Search Results (24)

Rhododendron hybridum Ker Gawl, a widely cultivated horticultural species in China, is highly valued for its ornamental and medicinal properties. However, with the expansion of its cultivation, leaf spot disease has become more prevalent, significantly affecting the ornamental value of R. hybridum Ker Gawl. In this study, R. hybridum Ker Gawl from the Kunming area was selected as the experimental material. The tissue isolation method was employed in this study to isolate pathogenic strains. The biological characteristics of the pathogens were determined using the mycelial growth rate method. The pathogens’ influence on the host plant’s ultrastructure was investigated using transmission electron microscopy (TEM). Colletotrichum nymphaeae was identified as the pathogen implicated in the development of leaf spot disease in R. hybridum Ker Gawl across three regions in Kunming City through the integration of morphological traits and phylogenetic analyses of multiple genes (ITS, ACT, GAPDH, HIS3, CHS1, and TUB2). Its mycelial growth is most effective at a temperature of 25 °C. pH and light have relatively minor effects on the growth of mycelium. The preferred carbon and nitrogen sources were identified as mannitol and yeast extract, respectively. Additionally, TEM observations revealed significant damage to the cell structure of R. hybridum Ker Gawl leaves infected by the pathogen. The cell walls were dissolved, the number of chloroplasts decreased markedly, starch granules within chloroplasts were largely absent, and the number of osmiophilic granules increased. This is the first report of leaf spot disease in R. hybridum Ker Gawl caused by C. nymphaeae. The results of this study provide valuable insights for future research on the prevention and control of this disease. Full article

Objectives: Isostrictiniin (ITN), a natural polyphenol extracted from Nymphaea candida (snow-white waterlily), has antioxidant and hepatoprotective activities that may be beneficial in treating metabolic dysfunction-associated steatotic liver disease (MASLD). This study aimed to investigate the protective effects of ITN on high-fat, high-sugar diet (HFSD)-induced steatosis in MASLD mice and its mechanisms. Methods: Kunming mice were randomly divided into normal control and HFSD groups. After being fed for 4 weeks, the HFSD group was randomly divided into model, atorvastatin calcium (ATC; 10 mg/kg), and ITN (25, 50, and 100 mg/kg) groups. After continued feeding for 4 weeks, the biochemical indexes in the mice were determined. Results: Compared with the model group, the liver index; FBG; HOMA-IR; serum AST, ALT, TG, TC, and LDL-C; and liver MDA, IL-6, TNF-α, and IL-1β levels in the ITN (25, 50, and 100 mg/kg) and ATC (10 mg/kg) groups were significantly decreased (p < 0.05), while serum HDL-C and liver SOD and GSH-Px levels were increased (p < 0.05). Pathological observation showed that ITN treatment mitigated the lipid liver deposition in the HFSD mice. Moreover, ITN could upregulate liver-tissue p-AMPK/AMPK protein expression in the HFSD-induced MASLD mice and downregulate SREBP-1c and ACC levels (p < 0.05). Conclusions: ITN can significantly improve MASLD mice, and its mechanism may be related to the regulation of the AMPK/SREBP-1c/ACC pathway. Full article

