Plant pathogen effectors play important roles in parasitism, including countering plant immunity. However, investigations of the emergence and diversification of fungal effectors across host-adapted populations has been limited. We previously identified a gene encoding a suppressor of plant cell death in Pyricularia oryzae (syn. Magnaporthe oryzae). Here, we report the gene is one of a 21-member gene family and we characterize sequence diversity in different populations. Within the rice pathogen population, nucleotide diversity is low, however; the majority of gene family members display presence-absence polymorphism or other null alleles. Gene family allelic diversity is greater between host-adapted populations and, thus, we named them host-adapted genes (HAGs). Multiple copies of HAGs were found in some genome assemblies and sequence divergence between the alleles in two cases suggested they were the result of repeat-induced point mutagenesis. Transfer of family members between populations and novel HAG haplotypes resulting from apparent recombination were observed. HAG family transcripts were induced in planta and a subset of HAGs are dependent on a key regulator of pathogenesis, PMK1. We also found differential intron splicing for some HAGs that would prevent ex planta protein expression. For some genes, spliced transcript was expressed in antiphase with an overlapping antisense transcript. Characterization of HAG expression patterns and allelic diversity reveal novel mechanisms for HAG regulation and mechanisms generating sequence diversity and novel allele combinations. This evidence of strong in planta–specific expression and selection operating on the HAG family is suggestive of a role in parasitism. [ ] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Smooth cordgrass (Spartina alterniflora) is a native salt marsh plant along the Atlantic coast but has become an invasive species in coastal regions in China, as well as other areas. Utilizing it for resources has become a control measure in reducing the spread of S. alterniflora. This study assesses the nutritional and phytochemical properties of the edible stems of S. alterniflora collected from three locations in Fujian province, China. The tender stems of S. alterniflora exhibit a rich nutritional profile, with high levels of protein, carbohydrates, and fats, and significant amounts of essential vitamins, minerals, and antioxidants, indicating their potential as a nutritious addition to the diet or forage. In addition, the levels of potential contaminants, including nitrate, nitrite, cadmium, lead, and chromium, are below the established safe thresholds for consumption. Our results provide valuable information for the sustainable utilization of S. alterniflora resources and will contribute to the integrated control of S. alterniflora.

Jacalin-related lectins play crucial roles in plant adaptation to abiotic and biotic stresses. The rice genome encodes four putative jacalin-related lectin kinase genes (OsJacLKs), but their functions toward environmental stresses remain largely uncharacterized. This study demonstrates that a putative jacalin-related lectin kinase, OsJacLK1, conferred resistance to the rice blast fungus Magnaporthe oryzae rather than salt stress. OsJacLK1 protein exhibited agglutination activities and affinity toward chitin, fungal cell wall, and mannose. OsJacLK1 was transcriptionally activated by stress-related phytohormones salicylic acid (SA), methyl jasmonate (MeJA), abscisic acid (ABA), and indoleacetic acid (IAA), as well as salinity, chitin, and M. oryzae inoculation, suggesting its involvement in broad stress-responsive signaling pathways. Overexpression of OsJacLK1 in rice led to reduced susceptibility to rice blast disease, whereas loss-of-function osjaclk1 lines showed no significant phenotypic difference from wild-type plants upon infection. Enhanced resistance in OsJacLK1-overexpressing lines was associated with a stronger reactive oxygen species (ROS) burst and elevated hydrogen peroxide accumulation, accompanied by the up-regulation of defense-related genes (OsRac1, OsSGT1, OsMAPK6, OsPAL1, OsNAC4, OsPBZ1, OsAOS2, and OsJAZ8). Collectively, our findings establish that OsJacLK1 acts as a positive regulator of rice immunity against M. oryzae, modulating the cellular redox state, highlighting its potential as a candidate for genetic improvement of disease resistance in rice.

