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<jats:p><jats:italic>Camellia oleifera</jats:italic> Abel is a highly valued woody edible oil tree, which is endemic to China. It has great economic value because <jats:italic>C. oleifera</jats:italic> seed oil contains a high proportion of polyunsaturated fatty acids. <jats:italic>C. oleifera</jats:italic> anthracnose caused by <jats:italic>Colletotrichum fructicola</jats:italic>, poses a serious threat to <jats:italic>C. oleifera</jats:italic> growth and yield and causes the benefit of the <jats:italic>C. oleifera</jats:italic> industry to suffer directly. The WRKY transcription factor family members have been widely characterized as vital regulators in plant response to pathogen infection. Until now, the number, type and biological function of <jats:italic>C. oleifera WRKY</jats:italic> genes are remains unknown. Here, we identified 90 C<jats:italic>. oleifera</jats:italic> WRKY members, which were distributed across 15 chromosomes. <jats:italic>C. oleifera WRKY</jats:italic> gene expansion was mainly attributed to segmental duplication. We performed transcriptomic analyses to verify the expression patterns of <jats:italic>CoWRKYs</jats:italic> between anthracnose-resistant and -susceptible cultivars of <jats:italic>C. oleifera</jats:italic>. These results demonstrated that multiple candidate <jats:italic>CoWRKY</jats:italic>s can be induced by anthracnose and provide useful clues for their functional studies. <jats:italic>CoWRKY78</jats:italic>, an anthracnose-induced <jats:italic>WRKY</jats:italic> gene, was isolated from <jats:italic>C. oleifera</jats:italic>. It was significantly down-regulated in anthracnose-resistant cultivars. Overexpression of <jats:italic>CoWRKY78</jats:italic> in tobacco markedly reduced resistance to anthracnose than WT plants, as evidenced by more cell death, higher malonaldehyde content and reactive oxygen species (ROS), but lower activities of superoxide dismutase (SOD), peroxidase (POD), as well as phenylalanine ammonia-lyase (PAL). Furthermore, the expression of multiple stress-related genes, which are associated with ROS-homeostasis (<jats:italic>NtSOD</jats:italic> and <jats:italic>NtPOD</jats:italic>), pathogen challenge (<jats:italic>NtPAL</jats:italic>), and pathogen defense (<jats:italic>NtPR1</jats:italic>, <jats:italic>NtNPR1</jats:italic>, and <jats:italic>NtPDF1.2</jats:italic>) were altered in the <jats:italic>CoWRKY78</jats:italic>-overexpressing plants. These findings increase our understanding of the <jats:italic>CoWRKY</jats:italic> genes and lay the foundation for the exploration of anthracnose resistance mechanisms and expedite the breeding of anthracnose-resistant <jats:italic>C. oleifera</jats:italic> cultivars.</jats:p>

<jats:p>Shrubs are the main species in desert ecosystems. Better understanding shrubs fine root dynamics and its contribution to soil organic carbon (SOC) stocks can improve the accuracy of carbon sequestration estimation and provide basic data for the calculation of carbon sequestration potential. The ingrowth core method was used to investigate the fine root (&amp;lt; 1 mm in diameter) dynamics of <jats:italic>Caragana intermedia</jats:italic> Kuang et H. C. Fu plantation with different age (4-, 6-, 11-, 17-, and 31-year-old) in Gonghe Basin of the Tibetan Plateau, and the annual fine root mortality was used for calculation the annual carbon input to SOC pool. The results showed that fine root biomass, production, and mortality first increased and then decreased as the plantation age increased. Fine root biomass peaked in 17-year-old plantation, production and mortality peaked in 6-year-old plantation, and turnover rate of 4- and 6-year-old plantations were significantly higher than other plantations. Fine root production and mortality were negative correlated with soil nutrients at depth of 0–20 and 20–40 cm. The variation range of carbon input by fine root mortality across different plantation age at 0–60 cm soil depth was 0.54–0.85 Mg ha<jats:sup>-1</jats:sup> year<jats:sup>-1</jats:sup>, accounting for 2.40–7.54% of the SOC stocks. <jats:italic>C. intermedia</jats:italic> plantation has a strong carbon sequestration potential from long time scale. Fine roots regenerate faster in young stands and lower soil nutrients environment. Our results suggest that the influences of plantation age and soil depth should be taken into account when calculating the contribution of fine root to SOC stocks in desert ecosystems.</jats:p>