Excess nitrogen in agricultural drainage poses a serious threat to the water quality safety of the Yellow River basin. Utilizing aquatic plants to modify the rhizosphere microbial community structure and facilitate nitrogen transformation is a crucial strategy for mitigating regional water eutrophication. We here compare key processes of nitrogen transformation occurring in the rhizosphere of sediments of a ditch artificially planted with a mix of species (Phragmites australis, Typha orientalis, Nymphaea tetragon) with the rhizosphere of a ditch occupied by naturally occurring aquatic vegetation, dominated either by P. australis or T. orientalis. Our results revealed a species effect, with an increased denitrification rate (DR) and dissimilatory nitrate reduction to ammonium rate (DNRAR) in the cultivated ditch for P. australis, compared to the naturally occurring T. orientalis vegetation. The nitrogen fixation rate (NFR) increased in the artificial setting with T. orientalis in comparison to natural P. australis vegetation. The richness of the bacterial community and the relative abundances of Bacteroidota, Firmicutes, and Geobacter were significantly greater in the rhizosphere of the artificially cultivated ditch due a greater availability in nitrogen and organic carbon. In the artificially cultivated ditch, the dominant functional genes affecting DRNARs in the rhizosphere sediments of P. australis were nrfC and nrfA, whereas DRs were driven mainly by norB and napA, which were influenced by the nitrogen and carbon levels. The dominant functional genes affecting NFRs in the rhizosphere sediments of T. orientalis were nifD, nifK, and nifH. Our results provide a scientific basis for the use of aquatic plants for mitigating excess nitrogen levels in agricultural drainage. Full article

Olive anthracnose outbreaks caused by the Colletotrichum species complex in the Mediterranean region decrease both fruit yield and olive oil production while also drastically degrading olive oil quality. The presence of various Colletotrichum species able to produce disease symptoms in olive fruits significantly deteriorates the efforts for an efficient crop protection strategy. In this report, the major olive productive area of Peloponnese was screened for Colletotrichum species capable of generating anthracnose symptoms. Olive fruits of 12 different olive cultivars were collected from 60 groves distributed analogously in the Peloponnese. Thirty-two fungal strains isolated from asymptomatic olive drupes were identified morphologically as Colletotrichum spp. and were multilocus genetically analyzed. The 32 isolates were grouped into two primary lineages resembling the previously characterized Colletotrichum acutatum and Colletotrichum nymphaeae based on the conducted genetic analysis for five genetic loci. The virulence of 16 Colletotrichum spp. strains were evaluated in a detached fruit assay of 10 Greek olive cultivars. The results clearly suggested that fungal isolates belonging to both C. acutatum and C. nymphaeae exhibited different levels of pathogenicity in a cultivar-dependent manner. Thus, cultivars examined in terms of the % Disease Index (%DI) were divided into highly tolerant, tolerant, and susceptible, and those analyzed regarding the % Disease Severity Index (%DSI) were divided into tolerant and susceptible. Our results suggest that the Greek cultivars of Athinolia and Megaritiki are highly tolerant to the vast majority of Colletotrichum strains isolated from Peloponnesian groves and consist of a significant genetic material for the future design of crop protection programs against anthracnose breakouts. Full article

Bitter rot of apple is an economically important worldwide disease caused by different Colletotrichum species, depending on many factors such as climate, geography, other hosts, and crop management practices. Culture, morphology, and single-locus sequencing-based methods for identifying the Colletotrichum species are severely limited in effectiveness, while the multilocus sequence typing methods available for delineating species are costly, time-intensive, and require high expertise. We developed species-specific hydrolysis probe real-time PCR assays for the following nine Colletotrichum species causing bitter rot in the Mid-Atlantic U.S.A.: C. fructicola, C. chrysophilum, C. noveboracense, C. gloeosporioides s.s., C. henanense, C. siamense and C. theobromicola from the C. gloeosporioides species complex, and C. fioriniae and C. nymphaeae from the C. acutatum species complex. After searching 14 gene regions, we designed primers and probes in 5 of them for the nine target species. Four primer–probe set pairs were able to be duplexed. Sensitivity tests showed as little as 0.5 pg DNA were detectable. These real-time PCR assays will provide rapid and reliable identification of these key Colletotrichum species and will be critically important for studies aiming to elucidate their biology, epidemiology, and management on apples as the number one produced and consumed tree fruit in the U.S.A. Full article

