[Epidemiology, clinical characteristics and treatment in 278 patients with coronavirus disease 2019 in Guangzhou]

Objective: To retrospective analyze the epidemiology, clinical characteristics, treatment and prognosis in patients with coronavirus disease 2019 (COVID-19). Methods: A total of 278 patients with COVID-19 admitted to Guangzhou Eighth People's Hospital from January 20 to February 10, 2020 were selected. The general demographic data, epidemiological data, clinical symptoms, laboratory examinations, lung CT imaging, treatment and prognosis were analyzed. Results: There were 130 male patients (46.8%) and 148 females (53.2%) with age (48.1±17.0) years and 88.8% patients between 20-69 years. Two hundred and thirty-six (84.9%) patients had comorbidities. Two hundred and eleven cases (75.9%) were common type. The in-hospital mortality was 0.4% (1/278). The majority (201, 72.3%) were imported cases mainly from Wuhan (89, 44.3%). The most common clinical manifestations were fever (70.9%) and dry cough (61.5%). In some patients, hemoglobin (10.4%), platelets (12.6%) and albumin (55.4%) were lower than the normal range. Other biochemical tests according to liver and function were normal, while lactic dehydrogenase (LDH) was elevated in 61 patients (21.9%), creatine kinase increased in 26 patients (9.4%). Prolonged activated partial thromboplastin time (APTT) was seen in 52 patients (18.7%), D-dimer higher than normal in 140 patients (50.4%), while 117 patients (42.1%) had elevated high-sensitivity C-reactive protein. Typical CT manifestations included single or multiple ground glass shadows especially in lung periphery in early disease which infiltrated and enlarged during progressive stage. Diffuse consolidation with multiple patchy density in severe/critical cases and even "white lung" presented in a few patients. Two hundred and forty-two patients (87.1%) received one or more antiviral agents, 242 (87.1%) combined with antibacterials, 191 (68.7%) with oxygen therapy. There were 198 patients (71.2%) treated with traditional Chinese medicine. Conclusions: COVID-19 could attack patients in all ages with majority of common type and low mortality rate. Clinical manifestations involve multiple organs or systems. Progression of the disease results in critical status which should be paid much attention.

Functional characterization of rice CW-domain containing zinc finger proteins involved in histone recognition

Histone recognition is important for understanding the mechanisms of histone modification, which play a pivotal role in transcriptional regulation during plant development. Here, we identified three cysteine-tryptophan (CW)-domain containing zinc finger (ZF) proteins involved in histone recognition, namely OsCW-ZF3, OsCW-ZF5 and OsCW-ZF7. Protein sequence analysis showed that they have two unknown motifs in addition to the CW domain. All three OsCW-ZFs were expressed in aerial tissues, with relatively high levels in developing panicles. Subcellular localization revealed that the OsCW-ZFs target the cell nucleus and CW domains are not necessary for their nuclear localization. In contrast to OsCW-ZF3 and OsCW-ZF5 where the CW domains bind histone H3 lysine 4 with different methylated forms (H3K4me), the CW domain from OsCW-ZF7 recognizes only trimethylated histone H3 lysine 4 (H3K4me3). Analysis of mutant suggested that three conserved tryptophan residues in the CW domain are essential for binding to H3K4me. Further study found that OsCW-ZF7 interacts with TAFII20, a transcription initiation factor TFIID 20kDa subunit. Knockout of OsCW-ZF7 caused defective development of awns. This study provides new insights into our understanding of the CW domain and lays a foundation for further investigation of its roles in rice.