<jats:p>Symbiotic nodules formed on legume roots with rhizobia fix atmospheric N<jats:sub>2</jats:sub>. Bacteria reduce N<jats:sub>2</jats:sub> to NH<jats:sub>4</jats:sub><jats:sup>+</jats:sup> that is assimilated into amino acids by the plant. In return, the plant provides photosynthates to fuel the symbiotic nitrogen fixation. Symbiosis is tightly adjusted to the whole plant nutritional demand and to the plant photosynthetic capacities, but regulatory circuits behind this control remain poorly understood. The use of split-root systems combined with biochemical, physiological, metabolomic, transcriptomic, and genetic approaches revealed that multiple pathways are acting in parallel. Systemic signaling mechanisms of the plant N demand are required for the control of nodule organogenesis, mature nodule functioning, and nodule senescence. N-satiety/N-deficit systemic signaling correlates with rapid variations of the nodules’ sugar levels, tuning symbiosis by C resources allocation. These mechanisms are responsible for the adjustment of plant symbiotic capacities to the mineral N resources. On the one hand, if mineral N can satisfy the plant N demand, nodule formation is inhibited, and nodule senescence is activated. On the other hand, local conditions (abiotic stresses) may impair symbiotic activity resulting in plant N limitation. In these conditions, systemic signaling may compensate the N deficit by stimulating symbiotic root N foraging. In the past decade, several molecular components of the systemic signaling pathways controlling nodule formation have been identified, but a major challenge remains, that is, to understand their specificity as compared to the mechanisms of non-symbiotic plants that control root development and how they contribute to the whole plant phenotypes. Less is known about the control of mature nodule development and functioning by N and C nutritional status of the plant, but a hypothetical model involving the sucrose allocation to the nodule as a systemic signaling process, the oxidative pentose phosphate pathway, and the redox status as potential effectors of this signaling is emerging. This work highlights the importance of organism integration in plant biology.</jats:p>

<jats:p>The aim of this study was to determine intra- and interspecies variation in the qualitative and quantitative composition of methanol-soluble metabolites in the leaves of three <jats:italic>Digitalis</jats:italic> species (<jats:italic>D. lanata</jats:italic>, <jats:italic>D. ferruginea</jats:italic>, and <jats:italic>D. grandiflora</jats:italic>) from the central Balkans. Despite the steady use of foxglove constituents for human health as valuable medicinal products, populations of the genus <jats:italic>Digitalis</jats:italic> (<jats:italic>Plantaginaceae</jats:italic>) have been poorly investigated to describe their genetic and phenetic variation. Following untargeted profiling using UHPLC-LTQ Orbitrap MS, by which we identified a total of 115 compounds, 16 compounds were quantified using the UHPLC(–)HESI–QqQ-MS/MS approach. In total, 55 steroid compounds, 15 phenylethanoid glycosides, 27 flavonoids, and 14 phenolic acid derivatives were identified across the samples with <jats:italic>D. lanata</jats:italic> and <jats:italic>D. ferruginea</jats:italic> showing a great similarity, while 15 compounds were characteristic only for <jats:italic>D. grandiflora</jats:italic>. The phytochemical composition of methanol extracts, considered here as complex phenotypes, are further examined along multiple levels of biological organization (intra- and interpopulation) and subsequently subjected to chemometric data analysis. The quantitative composition of the selected set of 16 chemomarkers belonging to the classes of cardenolides (3 compounds) and phenolics (13 compounds) pointed to considerable differences between the taxa studied. <jats:italic>D. grandiflora</jats:italic> and <jats:italic>D. ferruginea</jats:italic> were found to be richer in phenolics as compared to cardenolides, which otherwise predominate in <jats:italic>D. lanata</jats:italic> over other compounds. PCA revealed lanatoside C, deslanoside, hispidulin, and <jats:italic>p</jats:italic>-coumaric acid to be the main compounds contributing to the differences between <jats:italic>D. lanata</jats:italic> on one side and <jats:italic>D. grandiflora</jats:italic> and <jats:italic>D. ferruginea</jats:italic> on the other, while <jats:italic>p</jats:italic>-coumaric acid, hispidulin, and digoxin contribute to the diversification between <jats:italic>D. grandiflora</jats:italic> and <jats:italic>D. ferruginea</jats:italic>. However, quantitative variation in the metabolite content within species was faint with mild population diversification visible in <jats:italic>D. grandiflora</jats:italic> and particularly in <jats:italic>D. ferruginea.</jats:italic> This pointed to the highly conserved content and ratio of targeted compounds within the analyzed species, which was not severely influenced by the geographic origin or environmental conditions. The presented metabolomics approach might have, along with morphometrics and molecular genetics studies, a high information value for further elucidation of the relationships among taxa within the genus <jats:italic>Digitalis</jats:italic>.</jats:p>

