Botanical Studies最新文献

Background: Due to global warming and gradual climate change, plants are subjected to a wide range of environmental stresses, adversely affecting plant growth and production worldwide. Plants have developed various mechanisms to overpower these abiotic stresses, including salt stress, drought, and high light intensity. Apart from their own defense strategies, plants can get help from the beneficial endophytic bacteria inside host plants and assist them in enduring severe growth conditions. A previously isolated plant endophytic bacteria, Burkholderia seminalis 869T2, from vetiver grass can produce auxin, synthesize siderophore, and solubilize phosphate. The B. seminalis 869T2 can colonize inside host plants and increase the growth of bananas, Arabidopsis, and several leafy vegetables.

Results: We further demonstrated that different growth parameters of Arabidopsis and pak choi plants were significantly increased after inoculating the B. seminalis 869T2 under normal, salt, and drought stress conditions compared to the mock-inoculated plants. Both transcriptome analysis and quantitative real-time PCR results showed that expression levels of genes related to phytohormone signal transduction pathways, including auxin, gibberellin, cytokinin, and abscisic acid were altered in Arabidopsis plants after inoculated with the strain 869T2 under salt stress, in comparison to the mock-inoculated control with salt treatments. Furthermore, the accumulation levels of hydrogen peroxide (H₂O₂), electrolyte leakage (EL), and malondialdehyde (MDA) were lower in the 869T2-inoculated Arabidopsis and pak choi plants than in control plants under salt and drought stresses.

Conclusions: The plant endophytic bacterium strain B. seminalis 869T2 may affect various phytohormone responses and reduce oxidative stress damage to increase salt and drought stress tolerances of host plants.

Background: Rice is a staple food for the global population. However, extreme weather events threaten the stability of the water supply for agriculture, posing a critical challenge to the stability of the food supply. The use of technology to assess the water status of rice plants enables the precise management of agricultural water resources.

Results: The results of this study reveal that rice-producing regions with more severe drought have higher ion leakage rates, lower Soil Plant Analysis Development (SPAD) meter values, and reduced total chlorophyll content in plants. Although no significant differences were observed in red-green-blue (RGB) images, physiological parameters and canopy temperature differed significantly from conventional farming when infrared thermography was used to capture rice plants in the early stages of drought. The Crop Water Stress Index (CWSI), calculated from canopy temperature and atmospheric temperature, indicated a high correlation between access to water for rice plants and their physiological parameters. Regression analysis using CWSI and plant water status yielded a corrected coefficient of determination of 0.86.

Conclusion: Our study demonstrate that infrared thermography can effectively detect early signs of water stress in rice, aiding farmers in irrigation planning and enabling precise management and optimal utilization of water resources.

Ice plant (Mesembryanthemum crystallinum L.) is a halophyte and an inducible CAM plant. Ice plant seedlings display moderate salt tolerance, with root growth unaffected by 200 mM NaCl treatments, though hypocotyl elongation is hindered in salt-stressed etiolated seedlings. Superoxide anion accumulation was prominent in cotyledons and primary leaves but decreased in root tissues over time, with no significant effect from salt treatment. Hydrogen peroxide levels initially surged in both control and salt-treated seedlings, with higher and more persistent accumulation in the salt-treated seedlings. The activities of H₂O₂-scavenging ascorbate-glutathione cycle enzymes ascorbate peroxidase (APX), monodehydroascorbate reductase, and dehydroascorbate reductase increased, while guaiacol-dependent peroxidase activity decreased and catalase activity showed no change, indicating APX activity as the primary response to salt stress. Salt-induced APX activities were detected mainly in the microsomal fraction for light-grown seedlings and the cytosolic fraction for etiolated seedlings, highlighting plastids as the primary site of ROS accumulation under salt stress. An RNA-seq analysis of etiolated seedlings revealed about 8% unigenes showing more than a four-fold change in expression after a 6-h 200 mM NaCl treatment. GO enrichment analysis indicated that differentially expressed genes (DEGs) with increased transcript abundance were associated with ion transport, antioxidant activity, and stress responses, while DEGs with decreased transcript abundance were linked to metabolic and biosynthesis processes such as ribosomal protein synthesis and cell wall formation. This indicates that salt stress hinders growth but enhances ion homeostasis and stress response mechanisms. The expression of all eight APX genes were induced by a 48-hour salt treatment, with varying expression patterns. For class III peroxidase family, 14 out of 53 identified unigenes qualified as DEGs. The time-course expression patterns revealed that the transcript levels of McPrx4.1, McPrx12.1, and McPrx12.3 increased, while McPrx60.3 decreased. These findings highlight the distinct roles of class III peroxidases in balancing plant growth and stress responses, advancing our understanding of the mechanisms behind salt tolerance in halophytes. This study comprehensively analyzed changes in gene expression, antioxidant enzyme activity, and ROS accumulation in ice plant seedlings. Unveiling these responses will advance our understanding of the growth-stress balance in the intrinsic salt tolerance in halophytes.