OsHSD1, a hydroxysteroid dehydrogenase, is involved in cuticle formation and lipid homeostasis in rice

Cuticular wax, a hydrophobic layer on the surface of all aerial plant organs, has essential roles in plant growth and survival under various environments. Here we report a wax-deficient rice mutant oshsd1 with reduced epicuticular wax crystals and thicker cuticle membrane. Quantification of the wax components and fatty acids showed elevated levels of very-long-chain fatty acids (VLCFAs) and accumulation of soluble fatty acids in the leaves of the oshsd1 mutant. We determined the causative gene OsHSD1, a member of the short-chain dehydrogenase reductase family, through map-based cloning. It was ubiquitously expressed and responded to cold stress and exogenous treatments with NaCl or brassinosteroid analogs. Transient expression of OsHSD1-tagged green fluorescent protein revealed that OsHSD1 localized to both oil bodies and endoplasmic reticulum (ER). Dehydrogenase activity assays demonstrated that OsHSD1 was an NAD(+)/NADP(+)-dependent sterol dehydrogenase. Furthermore, OsHSD1 mutation resulted in faster protein degradation, but had no effect on the dehydrogenase activity. Together, our data indicated that OsHSD1 plays a specialized role in cuticle formation and lipid homeostasis, probably by mediating sterol signaling. This work provides new insights into oil-body associated proteins involved in wax and lipid metabolism.

A rice virescent-yellow leaf mutant reveals new insights into the role and assembly of plastid caseinolytic protease in higher plants

The plastidic caseinolytic protease (Clp) of higher plants is an evolutionarily conserved protein degradation apparatus composed of a proteolytic core complex (the P and R rings) and a set of accessory proteins (ClpT, ClpC, and ClpS). The role and molecular composition of Clps in higher plants has just begun to be unraveled, mostly from studies with the model dicotyledonous plant Arabidopsis (Arabidopsis thaliana). In this work, we isolated a virescent yellow leaf (vyl) mutant in rice (Oryza sativa), which produces chlorotic leaves throughout the entire growth period. The young chlorotic leaves turn green in later developmental stages, accompanied by alterations in chlorophyll accumulation, chloroplast ultrastructure, and the expression of chloroplast development- and photosynthesis-related genes. Positional cloning revealed that the VYL gene encodes a protein homologous to the Arabidopsis ClpP6 subunit and that it is targeted to the chloroplast. VYL expression is constitutive in most tissues examined but most abundant in leaf sections containing chloroplasts in early stages of development. The mutation in vyl causes premature termination of the predicted gene product and loss of the conserved catalytic triad (serine-histidine-aspartate) and the polypeptide-binding site of VYL. Using a tandem affinity purification approach and mass spectrometry analysis, we identified OsClpP4 as a VYL-associated protein in vivo. In addition, yeast two-hybrid assays demonstrated that VYL directly interacts with OsClpP3 and OsClpP4. Furthermore, we found that OsClpP3 directly interacts with OsClpT, that OsClpP4 directly interacts with OsClpP5 and OsClpT, and that both OsClpP4 and OsClpT can homodimerize. Together, our data provide new insights into the function, assembly, and regulation of Clps in higher plants.

Disruption of a rice pentatricopeptide repeat protein causes a seedling-specific albino phenotype and its utilization to enhance seed purity in hybrid rice production

The pentatricopeptide repeat (PPR) gene family represents one of the largest gene families in higher plants. Accumulating data suggest that PPR proteins play a central and broad role in modulating the expression of organellar genes in plants. Here we report a rice (Oryza sativa) mutant named young seedling albino (ysa) derived from the rice thermo/photoperiod-sensitive genic male-sterile line Pei'ai64S, which is a leading male-sterile line for commercial two-line hybrid rice production. The ysa mutant develops albino leaves before the three-leaf stage, but the mutant gradually turns green and recovers to normal green at the six-leaf stage. Further investigation showed that the change in leaf color in ysa mutant is associated with changes in chlorophyll content and chloroplast development. Map-based cloning revealed that YSA encodes a PPR protein with 16 tandem PPR motifs. YSA is highly expressed in young leaves and stems, and its expression level is regulated by light. We showed that the ysa mutation has no apparent negative effects on several important agronomic traits, such as fertility, stigma extrusion rate, selfed seed-setting rate, hybrid seed-setting rate, and yield heterosis under normal growth conditions. We further demonstrated that ysa can be used as an early marker for efficient identification and elimination of false hybrids in commercial hybrid rice production, resulting in yield increases by up to approximately 537 kg ha(-1).