Olive anthracnose, caused by Colletotrichum fungi, is responsible for major fruit yield losses and poor olive oil quality worldwide. In the Mediterranean basin, some Colletotrichum spp. appear to be replacing others, possibly due to climate change and modification in cultural systems. To update the situation in Portugal, 525 olive groves were surveyed throughout the country over two years, revealing a decrease in disease incidence, associated with scarcer rainfall and new cropping systems using less susceptible cultivars. A collection of 212 isolates was obtained, and phylogenetic analyses using a multi-locus sequencing approach (five and six loci in the acutatum and gloeosporioides species complex, respectively) revealed the presence of seven Colletotrichum species within the collection. Compared to surveys conducted in the first decade of the 21st century, the species composition of olive anthracnose pathogens in Portugal remains mostly unchanged, with C. nymphaeae as the prevalent species, followed by C. godetiae, but with C. acutatum geographically expanding and with C. alienum and C. cigarro being reported for the first time as causal agents of olive anthracnose in Portugal. A close attention to pathogen population shifts, in the context of climate change and modification of cultivation systems, is fundamental for anticipating plant protection measures. Full article

Cyclocarya paliurus, native to China, is a medicinal and edible plant with important health benefits. Anthracnose is an emerging disease in southern China that causes severe economic losses and poses a great threat to the C. paliurus tea industry. However, to date, the species diversity of pathogens causing C. paliurus anthracnose has remained limited. From 2018 to 2022, a total of 331 Colletotrichum isolates were recovered from symptomatic leaves in eight major C. paliurus planting provinces of southern China. Phylogenetic analyses based on nine loci (ITS, GAPDH, ACT, CHS-1, TUB, CAL, HIS3, GS and ApMat) coupled with phenotypic characteristics revealed that 43 representative isolates belonged to seven known Colletotrichum species, including C. brevisporum, C. fructicola, C. gloeosporioides sensu stricto, C. godetiae, C. nymphaeae, C. plurivorum and C. sojae. Pathogenicity tests demonstrated that all species described above were pathogenic to wounding detached leaves of C. paliurus, with C. fructicola being the most aggressive species. However, C. brevisporum, C. plurivorum and C. sojae were not pathogenic to the intact plant of C. paliurus. These findings reveal the remarkable species diversity involved in C. paliurus anthracnose and will facilitate further studies on implementing effective control of C. paliurus anthracnose in China. Full article

Anthracnose of pepper is a significant disease caused by Colletotrichum spp. In 2017 and 2021, 296 isolates were obtained from 69 disease samples. Through morphological analysis, pathogenicity detection, and polygenic phylogenetic analysis, the above strains were attributed to 10 species: C. scovillei, C. fructicola, C. karstii, C. truncatum, C. gloeosporioides, C. kahawae, C. boninense, C. nymphaeae, C. plurivorum, and C. nigrum. C. scovillei had the most strains (150), accounting for 51.02% of the total isolates; C. fructicola came in second (72 isolates), accounting for 24.49%. Regarding regional distribution, Zunyi City has the highest concentration of strains—92 strains total, or 34.18%—across seven species. Notably, this investigation showed that C. nymphaeae infected pepper fruit for the first time in China. Genetic diversity analysis showed that C. fructicola could be divided into seven haplotypes, and the population in each region had apparent genetic differentiation. However, the genetic distance between each population was not significantly related to geographical distance. Neutral detection and nucleotide mismatch analysis showed that C. fructicola might have undergone population expansion. Full article

In Arabidopsis thaliana (Arabidopsis), nonhost resistance (NHR) is influenced by both leaf age and the moment of inoculation. While the circadian clock and photoperiod have been linked to the time-dependent regulation of NHR in Arabidopsis, the mechanism underlying leaf age-dependent NHR remains unclear. In this study, we investigated leaf age-dependent NHR to Pyricularia oryzae in Arabidopsis. Our findings revealed that this NHR type is regulated by both miR156-dependent and miR156-independent pathways. To identify the key players, we utilized rice-FOX Arabidopsis lines and identified the rice HD-Zip I OsHOX6 gene. Notably, OsHOX6 expression confers robust NHR to P. oryzae and Colletotrichum nymphaeae in Arabidopsis, with its effect being contingent upon leaf age. Moreover, we explored the role of AtHB7 and AtHB12, the Arabidopsis closest homologues of OsHOX6, by studying mutants and overexpressors in Arabidopsis–C. higginsianum interaction. AtHB7 and AtHB12 were found to contribute to both penetration resistance and post-penetration resistance to C. higginsianum in a leaf age- and time-dependent manner. These findings highlight the involvement of HD-Zip I AtHB7 and AtHB12, well-known regulators of development and abiotic stress responses, in biotic stress responses in Arabidopsis. Full article

