Broad-spectrum resistance gene RPW8.1 balances immunity and growth via feedback regulation of WRKYs.

Arabidopsis RESISTANCE TO POWDERY MILDEW 8.1 (RPW8.1) is an important tool for engineering broad-spectrum disease resistance against multiple pathogens. Ectopic expression of RPW8.1 leads to enhanced disease resistance with cell death at leaves and compromised plant growth, implying a regulatory mechanism balancing RPW8.1-mediated resistance and growth. Here, we show that RPW8.1 constitutively enhances the expression of transcription factor WRKY51 and activates salicylic acid and ethylene signalling pathways; WRKY51 in turn suppresses RPW8.1 expression, forming a feedback regulation loop. RPW8.1 and WRKY51 are both induced by pathogen infection and pathogen-/microbe-associated molecular patterns. In ectopic expression of RPW8.1 background (R1Y4), overexpression of WRKY51 not only rescues the growth suppression and cell death caused by RPW8.1, but also suppresses RPW8.1-mediated broad-spectrum disease resistance and pattern-triggered immunity. Mechanistically, WRKY51 directly binds to and represses RPW8.1 promoter, thus limiting the expression amplitude of RPW8.1. Moreover, WRKY6, WRKY28 and WRKY41 play a role redundant to WRKY51 in the suppression of RPW8.1 expression and are constitutively upregulated in R1Y4 plants with WRKY51 being knocked out (wrky51 R1Y4) plants. Notably, WRKY51 has no significant effects on disease resistance or plant growth in wild type without RPW8.1, indicating a specific role in RPW8.1-mediated disease resistance. Altogether, our results reveal a regulatory circuit controlling the accumulation of RPW8.1 to an appropriate level to precisely balance growth and disease resistance during pathogen invasion.

Osa-miR535 targets SQUAMOSA promoter binding protein-like 4 to regulate blast disease resistance in rice.

Many rice microRNAs have been identified as fine-tuning factors in the regulation of agronomic traits and immunity. Among them, Osa-miR535 targets SQUAMOSA promoter binding protein-like 14 (OsSPL14) to positively regulate tillers but negatively regulate yield and immunity. Here, we uncovered that Osa-miR535 targets another SPL gene, OsSPL4, to suppress rice immunity against Magnaporthe oryzae. Overexpression of Osa-miR535 significantly decreased the accumulation of the fusion protein SPL4TBS -YFP that contains the target site of Osa-miR535 in OsSPL4. Consistently, Osa-miR535 mediated the cleavage of OsSPL4 mRNA between the 10th and 11th base pair of the predicted binding site at the 3' untranslated region. Transgenic rice lines overexpressing OsSPL4 (OXSPL4) displayed enhanced blast disease resistance accompanied by enhanced immune responses, including increased expression of defense-relative genes and up-accumulated H2 O2 . By contrast, the knockout mutant osspl4 exhibited susceptibility. Moreover, OsSPL4 binds to the promoter of GH3.2, an indole-3-acetic acid-amido synthetase, and promotes its expression. Together, these data indicate that Os-miR535 targets OsSPL4 and OsSPL4-GH3.2, which may parallel the OsSPL14-WRKY45 module in rice blast disease resistance.

RESISTANCE TO POWDERY MILDEW8.1 boosts pattern-triggered immunity against multiple pathogens in Arabidopsis and rice.

