Xanthomonas hortorum pv. carotae is a pathogen responsible for the bacterial blight of carrot. Although it infects carrot fields worldwide, its diversity remains unknown. Here, we validated by PCR the identification as X. hortorum pv. carotae of most of the strains isolated from symptomatic carrots. We studied their diversity by sequencing seven housekeeping genes. The analysis confirmed the identity of most of the strains previously identified as X. hortorum pv. carotae and highlighted the presence of two clusters inside the pathovar carotae. The 18 non- X. hortorum pv. carotae have been identified as Xanthomonas from other species. As the X. hortorum pv. carotae strains clustered only in two groups by this analysis, a new multilocus variable number of tandem repeats analysis scheme was developed. It allowed us to validate the subclustering in two groups and observe diversity among them. At the same time, based on this study and data from the literature, we proposed the strain CFBP 7900 as the neopathotype strain of the pathovar. The strain should replace the holopathotype strain CFBP 4997, as it is no longer available in international collections. [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 .

Mixed infections caused by multiple pathogenic and weakly pathogenic strains inhabiting the same host plants are common in nature and may modify pathogen dynamics. However, traditional plant pathogen studies have mostly focused on the binary interaction between a single host and a single pathogen. In this study, we have looked beyond this binary interaction and evaluated the impact of coinfection on disease dynamics on tomato using the bacterial spot pathogen Xanthomonas perforans (Xp), the co-occurring weakly pathogenic strain of X. arboricola (Xa), and the co-occurring potential weak pathogenic strain of Pseudomonas capsici (Pc). Time-series coinfection experiments monitoring disease severity and within-host population dynamics revealed higher disease severity in coinfection by three species compared with infection by Xp alone. However, coinfection by dual species, Xp and Pc, or Xa resulted in lower disease severity compared with Xp alone. Thus, coinfection outcomes depend on interacting species. Weak pathogens could exploit Xp to colonize the host plant as indicated by their higher populations in coinfection. However, Xp population dynamics were dependent on the coinfecting partner. While resource competition might be a possible explanation for lower Xp population in dual coinfection, interaction of Pc with the host was found to influence Xp population. Interestingly, Xp population was higher in the presence of three-species interaction compared with Xp and Xa coinfection, suggesting potential modulation of cooperative interactions among Xp and Xa in three-species coinfection rather than competitive interactions. Humidity played a significant role in population dynamics of the three species. Overall, this study highlighted the importance of coinfection dynamics in studying plant disease outbreaks.

Our ability to predict temperature responses of leaf respiration in light and darkness (RL and RDk ) is essential to models of global carbon dynamics. While many models rely on constant thermal sensitivity (characterized by Q10 ), uncertainty remains as to whether Q10 of RL and RDk are actually similar. We measured short-term temperature responses of RL and RDk in immature and mature leaves of two evergreen tree species, Castanopsis carlesii and Ormosia henry in an open field. RL was estimated by the Kok method, the Yin method and a newly developed Kok-iterCc method. When estimated by the Yin and Kok-iterCc methods, RL and RDk had similar Q10 (c. 2.5). The Kok method overestimated both Q10 and the light inhibition of respiration. RL /RDk was not affected by leaf temperature. Acclimation of respiration in summer was associated with a decline in basal respiration but not in Q10 in both species, which was related to changes in leaf nitrogen content between seasons. Q10 of RL and RDk in mature leaves were 40% higher than in immature leaves. Our results suggest similar Q10 values can be used to model RL and RDk while leaf development-associated changes in Q10 require special consideration in future respiration models.