Halophytes are gaining considerable attention due to their applications in saline agriculture, phytoremediation, medicine, and secondary metabolite production. This study investigated the bioactive components present in Silene uniflora (sea campion) hydromethanolic extract, and their antimicrobial activity was evaluated both in vitro and ex situ against two strawberry phytopathogens, namely Botrytis cinerea (grey mold) and Colletotrichum nymphaeae (anthracnose fruit rot). The main identified phytochemicals were mome inositol, saturated fatty acid esters, and cyclotetracosane. In vitro tests demonstrated complete inhibition of the growth of B. cinerea and C. nymphaeae at extract concentrations of 1000 and 1500 μg·mL⁻¹, respectively, with an activity comparable to that of fosetyl-Al and substantially higher than that of azoxystrobin. This activity was improved upon conjugation with chitosan oligomers (COS), yielding inhibition values of 750 and 1000 μg·mL⁻¹. The COS-S. uniflora conjugate complexes were then tested as protective treatments for postharvest storage of strawberry fruit, resulting in high protection against artificially inoculated B. cinerea and C. nymphaeae at doses of 3750 and 5000 μg·mL⁻¹, respectively. The reported results open the door to the valorization of this halophyte as a source of biorationals for strawberry protection. Full article

Colletotrichum species are among the most devastating plant pathogens in a wide range of hosts. Their accurate identification requires a polyphasic approach, including geographical, ecological, morphological, and genetic data. Solanaceous crops are of significant economic importance for Bulgarian agriculture. Colletotrichum-associated diseases pose a serious threat to the yield and quality of production but are still largely unexplored. The aim of this study was to identify and characterize 26 pathogenic Colletotrichum isolates that threaten solanaceous crops based on morphological, pathogenic, and molecular data. DNA barcodes enabled the discrimination of three main taxonomic groups: C. acutatum, C. gloeosporioides, and C. coccodes. Three different species of acutatum complex (C. nymphaeae, C. godetiae, and C. salicis) and C. cigarro of the gloeosporioides complex were associated with fruit anthracnose in peppers and tomatoes. The C. coccodes group was divided in two clades: C. nigrum, isolated predominantly from fruits, and C. coccodes, isolated mainly from roots. Only C. salicis and C. cigarro produced sexual morphs. The species C. godetiae, C. salicis, and C. cigarro have not previously been reported in Bulgaria. Our results enrich the knowledge of the biodiversity and specific features of Colletotrichum species, which are pathogenic to solanaceous hosts, and may serve as a scientific platform for efficient disease control and resistance breeding. Full article

Colletotrichum species are important plant pathogens, causing anthracnose in virtually every crop grown throughout the world. However, little is known about the species that infect watermelon. A total of 526 strains were isolated from diseased watermelon samples of eight major watermelon growing provinces in China. Phylogenetic analyses using seven loci (ITS, gadph, chs-1, his3, act, tub2, and gs) coupled with morphology of 146 representative isolates showed that they belonged to 12 known species of Colletotrichum, including C. aenigma, C. chlorophyti, C. fructicola, C. jiangxiense, C. karstii, C. magnum, C. nymphaeae, C. nigrum, C. orbiculare, C. plurivorum, C. sojae, and C. truncatum and three new species, here described as C. citrulli, C. kaifengense, and C. qilinense. Colletotrichum orbiculare was the dominant species. Pathogenicity tests revealed that all isolates of the species described above were pathogenic, with C. magnum and C. kaifengense being the most aggressive to leaves and fruits, respectively. This is the first report of C. aenigma, C. chlorophyti, C. fructicola, C. jiangxiense, C. nymphaeae, C. nigrum, C. plurivorum, and C. sojae on watermelon. These findings shed light on the Colletotrichum spp. involved in watermelon anthracnose and provide useful information for implementing effective control of watermelon anthracnose in China. Full article