Fine mapping of qPAA8, a gene controlling panicle apical development in rice

In rice, one detrimental factor influencing single panicle yield is the frequent occurrence of panicle apical abortion (PAA) under unfavorable climatic conditions. Until now, no detailed genetic information has been available to avoid PAA in rice breeding. Here, we show that the occurrence of PAA is associated with the accumulation of excess hydrogen peroxide. Quantitative trait loci (QTLs) mapping for PAA in an F(2) population derived from the cross of L-05261 (PAA line) × IRAT129 (non-PAA variety) identified seven QTLs over a logarithm of the odd (LOD) threshold of 2.5, explaining approximately 50.1% of phenotypic variance for PAA in total. Five of the QTLs with an increased effect from L-05261, were designated as qPAA3-1, qPAA3-2, qPAA4, qPAA5 and qPAA8, and accounted for 6.8%, 5.9%, 4.2%, 13.0% and 12.2% of phenotypic variance, respectively. We found that the PAA in the early heading plants was mainly controlled by qPAA8. Subsequently, using the sub-populations specific for qPAA8 based on marker-assisted selection, we further narrowed qPAA8 to a 37.6-kb interval delimited by markers RM22475 and 8-In112. These results are beneficial for PAA gene clone.

A novel simple extracellular leucine-rich repeat (eLRR) domain protein from rice (OsLRR1) enters the endosomal pathway and interacts with the hypersensitive-induced reaction protein 1 (OsHIR1)

Receptor-like protein kinases (RLKs) containing an extracellular leucine-rich repeat (eLRR) domain, a transmembrane domain and a cytoplasmic kinase domain play important roles in plant disease resistance. Simple eLRR domain proteins structurally resembling the extracellular portion of the RLKs may also participate in signalling transduction and plant defence response. Yet the molecular mechanisms and subcellular localization in regulating plant disease resistance of these simple eLRR domain proteins are still largely unclear. We provided the first experimental evidence to demonstrate the subcellular localization and trafficking of a novel simple eLRR domain protein (OsLRR1) in the endosomal pathway, using both confocal and electron microscopy. Yeast two-hybrid and in vitro pull-down assays show that OsLRR1 interacts with the rice hypersensitive-induced response protein 1 (OsHIR1) which is localized on plasma membrane. The interaction between LRR1 and HIR1 homologs was shown to be highly conserved among different plant species, suggesting a close functional relationship between the two proteins. The function of OsLRR1 in plant defence response was examined by gain-of-function tests using transgenic Arabidopsis thaliana. The protective effects of OsLRR1 against bacterial pathogen infection were shown by the alleviating of disease symptoms, lowering of pathogen titres and higher expression of defence marker genes.

Evaluation of monoterpenes for the control of Tribolium castaneum (Herbst) and Sitophilus zeamaise Motschulsky

The effects of the monoterpenes of 3-carene, 1,8-cineole, beta-pinene, terpinene and terpinolene on the repellent, contact toxicity of Tribolium castaneum adults and sustaining fumigant toxicity of Sitophilus zeamaise adults were examined. Monoterpene of 1,8-cineole in 20 microL mL(-1) and beta-pinene in 20 microL mL(-1) exhibited the highest percentage repellency, whereas 3-carene in concentration of 4 microL mL(-1) exhibited the significantly lower percentage repellency. Topical application and fumigant assays were used across a range of concentrations to develop dosage-mortality regressions. Among the monoterpenes tested, the most contact toxic compound was beta-pinene (with LC(50) values ranging between 31.44 and 62.07 microg mg(-1)), whereas 3-carene was the least (with LC(50) values ranging between 66.58 and 93.68 microg mg(-1)). All five monoterpenes were fumigant toxic to S. zeamaise adults, and the fumigant effect varied, along with the exposure time and the dosage. Terpinene and terpinolene were consistently the most fumigant toxic compounds on S. zeamaise, and the trend of high-to-low toxicity based on LC(50) values was not changed when treated for 24, 48, 72 and 96 h; the lethal concentration causing 50% mortality (LC(50)) with terpinolene was reduced by 71.5% after a 96 h treatment time, compared to beta-pinene and 3-carene, where only 35.0 and 31.4% reduction were observed, respectively. The data presented here indicated that the monoterpenes had repellent or toxic effects and could be screened for the control of storage pests.

