New insight into Ca2+ -permeable channel in plant immunity.

Calcium ions (Ca2+ ) are crucial intracellular second messengers in eukaryotic cells. Upon pathogen perception, plants generate a transient and rapid increase in cytoplasmic Ca2+ levels, which is subsequently decoded by Ca2+ sensors and effectors to activate downstream immune responses. The elevation of cytosolic Ca2+ is commonly attributed to Ca2+ influx mediated by plasma membrane-localized Ca2+ -permeable channels. However, the contribution of Ca2+ release triggered by intracellular Ca2+ -permeable channels in shaping Ca2+ signaling associated with plant immunity remains poorly understood. This review discusses recent advances in understanding the mechanism underlying the shaping of Ca2+ signatures upon the activation of immune receptors, with particular emphasis on the identification of intracellular immune receptors as non-canonical Ca2+ -permeable channels. We also discuss the involvement of Ca2+ release from the endoplasmic reticulum in generating Ca2+ signaling during plant immunity.

Interkingdom Hormonal Regulations between Plants and Animals Provide New Insight into Food Safety.

Food safety has become an attractive topic among consumers. Raw material production for food is also a focus of social attention. As hormones are widely used in agriculture and human disease control, consumers' concerns about the safety of hormone agents have never disappeared. The present review focuses on the interkingdom regulations of exogenous animal hormones in plants and phytohormones in animals, including physiology and stress resistance. We summarize these interactions to give the public, researchers, and policymakers some guidance and suggestions. Accumulated evidence demonstrates comprehensive hormonal regulation across plants and animals. Animal hormones, interacting with phytohormones, help regulate plant development and enhance environmental resistance. Correspondingly, phytohormones may also cause damage to the reproductive and urinary systems of animals. Notably, the disease-resistant role of phytohormones is revealed against neurodegenerative diseases, cardiovascular disease, cancer, and diabetes. These resistances derive from the control for abnormal cell cycle, energy balance, and activity of enzymes. Further exploration of these cross-kingdom mechanisms would surely be of greater benefit to human health and agriculture development.

WeiTsing, a pericycle-expressed ion channel, safeguards the stele to confer clubroot resistance.

Plant roots encounter numerous pathogenic microbes that often cause devastating diseases. One such pathogen, Plasmodiophora brassicae (Pb), causes clubroot disease and severe yield losses on cruciferous crops worldwide. Here, we report the isolation and characterization of WeiTsing (WTS), a broad-spectrum clubroot resistance gene from Arabidopsis. WTS is transcriptionally activated in the pericycle upon Pb infection to prevent pathogen colonization in the stele. Brassica napus carrying the WTS transgene displayed strong resistance to Pb. WTS encodes a small protein localized in the endoplasmic reticulum (ER), and its expression in plants induces immune responses. The cryoelectron microscopy (cryo-EM) structure of WTS revealed a previously unknown pentameric architecture with a central pore. Electrophysiology analyses demonstrated that WTS is a calcium-permeable cation-selective channel. Structure-guided mutagenesis indicated that channel activity is strictly required for triggering defenses. The findings uncover an ion channel analogous to resistosomes that triggers immune signaling in the pericycle.

SHOU4/4L link cell wall cellulose synthesis to pattern-triggered immunity.

Pattern recognition receptors (PRRs) are plasma membrane-localised proteins that sense molecular patterns to initiate pattern-triggered immunity (PTI). Receptor-like cytoplasmic kinases (RLCKs) function downstream of PRRs to propagate signal transduction via the phosphorylation of substrate proteins. The identification and characterisation of RLCK-regulated substrate proteins are critical for our understanding of plant immunity. We showed that SHOU4 and SHOU4L are rapidly phosphorylated upon various patterns elicitation and are indispensable for plant resistance to bacterial and fungal pathogens. Protein-protein interaction and phosphoproteomic analysis revealed that BOTRYTIS-INDUCED KINASE 1, a prominent protein kinase of RLCK subfamily VII (RLCK-VII), interacted with SHOU4/4L and phosphorylated multiple serine residues on SHOU4L N-terminus upon pattern flg22 treatment. Neither phospho-dead nor phospho-mimic SHOU4L variants complemented pathogen resistance and plant development defect of the loss-of-function mutant, suggesting that reversible phosphorylation of SHOU4L is critical to plant immunity and plant development. Co-immunoprecipitation data revealed that flg22 induced SHOU4L dissociation from cellulose synthase 1 (CESA1) and that a phospho-mimic SHOU4L variant inhibited the interaction between SHOU4L and CESA1, indicating the link between SHOU4L-mediated cellulose synthesis and plant immunity. This study thus identified SHOU4/4L as new components of PTI and preliminarily revealed the mechanism governing SHOU4L regulation by RLCKs.

A surface-receptor-coupled G protein regulates plant immunity through nuclear protein kinases.

Plants employ cell-surface-localized pattern recognition receptors (PRRs) to recognize immunogenic patterns and activate defenses. How these receptors regulate immune signaling in the nucleus is not well understood. Our previous studies showed that BIK1, a central kinase associated with PRRs, phosphorylates a plant-specific Gα protein called extra-large G protein 2 (XLG2) to positively regulate immunity. Here, we show that this phosphorylation promotes XLG2 nuclear translocation, which is essential for antibacterial immunity. XLG2 interacts with nuclear-localized MUT9-like kinases (MLKs) to regulate transcriptome programming. MLKs negatively regulate plant immunity in a kinase activity-dependent manner, whereas XLG2 promotes defense gene expression and antibacterial immunity likely by inhibiting MLK kinase activity. A C-terminal motif in MLKs is essential for the interaction with XLG2, and this motif is required for the XLG2-mediated defense activation. Together, our findings reveal a previously unknown pathway and mechanisms by which cell surface receptors regulate transcriptome during pathogen invasion.

Responses of greenhouse gas emissions to residue returning in China's croplands and influential factors: A meta-analysis.

Climate change is a global issue threatening agricultural production and human survival. However, agriculture sector is a major source of global greenhouse gases (GHGs), especially CH4 and N2O. Crop residue returning (RR) is an efficient practice to sequestrate soil carbon and increase crop yields. However, the efficiency of RR to mitigate climate change and maintain food security will be affected by the response of GHG emissions at both per area-scale and per yield-scale. Therefore, a national meta-analysis was conducted using 309 comparisons from 44 publications to assess the responses of GHG emissions to RR in China's croplands. The results indicated that little response of GWP to RR was observed with conditions under lower nitrogen fertilizer input rates (0-120 kg ha-1), mulch retention, returning one time in double cropping systems, returning with half residue, weakly acidic soil (pH 5.5-6.5), initial SOC contents >20 g kg-1, or mean annual precipitation <1000 mm. In order to mitigate climate change and sustain food security, RR combined with paddy-upland rotation, nitrogen fertilizer input rates of 240-360 kg ha-1, and neutral soil (pH 6.5-7.5) could decrease GWP at per unit of crop yield, which ultimately leads to a lower effect on GHGI and a higher crop production efficiency. In-depth studies should be conducted in the future to explore the interactions between various factors influencing GHG emissions under RR conditions. Overall, optimizing the interactions with management and site-specific conditions, potential for regulating GHGs emissions of RR can be enhanced.