The International Panel on Climate Change (IPCC) projects a global temperature rise of 4.3 ± 0.7 °C by 2100 and an extinction of 8.5% in one out of every six species. Australia’s aquatic ecosystem is no exception; habitat loss, fragmentation, and loss of biodiversity are being experienced. As the center for Nymphaea species distribution, it presents the culturally, ecologically, and scientifically important genus as the best candidate for habitat suitability assessment in climate change, whose habitat suitability is presumed to decline. The models were run according to the maximum entropy (MaxEnt) method, using one general circulation model (GCM). Projections were made for the current, past, and future in medium (4.5) and high (8.5) representative concentration pathways. Significantly, bio2 and bio15 were highly preferred among the species. Less distribution was noted in West Australia compared to the north, east, and south of the continent, while north of the continent in Western Australia, Northern Territory, and Queensland indicate more habitat contractions compared to the east and southeast of Queensland and New South Wales, although it receives high precipitation. Generally, the species respond variably to both temperature and precipitation variables which is a key species response factor for planners and decision makers in species habitat and biodiversity conservation. Full article

Bitter rot and Glomerella leaf spot (GLS) of apples, caused by Colletotrichum species, are major diseases of apples around the world. A total of 98 isolates were obtained from apple fruits with bitter rot, and 53 isolates were obtained from leaves with leaf spot in the primary apple production regions in China. These isolates were characterized morphologically, and five gene regions (ITS, ACT, GAPDH, CHS-1 and TUB2) were sequenced for each isolate. A phylogenetic analysis, combined with a comparison of the morphological, cultural and pathogenic characters, sorted bitter rot isolates into six species: C. alienum, C. fructicola, C. gloeosporioides sensu stricto, C. nymphaeae, C. siamense and one new species, C. orientalis Dandan Fu & G.Y. Sun. Among these, C. siamense was the predominant pathogen associated with bitter rot. Isolates from leaf spot were identified as two species, C. aenigma and C. fructicola. This is the first report of C. orientalis as an apple bitter rot pathogen worldwide, and the results provide important insights into the diversity of Colletotrichum species in China. Full article

Colletotrichum is regarded as one of the 10 most important genera of plant pathogens in the world. It causes diseases in a wide range of economically important plants, including peaches. China is the largest producer of peaches in the world but little is known about the Colletotrichum spp. affecting the crop. In 2017 and 2018, a total of 286 Colletotrichum isolates were isolated from symptomatic fruit and leaves in 11 peach production provinces of China. Based on multilocus phylogenetic analyses (ITS, ACT, CAL, CHS-1, GAPDH, TUB2, and HIS3) and morphological characterization, the isolates were identified to be C. nymphaeae, C. fioriniae, and C. godetiae of the C. acutatum species complex, C. fructicola and C. siamense of the C. gloeosporioides species complex, C. karsti of the C. boninense species complex, and one newly identified species, C. folicola sp. nov. This study is the first report of C. karsti and C. godetiae in peaches, and the first report of C. nymphaeae, C. fioriniae, C. fructicola, and C. siamense in peaches in China. C. nymphaeae is the most prevalent species of Colletotrichum in peaches in China, which may be the result of fungicide selection. Pathogenicity tests revealed that all species found in this study were pathogenic on both the leaves and fruit of peaches, except for C. folicola, which only infected the leaves. The present study substantially improves our understanding of the causal agents of anthracnose on peaches in China. Full article