MAPKK Regulates Cell Wall Biogenesis in Cooperation with the Cek1-Pathway in Candida albicans

The Slt2-Swi6 signaling pathway plays a pivotal role in regulating cell wall biosynthesis, secondary metabolite production, and the pathogenicity of pear fungal A. alternata

A physical interaction is identified between AaSlt2 and Swi6/RlmA, suggesting that these components are critical for cell wall synthesis, which advances the understanding of pathogenic mechanisms of A. alternata and proposes potential strategies for controlling postharvest diseases.

Cell wall stress delays yeast cell separation by altering septin dynamics and chitinase localization via the cell wall integrity pathway.

The Cell Wall Integrity (CWI) MAPK pathway in Saccharomyces cerevisiae is crucial for coordinating adaptive responses to cell wall stress. We investigated the effects of zymolyase (ZY), a cell wall-perturbing agent, on cell morphology and cell separation. Our findings reveal that sublethal ZY treatment transiently delays mother-daughter cell separation, leading to multibudded cell clusters. This phenotype, which is accompanied by initiation of a new budding cycle before cell separation is complete, was observed with cell wall perturbations but not with osmotic, oxidative, or ER stress. Genetic and molecular analyses indicate that this cell separation defect depends on phosphorylation-dependent activation of Slt2, the MAP kinase of the CWI pathway. The phenotype is not fully mediated by the primary transcriptional regulator of the pathway, Rlm1, suggesting that Slt2-dependent outputs beyond canonical Rlm1 transcription contribute to the response. We also show that ZY treatment is associated with altered spatiotemporal localization and dynamics of septin rings, as well as changes in the intracellular trafficking of key septal proteins. Notably, delivery of the endochitinase Cts1 to the bud neck is delayed, and the residence time of the exocyst subunit Exo84 and the myosin Myo2 at the septum is reduced. Despite altered protein trafficking, the transcriptional program governed by the daughter-specific transcription factor Ace2 remains largely unaffected. Our data are consistent with a cell-separation delay resulting from a coordinated response involving the CWI pathway, which correlates with changes in septin dynamics and cytokinetic protein trafficking. These findings, which suggest a mechanism that transiently halts cell separation when cell wall integrity is compromised, highlight a link between cell wall homeostasis and the regulation of cell division in yeast.

Integrin-Linked Kinases 1 and 4 participate in cell-wall-associated immune responses to leaf and root pathogens.

It is proposed that ILKs contribute to pathways connecting elicitor-triggered immune signaling with cell-wall-associated stress responses and that ILK-related defense functions may extend to the cotton root-nematode interaction, while the mechanism remains to be elucidated.

MEKK1/YDA-MKK4/5-MPK3/6 cascade is involved in extracellular ATP-regulated root growth of Arabidopsis thaliana.

The mitogen-activated protein kinase (MAPK) cascades play vital roles in mediating plant cell responses to external stimuli by regulating intracellular metabolism. We have previously reported that extracellular ATP (eATP) acts as an apoplastic messenger to regulate root growth, and that two receptor-like kinases, LRK10L3 and BAK1, play essential roles in this process. However, the intracellular signaling mechanisms through which eATP influences root growth remain unclear. In this study, we found that roots of loss-of-function mutants of several MAPK cascade components exhibited significantly reduced responsiveness to eATP compared with the wild type. eATP stimulated the expression of genes encoding MAPK cascade components, and in several upstream-element null mutants, eATP-induced expression of downstream members was enhanced. Moreover, eATP increased the phosphorylation of MAPK cascade components, suggesting that a cascade comprising MEKK1/YDA-MKK4/5-MPK3/6 is involved in the response of root cells to eATP. eATP may activate this MAPK cascade via LRK10L3 and BAK1, because eATP-stimulated phosphorylation of MEKK1 and YDA was impaired in double-null mutants lacking both receptor-like kinases. eATP also induced the translocation of MKK4/5 and MPK3/6 from the cytoplasm to the nucleus, a process partially dependent on phosphorylation. In mutants lacking functional MAPKs, eATP-stimulated expression of several jasmonic acid (JA) biosynthesis-related genes was compromised. Collectively, these results demonstrate that the MAPK cascade may serve as a crucial signaling module in eATP-regulated root growth in Arabidopsis thaliana, providing insights for further investigation of eATP signaling mechanisms.

The extracellular regulatory network and key factors governing early embryogenesis in Nicotiana tabacum.

It is reported that NtProRP1, an extracellular protein, localizes to the cell wall immediately after fertilization in Nicotiana tabacum, uncovering a new mechanism for NtProRP1 in regulating early embryogenesis and delivering a unique transcriptomic resource that advances understanding of extracellular signaling in plant embryogenesis.

Infection related stress adaptations in the secretome and wall proteome of