The Arabidopsis gene RESISTANCE TO POWDERY MILDEW8.1 (RPW8.1) confers resistance to virulent fungal and oomycete pathogens that cause powdery mildew and downy mildew, respectively. However, the underlying mechanism remains unclear. Here, we show that ectopic expression of RPW8.1 boosts pattern-triggered immunity (PTI) resulting in enhanced resistance against different pathogens in both Arabidopsis and rice. In Arabidopsis, transcriptome analysis revealed that ectopic expression of RPW8.1-YFP constitutively up-regulates expression of many pathogen-associated molecular pattern (PAMP-)-inducible genes. Consistently, upon PAMP application, the transgenic line expressing RPW8.1-YFP exhibited more pronounced PTI responses such as callose deposition, production of reactive oxygen species, expression of defence-related genes and hypersensitive response-like cell death. Accordingly, the growth of a virulent bacterial pathogen was significantly inhibited in the transgenic lines expressing RPW8.1-YFP. Conversely, impairment of the PTI signalling pathway from PAMP cognition to the immediate downstream relay of phosphorylation abolished or significantly compromised RPW8.1-boosted PTI responses. In rice, heterologous expression of RPW8.1-YFP also led to enhanced resistance to the blast fungus Pyricularia oryzae (syn. Magnaporthe oryzae) and the bacterial pathogen Xanthomonas oryzae pv. oryzae (Xoo). Taken together, our data suggest a surprising mechanistic connection between RPW8.1 function and PTI, and demonstrate the potential of RPW8.1 as a transgene for engineering disease resistance across wide taxonomic lineages of plants.

Progression of periodontal inflammation in adolescents is associated with increased number of Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythensis, and Fusobacterium nucleatum.

OBJECTIVE: The study aims to evaluate the change of related subgingival periodontopathogens among different stage of gingivitis in adolescent and assess the relationship between periodontopathogens and the progression of periodontal inflammation. METHODS: A total of 77 subgingival plaque samples from 35 adolescent individuals were divided into three groups including gingivitis group (mild, 15 samples; moderate, 16 samples; severe, 15 samples), chronic periodontitis group (15 samples) and healthy group (15 samples). Real-time PCR was used to quantitate Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythensis, and Fusobacterium nucleatum in subgingival plaque samples. RESULTS: All species, except for F. nucleatum, were detected in samples from gingivitis and periodontitis groups in significantly greater number than in those from healthy group (P < 0.05). In gingivitis groups, the number of P. gingivalis, T. forsythensis, and F. nucleatum in moderate and severe gingivitis groups was significantly higher than in mild gingivitis group (P < 0.05). After merging moderate gingivitis and severe gingivitis groups into moderate-to-severe gingivitis group, the four periodontopathogens were detected in samples from periodontitis group in significantly greater number than in those from moderate-to-severe gingivitis group (P < 0.05). CONCLUSION: The number of P. gingivalis, P. intermedia, T. forsythensis, and F. nucleatum in subgingival plaque increases with progression of periodontal inflammation in adolescents. Examination of periodontopathogens number in adolescents may be of some value for monitoring of periodontal disease development.

Evaluation of repellency of some Chinese medicinal herbs essential oils against Liposcelis bostrychophila (Psocoptera: Liposcelidae) and Tribolium castaneum (Coleoptera: Tenebrionidae).

The screening for repellency against the booklouse, Liposcelis bostrychophila (Badonnel), and the red flour beetle, Tribolium castaneum (Herbst), from 14 Chinese medicinal herbs showed that the essential oils of Curcuma longa L., Epimedium pubescens Maximouwicz, Lindera aggregate (Sims) Kostermans, Nardostachys chinensis Battandier, Schizonepeta tenuifolia Briquet, Zanthoxylum schinifolium Sieber et Zuccarini, and Z. officinale Roscoe exhibited strong repellency against L. bostrychophila and T. castaneum. A total of 35 components of the essential oil of E. pubescens were identified by gas chromatography and gas chromatography-mass spectrometry. Beta-Eudesmol (14.89%), alpha-pinene (13.38%), borneol (9.56%), (R)-carvone (7.89%), and menthol (7.45%) were the main components of the essential oil of E. pubescens. From the essential oil of E. pubescens, four monoterpenoids and one sesquiterpenoid were isolated by bioassay-guided fractionation. The compounds were identified alpha-pinene, borneol, menthol, carvone, and beta-eudesmol. (R) -carvone, menthol, borneol, and beta-eudesmol were strongly repellent against L. bostrychophila at concentration of 8.5 nl/cm2 after 2 h exposure whereas alpha-pinene exhibited moderate repellency. (R)-carvone exhibited stronger repellency against the booklouse than the positive control, N, N-diethyl-3-methylbenzamide (DEET). Moreover, (R)-carvone also possessed stronger repellency against T. castaneum than DEET. The other four constituents, menthol, borneol, and beta-eudesmol also showed repellency against the red flour beetles but weaker than DEET at lower concentrations.