Background: Fungus gardens of the termite Odontotermes formosanus, excavated from Iriomote Island, Okinawa Prefecture, Japan, were subsequently incubated under laboratory conditions. A Xylaria species emerging from these fungus gardens was initially identified as X. angulosa, a species originally described from North Sulawesi, Indonesia. The Iriomote fungus is now described as a distinct species, X. iriomotensis.

Results: Xylaria iriomotensis is peculiar in producing the teleomorph in culture but lacking an anamorph. Cultures of X. angulosa were obtained from two Taiwan specimens, which agree with the holotype from BO and the isotypes from NY and WSP in their stromata being repeatedly dichotomously branched and possessing a black core. In contrast to X. iriomotensis, X. angulosa does not form the teleomorph in culture but a typical Xylaria anamorph with conidiophores densely arranged in palisades. The ITS sequence obtained from the WSP isotype shared high similarities with those two Taiwan specimens as well as an Indian specimen, reconfirming the latter three specimens as X. angulosa. These four specimens shared 98.28-99.66% similarities at ITS sequences among themselves but only 84.25-85.01% similarities with X. iriomotensis. Molecular phylogenetic studies based on sequences of multiple protein-coding loci indicate that, while X. iriomotensis is grouped with three soil-dwelling species of the X. guepini cluster, X. angulosa belongs to the X. nigripes cluster, which includes all known species capable of producing massive sclerotia.

Conclusion: Xylaria iriomotensis has the teleomorph known only in culture, remaining to be rediscovered in its natural habitat where the stromatal morphology may be somewhat varied. The geographic distribution of X. angulosa, previously known only in Indonesia, has been expanded to Taiwan and India. Xylaria angulosa grouping with the X. nigripes cluster in our phylogenetic analyses indicates its potential to form massive sclerotia within termite nests.

Background: Large-scale coral bleaching events have become increasingly frequent in recent years. This process occurs when corals are exposed to high temperatures and intense light stress, leading to an overproduction of reactive oxygen species (ROS) by their endosymbiotic dinoflagellates. The ROS buildup prompts corals to expel these symbiotic microalgae, resulting in the corals' discoloration. Reducing ROS production and enhancing detoxification processes in these microalgae are crucial to prevent the collapse of coral reef ecosystems. However, research into the cell physiology and genetics of coral symbiotic dinoflagellates has been hindered by challenges associated with cloning these microalgae.

Results: A procedure for cloning coral symbiotic dinoflagellates was developed in this study. Several species of coral symbionts were successfully cloned, with two of them further characterized. Experiments with the two species isolated from Turbinaria sp. showed that damage from light intensity at 340 μmol photons/m²/s was more severe than from high temperature at 36 °C. Additionally, preincubation in high salinity conditions activated their endogenous tolerance to bleaching stress. Pretreatment at 50 ppt salinity reduced the percentage of cells stained for ROS by 59% and 64% in the two species under bleaching stress compared to those incubated at 30 ppt. Furthermore, their Fv'/Fm' during the recovery period showed a significant improvement compared to the controls.

Conclusions: These findings suggest that intense light plays a more important role than high temperatures in coral bleaching by enhancing ROS generation in the symbiotic dinoflagellates. The findings also suggest the genomes of coral symbiotic dinoflagellates have undergone evolutionary processes to develop mechanisms, regulated by gene expression, to mitigate damages caused by high temperature and high light stress. Understanding this gene expression regulation could contribute to strengthening corals' resilience against the impact of global climate change.

Background: Trichoderma species, known as biocontrol agents against plant diseases, contain diverse compounds, especially terpenoids, with various bioactivities. To facilitate the exploration of bioactive secondary metabolites of Trichoderma harzianum NTU2180, the OSMAC approach MS/MS molecular networking was applied in the current study.

