New Phytologist, Год журнала: 2024, Номер unknown
Опубликована: Ноя. 23, 2024
The gene-for-gene hypothesis, proposed by Flor in 1942, postulates that for each dominant avirulence (Avr) protein a pathogen, there is corresponding resistance (R) gene the host. This interaction triggers host defense mechanisms, such as hypersensitive response, which effectively limits biotrophic pathogen growth (Flor, 1942). Decades later, term 'effector protein' was introduced to describe proteins secreted or translocated pathogens manipulate Understanding how process and secrete these effectors crucial deciphering their pathogenicity. '…the cleavage of RXLR EER motifs P. infestans provide important insights into function effector processing secretion.' zigzag model has been classically used plant immune responses through dynamic between pathogen-associated molecular patterns (PAMPs) effectors. readily applied oomycetes, where plants detect oomycete PAMPs, β-1,3- β-1,6-glucans, cellulose-binding XEG1 endoglucanase (Judelson & Ah-Fong, 2019) via pattern recognition receptors (PRRs), leading PAMP-triggered immunity (PTI). In oomycetes evolved suppress PTI, causing effector-triggered susceptibility (ETS), but counter this recognizing specific R proteins, activating (ETI), again thought be more robust (Jones Dangl, 2006). Though still holding true evolution, critiqued oversimplification when it comes plant–oomycete interaction. critique based on data showing are sometimes recognized before physical contact even occurs; ETS ETI rather parallel than separate mechanisms. Despite role infection, surprisingly little known about secretion mechanisms oomycetes. other eukaryotic systems, well established conventional follows classical secretory pathway, directed endoplasmic reticulum (ER) an N-terminal signal peptide. From there, processed transported Golgi apparatus being out cell. Unconventional secretion, hand, bypasses ER–Golgi pathway involves alternative direct translocation across plasma membrane endosomal vesicular pathways (Wang et al., 2018). It expected some clades have new variations. L. Xu al. (2024), secretion. While remain central, possibility routes, influenced structural positioning motifs, highlights complex posttranslational modifications occur delivered plant. case effectors, peptide (SP) cleaved off during after ER. followed additional modifications, including proteolytic at motif, shown Y. al.'s (2024) study. general rule follow dependent cellular machinery proper delivery Proteolytic motif mirrors similar mechanism seen pathogens. bears striking resemblance RXLXE/D/Q also Plasmodium export element (PEXEL), found malaria parasite These like those from infestans, cells – case, red blood human (Gabriela 2024). Just spatially constrained within 40 amino acids site, so PEXEL motif. Plasmodium, constraint correct subsequent After cleavage, residue acetylated, essential modification specialized (Boddey 2016). spatial functional conservation suggests both share fundamental ensuring correctly cells, albeit different organisms. Phytophthora species, many contain adjacent Glu-Glu-Arg (EER) similarly implicated (Whisson 2007). build upon demonstrating first time can proteolytically (Fig. 1). Their findings challenge previous assumptions solely involved cell delivery, instead serves site contrast Phytophthora, lack necessary cleave motifs. Beyond themselves, context plays critical function. conserved WY domain, commonly C-terminal region contributes target specificity stability (Bentham 2023; Li 2023). presence (Trp-Tyr) domain closely coordinated with elements mediate interactions targets. Interestingly, Bremia lactucae lettuce only raising alone may serve (Wood 2020). further reinforces idea, discussed Wang (2023), sites diverse Gabriela provided evidence certain dual functions. Mutations residues significantly reduce increased retention ER decreased export. mutations lesser effect, allowing reach parasitophorous vacuole, though reduced efficiency. We learn experiments contribute differently dependents acid characteristics However, hypothesis will need testing, example, using single point degenerate [KHGQ][X][LMYFIV][RNK] observed downy mildews expand our understanding providing experimental widespread phenomenon. not supports idea pathogens, opens avenues exploring highlighting evolutionary parallels Furthermore, raises questions evolution infection strategies, given all possess RXLR(-like) discovery adds complexity biology infestans. Combined recent uptake endocytosis (Oliveira-Garcia 2023), research points toward exciting direction fully beyond. authors acknowledge funding Eccersall's PhD scholarship RPBC, support project plant–Phytophthora interactions, funded Bioprotection Aotearoa grant awarded Meisrimler.
Язык: Английский