Editorial: Plant cell wall in pathogenesis, parasitism and symbiosis, Volume II

Editorial on the Research Topic Plant cell wall in pathogenesis, parasitism and symbiosis, Volume II A wide range of organisms that interact with plants must interface with the plant cell wall (CW) (Lionetti and Metraux, 2014). The view of the CW as only a static cellular barrier in these interactions is outdated. Cell wall polysaccharides, phenolic compounds, and proteins, in addition to regulating important growth and development processes, are also sources of elicitors that activate cell signaling pathways (Nguema-Ona et al., 2013). Surveillance mechanisms detect CW contacts with other organisms, and specific signaling pathways and responses are activated (Swaminathan et al., 2022) (Figure 1). During biotic interactions and abiotic stresses, the structure and composition of plant CW can be regulated at the biosynthetic level and through precise, continuous post-synthetic remodeling. As a consequence, the CW must be understood as a strategic space between organisms where intelligent and dynamic molecular strategies are implemented to overwhelm a fight or cooperate for specific physiological processes (Bacete et al., 2018; Castilleux et al., 2018; De Lorenzo et al., 2019). Cell wall enzymes and their inhibitors play key roles in apoplastic metabolism (Rui and Dinneny, 2020). Invertases (INVs) and pectin methylesterases (PMEs) play essential roles in carbohydrate metabolism, stress responses, and sugar signaling (Bellincampi et al., 2014; Tauzin and Giardina, 2014; Del Corpo et al., 2020). In this collection, Coculo and Lionetti reviewed the roles of invertase inhibitors (INVI) and pectin methylesterase inhibitors (PMEI) belonging to the "Plant Invertase/Pectin Methylesterase Inhibitor Superfamily" (Lionetti et al., 2017). An updated overview of the specific activity of the characterized isoforms, their specific functions in plant physiology, and their applications in biotechnology is provided. After the pioneering work in 2007 (Lionetti et al., 2007), several piece of evidence supported the role of PMEIs in plant resistance to stresses (An et al., 2008; Liu et al., 2018). With a genome-wide analysis and transcriptomics of the PMEI genes in Brassica napus, Wang et al. identified several BnPMEIs as resistance gene candidates in response to Sclerotinia sclerotiorum, suggesting them as possible tools to breed new and improved genotypes more resistant to Sclerotinia stem rot.