The conserved DNA damage repair complex, MMS21–SMC5/6 (Methyl methane sulfonate 21–Structural maintenance of chromosomes 5/6), has been extensively studied in yeast, animals, and plants.  However, its role in phytopathogenic fungi, particularly in the highly destructive rice blast fungus Magnaporthe oryzae, remains unknown.  In this study, we functionally characterized the homologues of this complex, MoMMS21 and MoSMC5, in M. oryzae.  We first demonstrated the importance of DNA damage repair in M. oryzae by showing that the DNA damage inducer phleomycin inhibited vegetative growth, infection-related development and pathogenicity in this fungus.  Additionally, we discovered that MoMMS21 and MoSMC5 interacted in the nuclei, suggesting that they also function as a complex in M. oryzae.  Gene deletion experiments revealed that both MoMMS21 and MoSMC5 are required for infection-related development and pathogenicity in M. oryzae, while only MoMMS21 deletion affected growth and sensitivity to phleomycin, indicating its specific involvement in DNA damage repair.  Overall, our results provide insights into the roles of MoMMS21 and MoSMC5 in M. oryzae, highlighting their functions beyond DNA damage repair.

One of the main diseases that adversely impacts the global citrus industry is citrus bacterial canker (CBC), caused by the bacteria Xanthomonas citri subsp. citri (Xcc).  Response to CBC is a complex process, with both protein-DNA as well as protein–protein interactions for the regulatory network.  To detect such interactions in CBC resistant regulation, a citrus high-throughput screening system with 203 CBC-inducible transcription factors (TFs), were developed.  Screening the upstream regulators of target by yeast-one hybrid (Y1H) methods was also performed.  A regulatory module of CBC resistance was identified based on this system.  One TF (CsDOF5.8) was explored due to its interactions with the 1-kb promoter fragment of CsPrx25, a resistant gene of CBC involved in reactive oxygen species (ROS) homeostasis regulation.  Electrophoretic mobility shift assay (EMSA), dual-LUC assays, as well as transient overexpression of CsDOF5.8, further validated the interactions and transcriptional regulation.  The CsDOF5.8–CsPrx25 promoter interaction revealed a complex pathway that governs the regulation of CBC resistance via H₂O₂ homeostasis.  The high-throughput Y1H/Y2H screening system could be an efficient tool for studying regulatory pathways or network of CBC resistance regulation.  In addition, it could highlight the potential of these candidate genes as targets for efforts to breed CBC-resistant citrus varieties.

Nicotinamide mononucleotide (NMN), a precursor in nicotinamide adenine dinucleotide (NAD) biosynthesis, has long been recognized for its pivotal role in medicine. Recent investigations have suggested its potential as a plant immunity inducer for controlling fungal diseases. However, whether NMN confers plant broad-spectrum resistance against diverse phytopathogens, and its underlying mechanisms remain ambiguous. In this study, we investigate the effect of NMN against multiple phytopathogens in tobacco. Our results demonstrate that tobacco pretreated with NMN exhibits enhanced resistance against Rastonia solanacearum CQPS-1, Pseudomonas syringae DC3000 ∆hopQ1-1, Phytophthora parasitica, and tobacco mosaic virus (TMV). NMN displays effectiveness within the concentration range of 50-600 μM, with 75 μM NMN exhibiting the most pronounced effect. The impact of NMN pretreatment could persist for up to 10 days. Beyond tobacco, NMN pretreatment enhances disease resistance in tomato and pepper plants against diverse pathogens, underscoring NMN’s capacity to confer broad-spectrum disease resistance in crops. Moreover, RT-qPCR analysis reveals that NMN significantly upregulates the expression of the pattern-triggered immunity (PTI) marker gene NbCYP71D20 and salicylic acid (SA) marker gene NbPR1a. This suggests that NMN enhances plant resistance by inducing both PTI and SA-mediated immunity. Interestingly, the positive impact of NMN on plant disease resistance is not significantly compromised in both NMN adenylyltransferase (NMNAT)-silenced plants and NAD receptor mutant lecrk-I.8, suggesting the existence of NAD-independent signaling pathways for NMN-induced plant immunity. In conclusion, our study establishes that the bioactive molecule NMN imparts broad-spectrum disease resistance in plants, offering a simple, environmental-friendly, and promising strategy for safeguarding crops against diverse phytopathogens. These findings also provide valuable insights for future in-depth studies into the functional mechanisms of NMN. 

