roles of jasmonoyl-isoleucine (JA-Ile) in governing plant growth and environmental acclimation, it remains unclear what intracellular processes lead to its induction. Here, we provide compelling genetic evidence that mechanical and osmotic regulation of turgor pressure represents a key elicitor of JA-Ile biosynthesis. After identifying cell wall mutant alleles in KORRIGAN1 (KOR1) with elevated JA-Ile in seedling roots, we found that ectopic JA-Ile resulted from cell nonautonomous signals deriving from enlarged cortex cells compressing inner tissues and stimulating JA-Ile production. Restoring cortex cell size by cell type–specific KOR1 complementation, by isolating a genetic kor1 suppressor, and by lowering turgor pressure with hyperosmotic treatments abolished JA-Ile signaling. Conversely, hypoosmotic treatment activated JA-Ile signaling in wild-type plants. Furthermore, constitutive JA-Ile levels guided mutant roots toward greater water availability. Collectively, these findings enhance our understanding on JA-Ile biosynthesis initiation and reveal a previously undescribed role of JA-Ile in orchestrating environmental resilience.

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