Low nitrogen (LN) availability is a major constraint limiting plant vegetative growth and reproductive development. To investigate the physiological and molecular mechanisms underlying LN stress in tall fescue (Festuca arundinacea), a comprehensive analysis of phenotypic, physiological, and transcriptional responses was conducted. The results showed that LN stress significantly reduced shoot height, tiller number, leaf length, and shoot biomass. In addition, root system architecture was markedly altered, with increased total root length but decreased root number and root volume. Physiological assays revealed that total chlorophyll content, photochemical efficiency, and net photosynthetic rate were significantly reduced. Concurrently, nitrate reductase activity, NO3− concentration, and N content were significantly reduced, while soluble sugar content was significantly enhanced. Transcriptomic analysis identified a total of 1185 differential expression genes (585 upregulated and 600 downregulated), with significant changes in genes involved in N transport, N assimilation, glycolysis, and the tricarboxylic acid cycle. In addition, 27 transcription factor genes across seven distinct families were significantly differentially expressed. Three bHLH transcription factors, FaIRO2, FabHLH69, and FabHLH062, were identified as candidate regulators of the LN response in tall fescue based on their expression patterns under LN stress. Collectively, this study provides integrated physiological and transcriptional insights into tall fescue responses to LN stress and highlights potential target genes for genetic improvement of perennial forage and turf grasses with high N use efficiency.
Olive (Olea europaea L.) leaf composition depends on both collection date and cultivar, yet these two sources of variation are rarely separated within one orchard over a full year. Leaves of the indigenous Istrian cultivars ‘Istarska bjelica’ and ‘Rošinjola’ and the introduced ‘Leccino’ were sampled in one orchard every two months from April 2025 to February 2026. Of 82 metabolites quantified by LC-MS/MS, 64 were detected in every cultivar and period and analysed. The sampling period significantly affected 56 metabolites, while cultivar influenced 35. Their interaction was significant for 23 metabolites, indicating that seasonal changes are cultivar-dependent. Effect sizes confirmed this ordering: PERMANOVA attributed 45.3% of the total metabolome variance to sampling period against 17.3% to cultivar. At the whole-metabolome level, sampling period affected all three cultivars, whereas cultivar differentiation was absent in one period. By class, sampling period affected all six classes, whereas cultivar was significant for phenolic acids, flavonoids and B-group vitamins, with no effect on the total metabolite pool (p = 0.189). Unsupervised PCA grouped samples by season, and supervised PLS-DA detected cultivar differences (96.3% cross-validated accuracy, permutation p = 0.012) although they were not resolved by the first two principal components; this accuracy describes separability within this dataset of nine experimental units rather than predictive performance. Cultivar information is therefore spread across many metabolites, and fixed sampling dates are essential when comparing cultivars or assessing leaves as raw material.
The AP2/ERF transcription factor family plays crucial roles in plant growth, development, and stress responses, as well as in organ regeneration. Here, a comprehensive genome-wide analysis of ERF subfamily of Lilium davidii var. unicolor (Lanzhou lily) was performed, and the functional role of a candidate gene, LdERF179, in bulblet regeneration was further investigated. A total of 206 LdERF genes were identified and phylogenetic evolution, chromosomal distribution, gene structure, conserved motifs, cis-regulatory elements, and collinearity were analyzed. Expression patterns suggested that there are 6 expression patterns of LdERF genes exhibited tissue-specific and stage-specific expression profiling during bulblet regeneration. LdERF179 was highly expressed at the regeneration initiation (RI) stage (S1), suggested its potential involvement in the early morphogenesis of bulb regeneration. Subcellular localization analysis demonstrated that LdERF179 protein localized in the nucleus. The results of the virus-induced gene silencing (VIGS) functional validation analysis show that suppression of LdERF179 significantly reduced bulblet formation efficiency from 40.67% to 9.43%. Further expression analysis indicated some key genes involved in auxin biosynthesis, transport, and signaling, and some regeneration-related genes showed decreased expression, such as TRV2-LdERF179, while increased expression was found in LdERF179-OE (LdASA1, LdAUX1, LdWOX11). Therefore, we propose that LdERF179 influenced the morphogenesis of bulblet regeneration by regulating the expression of auxin metabolism-related genes and key regeneration genes. However, further functional validation was required to clarify how LdERF179 regulates auxin metabolism genes and key regeneration genes. This study provides new insights into the molecular regulatory network of lily bulblet regeneration and offers potential candidate genes for improving vegetative propagation efficiency in lilies.
