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Leaf blight disease (LBD) caused by Pantoea agglomerans is a newly emerged oat disease in China that causes great economic and yield losses of oat production. Laboratory and field experiments were conducted to evaluate the efficacy of 13 antimicrobial agents against P. agglomerans and recommend agents with better control efficacy for use. The antibacterial potential of four concentrations of each agent was evaluated under in vitro conditions. Zhongshengmycin and ethylicin were the most effective in inhibiting the growth of P. agglomerans; their bacteriostatic rates (85.0% and 84.8%, respectively) were higher while EC50 lower (0.31 and 0.90, respectively) than other agents. The greenhouse and field experiment suggested that the greatest fresh weight per plant (57.26 g and 57.93 g), forage yield (22.53 t/ha and 22.21 t/ha) and control efficacy (>75%) were obtained after spraying twice with zhongshengmycin or ethylicin in the LBD occurrence phase, with lower yields and control by kasugamycin + dicopper chloride trihydroxide, kasugamycin + oxine copper, benziothiazolinone, copper hydroxide, phenanthrenecarboxylicacid, copper, picoxystrobin, chloroisobromine cyanuric acid, oxathiapiprolin or azoxystrobin. Foliar application of zhongshengmycin or ethylicin can therefore be used for the effective management of LBD of oat. [ABSTRACT FROM AUTHOR]

Seed-borne mycoflora can affect seed health and quality. The present study investigated the occurrence of seed-borne fungi in 600 seed samples of Avena sativa (B7) and A. nuda (B2) collected from Baicheng (BB), Dingxi (DB), and Haibei (HB) cities in China. Effects of seed-borne fungi on seed germination and seedling growth of oat were also studied. Among all isolated fungi, 10 fungal genera with high incidence were identified by colony color, spore morphology, and ITS sequence analysis, including Alternaria, Epicoccum, Fusarium, Bipolaris, Pyrenophora, Aspergillus, Cladosporium, Nigrospora, Pleospora, and Hypomyces. Alternaria spp. showed the highest incidence of 34.2%, while Nigrospora oryzae and Hypomyces sp. showed a lower incidence, 1.87% and 1.77%, respectively. The highest number of fungal species was isolated from HB-7 seeds compared to BB-2 which had the lowest species. Alternaria and Epicoccum were the dominant seed-borne species isolated from oat seeds in three regions, while B7 showed a higher infection incidence than B2. The pathogenicity tests of these seed-borne fungal pathogens against oat seed were conducted in the laboratory, and the results showed that the seed germination rate, germination potential, germination index, and vigor index of B2 and B7 seeds were significantly decreased by Alternaria spp., Bipolaris spp., C. allicinum, Pyrenophora sp., Fusarium spp., and N. oryzae (P < 0.05). The plumule length, radicle length, and dry weight of B2 and B7 seedlings were significantly reduced by Bipolaris spp. and Fusarium spp. (P < 0.05). Seed-borne fungal infection might inhibit seed germination and seedling growth of oat. [ABSTRACT FROM AUTHOR]

Cool season grasses often form reciprocal symbiotic relationships with endophytic fungal species in genus Epichloë. In this study, we characterized three fungal endophytes isolated from the grass Hordeum bogdanii native to northwest China. Based on morphological characteristics and phylogenetic analyses of tefA, tubB, and actG sequences, we identified them as Epichloë sp. HboTG-2 (H. bogdanii Taxonomic Group 2: E. bromicola × E. typhina). Alkaloid synthesis related genes analysis showed that Epichloë sp. HboTG-2 may have the ability only to produce peramine which is toxic to insects but not to animals. In the process of this study, we did not observe sexual structures or epiphyllous growth on leaves of infected plants. [ABSTRACT FROM AUTHOR]

