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.
Abstract
The cell wall integrity (CWI) pathway is triggered by plasma membrane-localized receptors in plant cells and serves to orchestrate responses to cell wall damage by initiating compensatory changes under stressful environments. The essential role of CWI maintenance as part of plants' interactions with pests or pathogens and during growth is well known. Nevertheless, CWI pathways remain to be fully characterized. Here, we show that altered Integrin-Linked Kinase 1 (ILK1) expression causes widespread defects in the transcriptional program activated by the bacterial elicitor flg22, primarily in genes associated with cell wall integrity and immunity. These transcriptional deficiencies are recapitulated in mutant lines with altered ILK4 or ILK5 expression. Analysis of molecular and cellular defenses in ilk mutants revealed reduced callose accumulation in leaves treated with bacterial (elf18) and plant (pep1) elicitors and increased pathogen susceptibility. Histochemical analysis of cell-wall-associated staining across diverse cells and organs of ilk mutants revealed modified lignin-associated patterns in the root xylem and altered calcofluor staining patterns in the seed coat. All ilk mutants exhibited altered root morphology due to mechano-touch and high-NaCl stress. Based on these results, we propose 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.
In the field of plant-microbe interactions, numerous cellular components of plants are known to play a critical role in interactions with pathogens. Nevertheless, a comprehensive understanding of all aspects of these interactions is lacking. Significant advancements have been made regarding the involvement of cell wall compounds in the plants’ overall response against biotic threats, and the findings indicate that certain molecules directly or indirectly influence cell wall alterations. The plant cell wall plays a vital role in providing a dynamic response against pathogenic microorganisms. Several groups of cellular components substantially affect cell wall structure, including enzymes involved in the synthesis and degradation of cellulose and hemicellulose, enzymes related to pectin modification, cell wall-associated non-enzymatic proteins, and pathogenesis-related proteins. These components contribute to the development of effective resistance, which can be manifested, for example, as a hypersensitive response. Conversely, the same components can cause vulnerability in different pathosystems, facilitating the growth of pathogens. The present review sums up the roles of enzymatic and non-enzymatic cell wall components in the defense response to important plant pathogens.
Piotr Rusin, E. Kozieł, C. Escalante et al.· Frontiers in Plant Science· 0 citations
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.
An Luo, Ying Qiao, Siyuan Li et al.· Plant and Cell Physiology· 0 citations
Plants are constantly challenged by pathogenic microorganisms that threaten growth and survival. While the individual signaling pathways involved in these immune responses have been well characterized, how plants balance growth with rapid pathogen perception and immune signal transduction remains largely unclear. Here, we report that the receptor-like kinase TaLYK5 receptor of wheat (Triticum aestivum) recognizes chitin on the fungal pathogen Puccinia striiformis f. sp. tritici (Pst) and initiates a cascade of events that increase immune response while reducing growth. TaLYK5 acts as a positive regulator of defense by phosphorylating the ankyrin-repeat-containing protein TaAKR2A, which supports reactive oxygen species (ROS) production and defense responses. In parallel, activated TaLYK5 negatively regulates growth responses by phosphorylating serine residue S234 in the ubiquitin-binding protein TaDSK2a, blocking its ability to degrade TaLYK5. Without infection by Pst, TaAKR2A does not initiate ROS signaling and immune responses and TaDSK2a associates with polyubiquitin chains on TaLYK5 to mediate its degradation, suppress TaLYK5-mediated plant defense. Meanwhile, TaDSK2a regulates gibberellin (GA) accumulation to promote plant growth, possibly by accelerating the degradation of TaEUI, a GA-deactivating enzyme. These findings demonstrate that the TaLYK5-TaDSK2a module functions as a molecular switch that dynamically regulates the trade-off between plant immunity and growth.
Yu Wu, Dan Yang, Haibin Zhao et al.· Proceedings of the National...· 0 citations
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.
Raúl García, J. M. Rodríguez-Peña, Alba Mangas-Losada et al.· Scientific Reports· 0 citations
Root-associated beneficial microbes prime host plants for induced systemic resistance (ISR) in leaves. Although continuous immune activation triggered by root endophytic fungi would impair leaf growth, how host plants avoid autoimmunity during endophytic fungi-mediated ISR priming is unknown. Here, we show that the Arabidopsis NatA N-terminal-acetyltransferase complex acts as a leaf-intrinsic brake on these root-to-leaf systemic responses. Impairment of the NatA subunit SUF1 (also named HYPK) or NAA15 unleashed chronic N-hydroxy-pipecolic-acid (NHP)/salicylic-acid (SA) signaling activation, converting beneficial ISR priming into growth-inhibitory leaf senescence. Transcriptome and quantitative proteomic analysis revealed the selective activation of defense and SA signaling pathways in the leaves of NatA mutants. Crossing suf1 or naa15 with fmo1 and eds5 abolished autoimmunity, confirming that the phenotype requires FMO1-dependent NHP and downstream SA synthesis and signaling activation. Thus, by destabilizing defense proteins, NatA enables plants to sustain lifelong ISR priming without growth penalty, guiding breeders to consider ISR control traits.
Xiao-Jie Chen, Gu-Zi Chen, Yao Xu et al.· Proceedings of the National...· 0 citations
MKK2 mediates the phosphorylation of the Mkc1 MAPK in response to cell wall assembly interfering agents such as zymolyase or tunicamycin and also to oxidative stress and it is shown here that Mkk2 mediates the phosphorylation of the Mkc1 MAPK under different stress conditions.
E. Román, R. Alonso-Monge, Alberto Miranda et al.· 0 citations