Biological control of Magnaporthe oryzae using natively isolated Bacillus subtilis G5 from Oryza officinalis roots.

Rice blast, caused by Magnaporthe oryzae, is a major threat to global rice production causing significant crop losses and impacting grain quality. The annual loss of rice production due to this disease ranges from 10% to 30%. The use of biologically controlled strains, instead of chemical pesticides, to control plant diseases has become a research hotspot. In this study, an antagonistic endophytic bacterial strain was isolated from the roots of Oryza officinalis using the traditional isolation and culture methods. A phylogenetic tree based on 16S RNA and whole-genome sequencing identified isolate G5 as a strain of Bacillus subtilis. This isolate displayed strong antagonistic effects against different physiological strains of M. oryzae. After co-culture in LB medium for 7 days, the inhibition rates of the mycelial growth of four strains of M. oryzae, ZB15, WH97, Guy11, and T-39800E were 98.07 ± 0.0034%, 98.59 ± 0.0051%, 99.16 ± 0.0012%, and 98.69 ± 0.0065%, respectively. Isolate G5 significantly inhibited the formation of conidia of M. oryzae, with an inhibition rate of 97% at an OD600 of 2. Isolate G5 was able to provide 66.81% protection against rice blast under potted conditions. Whole-genome sequencing revealed that the genome size of isolate G5 was 4,065,878 bp, including 4,182 coding genes. Using the anti-SMASH software, 14 secondary metabolite synthesis gene clusters were predicted to encode antifungal substances, such as fengycin, surfactin, and bacilysin. The G5 isolate also contained genes related to plant growth promotion. These findings provide a theoretical basis for expounding the biocontrol mechanisms of this strain and suggest further development of biogenic agents that could effectively inhibit rice blast pathogen growth and reduce crop damage, while being environmentally friendly, conducive to ecological development, and a sustainable alternative to chemical pesticides. This study also enriches the relevant research on endophytes of wild rice, which proves that wild rice is a valuable microbial resource bank.

Photosynthetic Regulation Under Salt Stress and Salt-Tolerance Mechanism of Sweet Sorghum.

Sweet sorghum is a C4 crop with the characteristic of fast-growth and high-yields. It is a good source for food, feed, fiber, and fuel. On saline land, sweet sorghum can not only survive, but increase its sugar content. Therefore, it is regarded as a potential source for identifying salt-related genes. Here, we review the physiological and biochemical responses of sweet sorghum to salt stress, such as photosynthesis, sucrose synthesis, hormonal regulation, and ion homeostasis, as well as their potential salt-resistance mechanisms. The major advantages of salt-tolerant sweet sorghum include: 1) improving the Na+ exclusion ability to maintain ion homeostasis in roots under salt-stress conditions, which ensures a relatively low Na+ concentration in shoots; 2) maintaining a high sugar content in shoots under salt-stress conditions, by protecting the structures of photosystems, enhancing photosynthetic performance and sucrose synthetase activity, as well as inhibiting sucrose degradation. To study the regulatory mechanism of such genes will provide opportunities for increasing the salt tolerance of sweet sorghum by breeding and genetic engineering.

[Ecological quality assessment of Xiongan New Area based on remote sensing ecological index]. / 基于遥感生态指数的雄安新区生态质量评估.