Summary: Stellera chamaejasme has become a problematic weed in northern and south‐western grasslands of China. To evaluate a possible role of endophytes in its strong competitive capacity, the endophytic bacterial community of S. chamaejasme was investigated by culture‐dependent and independent methods, and the growth‐promoting traits of some culturable isolates as well as the benefit of endophyte ST3CS3 (Brevundimonas sp.) on host plants growth were studied. The results showed that 823 OTUs were generated with a 97% similarity level in the culture‐independent study. They were classified into 29 phyla, 61 classes, 147 orders, 237 families and 440 genera. Among them, Pseudomonas and Ralstonia were the most dominant genera in belowground parts (G) (64.25%) and aboveground parts (S) (26.54%) respectively. The diversity and species richness of endophytes in S were significantly higher than that of G (P < 0.001, t‐test). Contrary to this, the number of culturable bacteria in S was a little lower than that of G (P > 0.05, t‐test). Totally, 176 isolates belonging to 30 morphotypes were obtained in the culture‐dependent study. Among them, Acinetobacter was the most dominant genus in G (51.30%), then followed by Pseudomonas (6.09%) and Brevundimonas (6.09%), while Lysinibacillus (21.31%) was the most dominant genus in S, followed by Pseudomonas (11.48%). Growth‐promoting trait tests indicated that 93.65% of the tested isolates (63) exhibited nitrogen‐fixing, IAA‐synthesizing, phosphorus or potassium solubilizing capacity, in which 77.97% belonged to Proteobacteria, a phylum found to contain more active isolates. Pot experiments demonstrated that endophyte ST3CS3 can significantly improve host plants growth and increase its nitrogen and chlorophyll content (P < 0.01, t‐test). Therefore, we suggest that strong competitiveness of S. chamaejasme may in part be due to possession of high ratios of plant growth‐promoting proteobacterial endophytes such as Pseudomonas, Acinetobacter and Brevundimonas. [ABSTRACT FROM AUTHOR]

The leaf blight disease (LBD) caused by Pantoea agglomerans is a new oat disease in China. In this study, greenhouse experiments were conducted to explore the effect of P. agglomerans on photosynthetic characteristics of oat at different growth stages. Our results showed that the leaf area, chlorophyll relative content (Soil and plant analyzer development, SPAD), net photosynthetic rate (Pn), stomatal conductance (Cs), transpiration rate (Tr), and water use efficiency (WUE) of Avena sativa (B7) and A. nuda (B2) were all significantly (P < 0.05) decreased by LBD after inoculation of P. agglomerans. LBD also inhibited the activity of Rubisco and SBPase. In contrast, oat's intercellular CO2 concentration (Ci) was increased after inoculation. Furthermore, A. nuda had stronger photosynthesis than A. sativa in all growth stages under inoculation and non-inoculation of P. agglomerans. The photosynthesis ability of oat in the flowering stage was higher than both the jointing and milking stages. Consequently, LBD showed negative influences on photosynthesis characteristics of oat at different growth stages by decreasing the leaf area, SPAD, Pn, Cs, Tr, WUE, and the activity of Rubisco and SBPase. [ABSTRACT FROM AUTHOR]

Drechslera leaf spot (DLS) is a serious leaf disease of oats chiefly caused by Pyrenophora chaetomioides in the main oat‐producing areas of the world. However, other species of Pyrenophora that may cause DLS have not been investigated in China. From 2018 to 2020, a total of 256 strains of Pyrenophora were isolated from nine oat‐producing areas in three provinces in western China. Using a combination of morphological characteristics and phylogenetic analysis of the rDNA internal transcribed spacer (ITS), 28S ribosomal RNA gene (LSU), RNA polymerase second largest subunit region (RPB2), and glyceraldehyde‐3‐phosphate dehydrogenase region (GAPDH), 66% of the isolates were identified as P. chaetomioides and 34% of isolates belonged to P. avenicola. Pathogenicity tests confirmed that P. avenicola also infected oat and caused DLS, but it was less virulent than P. chaetomioides. From our survey, DLS caused by P. avenicola generally occurred in warm areas at lower altitude and the annual average temperature was above 0°C (Huan and Zhenyuan county in Gansu, Huize county in Yunnan), compared to high‐altitude areas (Tianzhu county, Shandan county, Haiyan county). The combination of optimal and maximal temperature indicated that P. avenicola had greater tolerance to high temperature, which was also an important factor for its distribution on oats. Precise identification and understanding of virulence, distribution, and occurrence of these pathogens has significance for control of oat DLS in the future. [ABSTRACT FROM AUTHOR]

