Category: Pub Med

Mol Plant Pathol. 2025 May;26(5):e70096. doi: 10.1111/mpp.70096.

ABSTRACT

Harpins are proteins secreted by many gram-negative, plant-pathogenic bacteria that stimulate the hypersensitive reaction (HR), a host cell death defence response, when infiltrated into plant leaves as purified proteins. This activity of harpins was first discovered in Nicotiana tabacum (tobacco), which manifests an especially strong and rapid harpin-activated HR that becomes evident within 12-24 h after infiltration. HrpN is the major harpin of the fire blight pathogen Erwinia amylovora. We discovered natural variation in the HrpN-induced HR among tobacco accessions and identified candidate genes using genetic mapping and bulked-segregant analysis with whole genome sequencing. Virus-induced gene silencing of candidate gene Wall-Associated Kinase 2 (WAK2) abrogated the HR in response to HrpN and HpaG, a harpin from the soybean bacterial pustule pathogen Xanthomonas citri pv. glycines. WAK2 silencing also compromised the avirulence activity of harpin HrpZ in the tobacco wildfire pathogen Pseudomonas syringae pv. tabaci. A natural, disruptive mutation in WAK2 correlated with the inability of tobacco accessions to mount the harpin-mediated HR. We conclude that the predicted receptor-like kinase WAK2 is required for the strong HR induced in tobacco leaves by harpin protein infiltration and can potentially mediate resistance to bacterial pathogens based on harpin recognition.

PMID:40391583 | DOI:10.1111/mpp.70096

Genetics. 2025 May 14:iyaf091. doi: 10.1093/genetics/iyaf091. Online ahead of print.

ABSTRACT

In maize, there are two meiotic drive systems that target large heterochromatic knobs composed of tandem repeats known as knob180 and TR-1. The first meiotic drive haplotype, Abnormal chromosome 10 (Ab10) confers strong meiotic drive (∼75% transmission as a heterozygote) and encodes two kinesins: KINDR, which associates with knob180 repeats and TRKIN, which associates with TR-1 repeats. Prior data show that meiotic drive is conferred primarily by the KINDR/knob180 system while the TRKIN/TR-1 system seems to have little or no role, making it unclear why Trkin has been maintained in Ab10 haplotypes. The second meiotic drive haplotype, K10L2, confers a low level of meiotic drive (∼51-52%) and only encodes the TRKIN/TR-1 system. Here we used long-read sequencing to assemble the K10L2 haplotype and showed that it has strong homology to an internal portion of the Ab10 haplotype. We also carried out CRISPR mutagenesis to test the role of Trkin on Ab10 and K10L2. The data indicate that the Trkin gene on Ab10 does not improve drive or fitness but instead has a weak deleterious effect when paired with a normal chromosome 10. The deleterious effect is more severe when Ab10 is paired with K10L2: in this context functional Trkin on either chromosome nearly abolishes Ab10 drive. Mathematical modeling based on the empirical data suggest that Trkin is unlikely to persist on Ab10. We conclude that Trkin either confers an advantage to Ab10 in untested circumstances or that it is in the process of being purged from the Ab10 population.

PMID:40365704 | DOI:10.1093/genetics/iyaf091

Molecules. 2025 Apr 30;30(9):2020. doi: 10.3390/molecules30092020.

ABSTRACT

The discovery of bioactive natural products is often challenged by the complexity of isolating and characterizing active compounds within diverse mixtures. Previously, we introduced a ¹H NMR-based weighted gene correlation network analysis (WGCNA) approach to identify spectral features linked to growth inhibitory activity of Piper (Piperaceae) leaf extracts against model plant, fungal, and bacterial organisms. This method enabled us to prioritize specific spectral features linked to bioactivity, offering a targeted approach to natural product discovery. In this study, we validate the predictive capacity of the WGCNA by isolating the compounds responsible for the bioactivity-associated resonances and confirming their antifungal efficacy. Using growth inhibition assays, we verified that the isolated compounds, including three novel antifungal agents, exhibited significant bioactivity. Notably, one of these compounds contains a rare imidazolium heterocyclic motif, marking a new structural class in Piper. These findings substantiate the ¹H NMR-based WGCNA as a reliable tool for identifying structural types associated with biological activity, streamlining the process of discovering bioactive natural products in complex extracts.