The 13C isotope composition (δ13C) of leaf dry matter is a useful tool for physiological and ecological studies. However, how post-photosynthetic fractionation associated with respiration and carbon export influences δ13C remains uncertain. We investigated the effects of post-photosynthetic fractionation on δ13C of mature leaves of Cleistogenes squarrosa, a perennial C4 grass, in controlled experiments with different levels of vapour pressure deficit and nitrogen supply. With increasing leaf age class, the 12C/13C fractionation of leaf organic matter relative to the δ13C of atmosphere CO2 (ΔDM) increased while that of cellulose (Δcel) was almost constant. The divergence between ΔDM and Δcel increased with leaf age class, with a maximum value of 1.6‰, indicating the accumulation of post-photosynthetic fractionation. Applying a new mass balance model that accounts for respiration and export of photosynthates, we found an apparent 12C/13C fractionation associated with carbon export of -0.5‰ to -1.0‰. Different ΔDM among leaves, pseudostems, daughter tillers, and roots indicate that post-photosynthetic fractionation happens at the whole-plant level. Compared with ΔDM of old leaves, ΔDM of young leaves and Δcel are more reliable proxies for predicting physiological parameters due to the lower sensitivity to post-photosynthetic fractionation and the similar sensitivity in responses to environmental changes.

Abstract To address the major challenge of controlling flowering in roses, we studied the ectopic expression of a FLOWERING LOCUS T(FT) homolog, which plays an important role in flowering time regulation in plants. We detected seven rose genes of the phosphatidyl ethanolamine-binding protein(PEBP) family and selected one of them (RoFT) based on its co-localization with flowering and architecture QTLs to study its overexpression in two rose genotypes. Embryogenic lines were obtained and genetic transformation was performed on the rose genotypes. Regenerated plantlets were maintained in a greenhouse until flowering and then floral and architectural traits were scored. We observed substantial variation in phenotypic expression between genotypes and between events, especially in the flowering date and number of floral organs. The expression of 14 genes putatively involved in floral initiation (mainly FT targets) and floral development (from the class ABC model) was studied to gain insight into these variations. We noted than target genes are up- or down-regulation and can explain the observed phenotype. Our results revealed that a gene ectopically overexpressed in different genetic backgrounds could have diverse effects and that the overexpression RoFT gene can have pleiotropic effects.

Day respiration ( R) is the metabolic, non-photorespiratory process by which illuminated leaves liberate CO during photosynthesis. R is used routinely in photosynthetic models and is thus critical for calculations. However, metabolic details associated with R are poorly known, and this can be problematic to predict how R changes with environmental conditions and relates to night respiration. It is often assumed that day respiratory CO release just reflects ‘ordinary’ catabolism (glycolysis and Krebs ‘cycle’). Here, we carried out a pulse-chase experiment, whereby a CO pulse in the light was followed by a chase period in darkness and then in the light. We took advantage of non-targeted, isotope-assisted metabolomics to determine non-‘ordinary’ metabolism, detect carbon remobilisation, and compare light and dark C utilisation. We found that several concurrent metabolic pathways (‘ordinary’ catabolism, oxidative pentose phosphates pathway, amino acid production, nucleotide biosynthesis, and secondary metabolism) took place in the light and participate in net CO efflux associated with day respiration. Flux reconstruction from metabolomics leads to an underestimation of R, further suggesting the contribution of a variety of CO -evolving processes. Also, the cornerstone of the Krebs ‘cycle’, citrate, is synthetised de novo from photosynthates mostly in darkness, and remobilised or synthesised from stored material in the light. Collectively, our data provides direct evidence that leaf day respiration ( i) involves several CO -producing reactions and ( ii) is fed by different carbon sources, including stored carbon disconnected from current photosynthates.

Discovering new solutions for crop protection is a major challenge for the next decades as a result of the ecotoxicological impact of classical fungicides, the emergence of fungicide resistances, and the consequence of climate change on pathogen distribution. Previous work on fungal mutants deficient in the unfolded protein response (UPR) supported that targeting this pathway is a promising plant disease control strategy. In particular, we showed that the UPR is involved in fungal virulence by altering cell protection against host defense compounds, such as phytoalexins and phytoanticipins. In this study, we evaluated natural products targeting fungal IRE1 protein (UPR effector) and consequently increasing fungal susceptibility to plant defenses. Developing an in vitro cell-based screening assay allowed for the identification of seven potential IRE1 inhibitors with a focus on polyhydroxylated prenylated xanthones. Inhibition of hac1 mRNA splicing, which is mediated by IRE1, was then validated for the most active compound, namely, γ-mangostin 3. To study the mode of interaction between the binding site of IRE1 and active xanthones, molecular docking was also undertaken, revealing similar and novel interactions between the known inhibitor and the binding site. Eventually, active xanthones applied at subtoxic doses induced a significant reduction in necrosis size for leaves of Brassica oleracea inoculated with Alternaria brassicicola and Botrytis cinerea.

