Leaf blast disease reduction by rice-phyllosphere actinomycetes producing bioactive compounds

Fungal leaf blast, caused by Pyricularia oryzae, is a devastating disease of rice plants that annually causes severe production losses worldwide and is one of the top 10 fungal diseases that threaten global food security. Thus, a reliable control strategy against this disease is essential. In this study, the antagonistic activity of indigenous phyllosphere actinomycetes was elucidated against P. oryzae in vitro and in planta to develop an efficient, effective and environmental friendly approach to protect rice plants against P. oryzae. Of 75 isolates of actinomycetes isolated from the rice phyllosphere, 18 isolates inhibited P. oryzae by >45%. According to analysis of their 16 S rRNA gene sequences, the majority of the 18 isolates belonged to Streptomyces genera; others were identified as belonging to Saccharothrix, Gordonia, or Lentzea. Isolates that potentially produced a bioactive compound(s) were identified among the 18 isolates: 17 isolates (94.44%) had a domain marker for nonribosomal peptide synthetase (NRPS) gene and 12 (66.67%) had type-I polyketide synthase (PKS) gene in their corresponding genome. Interestingly, isolates JSN1.9, SKB2.14, and SKB2.3 suppressed disease suppression by approximately 88%. To our knowledge, this is the first report on the application of rice-phyllosphere actinomycetes producing bioactive compounds to control leaf blast disease in Indonesia. Thus, these findings have escalated the potential application of phyllosphere actinomycetes as a supreme biocontrol agent against fungal leaf blast disease.     

Chimeric mice with humanized liver as a model for testing organophosphate and carbamate pesticide exposure

BACKGROUND

Diagnosis of acute intoxication with organophosphate (OP) or carbamate (CM) pesticides in humans is achieved by measuring plasma butyrylcholinesterase (BuChE) activity. However, BuChE activity is not an ideal biomarker in experimental animal models. The aim of this study was to establish an experimental mouse model for evaluating exposure to OP and CM pesticides by monitoring BuChE activity using chimeric mice in which the liver was reconstituted with human hepatocytes.

RESULTS

A single oral administration of acephate (300 mg/kg), chlorpyrifos (10 mg/kg), fenobucarb (300 mg/kg) or molinate (250 mg/kg) in chimeric mice led to inhibition of >95%, > 95%, 28% and 60% of plasma BuChE activity after 7, 0.5, 0.5 and 7 h, respectively. Dose‐dependent decreases in plasma BuChE activity were also observed for acephate and chlorpyrifos. A 5‐day repeated‐dose study with 10 or 30 mg/kg acephate found a constitutive reduction in plasma BuChE activity to 80% and 70% of pre‐dose levels, respectively.

CONCLUSION

Changes in plasma BuChE activity in chimeric mice with humanized liver clearly reflected the exposure levels of OP and CM pesticides. These results suggest that the humanized‐liver mouse model may be suitable for estimating levels of exposure to these pesticides in humans. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Different cross-reactivity of human and rodent sera to Tula virus and Puumala virus

Tula virus (TULV) and Puumala virus (PUUV) are hantaviruses carried by the bank vole (Myodes glareolus) and European common vole (Microtus arvalis), respectively. PUUV is a causative agent of hemorrhagic fever with renal syndrome (HFRS), while TULV is thought to be apathogenic to humans. The N-terminal regions of the N proteins from TULV and PUUV were expressed and applied as enzyme-linked immunosorbent assay (ELISA) antigens. Colonized Japanese grass voles (Microtus montebelli) and BALB/c mice were used for experimental inoculation of the vole-borne hantaviruses TULV and PUUV. Voles and mice showed significant antibody production toward both viruses, but these antisera showed little cross-reactivity between TULV and PUUV in the immunofluorescence antibody assay and ELISA. In contrast, sera from patients with HFRS caused by PUUV exhibited high cross-reactivity against the TULV antigen, and sera from a natural rodent reservoir showed moderate cross-reactivity against the heterologous antigen, indicating that the antigenic cross-reactivity between TULV and PUUV differs in sera from rodents and humans.     