A new leaf blight disease of oat (Avena sativa) was observed in many oat fields in Huan county, Gansu Province of China, during 2018–2019. Typical symptoms appeared as yellow necrotic and water‐soaked lesions. The lesions developed from tip to base of leaves and eventually resulted in leaf withering. Disease incidence on plants (leaves) was approximately 36%–100%. A gram‐negative bacterium was isolated from the necrotic lesions of all samples. Coupled with multigene sequence (16S rRNA and gyrB gene) analyses, Biolog Gen III MicroStation, morphological, physiological, and biochemical characterization identified the pathogen as Pantoea agglomerans. Pathogenicity tests by wounding and injection inoculations in the greenhouse established that P. agglomerans could induce typical symptoms as observed in the field. The infection rate in leaves was 44%–71% after 14 days. In addition, host range tests showed that P. agglomerans could infect other plant hosts, including Sorghum sudanense, Medicago sativa, Fagopyrum esculentum, Setaria italica, and Zea mays. This is the first report of P. agglomerans causing bacterial leaf blight disease (LBD) on oat in China. The current study can provide a foundation for the prevention of this disease in the future. [ABSTRACT FROM AUTHOR]

Head blight (HB) of oat (Avena sativa) has caused significant production losses in oats growing areas of western China. A total of 314 isolates, associated with HB were collected from the major oat cultivating areas of Gansu, Qinghai, and Yunnan Provinces in western China. Based on morphological characters, the isolates were initially classified into three genera, as differentiation to species was a bit difficult. Taxonomic analysis of these isolates based on muti-gene phylogenetic analyses (ITS, TEF1 , TUB2 , and RPB2) revealed four known Fusarium species, F. proliferatum , F. avenaceum , F. poae , and F. sibiricum , and one Acremonium specie (A. sclerotigenum). In addition, a new genus Neonalanthamala gen. nov., similar to genus Nalanthamala was introduced herein with a new combination, Neonalanthamala graminearum sp. nov., to accommodate the HB fungus. The molecular clock analyses estimated the divergence time of the Neonalanthamala and Nalanthamala based on a dataset (ITS, TUB2 , RPB2), and we recognized the mean stem ages of the two genera are 98.95 Mya, which showed that they evolved from the same ancestor. N. graminearum was the most prevalent throughout the surveyed provinces. Pathogenicity test was carried out by using two different methods: seed inoculation and head inoculation. Results showed that F. sibiricum isolates were the most aggressive on the seed and head. A. sclerotigenum isolates were not pathogenic to seeds, and were developed less symptoms to the head compared to other species. Data analyses showed that the correlation of the germination potential, germination index, and dry weight of seed inoculation and disease index of plant inoculation had a highly significant negative correlation (P < 0.001). These results showed that the development of HB might be predicted by seed tests for this species. A. sclerotigenum and N. graminearum causing HB are being firstly reported on oat in the world. Similarly, F. proliferatum , F. avenaceum , F. poae and F. sibiricum causing oat HB are firstly reported in China. • A new genus, with a new combination, to accommodate the oat head blight fungus. • The Neonalanthamala and Nalanthamala from the same ancestor. • Six new diseases reported for the first time in China. • A strong correlation between seed and plant inoculation in pathogenicity. [ABSTRACT FROM AUTHOR]

Background: the cool-season grass Achnatherum inebrians (drunken horse grass) is an important species in the northwest grasslands of China. This grass engages in a symbiotic relationship with Epichloë endophytes, which affect host plants by increasing growth, repelling herbivores, and increasing tolerance to stressful environments. Methods: in this work, we evaluated the interaction effects of the endophyte on various dormancy-breaking treatments on A. inebrians seeds from six different locations. We used both endophyte-infected plants and noninfected plants and applied four dormancy-breaking methods to test germination. Results: our results showed that the germination rate of endophytic Achnatherum inebrians seeds from the Xiahe site (with highest altitude) was significantly higher than that from other sites when water soaking was applied (p < 0.05). Endophytic seeds had a greater germination rate, and soluble sugar, indole acetic acid (IAA), and gibberellin (GA) contents, under any condition. There was a significant interaction among the method, endophyte status, and origin regarding germination (p < 0.001); particularly, the effects of warm water soaking and endophyte infection on the germination of seeds from the Xiahe site was significant (p < 0.05). Conclusions: the infection of Epichloë endophyte is able to increase the content of soluble sugar, IAA, and GA, and stimulate the seed germination of A. inebrians. [ABSTRACT FROM AUTHOR]

