The plant cytoskeleton, consisting of actin filaments and microtubules, is a highly dynamic filamentous framework involved in plant growth, development, and stress responses. Recently, research has demonstrated that the plant cytoskeleton undergoes rapid remodeling upon sensing pathogen attacks, coordinating the formation of microdomain immune complexes, the dynamic and turnover of pattern-recognizing receptors (PRRs), the movement and aggregation of organelles, and the transportation of defense compounds, thus serving as an important platform for responding to pathogen infections. Meanwhile, pathogens produce effectors targeting the cytoskeleton to achieve pathogenicity. Recent findings have uncovered several cytoskeleton-associated proteins mediating cytoskeletal remodeling and defense signaling. Furthermore, the reorganization of the actin cytoskeleton is revealed to further feedback-regulate reactive oxygen species (ROS) production and trigger salicylic acid (SA) signaling, suggesting an extremely complex role of the cytoskeleton in plant immunity. Here, we describe recent advances in understanding the host cytoskeleton dynamics upon sensing pathogens and summarize the effectors that target the cytoskeleton. We highlight advances in the regulation of cytoskeletal remodeling associated with the defense response and assess the important function of the rearrangement of the cytoskeleton in the immune response. Finally, we propose suggestions for future research in this area.

The plasma membrane (PM), which is composed of a lipid layer implanted with proteins, has diverse functions in plant responses to environmental triggers. The heterogenous dynamics of lipids and proteins in the plasma membrane play important roles in regulating cellular activities with an intricate pathway that orchestrates reception, signal transduction and appropriate response in the plant immune system. In the process of the plasma membrane participating in defense responses, the cytoskeletal elements have important functions in a variety of ways, including regulation of protein and lipid dynamics as well as vesicle trafficking. In this review, we summarized how the plasma membrane contributed to plant immunity and focused on the dynamic process of cytoskeleton regulation of endocytosis and exocytosis and propose future research directions.

Sandalwood (Santalum album), a culturally significant and economically valuable horticultural species, is renowned for its heartwood and essential oils enriched with sesquiterpene compounds such as santalol. Despite progress in elucidating the biosynthetic pathway of these valuable metabolites, the transcriptional regulation of this process, particularly under abiotic stress conditions, remains largely unexplored. Under drought conditions, we observed a marked increase in SaAREB6 expression, paralleled by elevated levels of santalols. Moreover, we identified SaCYP736A167, a cytochrome P450 mono-oxygenase gene, as a direct target of SaAREB6. Using electrophoretic mobility shift assays (EMSAs), microscale thermophoresis assays (MSTs), and dual luciferase assays (DLAs), we validated the precise and specific interaction of SaAREB6 with the promoter region of SaCYP736A167. This interaction leads to the upregulation of SaCYP736A167, which in turn catalyzes the final steps in the conversion of sesquiterpene precursors to santalols, thereby reinforcing the connection between SaAREB6 activity and increased santalol production during drought. Collectively, our work illuminates the previously uncharacterized role of SaAREB6 in orchestrating a transcriptional regulation that facilitates drought-induced santalol biosynthesis in sandalwood, presenting opportunities for genetic engineering strategies to improve heartwood and essential oil yields in this economically vital species.

Woody plants must acclimate to environmental stresses, including soil salinity, for proper growth and development. Microtubule reorganization supports plant survival in saline-rich soils, but the underlying molecular mechanism in tree species remains unclear. In this study, we identified a salinity stress response mechanism in hybrid poplar seedlings. This mechanism involves regulation of microtubule dynamics by the microtubule-associated protein PLASMA MEMBRANE–ASSOCIATED CATION BINDING PROTEIN 1a (PagPCaP1a). Salinity stress induced PagPCaP1a expression and phase separation of PagPCaP1a protein to form PagPCaP1a condensates in a calcium-dependent manner. The formation of PagPCaP1a condensates was partially driven by the VEEEKK motif within the carboxyl terminus of the protein, which rapidly depolymerizes microtubules under salinity stress. Our study reveals that the liquid-liquid phase separation of PagPCaP1a represents an additional regulatory layer for microtubule depolymerization, and we propose an effective strategy to manipulate the phase separation of PagPCaP1a to improve plant stress tolerance.

Microtubules are essential for regulating cell morphogenesis, plant growth, and the response of plants to abiotic stresses. TPX2 proteins are the main players determining the spatiotemporally dynamic nature of the MTs. However, how TPX2 members respond to abiotic stresses in poplar remains largely unknown. Herein, 19 TPX2 family members were identified from the poplar genome and analyzed the structural characteristics as well as gene expression patterns. All TPX2 members had the conserved structural characteristics, but exhibited different expression profiles in different tissues, indicating their varying roles during plant growth. Additionally, several light, hormone, and abiotic stress responsive cis-acting regulatory elements were detected on the promoters of PtTPX2 genes. Furthermore, expression analysis in various tissues of Populus trichocarpa showed that the PtTPX2 genes responded differently to heat, drought and salt stress. In summary, these results provide a comprehensive analysis for the TPX2 gene family in poplar and an effective contribution to revealing the mechanisms of PtTPX2 in the regulatory network of abiotic stress.

Microtubules undergo dynamic remodeling in response to diverse abiotic stress in plants. The plant-specific IQ67 DOMAIN (IQD) family proteins serve as microtubule-associated proteins, playing multifaceted roles in plant development and response to abiotic stress. However, the biological function of IQD genes in apple remains unclear. In this study, we conducted a comprehensive analysis of the Malus domestica genome, identifying 42 IQD genes distributed across 17 chromosomes and categorized them into four subgroups. Promoter analysis revealed the presence of stress-responsive elements. Subsequent expression analysis highlighted the significant upregulation of MdIQD17 and MdIQD28 in response to cold treatments, prompting their selection for further functional investigation. Subcellular localization studies confirmed the association of MdIQD17 and MdIQD28 with microtubules. Crucially, confocal microscopy and quantification revealed diminished microtubule depolymerization in cells transiently overexpressing MdIQD17 and MdIQD28 compared to wild-type cells during cold conditions. In conclusion, this study provides a comprehensive analysis of IQD genes in apple, elucidating their molecular mechanism in response to cold stress.