Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most destructive diseases of wheat. Here we report a 110-Mb draft sequence of Pst isolate CY32, obtained using a ‘fosmid-to-fosmid’ strategy, to better understand its race evolution and pathogenesis. The Pst genome is highly heterozygous and contains 25,288 protein-coding genes. Compared with non-obligate fungal pathogens, Pst has a more diverse gene composition and more genes encoding secreted proteins. Re-sequencing analysis indicates significant genetic variation among six isolates collected from different continents. Approximately 35% of SNPs are in the coding sequence regions, and half of them are non-synonymous. High genetic diversity in Pst suggests that sexual reproduction has an important role in the origin of different regional races. Our results show the effectiveness of the ‘fosmid-to-fosmid’ strategy for sequencing dikaryotic genomes and the feasibility of genome analysis to understand race evolution in Pst and other obligate pathogens.

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Plant reoviruses are thought to replicate and assemble within cytoplasmic, nonmembranous structures called viroplasms. Here, we established continuous cell cultures of the white-backed planthopper (Sogatella furcifera Horváth) to investigate the mechanisms for the genesis and maturation of the viroplasm induced by Southern rice black-streaked dwarf virus (SRBSDV), a fijivirus in the family Reoviridae, during infection of its insect vector. Electron and confocal microscopy revealed that the viroplasm consisted of a granular region, where viral RNAs and nonstructural proteins P6 and P9-1 accumulated, and a filamentous region, where viral RNAs, progeny cores, viral particles, as well as nonstructural proteins P5 and P6 accumulated. Our results suggested that the filamentous viroplasm matrix was the site for the assembly of progeny virions. Because viral RNAs were produced by assembled core particles within the filamentous viroplasm matrix, we propose that these viral RNAs might be transported to the granular viroplasm matrix. P5 formed filamentous inclusions and P9-1 formed granular inclusions in the absence of viral infection, suggesting that the filamentous and granular viroplasm matrices were formed primarily by P5 and P9-1, respectively. P6 was apparently recruited in the whole viroplasm matrix by direct interaction with P9-1 and P5. Thus, the present results suggested that P5, P6, and P9-1 are collectively required for the genesis and maturation of the filamentous and granular viroplasm matrix induced by SRBSDV infection. Based on these results, we propose a new model to explain the genesis and maturation of the viroplasms induced by fijiviruses in insect vector cells.

The 2019 novel coronavirus (now named as SARS-CoV-2) caused an outbreak of SARS-like illness in the late of December 2019. At present, the origin, susceptible population, and infection sources already have been clear. 1,2 However, the transmission routes, a key step to the epidemic control, have not yet been fully ascertained. Here, we focus on the potential transmission routes that have been investigated in the SARS-CoV-2 epidemic recently. SARS-CoV-2, similar to SARS and MERS, is predominantly spread via respiratory tract with high infectivity. It is commonly recognized that droplet transmission is the main route. Spread by aerosol is suspected to be another important route of transmission but unestablished now. Epidemiological experts, as well as the WHO, consider more evidence is needed to confirm. 3 Besides, there are other routes except respiratory transmission. The previous study indicated that different human coronaviruses, such as SARS-CoV and MERS-CoV, can maintain infectious for a different time on inanimate surfaces. 4Meanwhile, it was reported that SARS-CoV-2 was also founded on the surface of the door handles, cell phones, and other items in the residential sites of confirmed cases. 5 Therefore, individuals will be probably infected if they touch the nose, mouth, or eyes after contacting the contaminated items.Currently, the existing of live SARS-CoV-2 in the stool has been confirmed because researchers at two independent state key laboratories isolated this live virus from the stool specimens of cases with novel coronavirus-infected pneumonia (NCIP). 6 This phenomenon is coincident with that of SARS-CoV as a result of ACE2 highly expressing in epithelia of the small intestine. 7,8 Furthermore, retrospecting the transmissibility of the SARS-CoV in the 2002-2003 pandemic, a shocking news reported that a major outbreak of SARS-CoV involving 321 patients occurred in a high-rise housing estate in Hong Kong. 9 Sewage is considered to play a definite role in this transmission. In summary, fecal-oral or fecal-droplet mode of transmission may be one of the several routes and cannot be ignored.Vertical transmission is another important mode of concern.A new retrospective study reviewed for nine pregnant women developing NCIP in late pregnancy at Zhongnan Hospital of Wuhan University suggests that no evidence is found for vertical transmission. 10 Moreover, no SARS-CoV-2 was detected in breast milk, indicating that the virus may not be transmitted through breastfeeding neither. 10 However, two newborns were confirmed in Wuhan women and children's healthcare center, one of whom was 30-hour-old, suggesting that the transmission via mothers to infants should not be ignored. 11Additionally, some researchers propose a hypothesis about the transmission through the ocular surface. 12 Latest investigation reveals that although SARS-CoV-2 (1 of 67 cases) was tested positive in the conjunctival sac of NCIP patients, the hypothesis is not supported. 13 Nevertheless, goggle is necessary to protect eyes for all medical wo...