Soil properties affect plant growth and cause variation in leaf functional traits. Lycium ruthenicum Murray is one of the desert dominant shrubs and halophytes in the lower reaches of Heihe River, Northwest China. We analyzed the trade-off relationships of 14 leaf functional traits of eight L. ruthenicum populations growing at varying distances from the river and discussed the effects that soil properties have on leaf functional traits. The results showed that: Lower leaf nitrogen (N) content indicated that L.ruthenicum was located at the slow investment–return axis of the species resource utilization graph. Compared with non-saline and very slightly saline habitats, populations of slightly saline habitats showed a higher carbon to nitrogen ratio (C:N). Redundancy analysis (RDA) revealed a relatively strong relationship between leaf functional traits and soil properties, the first RDA axis accounted for 70.99 and 71.09% of the variation in 0–40 and 40–80 cm of soil properties. Relative importance analysis found that in the 0–40 cm soil layer, leaf traits variations were mainly influenced by soil moisture (SWC), HCO3− and CO32− ions content, while leaf traits variations in the 40–80 cm soil layer were mainly influenced by HCO3− and SO42−. L.ruthenicum has a foliar resource acquisition method and a resource conservation trade-off with a flexible life history strategy in habitats with drought and salinity stress. In the shallow soil layers, water affects leaf traits variation greater than salt, and in both shallow and deep soil layers, HCO3− plays a dominant role on leaf traits. This study provides insights into the adversity adaptation strategies of desert plants and the conservation and restoration of arid-saline ecosystems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Potential niche preference of phyla Thaumarchaeota and Euryarchaeota were opposite. • The highest salinity soils harbored complex archaeal network with kinless hubs. • Interplay between stochastic and deterministic processes mediates archaeal assembly. Archaea are present in most ecosystems and are known to play a pivotal role in many ecological and biogeochemical processes. However, archaeal biogeographic patterns and driving processes in saline agricultural ecosystems remain poorly understood. To address this, we conducted a regional-scale survey of archaeal communities in saline agricultural soils throughout northwest China. While archaeal abundance was positively correlated with soil organic matter and total nitrogen levels, archaeal diversity was positively associated with salinity and ammonium-nitrogen (NH 4 +-N) levels. Dominant phyla belonged to Thaumarchaeota (45.52%) and Euryarchaeota (37.32%), however, the environmental factors affected these two phyla in opposing ways. Archaeal spatial distribution patterns and environmental preferences were also assessed and significant distance-decay relationships for dissimilarity in archaeal community structures were identified. Soil physicochemical properties, particularly salinity and organic matter, were strong determinants of archaeal community variation. Sixty percent of the variation could be explained by edaphic factors (34.5%) and spatial parameters (25.7%). Archaeal co-occurrence patterns were explored and more intra- than inter-kingdom associations were observed. The network topological features revealed that archaeal networks under the highest soil salinity level (>20 g kg−1) were more complex and had greater associations than those under a medium salinity level (5–20 g kg−1). Phylogenetic null modeling of community assembly suggested that archaea may transition from stochasticity in medium salinity soils to determinism in higher salinity soils. Overall, these findings offer new insight into the distribution patterns and drivers of archaeal community assembly in saline soils. [ABSTRACT FROM AUTHOR]

Entomosporium leaf spot (ELS) is a serious hawthorn disease that mainly causes premature leaf senescence in various hawthorn growing areas worldwide. Diplocarpon mespili is the most commonly reported pathogen causing hawthorn ELS. From 2016 to 2018, hawthorn ELS disease surveys and samplings were carried out in five regions in three provinces of China. The disease incidence was about 20 to 95%. A total of 186 single-spored Diplocarpon isolates were obtained and identified using morphological and molecular phylogenetic analysis. The results showed that all isolates clustered, suggesting a distinct species that is here proposed as D. mespilicola sp. nov. This is the first report of the pathogen causing ELS on hawthorn in China, and it is similar to the species D. mespili . To explore the influence of temperature on the epidemiology of D. mespilicola , we studied the continuous influence of temperature and time on the germination of conidia by using nine time points and eight temperature gradient observations. This study indicated that the optimum temperature for conidial germination was 20.4°C, and the minimum germination time was 4.9 h. Using this information to develop a predictive model may provide a basis for disease management in hawthorn production in the future.