Quantitative trait loci mapping of resistance to Laodelphax striatellus (Homoptera: Delphacidae) in rice using recombinant inbred lines

Laodelphax striatellus Fallén (Homoptera: Delphacidae), is a serious pest in rice, Oryza sativa L., production. A mapping population consisting of 81 recombinant inbred lines (RILs), derived from a cross between japonica' Kinmaze' and indica' DV85' rice, was used to detect quantitative trait loci (QTLs) for the resistance to L. striatellus. Seedbox screening test (SST), antixenosis test, and antibiosis test were used to evaluate the resistance response of the two parents and 81 RILs to L. striatellus at the seedling stage, and composite interval mapping was used for QTL analysis. When the resistance was measured by SST method, two QTLs conferring resistance to L. striatellus were mapped on chromosome 11, namely, Qsbph11a and Qsbph11b, with log of odds scores 2.51 and 4.38, respectively. The two QTLs explained 16.62 and 27.78% of the phenotypic variance in this population, respectively. In total, three QTLs controlling antixenosis against L. striatellus were detected on chromosomes 3, 4, and 11, respectively, accounting for 37.5% of the total phenotypic variance. Two QTLs expressing antibiosis to L. striatellus were mapped on chromosomes 3 and 11, respectively, explaining 25.9% of the total phenotypic variance. The identified QTL located between markers XNpb202 and C1172 on chromosome 11 was detected repeatedly by three different screening methods; therefore, it may be important to confer the resistance to L. striatellus. Once confirmed in other mapping populations, these QTLs should be useful in breeding for resistance to L. striatellus by marker-assisted selection of different resistance genes in rice varieties.

QTL analysis for rice grain length and fine mapping of an identified QTL with stable and major effects

Grain length in rice plays an important role in determining rice appearance, milling, cooking and eating quality. In this study, the genetic basis of grain length was dissected into six main-effect quantitative trait loci (QTLs) and twelve pairs of epistatic QTLs. The stability of these QTLs was evaluated in four environments using an F7 recombinant inbred line (RIL) population derived from the cross between a Japonica variety, Asominori, and an Indica variety, IR24. Moreover, chromosome segment substitution lines (CSSLs) harboring each of the six main-effect QTLs were used to evaluate gene action of QTLs across eight environments. A major QTL denoted as qGL-3a, was found to express stably not only in the isogenic background of Asominori but also in the recombinant background of Asominori and IR24 under multiple environments. The IR24 allele at qGL-3a has a positive effect on grain length. Based on the test of advanced backcross progenies, qGL-3a was dissected as a single Mendelian factor, i.e., long rice grain was controlled by a recessive gene gl-3. High-resolution genetic and physical maps were further constructed for fine mapping gl-3 by using 11 simple sequence repeat (SSR) markers designed using sequence information from seven BAC/PAC clones and a BC4F2 population consisting of 2,068 individuals. Consequently, the gl-3 gene was narrowed down to a candidate genomic region of 87.5 kb long defined by SSR markers RMw357 and RMw353 on chromosome 3, which provides a basis for map-based cloning of this gene and for marker-aided QTL pyramiding in rice quality breeding.

[Genetic studies of blast resistance of indica variety Zhefu 802]

One indica variety, Zhefu 802, was studied for its inheritance of blast resistance by inoculation of two strains Ken54-04 and 95-t2. The B1F1 and F2 populations from cross of Zhefu 802(R) x Lijiangxintuanheigu (S) and related parents were inoculated by spray inoculation method with the two above mentioned strains to determine R:S ratio of segregating populations of this cross. The results indicated that Zhefu 802 has two dominant resistance genes to strain Ken 54-04. One of the two genes showed resistant reaction and the other is susceptible to strain 95-t2. The allelism test indicated that one gene in Zhefu 802, which showed resistant reaction to strain 95-t2, is allelic to Pi-i gene locus and non-allelic to loci of Pi-a, Pi-sh, Pi-k, Pi-z, Pi-ta, Pi-b, Pi-t. The other gene in this variety was also estimated to be different from all of the known genes. So it may be an unknown gene. But this point needs to be confirmed further.