A Calcium-Dependent Protein Kinase Regulates the Defense Response in Citrus sinensis.

Citrus Huanglongbing (HLB), which is caused by 'Candidatus Liberibacter asiaticus' (CLas), is one of the most destructive citrus diseases worldwide, and defense-related Citrus sinensis gene resources remain largely unexplored. Calcium signaling plays an important role in diverse biological processes. In plants, a few calcium-dependent protein kinases (CDPKs/CPKs) have been shown to contribute to defense against pathogenic microbes. The genome of C. sinensis encodes dozens of CPKs. In this study, the role of C. sinensis calcium-dependent protein kinases (CsCPKs) in C. sinensis defense was investigated. Silencing of CsCPK6 compromised the induction of defense-related genes in C. sinensis. Expression of a constitutively active form of CsCPK6 (CsCPK6CA) triggered the activation of defense-related genes in C. sinensis. Complementation of CsCPK6 rescued the defense-related gene induction in an Arabidopsis thaliana cpk4/11 mutant, indicating that CsCPK6 carries CPK activity and is capable of functioning as a CPK in Arabidopsis. Moreover, an effector derived from CLas inhibits defense induced by the expression of CsCPK6CA and autophosphorylation of CsCPK6, which suggests the involvement of CsCPK6 and calcium signaling in defense. These results support a positive role for CsCPK6 in C. sinensis defense against CLas, and the autoinhibitory regulation of CsCPK6 provides a potential genome-editing target for improving C. sinensis defense. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Combination of fingerprint and chemometric analytical approaches to identify the geographical origin of Qinghai-Tibet plateau rapeseed oil.

Verification of the geographical origin of rapeseed oil is essential to protect consumers from fraudulent products. A prospective study was conducted on 45 samples from three rapeseed oil-producing areas in Qinghai Province, which were analyzed by GC-FID and GC-MS. To assess the accuracy of the prediction of origin, classification models were developed using PCA, OPLS-DA, and LDA. It was found that multivariate analysis combined with PCA separate 96% of the samples, and the correct sample discrimination rate based on the OPLS-DA model was over 98%. The predictive index of the model was Q2 = 0.841, indicating that the model had good predictive ability. The LDA results showed highly accurate classification (100%) and cross-validation (100%) rates for the rapeseed oil samples, demonstrating that the model had strong predictive capacity. These findings will serve as a foundation for the implementation and advancement of origin traceability using the combination of fatty acid, phytosterol and tocopherol fingerprints.

A complete MAP kinase cascade controls hyphopodium formation and virulence of Verticillium dahliae.

Phytopathogens develop specialized infection-related structures to penetrate plant cells during infection. Different from phytopathogens that form appressoria or haustoria, the soil-borne root-infecting fungal pathogen Verticillium dahliae forms hyphopodia during infection, which further differentiate into penetration pegs to promote infection. The molecular mechanisms underlying the regulation of hyphopodium formation in V. dahliae remain poorly characterized. Mitogen-activated protein kinases (MAPKs) are highly conserved cytoplasmic kinases that regulate diverse biological processes in eukaryotes. Here we found that deletion of VdKss1, out of the five MAPKs encoded by V. dahliae, significantly impaired V. dahliae hyphopodium formation, in vitro penetration, and pathogenicity in cotton plants. Constitutive activation of MAPK kinase (MAPKK) VdSte7 and MAPK kinase kinase (MAPKKK) VdSte11 specifically activate VdKss1. Deletion of VdSte7 or VdSte11 resulted in a phenotype similar to that of the mutant with VdKss1 deletion. Thus, this study demonstrates that VdSte11-VdSte7-VdKss1 is a core MAPK cascade that regulates hyphopodium formation and pathogenicity in V. dahliae. Supplementary Information: The online version contains supplementary material available at 10.1007/s42994-023-00102-y.

Formation of Ohmic contacts between ferromagnetic Cr2Ge2Te6and two-dimensional metals.