Oxygen and hydrogen isotopes of cellulose in plant biology are commonly used to infer environmental conditions, often from time series measurements of tree rings. However, the covariation (or the lack thereof) between δ18 O and δ2 H in plant cellulose is still poorly understood. We compared plant water, and leaf and branch cellulose from dominant tree species across an aridity gradient in Northern Australia, to examine how δ18 O and δ2 H relate to each other and to mean annual precipitation (MAP). We identified a decline in covariation from xylem to leaf water, and onwards from leaf to branch wood cellulose. Covariation in leaf water isotopic enrichment (Δ) was partially preserved in leaf cellulose but not branch wood cellulose. Furthermore, whilst δ2 H was well-correlated between leaf and branch, there was an offset in δ18 O between organs that increased with decreasing MAP. Our findings strongly suggest that postphotosynthetic isotope exchange with water is more apparent for oxygen isotopes, whereas variable kinetic and nonequilibrium isotope effects add complexity to interpreting metabolic-induced δ2 H patterns. Varying oxygen isotope exchange in wood and leaf cellulose must be accounted for when δ18 O is used to reconstruct climatic scenarios. Conversely, comparing δ2 H and δ18 O patterns may reveal environmentally induced shifts in metabolism.

Quantitative nuclear magnetic resonance (NMR) for isotopic measurements, known as irm-NMR (isotope ratio measured by NMR), is well suited for the quantitation of 13C-isotopomers in position-specific isotope analysis and thus for measuring the carbon isotope composition (δ13C, mUr) in C-atom positions. Irm-NMR has already been used with glucose after derivatization to study sugar metabolism in plants. However, up to now, irm-NMR has exploited a "single-pulse" sequence and requires a relatively large amount of material and long experimental time, precluding many applications with biological tissues or extracts. To reduce the required amount of sample, we investigated the use of 2D-NMR analysis. We adapted and optimized the NMR sequence so as to be able to analyze a small amount (10 mg) of a glucose derivative (diacetonide glucofuranose, DAGF) with a precision better than 1 mUr at each C-atom position. We also set up a method to correct raw data and express 13C abundance on the usual δ13C scale (δ-scale). In fact, due to the distortion associated with polarization transfer and spin manipulation during 2D-NMR analyses, raw 13C abundance is found to be on an unusual scale. This was compensated for by a correction factor obtained via comparative analysis of a reference material (commercial DAGF) using both previous (single-pulse) and new (2D) sequences. Glucose from different biological origins (CO2 assimilation metabolisms of plants, namely, C3, C4, and CAM) was analyzed with the two sequences and compared. Validation criteria such as selectivity, limit of quantification, precision, trueness, and robustness are discussed, including in the framework of green analytical chemistry.

Terminology work requires a lot of data processing in the practical research of comparative linguistics, especially when studying linguistic and terminological changes over time. The lack of appropriate wide-usage electronic tools and databases can slow down such research. Thus, an efficient information management solution is necessary to improve the efficiency of terminology and comparative linguistic research. Since 2021, a team of terminologists, translators, researchers, and information system developers worked together for two years, during which the open access interactive multifunctional database management system (IMDS) was designed and developed for data storage and a wide range of statistical and search options, especially for language research purposes and comparative multilingual studies in linguistics and terminology. The information system consists of multiple modules (input, statistics, export, etc.). The data input module was successfully designed and developed and has been used effectively by researchers for entering and collecting special lexis units. The article mainly describes the statistical data that can be obtained from the IMDS, as well as problems encountered during the development of the system. The IMDS data collection has been updated with 50,846 entries of scientific (Latin) organism names, 60,585 entries of local names of different organisms (mainly in Latvian, but also in other languages), 1427 entries of names of organism-caused diseases, 2942 entries of dictionary words and 313 entries of terms with definitions collected based on excerpts from different publications containing common names linked with their scientific names.