Activation and Autoinhibition Mechanisms of NLR Immune Receptor Pi36 in Rice.

Nucleotide-binding and leucine-rich repeat receptors (NLRs) are the most important and largest class of immune receptors in plants. The Pi36 gene encodes a canonical CC-NBS-LRR protein that confers resistance to rice blast fungal infections. Here, we show that the CC domain of Pi36 plays a role in cell death induction. Furthermore, self-association is required for the CC domain-mediated cell death, and the self-association ability is correlated with the cell death level. In addition, the NB-ARC domain may suppress the activity of the CC domain through intramolecular interaction. The mutations D440G next to the RNBS-D motif and D503V in the MHD motif autoactivated Pi36, but the mutation K212 in the P-loop motif inhibited this autoactivation, indicating that nucleotide binding of the NB-ARC domain is essential for Pi36 activation. We also found that the LRR domain is required for D503V- and D440G-mediated Pi36 autoactivation. Interestingly, several mutations in the CC domain compromised the CC domain-mediated cell death without affecting the D440G- or D503V-mediated Pi36 autoactivation. The autoactivate Pi36 variants exhibited stronger self-associations than the inactive variants. Taken together, we speculated that the CC domain of Pi36 executes cell death activities, whereas the NB-ARC domain suppressed CC-mediated cell death via intermolecular interaction. The NB-ARC domain releases its suppression of the CC domain and strengthens the self-association of Pi36 to support the CC domain, possibly through nucleotide exchange.

Dynamic characteristics of near-surface spontaneous combustion gas flux and its response to meteorological and soil factors in coal fire area.

Accurate identification of the early stages of coal-fire combustion is important for effectively controlling the spread of coal fires. CO2 and CO, as characteristic gases in the early stage of coal fire combustion, can be effectively monitored by in-situ monitoring near the surface. However, in the previous in-situ monitoring methods, the influence of surface meteorological and soil factors on the release law of characteristic gases is often ignored. Therefore, this paper considers the complexity of the geological conditions in the coal fire area, a system, and equipment for obtaining the near-surface CO2 and CO variation laws in the early stage of coal fire combustion proposed by the concentration gradient method (CGM). The system and equipment realize the simultaneous online coupling of multi-area and multi-parameter data and conduct field investigations on the Wuda coal fire area. The results show that in the early stage of coal combustion, the change patterns of CO2 and CO concentrations in different regions are anomalous, and the CO2 concentration was higher than the CO concentration. The CO2 and CO concentrations in shallow soil increased with the increase of soil depth, and compared with other areas, the CO2 and CO concentration was the highest. The shallow soil and CO2 were identified as the key areas and characteristic gases for identifying the early stage of coal-fire combustion. The CO2 flux (CF) of different shallow soil depths decreased with increased soil layer depth. Variation of soil-surface CO2 flux (S-SCF) estimated by flux extrapolation method (FLEM). The change of S-SCF is controlled by meteorological and soil factors, and there is a certain connection between it and the "respiration phenomenon" in the fissure area. Thus, this study provides a theoretical basis for effectively identifying the early stages of coal-fire combustion.