Rice (Oryza sativa L.) production is severely threatened by rice blast disease caused by the hemibiotrophic fungus Magnaporthe oryzae. Chemical fungicides, although effective, cause environmental pollution, disrupt soil microbiomes, and select for resistant pathogen populations, creating an urgent need for sustainable alternatives. In this study, we isolated Kitasatospora hibisci strain 21007 from mangrove soil and evaluated its biocontrol potential through integrated phenotypic and transcriptomic analyses. The cell-free culture filtrate (CFCF) extract showed potent antifungal activity, inhibiting M. oryzae mycelial growth and suppressing conidial germination as well as appressorium formation in a concentration-dependent manner via antibiosis. Fermentation optimization identified Gauze’s Synthetic Medium No. 1 as optimal for metabolite production. Both inoculation of M. oryzae spores with 21007 CFCF extract and pre-treatment of rice seedlings with 21007 CFCF significantly reduced disease severity under greenhouse conditions. Transcriptomic analysis revealed extensive reprogramming of gene expression in leaves of rice seedlings cultured with 21007 CFCF extract. KEGG pathway enrichment analysis indicated activation of the plant–pathogen interaction and MAPK signaling pathways in rice seedlings cultured with 5% and 10% CFCF extract, suggesting that 21007 CFCF induces host defense signaling. These results support the potential of K. hibisci 21007 as a candidate for sustainable biocontrol of rice blast disease and establish a foundation for future metabolomic and genomic investigations.

Phycobiliproteins from the red alga Porphyra umbilicalis are rich precursors of bioactive peptides, but targeted identification of high-potency sequences remains challenging. To address this, we combined an in silico screening pipeline with experimental validation to discover novel antioxidant peptides. Virtual enzymatic hydrolysis generated 908 candidate sequences, which were filtered down to 12 peptides based on molecular weight, toxicity, hydrophilicity, and bioactivity predictions. Molecular docking and molecular dynamics simulations further identified four candidate peptides (FK, FKP, FRS, and RRF) that were computationally predicted to bind stably within the KEAP1 Kelch domain. Chemical assays confirmed that all four synthesized peptides exhibited dose-dependent DPPH and ABTS radical-scavenging activities, along with Fe²⁺-chelating capacity and ferric reducing antioxidant power. In H₂O₂-stimulated Caco-2 cells, peptide pretreatment protected against cellular oxidative stress by restoring endogenous antioxidant enzyme activities, increasing total antioxidant capacity, and reducing lactate dehydrogenase leakage. Among these, RRF displayed the strongest protective efficacy. Overall, this study presents a practical workflow for mining marine-derived peptides and highlights four candidate peptides whose potential as functional food ingredients warrants further validation in actual P. umbilicalis hydrolysates.

Heat shock transcription factors (HSFs) play a crucial role in mediating responses to abiotic stresses. However, characterization of HSFs in macroalgae remains largely unexplored. In this study, a comprehensive analysis of HSFs was carried out in Saccharina japonica. A total of sixteen SjHSFs were identified. Phylogenetic analysis revealed that HSFs from brown algae form a distinct clade, separate from those from red algae, green algae, moss, and Arabidopsis thaliana. The DNA-binding domain was found to be highly conserved among SjHSFs. Analysis of cis-acting elements in SjHSF promoters suggested their potential roles in regulating growth, development, and stress responses. Tissue-specific expression profiles revealed differential expression of SjHSFs across various tissues of S. japonica. Under abiotic stresses, certain SjHSFs exhibited dynamic expression patterns, with particularly pronounced changes observed under high-temperature stress. We further employed a transcription factor-centered yeast one-hybrid (TF-Centered Y1H) to determine the motifs recognized by SjHSF-03. Seven conserved motifs were identified, and the distributions of these motifs were screened in the promoter regions of S. japonica genes involved in diverse biological processes and pathways. Notably, 23 heat shock protein (HSP) genes were among these motif-containing genes, and 21 out of these 23 SjHSPs were up-regulated under heat stress. Our results provide a solid foundation for future research on the specific functions of HSFs under different stress conditions and the regulatory mechanisms of HSF-mediated stress responses in S. japonica and other brown algae.