<jats:sec><jats:title>Background</jats:title><jats:p>Flooding is a major stress factor impacting watermelon growth and production globally. Metabolites play a crucial role in coping with both biotic and abiotic stresses.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>In this study, diploid (2X) and triploid (3X) watermelons were investigated to determine their flooding tolerance mechanisms by examining physiological, biochemical, and metabolic changes at different stages. Metabolite quantification was done using UPLC-ESI-MS/MS and a total of 682 metabolites were detected.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>The results showed that 2X watermelon leaves had lower chlorophyll content and fresh weights compared to 3X. The activities of antioxidants, such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), were higher in 3X than in 2X. 3X watermelon leaves showed lower O<jats:sub>2</jats:sub> production rates, MDA, and hydrogen peroxide (H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub>) levels in response to flooding, while higher ethylene production was observed. 3X had higher levels of dehydrogenase activity (DHA) and ascorbic acid + dehydrogenase (AsA + DHA), but both 2X and 3X showed a significant decline in the AsA/DHA ratio at later stages of flooding. Among them, 4-guanidinobutyric acid (mws0567), an organic acid, may be a candidate metabolite responsible for flooding tolerance in watermelon and had higher expression levels in 3X watermelon, suggesting that triploid watermelon is more tolerant to flooding.</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>This study provides insights into the response of 2X and 3X watermelon to flooding and the physiological, biochemical, and metabolic changes involved. It will serve as a foundation for future in-depth molecular and genetic studies on flooding response in watermelon.</jats:p></jats:sec>

<jats:p>Heterosis has been widely used in rice breeding, especially in improving rice yield. But it has rarely been studied in rice abiotic stress, including the drought tolerance, which is becoming one of the most important threaten in decreasing rice yield. Therefore, it is essential to studying the mechanism underlying heterosis in improving drought tolerance of rice breeding. In this study, Dexiang074B (074B) and Dexiang074A (074A) served as maintainer lines and sterile lines. Mianhui146 (R146), Chenghui727 (R727), LuhuiH103 (RH103), Dehui8258 (R8258), Huazhen (HZ), Dehui938 (R938), Dehui4923 (R4923), and R1391 served as restorer lines. The progeny were Dexiangyou (D146), Deyou4727 (D4727), Dexiang 4103 (D4103), Deyou8258 (D8258), Deyou Huazhen (DH), Deyou 4938 (D4938), Deyou 4923 (D4923), and Deyou 1391 (D1391). The restorer line and hybrid offspring were subjected to drought stress at the flowering stage. The results showed that Fv/Fm values were abnormal and oxidoreductase activity and MDA content were increased. However, the performance of hybrid progeny was significantly better than their respective restorer lines. Although the yield of hybrid progeny and restorer lines decreased simultaneously, the yield in hybrid offspring is significantly lower than the respective restorer line. Total soluble sugar content was consistent with the yield result, so we found that 074A can enhance drought tolerance in hybrid rice.</jats:p>