The continuous urbanization leads to increasing pressure on the ecological environment. It is a key point to measure regional ecological environment quality objectively, accurately and quickly from multiple directions in ecological research. In this study, the normalized vegetation index (NDVI), wet index (WET), land surface temperature (LST), and normalized difference building-soil index (NDBSI) were extracted from the aspects of greenness, humidity, heat and dryness. The ecological quality of Xiongan New Area between 1995 and 2015 was evaluated by integrating selected indicators to measure the remote sensing ecological index (RSEI) with principal component analysis technology based on ENVI platform. The results showed that the average RSEI of Xiongan New Area was 0.724, 0.710, and 0.682 in 1995, 2004 and 2015, respectively, showing a downward trend. RSEI mainly changed from 4, 5 to 1, 2 and 3 in the study area from 1995 to 2015. Ecological quality improved and deteriorated area accounted for 8.9% and 20.9% of the total area respectively. The ecological quality improved area was mainly located in the east and south of Xiongxian County, because a large area of forests and gardens was highly valued and strictly protected by the local government. The ecological quality deteriorated area was in the periphery of the town and the surrounding area of Baiyangdian due to the sharp decline of the water area of Baiyangdian and the continuous urbanization. The three-year average correlation coefficient between RSEI and each component index was 0.804, which was higher than that between other component indices. Our results showed that RSEI could efficiently integrate the information of each component index and comprehensively and accurately reflect the ecological quality of the study area.

Osa-miR169 Negatively Regulates Rice Immunity against the Blast Fungus Magnaporthe oryzae.

miR169 is a conserved microRNA (miRNA) family involved in plant development and stress-induced responses. However, how miR169 functions in rice immunity remains unclear. Here, we show that miR169 acts as a negative regulator in rice immunity against the blast fungus Magnaporthe oryzae by repressing the expression of nuclear factor Y-A (NF-YA) genes. The accumulation of miR169 was significantly increased in a susceptible accession but slightly fluctuated in a resistant accession upon M. oryzae infection. Consistently, the transgenic lines overexpressing miR169a became hyper-susceptible to different M. oryzae strains associated with reduced expression of defense-related genes and lack of hydrogen peroxide accumulation at the infection site. Consequently, the expression of its target genes, the NF-YA family members, was down-regulated by the overexpression of miR169a at either transcriptional or translational level. On the contrary, overexpression of a target mimicry that acts as a sponge to trap miR169a led to enhanced resistance to M. oryzae. In addition, three of miR169's target genes were also differentially up-regulated in the resistant accession upon M. oryzae infection. Taken together, our data indicate that miR169 negatively regulates rice immunity against M. oryzae by differentially repressing its target genes and provide the potential to engineer rice blast resistance via a miRNA.

[Phenotypic variation in Actinobacillus actinomycetemcomitans].

OBJECTIVE: To investigate the colony variation in Actinobacillus actinomycetemcomitans (Aa) from rough to smooth and recognize its different morphology during laboratory translations. METHODS: Primary strains isolated from subgingival plaque of two juvenile periodontitis patients were repeatedly subcultured on agar plates and broth; for broth culture, every generation was translated in broth and on solid medium separately to observe the corresponding morphologies of Aa grow in broth. RESULTS: Three smooth strains of Aa from the broth culture were obtained. The process was about 7-8 generations: colonies changed from a small and adherence phenotype to a bigger and sediment ones and finally the culture supernatant became turbid; the corresponding morphologies grow on agar exhibiting an adherent, small rough colony phenotype which had a star-shaped internal structure converted gradually to a kind of bigger, opaque, nonadherent, smooth phenotype, then the colony extended out from the margin of the colony and finally converted to a flat, almost parent morphology and the same time the star-like inner structure converted to a simpler and smaller type and finally disappeared. We could not get completely smooth variants of Aa from agar. CONCLUSIONS: The variation in colony morphology of Aa from rough to smooth is a process, in which the colony was gradually wetter and bigger and at the same time gradually lost the inner structure. During this process three colony morphologies at least can be seen, including rough, opaque smooth and almost translucent smooth.