Simultaneously enhancing plant growth and disease resistance is an ideal goal in Agriculture. Significant efforts have been made to promote plant growth or immunity through the use of biological reagents, such as the application of beneficial microbes and plant immunity inducers. However, balancing plant immunity and growth remains a challenging task. In this study, we engineered the plant growth-promoting bacterium Bacillus subtilis OKB105 to express a secreted microbial pattern, flg22, and accessed its activity in enhancing both plant growth and disease resistance. The OKB105 (flg22) strain exhibited plant growth-promoting activity similar to the OKB105 strain containing an empty vector, OKB105 (EV). Furthermore, the OKB105 (flg22) strain significantly enhanced plant resistance against two distinct pathogens, Pseudomonas syringae DC3000 ΔhopQ1-1 and Phytophthora parasitica, compared to OKB105 (EV), confirming that the engineered OKB105 (flg22) effectively enhances plant disease resistance. Interestingly, root irrigation with OKB105 (flg22) also markedly boosted the plant’s aboveground resistance to pathogens compared to OKB105 (EV). We further demonstrated that OKB105 (flg22) can be applied to confer resistance to pathogens in other plants that recognize flg22. Finally, RNA-Seq and qRT-PCR analyses illustrated that OKB105 (flg22) effectively induced the expression of defense-related genes in pattern-triggered immunity. Our results prove that employing an engineered beneficial microbe expressing a microbial pattern is a promising strategy for simultaneously enhancing plant growth and immunity. 

Geese, descendants of migratory birds, have preserved the distinct reproductive and lipid metabolism traits of their wild ancestors.  Therefore, compared to other poultry, geese have lower egg production ability and a more sensitive susceptibility to fatty liver.  Recent research underscores the impact of lipid metabolism disorders on female reproductive health.  In this context, we observed reproductive disorders (RD) and lipid metabolism anomalies in certain geese populations.  This study systematically elucidated the differences between RD and normal geese at various levels, including genomics, transcriptomics, bile acid metabolomics, and microbiomics, revealing the crucial role of microorganisms.  Our study provides a thorough examination of the ovarian anatomical, histological, and transcriptomic profiles between normal and RD geese.  Genomic analyses pinpoint mutations in genes associated with bile acid metabolism, highlighting their potential role in RD pathogenesis.  The genomic discoveries are substantiated by precise bile acid assays and ileum transcriptome analyses, which expose a significant disruption in bile acid absorption, activation of FXR, and an increase in serum chenodeoxycholic acid (CDCA) concentrations within RD geese.  Notably, 16S rRNA sequencing uncovers significantly greater beta diversity in the ileum microbiota of RD geese as compared to the normal group.  Both Wilcoxon rank sum test and LEfSe analyses highlighted a marked increase in Romboutsia abundance in RD geese. Experimental cultivation of microbiota with CDCA supplementation confirms the impact of CDCA on Romboutsia lituseburensis (R. lituseburensis) proliferation. Gavage experiments with R. lituseburensis elucidates its involvement in primary follicle reduction via immune-mediated pathways.  Collectively, our multi-faceted analysis unravels the intricate involvement of Romboutsia in goose RD, offering insights from genetic, physiological, and microbial dimensions. Our findings not only deepen our understanding of the etiology of RD in geese but also suggest potential avenues for therapeutic interventions targeting bile acid metabolism and the modulation of specific microbiota components.