<jats:p>GIGANTEA (GI) is a plant-specific nuclear protein that plays a pleiotropic role in the growth and development of plants. GI’s involvement in circadian clock function, flowering time regulation, and various types of abiotic stress tolerance has been well documented in recent years. Here, the role of GI in response to <jats:italic>Fusarium oxysporum</jats:italic> (<jats:italic>F. oxysporum</jats:italic>) infection is investigated at the molecular level comparing Col-0 WT with the <jats:italic>gi-100</jats:italic> mutant in <jats:italic>Arabidopsis thaliana</jats:italic>. Disease progression, photosynthetic parameters, and comparative anatomy confirmed that the spread and damage caused by pathogen infection were less severe in <jats:italic>gi-100</jats:italic> than in Col-0 WT plants. <jats:italic>F. oxysporum</jats:italic> infection induces a remarkable accumulation of GI protein. Our report showed that it is not involved in flowering time regulation during <jats:italic>F. oxysporum</jats:italic> infection. Estimation of defense hormone after infection showed that jasmonic acid (JA) level is higher and salicylic acid (SA) level is lower in <jats:italic>gi-100</jats:italic> compared to Col-0 WT. Here, we show that the relative transcript expression of <jats:italic>CORONATINE INSENSITIVE1</jats:italic> (<jats:italic>COI1</jats:italic>) and <jats:italic>PLANT DEFENSIN1.2</jats:italic> (<jats:italic>PDF1.2</jats:italic>) as a marker of the JA pathway is significantly higher while <jats:italic>ISOCHORISMATE SYNTHASE1</jats:italic> (<jats:italic>ICS1</jats:italic>) and <jats:italic>NON-EXPRESSOR OF PATHOGENESIS-RELATED GENES1</jats:italic> (<jats:italic>NPR1</jats:italic>), the markers of the SA pathway, are downregulated in the <jats:italic>gi-100</jats:italic> mutants compared to Col-0 plants. The present study convincingly suggests that the GI module promotes susceptibility to <jats:italic>F. oxysporum</jats:italic> infection by inducing the SA pathway and inhibiting JA signaling in <jats:italic>A. thaliana</jats:italic>.</jats:p>

<jats:p>Candidate genes (CG) for <jats:italic>Botrytis cinerea</jats:italic> resistance described in literature were mapped on gerbera linkage maps for which several QTL for Botrytis resistance had been found previously using a rapid, low-cost platform for SNP genotyping. In total, 29 CGs were mapped in either of two mapping populations. Four CGs were mapped within the previous identified QTL intervals and three co-localized with QTL. Two of these CGs for resistance against <jats:italic>B. cinerea</jats:italic>, <jats:italic>PG1</jats:italic> (polygalacturonase gene) and <jats:italic>sit</jats:italic> (<jats:italic>sitiens</jats:italic>, ABA-aldehyde oxidase gene) that mapped in QTL regions for the ray floret disease resistance test were studied in detail. Virus-induced gene silencing (VIGS) was used for gene function analysis to determine the CGs’ role in gerbera resistance to Botrytis. Ray florets, of which the CGs were silenced, showed a significantly delayed growth of lesions upon Botrytis infection compared to controls. Combining QTL analysis, candidate gene mapping and VIGS showed to be an useful combination to identify possible causal genes and for understanding the molecular mechanisms of Botrytis resistance in gerbera. The two genes seem to act as partial S-genes and are likely among the determining genes leading to the variation observed for <jats:italic>B. cinerea</jats:italic> resistance in gerbera.</jats:p>

<jats:sec><jats:title>Background and objective</jats:title><jats:p>The rapid diagnosis of rice nitrogen nutrition is of great significance to rice field management and precision fertilization. The nitrogen nutrition index (NNI) based on the standard nitrogen concentration curve is a common parameter for the quantitative diagnosis of rice nitrogen nutrition. However, the current NNI estimation methods based on hyperspectral techniques mainly focus on finding a better estimation model while ignoring the relationship between the critical nitrogen concentration curve and rice hyperspectral reflectance.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>This study obtained canopy spectral data using unmanned aerial vehicle (UAV) hyperspectral remote sensing and determined the rice critical nitrogen concentration curve and NNI. Taking the spectrum at critical nitrogen concentration as the standard spectrum, the original spectral reflectance and logarithmic spectral reflectance data were transformed by the difference method, and the features of the spectral data were extracted by a Autoencoder. Finally, the NNI inversion models of rice based on Extreme Learning Machine (ELM) and Bald Eagle Search-Extreme Learning Machine (BES-ELM) were constructed by taking the feature bands of four spectral extractions as input variables.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>1) from the feature extraction results of the self-encoder, simple logarithmic or difference transformation had little effect on NNI estimation, and logarithmic difference transformation effectively improved the NNI estimation results; 2) the estimation model based on the logarithmic difference spectrum and BES-ELM had the highest estimation accuracy, and the coefficient of determination (R2) values of the training set and verification set were 0.839 and 0.837, and the root mean square error (RMSE) values were 0.075 and 0.073, respectively; 3) according to the NNI, the samples were divided into a nitrogen-rich group (NNI ≥ 1) and nitrogen-deficient group (NNI &amp;lt; 1).</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>The logarithmic difference transformation of the spectrum can effectively improve the estimation accuracy of the NNI estimation model, providing a new approach for improving NNI estimation methods based on hyperspectral technology.</jats:p></jats:sec>