The inconsistent field performance of microbial biocontrol agents is often linked to resident soil microbiota, yet how indigenous microbiota influence Bacillus-mediated suppression of potato bacterial wilt remains insufficiently understood. In this study, sterilized and non-sterilized soils were used to evaluate how indigenous soil microbiota affect the biocontrol efficacy of Bacillus subtilis against Ralstonia solanacearum. Disease development, pathogen abundance, B. subtilis abundance, full-length 16S rRNA amplicon sequencing, and untargeted metabolomics were integrated to characterize rhizosphere microbial and metabolic responses. Soil microbial background strongly influenced disease progression and Bacillus performance. Under sterilized-soil conditions, R. solanacearum abundance remained 3–5-fold higher and disease severity increased more rapidly, whereas in non-sterilized soil, B. subtilis significantly reduced disease index and pathogen abundance. Microbiome analyses showed that sterilized soil was associated with limited Bacillus-mediated pathogen buffering, whereas non-sterilized soil supported the enrichment of potentially beneficial taxa, including Burkholderia, Devosia, and Rhizobium, together with soil-context-dependent microbial association patterns and shifts in predicted functional potential. Metabolomic profiling further revealed that Bacillus-associated metabolic profiles were highly soil-context-dependent, with low overlap between sterilized and non-sterilized soils under Bacillus treatment, as indicated by a Jaccard similarity of 0.059. In non-sterilized soil, Bacillus treatment was associated with defense-related metabolic profiles involving aromatic defense-related compounds and metabolites associated with antimicrobial activity and systemic resistance, whereas sterilized soil showed stronger damage-compensation-associated metabolic patterns. These findings suggest that indigenous soil microbiota may shape the ecological expression of B. subtilis-mediated biocontrol and highlight the importance of considering resident microbial backgrounds for potato bacterial wilt biocontrol.
Sakuranetin (SAK), a flavonoid phytoalexin synthesized by naringenin 7-O-methyltransferase (NOMT), contributes to rice immunity. However, the relationship between OsNOMT-dependent SAK accumulation, resistance to fungal and viral pathogens, and jasmonate (JA) homeostasis remains unclear. Here, we combined genetic, metabolite and transcriptomic analyses of OsNOMT-overexpression (OsNOMT-OE) and knockout (osnomt) lines. Loss of OsNOMT abolished SAK accumulation and was associated with increased susceptibility to Magnaporthe oryzae and Southern rice black-streaked dwarf virus, whereas OsNOMT-OE lines accumulated high levels of SAK and exhibited enhanced resistance to both pathogens. Co-expression network analysis identified a susceptibility-associated module containing OsWRKY62, OsFBX148, and a putative ACC oxidase as candidate hub nodes. OsNOMT-OE plants exhibited increased expression of JA-related genes and higher JA levels but lower basal levels of JA-Ile than wild-type ZH11 plants. In osnomt mutants, basal JA-Ile levels were reduced, whereas JA-Ile levels after M. oryzae infection were comparable to those in ZH11 plants, indicating that OsNOMT-dependent SAK accumulation is linked to a reconfiguration of JA homeostasis rather than a uniform increase in all JA metabolites. In addition, short-term exogenous SAK application promoted JA and JA-Ile accumulation. Collectively, these findings associate OsNOMT-mediated SAK biosynthesis with rice resistance to fungal and viral diseases and altered JA homeostasis.