PMID:40363825 | PMC:PMC12073215 | DOI:10.3390/molecules30092020

Int J Mol Sci. 2025 Apr 23;26(9):3999. doi: 10.3390/ijms26093999.

ABSTRACT

The mechanisms underlying leaf variegation in the ornamental Ilex × ‘Solar Flare’ remain poorly understood. To investigate this phenomenon, we conducted a comprehensive characterization of its variegated leaves. Compared to green sectors, yellow sectors exhibited severe chloroplast structural abnormalities, including swollen chloroplasts, damaged thylakoid membranes, and reduced chloroplast numbers. These yellow sectors also showed significantly lower chlorophyll and carotenoid levels, along with a depletion of key chlorophyll precursors-protoporphyrin IX (Proto IX), magnesium protoporphyrin IX (Mg-Proto IX), and protochlorophyllide (Pchlide). Photosynthetic efficiency was significantly impaired. Comparative transcriptome analysis identified 3510 differentially expressed genes (DEGs) between yellow and green sectors. Key disruptions in chlorophyll biosynthesis included upregulated CHLD expression and downregulated CHLH and CHLG expression, leading to impaired chlorophyll synthesis. Additionally, chlorophyll degradation was accelerated by PAO upregulation. Defective chloroplast development in yellow sectors was associated with the downregulation of GLK1, GLK2, and thylakoid membrane-related genes (PsbC, PsbO, PsbR, PsaD, and PsaH). These molecular alterations likely drive the variegated phenotype of I. × ‘Solar Flare’. These observations advance our understanding of the genetic and physiological mechanisms regulating leaf variegation in this cultivar.

PMID:40362242 | PMC:PMC12071917 | DOI:10.3390/ijms26093999

Ecol Lett. 2025 May;28(5):e70134. doi: 10.1111/ele.70134.

ABSTRACT

Species’ distributions are changing around the planet as a result of global climate change. Most research has focused on shifts in mean climate conditions, leaving the effects of increased environmental variability comparatively underexplored. This paper proposes two new macroecological hypotheses-the variability damping hypothesis and the variability adaptation hypothesis-to understand how ecological dynamics and evolutionary history could influence biogeographic patterns being forced by contemporary large-scale climate change across all major ecosystems. The variability damping hypothesis predicts that distributions of species living in deep water environments will be least affected by increasing climate-driven temperature variability compared with species in nearshore, intertidal and terrestrial environments. The variability adaptation hypothesis predicts the opposite. Where available, we discuss how the existing evidence aligns with these hypotheses and propose ways in which they may be empirically tested.

PMID:40344332 | PMC:PMC12061546 | DOI:10.1111/ele.70134

Integr Comp Biol. 2025 May 8:icaf028. doi: 10.1093/icb/icaf028. Online ahead of print.

ABSTRACT

Climate change is simultaneously increasing atmospheric carbon dioxide concentrations ([CO2]) and temperatures. We conducted a multi-factorial growth chamber experiment to examine how these climate change factors interact to influence the expression of ecologically-relevant traits, clines in these traits, and natural selection on morphology and phenology of diverse accessions of Boechera stricta (Brassicaceae) sourced from a broad elevational gradient in Colorado, USA. Plastic shifts in a key allocation trait (root mass fraction) in response to temperature accord with the direction of selection for probability of flowering, indicating that plasticity in this trait could be adaptive. However, plasticity in a foliar functional trait (leaf dry matter content) in response to temperature and [CO2] did not align with the direction of selection, indicating that plasticity could reduce fitness based on plant carbon allocation strategies. For another ecologically-important phenotype, selection favors resource acquisitive trait values (higher specific leaf area) under elevated [CO2] and resource conservative trait values (lower specific leaf area) at lower [CO2], despite the lack of plasticity in this trait. This pattern of selection counters published reports that elevated [CO2] induces low specific leaf area but could enable plants to reproduce across a greater period of the growing season under increasingly warm climates. Indeed, warmer temperatures prolonged the duration of flowering. This plasticity is likely adaptive, as selection favored increased flowering duration in the higher temperature treatment level. Thus, the two major results that emerged from our study are that climate change could impose novel and unanticipated patterns of natural selection on plant traits and that plasticity in these traits can be a maladaptive response to stress.

PMID:40338630 | DOI:10.1093/icb/icaf028