In recent years in China, leaf spot caused by Colletotrichum species has been an emerging disease of Philodendron tatei cv. Congo. From 2016 to 2019, typical symptoms, appearing as circular or ovoid, sunken, and brown lesions with a yellow halo, were commonly observed on P. tatei cv. Congo in and around Lanzhou, Gansu Province, China. Conidiomata were often visible on infected leaf surfaces. Leaf disease incidence was approximately 5 to 20%. A total of 126 single-spored Colletotrichum isolates were obtained from leaf lesions. Multilocus phylogenetic relationships were analyzed based on seven genomic loci (ITS, ACT , GAPDH , HIS3 , CAL , CHS-1 , and TUB2 ) and the morphological characters of the isolates determined. These isolates were identified as three Colletotrichum species in this study. A further 93 isolates, accounting for 74% of all Colletotrichum isolates, were described as new species and named as Colletotrichum philodendricola sp. nov. after the host plant genus name, Philodendron ; another two isolates were named as C. pseudoboninense sp. nov. based on phylogenetic and morphological relativeness to C. boninense ; the other 31 isolates, belonging to the C. orchidearum species complex, were identified as a known species- C. orchidearum . Both novel species C. philodendricola and C. pseudoboninense belong to the C. boninense species complex. Pathogenicity tests by both spray and point inoculations confirmed that all three species could infect leaves of P. tatei cv. Congo. For spray inoculation, the mean infection rate of leaves on the three species was only 4.7% (0 to 12%), and the size on lesions was mostly 1 to 2 mm in length. For point inoculation, 30 days after nonwounding inoculation, the infection rate on leaves was 0 to 35%; in wounding inoculation, the infection rate of leaves was 35 to 65%; wounding in healthy leaves greatly enhanced the pathogenicity of these three species to P. tatei cv. Congo; however, the sizes of lesions among the three species were not significantly different. To our knowledge, this is the first report of Colletotrichum species associated with anthracnose diseases on P. tatei cv. Congo. Results obtained in this study will assist the disease prevention and appropriate management strategies.

Drechslera leaf spot (DLS) caused by Pyrenophora ( Drechslera ) species is one of the most serious diseases affecting Italian ryegrass ( Lolium multiflorum ) in China. Between 2015 and 2018, this disease was observed in three Italian ryegrass fields in the province of Sichuan, China. Average leaf disease incidence was approximately 1 to 12% but could range up to 100%. Symptoms appeared as brown or tan spots surrounded by a yellow halo, or brown to dark brown net blotch; subsequently, spots increased in number and size, and they later covered a large area of leaf, eventually causing leaf death. In this study, 86 strains of Pyrenophora fungi were isolated from leaf lesions of Italian ryegrass. Coupled with phylogenetic analysis of the internal transcribed spacer region, partial 28S ribosomal RNA gene, and glyceraldehyde-3-phosphate dehydrogenase gene, morphological characteristics showed that Pyrenophora dictyoides and P. nobleae are associated with Italian ryegrass in southwest China. Pathogenicity tests confirmed that both species can infect Italian ryegrass, causing leaf spot, whereas the virulence of the two species differed; P. nobleae showed lower pathogenicity to Italian ryegrass. This is the first time that these two Pyrenophora species were formally reported on Italian ryegrass based on both morphological and molecular characters. Overall, this study improves knowledge of the Pyrenophora species associated with Italian ryegrass and provides a foundation for control of this disease in the future.

Brown spot disease caused by Colletotrichum species was found on leaves of mulberry ( Morus alba L.) in Dujiangyan, Sichuan Province, China. Fungal isolates from leaf lesions were identified as six Colletotrichum species based on morphological characteristics and DNA analysis of the combined sequences ITS, GAPDH , ACT , CHS-1 , TUB2 , and GS . These included Colletotrichum fioriniae , C. fructicola , C. cliviae , C. karstii , C. kahawae subsp. ciggaro , and C. brevisporum . Results showed that the most important causal agent of mulberry anthracnose was C. fioriniae , causing typical brown necrotic spots or streaks, followed by C. brevisporum , C. karstii , and C. kahawae subsp. ciggaro , whereas the two other species ( C. fructicola and C. cliviae ) showed no pathogenicity to mulberry. This study is the first report of these species associated with mulberry in China.