Results: The feature-based molecular networking (FBMN) analysis showed that T. harzianum NTU2180 fermented on germinated brown rice (GBR) produced more terpenoids. Here, two new acorane-sesequiterpenes, trichospirols A (1) and B (2), and 12 known compounds (3 - 14) were isolated from the EtOAc layer of T. harzianum NTU2180 fermentation on GBR. Structures of these compounds were determined through NMR, UV, IR, and MS analyses. The absolute configuration of trichospirols A (1) was also elucidated by x-ray with Cu K-α radiation. Among them, six compounds (1, 2, 3, 4, 5, and 11) were annotated as terpenoids by the NPClassifier on FBMN. 5-Hydroxy-3-hydroxmethyl-2-methyl-7-methoxychromone (7) and ergosterol peroxide (11) showed significant anti-angiogenic activity in ex vivo experiments with respective 0.57 ± 0.12- and 0.20 ± 0.12-fold changes. In addition, compound 11 displayed cytotoxicity against Y79 retinoblastoma cells with IC₅₀ value of 35.3 ± 6.9 µM.

Conclusions: The current study utilizes FBMN concept with OSMAC approach to accelerate the exploration of potential metabolites of the fungus Trichoderma harzianum NTU2180. Through a series of FBMN-guided isolation and purification, two new acorane-sesequiterpenes and 12 known compounds were obtained. The ex vivo and in vitro experiments were evaluated to assess anticancer isolates. It is worth noting that compound 11 was identified as a dual inhibitor targeting both angiogenesis and proliferation of retinoblastomas. Altogether, the results revealed the novel potential of T. harzianum for developing natural therapeutics against retinoblastomas.

Background: The genus Astragalus is the largest and one of the most diverse genera of flowering plants, particularly in the Northern Hemisphere, with a significant concentration of species in the Irano-Turanian region. Within this genus, section Hymenostegis is notable for its complexity and high levels of endemism, especially in northwestern Iran. During recent field explorations in West Azarbaijan province, a distinct population of Astragalus was identified, differing from known species within section Hymenostegis. This study aimes to describe and analyze this new species and clarify its relationship with closely related taxa using an integrative approach.

Results: Astragalus kuzehrashensis sp. nov. is described following detailed morphological comparisons with its closest relatives, A. chehreganii and A. hakkianus. The new species is distinguished by unique stipule characteristics, leaflet shape, inflorescence structure, and seed micromorphology. Molecular phylogenetic analysis using ITS and ycf1 sequences reveals that A. kuzehrashensis forms a clade with A. chehreganii and A. hakkianus, although it exhibits genetic differences. Genome size estimation confirms that A. kuzehrashensis is hexaploid (2n = 6x = 48), aligning it more closely with A. hakkianus than with the tetraploid A. chehreganii. The distinct morphological characters and genomic data support recognizing A. kuzehrashensis as a new species within section Hymenostegis.

Conclusions: The identification of A. kuzehrashensis underscores the importance of an integrative taxonomic approach, combining morphological, molecular, and cytogenetic data to resolve species boundaries within complex groups like Astragalus section Hymenostegis. This study highlights the rich biodiversity of the Irano-Turanian floristic region, emphasizing the need for ongoing exploration and conservation efforts, particularly in areas of high endemism. Our findings contribute to a deeper understanding of the taxonomy and evolutionary relationships within the genus Astragalus.

Background: The genus Allium is known for its high chromosomal variability, but most chromosome counts are based on a few individuals and genome size (GS) reports are limited in certain taxonomic groups. This is evident in the Allium sect. Codonoprasum, a species-rich (> 150 species) and taxonomically complex section with weak morphological differences between taxa, the presence of polyploidy and frequent misidentification of taxa. Consequently, a significant proportion of older karyological reports may be unreliable and GS data are lacking for the majority of species within the section. This study, using chromosome counting and flow cytometry (FCM), provides the first comprehensive and detailed insight into variation in chromosome number, polyploid frequency and distribution, and GS in section members, marking a step towards understanding the unresolved diversification and evolution of this group.

