WeiTsing: a new face of Ca2+-permeable channels in plant immunity

Abstract

Plants employ pattern- and effector-triggered immunity (PTI and ETI) to synergistically defend invading pathogens and insect herbivores. Both PTI and ETI can induce cytosolic Ca2+ spikes, despite in different spatiotemporal patterns, to activate downstream Ca2+-dependent immune signaling cascades. While multiple families of Ca2+-permeable channels at the plasma membrane have been uncovered, the counterparts responsible for Ca2+ release from intracellular stores remain poorly understood. In a groundbreaking paper published recently by Cell, the authors reported that WeiTsing, an Arabidopsis endoplasmic reticulum (ER)-resident protein that was specifically expressed in the pericycle upon Plasmodiophora brassicae (Pb) infection, could form resistosome-like Ca2+-conducting channel and protect the stele of Brassica crops from Pb colonization. As the channel activity of WeiTsing was indispensable for its immune function, the findings highlight a previously underappreciated role of Ca2+ release from intracellular repertoire in promoting plant disease resistance.

New insight into Ca2+‐permeable channel in plant immunity

“…Several families of Ca 2+ ‐permeable channels are part of the signaling pathway downstream of PRR activation and contribute to pattern‐triggered Ca 2+ influx in Arabidopsis . These families include CYCLIC NUCLEOTIDE‐GATED ION CHANNELs (CNGCs), glutamate receptor‐like (GLR) proteins, REDUCED HYPEROSMOLALITY‐INDUCED Ca 2+ INCREASE (OSCA) channels, TWO‐PORE CHANNELs (TPCs), and ANNEXINs (ANNs) (Köster et al, 2022; Xu et al, 2022; Wang and Li, 2023a). Recent studies have revealed how these Ca 2+ ‐permeable channels are regulated during PRR signaling.…”

“…This dynamic change in cytosolic Ca 2+ concentration is referred to as a “Ca 2+ signature” and is mediated by various Ca 2+ ‐permeable channels that enable Ca 2+ entry from the external space or Ca 2+ release from intracellular stores (Luan and Wang, 2021; Jiang and Ding, 2023). Activated PRRs and NLRs trigger Ca 2+ signatures with different amplitudes and durations, which are subsequently interpreted and decoded by various Ca 2+ ‐binding proteins, thereby regulating downstream defense responses (Kim et al, 2022; Köster et al, 2022; Xu et al, 2022; Wang and Li, 2023a). In recent decades, numerous studies have revealed that multiple canonical Ca 2+ ‐permeable channels are involved in the precise shaping of Ca 2+ signatures in plants in response to pathogens.…”

“…However, the mechanisms through which Ca 2+ ‐permeable channels are activated during plant immunity have only recently been elucidated. In particular, NLRs have been reported to function as Ca 2+ ‐permeable channels mediating Ca 2+ influx, subsequently activating the immune response (Kim et al, 2022; Köster et al, 2022; Xu et al, 2022; Wang and Li, 2023a). Furthermore, a recent study reported on the involvement of a channel localizing to the endoplasmic reticulum (ER) and being responsible for Ca 2+ release during immune activation, considerably advancing our knowledge of Ca 2+ signaling in plant immunity.…”

Fungal signals and calcium‐mediated transduction pathways along the plant defence–symbiosis continuum

“…Furthermore, extending investigations into plant organellar Ca 2+ signalling (Stael et al ., 2012; Costa et al ., 2018; Resentini et al ., 2021) may be essential to fully understand the complexity of the whole cellular Ca 2+ network in beneficial plant–fungus interactions. Indeed, Ca 2+ released from intracellular stores seems to play a crucial role not only in symbiosis (Charpentier et al ., 2016; Del Cerro et al ., 2022) but also in immunity signalling (Wang et al ., 2024). In short, an integrative approach combining different GECIs, merging distinct advantages, that is, qualitative and quantitative analyses of Ca 2+ signals, appears to be critical for fully dissecting and reconstructing Ca 2+ signalling in plant–microbe interactions.…”