As a ferromagnetic semiconductor, two-dimensional (2D) Cr2Ge2Te6holds significant implications for electronic and spintronic devices. To achieve 2D electronics, it is essential to integrate Cr2Ge2Te6with 2D electrodes to form Schottky-barrier-free Ohmic contacts with enhanced carrier injection efficiency. Herein, by using first-principles calculations based on density-functional theory, we systematically investigate the structural, energetic, electronic and magnetic properties of 2D heterojunctions by combining Cr2Ge2Te6with a series of 2D metals, including graphene, ZrCl, NbS2, TaS2, TaSe2, Zn3C2, Hg3C2, and Zr2N. Results show that NbS2, TaS2, TaSe2, Zn3C2, Hg3C2, and Zr2N form Ohmic contacts with Cr2Ge2Te6, in contrast to graphene and ZrCl that exhibit a finite Schottky barrier. By examining the tunneling barriers and Fermi level shift, we reveal that the heterojunctions with Zn3C2and Hg3C2as electrodes exhibit advantages of both high electron injection efficiency and spin injection efficiency, for which an apparent decrease of the magnetic moment of Cr atoms in Cr2Ge2Te6can be observed. These findings not only provide physical insights into the role of interfacial interaction in regulating the physical properties of 2D heterojunctions, but also pave way for the development of high-performance spintronic nanodevices for practical implementation.

Chitin Synthase Genes Are Differentially Required for Growth, Stress Response, and Virulence in Verticillium dahliae.

Crop wilt disease caused by Verticillium dahliae usually leads to serious yield loss. Chitin, an important component of most fungal cell walls, functions to maintain the rigidity of cell walls and septa. Chitin synthesis mainly relies on the activity of chitin synthase (CHS). Eight CHS genes have been predicted in V. dahliae. In this study, we characterized the functions of these genes in terms of growth, stress responses, penetration, and virulence. Results showed that VdCHS5 is important for conidia germination and resistance to hyperosmotic stress. Conidial production is significantly decreased in Vdchs1, Vdchs4, and Vdchs8 mutants. VdCHS1, VdCHS2, VdCHS4, VdCHS6, VdCHS7, and VdCHS8 genes are important for cell wall integrity, while all mutants are important for cell membrane integrity. All of the VdCHS genes, except for VdCHS3, are required for the full pathogenicity of V. dahliae to Arabidopsis thaliana and cotton plants. The in vitro and in vivo penetration of Vdchs1, Vdchs4, Vdchs6, and Vdchs7 mutants was impaired, while that of the other mutants was normal. Overall, our results indicate that the VdCHS genes exert diverse functions to regulate the growth and development, conidial germination, conidial production, stress response, penetration, and virulence in V. dahliae.

iTRAQ-based proteomics analysis of autophagy-mediated immune responses against the vascular fungal pathogen Verticillium dahliae in Arabidopsis.

The mechanisms underlying the functional link between autophagy and plant innate immunity remain largely unknown. In this study, we investigated the autophagy-mediated plant defense responses against Verticillium dahliae (V. dahliae) infection by comparative proteomics and cellular analyses. An assessment of the autophagy activity and disease development showed that autophagic processes were tightly related to the tolerance of Arabidopsis plant to Verticillium wilt. An isobaric tags for relative and absolute quantification (iTRAQ)-based proteomics analysis was performed, and we identified a total of 780 differentially accumulated proteins (DAPs) between wild-type and mutant atg10-1 Arabidopsis plants upon V. dahliae infection, of which, 193 ATG8-family-interacting proteins were identified in silico and their associations with autophagy were verified for several selected proteins. Three important aspects of autophagy-mediated defense against V. dahliae infection were revealed: 1) autophagy is required for the activation of upstream defense responses; 2) autophagy-mediated mitochondrial degradation (mitophagy) occurs and is an important player in the defense process; and 3) autophagy promotes the transdifferentiation of perivascular cells and the formation of xylem hyperplasia, which are crucial for protection against this vascular disease. Together, our results provide several novel insights for understanding the functional association between autophagy and plant immune responses.