Results: We analysed 1578 individuals from 316 populations of 25 taxa and reported DNA ploidy levels and their GS, with calibration from chromosome counts in 22 taxa. Five taxa had multiple ploidy levels. First estimates of GS were obtained for 16 taxa. A comprehensive review of chromosome number and DNA-ploidy levels in 129 taxa of the section revealed that all taxa have x = 8, except A. rupestre with two polyploid series (x = 8, descending dysploidy x = 7), unique for this section. Diploid taxa dominated (72.1%), while di- & polyploid (12.4%) and exclusively polyploid (15.5%) taxa were less common. Ploidy diversity showed that diploid taxa dominated in the eastern Mediterranean and decreased towards the west and north, whereas only polyploid cytotypes of di- & polyploid taxa or exclusively polyploid taxa dominated in northern and northwestern Europe. A 4.1-fold variation in GS was observed across 33 taxa analysed so far (2C = 22.3-92.1 pg), mainly due to polyploidy, with GS downsizing observed in taxa with multiple ploidy levels. Intra-sectional GS variation suggests evolutionary relationships, and intraspecific GS variation within some taxa may indicate taxonomic heterogeneity and/or historical migration patterns.

Conclusions: Our study showed advantages of FCM as an effective tool for detecting ploidy levels and determining GS within the section. GS could be an additional character in understanding evolution and phylogenetic relationships within the section.

Background: The research aims to assess the effectiveness of artificial intelligence models in predicting the risk level in tulip greenhouses using different varieties. The study was conducted in 2022 in the Almaty region, Panfilov village.

Results: Two groups of 10 greenhouses each (area 200 m2) were compared: the control group used standard monitoring methods, while the experimental group employed AI-based monitoring. We applied ANOVA, regression analysis, Bootstrap, and correlation analysis to evaluate the impact of factors on the risk level. The results demonstrate a statistically significant reduction in the risk level in the experimental group, where artificial intelligence models were employed, especially the recurrent neural network "Expert-Pro." A comparison of different tulip varieties revealed differences in their susceptibility to risks. The results provide an opportunity for more effective risk management in greenhouse cultivation.

Conclusions: The high accuracy and sensitivity exhibited by the "Expert-Pro" model underscore its potential to enhance the productivity and resilience of crops. The research findings justify the theoretical significance of applying artificial intelligence in agriculture and its practical applicability for improving risk management efficiency in greenhouse cultivation conditions.

Background: Rice blast caused by Pyricularia oryzae is a major threat to rice production worldwide. Tainung 84 (TNG84) is an elite japonica rice cultivar developed through the traditional pedigree method. It has maintained superior blast resistance since its release in 2010. This study aimed to investigate the genetic factors underlying the durable resistance of TNG84 in Taiwan.

Results: Quantitative trait locus (QTL) mapping was conducted using 122 F₂ individuals and F_2:3 families derived from the cross of TNG84 and a susceptible japonica cultivar Tainan 11 (TN11). Using 733 single nucleotide polymorphisms (SNPs) obtained through genotyping-by-sequencing and three P. oryzae isolates (D41-2, 12CY-MS1-2, and 12YL-TT4-1) belonging to different physiological races and Pot2 lineages, a major QTL was identified in the region of 52-54 cM (9.54-15.16 Mb) on chromosome 12. Fine-mapping using 21 F_5:6 recombinants delimited the QTL to a 140.4-kb region (10.78 to 10.93 Mb) containing the known resistance gene Ptr. Sequencing analysis indicated that TNG84 carries the resistant PtrA allele and TN11 carries the susceptible PtrD allele. Investigation of the Ptr haplotypes in 41 local japonica rice cultivars revealed that eight PtrA-containing cultivars (19.5%) consistently exhibited good field resistance in Taiwan from 2008 to 2024. Subsequently, a few F_5:6 lines (P026, P044, P092, and P167) lacking the resistant Ptr allele were observed to exhibit a resistant phenotype against P. oryzae 12YL-TT4-1-lab. Trait-marker association analyses using eight F_6:7 homozygous recombinants, 378 BC₁F₂ from P044 backcrossed to TN11, and 180 BC₁F₂ from P092 backcrossed to TN11, identified Piz-t on chromosome 6 and a new QTL located between 3.3 Mb and 4.4 Mb on chromosome 12 (designated as qBR12_3.3-4.4). Analysis of 12 selected BC₁F_2:3 lines derived from P044 demonstrated that in the absence of Ptr and Piz-t, qBR12_3.3-4.4 alone reduced the disease severity index from approximately 6.3 to 3.9.

Conclusions: PtrA is likely the primary gene responsible for the broad-spectrum and durable resistance of TNG84. Piz-t confers narrow-spectrum resistance, while qBR12_3.3-4.4 contributes partial resistance. The discovery of qBR12_3.3-4.4 has provided a new source of blast resistance, and the markers developed in this study can be utilized in future breeding programs.