Novel reovirus isolation from an Ostrich (Struthio camelus) in Japan

An orthoreovirus was isolated from an Ostrich (Struthio camelus) and rapidly identified as orthoreovirus by the rapid determination of viral RNA sequences (RDV) system and electron microscopy. Phylogenetic analysis of the sigma A protein indicated that the isolate belonged to avian species and was closely related to chicken orthoreovirus strain 138. The results of the present study indicated that an ostrich orthoreovirus is slight different from other chicken orthoreoviruses and provided evidence of diversity among avian orthoreoviruses. To our knowledge, this is the first genetic report of an orthoreovirus isolated from an ostrich.     

Emerging technologies for the chemical control of root parasitic weeds

Parasitic plants in the Orobanchaceae family include devastating weed species, such as Striga, Orobanche, and Phelipanche, which parasitize major crops, drastically reduces crop yields and cause economic losses of over a billion US dollars worldwide. Advances in basic research on molecular and cellular processes responsible for parasitic relationships has now achieved steady progress through advances in genome analysis, biochemical analysis and structural biology. On the basis of these advances it is now possible to develop chemicals that control parasitism and reduce agricultural damage. In this review we summarized the recent development of chemicals that can control each step of parasitism from strigolactone biosynthesis in host plants to haustorium formation.     

Classification of Southeast Asian mints (Mentha spp.) based on simple sequence repeat markers

Mentha is a complex genus encompassing many species as a consequence of their interspecific hybridization and polyploidy. Southeast Asian mints have been poorly distinguished though they are widely used for culinary and medical purposes. In this study, we have analyzed Southeast Asian mints and known varieties as well as a related Lamiaceae species (Nepeta sp.) using simple sequence repeat (SSR) markers and leaf morphology. Two types of mints were clearly distinguished based on their venation pattern and leaf shape index. We developed 12 SSR markers that allowed good amplification in the Mentha and another Lamiaceae species. In the SSR-based phylogram, the Mentha lines could be delimited into groups I–VI. The Southeast Asian mints divided into groups I and II, and the phylogram separated most of the available species, with groups I and II containing the known species M. × cordifolia and M. arvensis, respectively. The separation of the two groups was supported by a population structure analysis. The SSR markers developed in this study enabled the simultaneous classification of mints and will help improve our understanding of the genetic composition of known mint varieties and as yet unclassified Southeast Asian mints.     

Specific Glu‐D1ƒ Allele Frequency of Japanese Common Wheat Compared with Distribution of Glu‐1 Alleles in Chinese Wheat

The quality of wheat (Triticum aestivum L.) grain favored in breadmaking is strongly affected by components of seed storage protein, particularly high molecular weight glutenin subunits (HMW‐GS). The HMW‐GS 2.2 controlled by the Glu‐D1ƒ allele is frequently found in Japanese cultivars and landraces. In the investigation into the factors affecting the distribution of the allele, the available data on HMW‐GS of common wheats from Japan were analyzed and compared with the data for intensity of winter habit and wheat flour hardness. We show that the main factors affecting the Glu‐D1ƒ allele frequency in Japanese wheat were the intensity of natural selection for winter habit and artificial selection for flour hardness. According to a study of the worldwide distribution of Glu‐1 alleles, the Glu‐D1ƒ allele is rare. However, Glu‐D1ƒ allele was the most common Japanese wheat seed storage protein allele. It is well known that Chinese wheat contributed to Japanese landraces, and Japanese landraces contributed to modern cultivars from Japan. However, common Japanese and Chinese wheats differ in the frequencies of Glu‐D1ƒ allele. These results may be explained either by the founder effect or by a selective bottleneck in Japanese common wheat genetic resources.