The photo is schematic diagram of influenza A virus. The genome of influenza A virus contains eight single-stranded, negative-sense RNA segments that encode at least 10 viral proteins depending on the isolate. Segments 1–6 encode basic polymerase 2 (PB2), polymerase 1 (PB1), acidic polymerase (PA), hemagglutinin (HA), nucleoprotein (NP), and neuraminidase (NA), respectively. Segment 7 encodes the matrix capsid protein 1 (M1) and the matrix capsid protein 2 (M2) through alternate splicing. Segment 8 encodes the non-structural protein (NS1) and nuclear export protein (NS2). Viral ribonucleoprotein (vRNP) complex consists of viral RNA, NP protein and polymerase complex that comprises the PB2, PB1, and PA proteins. The photo is provided by Prof. ZHAO Dongming from Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences. See pages 1419–1472 for details.
Bacterial leaf blight (BLB) and bacterial leaf streak (BLS) caused by Xanthomonas oryzae pv. oryzae (Xoo) and X. oryzae pv. oryzicola (Xoc), respectively, are two important bacterial diseases of rice. The pathogens depend on the transcription activator-like effectors (TALEs) and non-TAL effectors (non-TALEs) to trigger resistance or susceptibility of the host rice. The elucidation of novel molecular mechanism by which TALEs and non-TALEs regulate inner immunity of rice will provide some valuable clues for plant resistance breeding. These photos show the possible molecular mechanisms of Xoc TALEs and non-TALEs disturb inner immunity of rice (1), symptoms of BLB (left) and BLS (right) (2), penetration of Xoc into a stomata of a rice leaf (3), the interaction of Xoc with rice callus cells (4) and the transmission electron micrograph of Xoc cells in the intercellular spaces of the mesophyll parenchyma of a rice leaf (5). The photos were provided by Prof. Ding Xinghua from Shandong Agricultural University, China (1) and Associate Prof. Zou Lifang from Shanghai Jiao Tong University, China (2, 3, 4 and 5), respectively. See pages 1177–1210 in detail.
Cry1Ai-h-loop 2 is a modified protein of Cry1Ai constructed by exchanging loop 2 from Cry1Ah protein and shows insecticidal activity against Helicoverpa armigera. To characterize the key sites of loop 2 in Cry1Ai-h-loop 2, Ala-substituted mutants were generated. The toxicity of these mutants against H. armigera indicated that dual-mutant on Gly373 and Asn375 caused a significant decrease in toxic activity. The reduction of toxicity in the mutant of interest was correlated with decreased binding affinity with midgut brush border membrane vesicles of H. armigera. Taken together with previously reported findings, the progress indicates that the exposed loops are essential for both toxicity and interaction, which could be considered as candidate sites for directional modification of Cry proteins for transgenic crops. See pages 1064–1071 by Liu et al. for more details.
Red imported fire ant Solenopsis invicta has been found in South China since 2003. Currently, S. invicta is found in over 400 counties of 15 provinces in South China, and is a threat to ecosystem, agriculture and human health in invaded areas. We reviewed literatures on S. invicta invasion biology and its impacts on ecosystem structure and function in South China from 2003–2018. The results showed that S. invicta invasion caused arthropod community structure disruption and decreases in diversity and abundance of native ant species. Meanwhile, S. invicta can replace the role of native ants in mutualisms between ants and honeydew-producing Hemiptera, which results in loss of important food resources for native ants and natural enemies of hemipterans. Further research is required to assess the complex ecosystem-level impacts of S. invicta in its introduced regions in large space-scale and long time-scale. Cover photo is provided by Mr. Liu Yan-ming. See pages 788–796 by Wang et al. for more details.
Lycopene is one of the strongest natural antioxidants and the main carotene in ripe tomato. Light is one of the most important environmental stimuli influencing lycopene biosynthesis in tomato study applied supplemental blue and red lighting on tomato plants after anthesis to monitor their effects on lycopene synthesis. The results showed that supplemental blue/red lighting induced higher lycopene content in tomato fruits; the expression of key genes in the lycopene synthesis pathway was induced by supplemental blue/red light. The expression of light signaling components, such as red-light receptor phytochromes (PHYs), blue-light receptor cryptochromes (CRYs) and light interaction factors (PIFs, HY5) were up- or down-regulated by blue/red lighting. Thus, blue and red lights increased lycopene content in tomatoes by inducing light receptors that modulate HY5 and PIFs activation to mediate PSY1 gene expression. These results provide a sound theoretical basis for further elucidation of the light regulating mechanism of lycopene synthesis in tomatoes, and for instituting a new generation of technological innovations for the enhancement of lycopene accumulation in crop production. The photo here shows tomato fruits at different stages under different lights, provided by Prof. Liu Houcheng from College of Horticulture, South China Agricultural University. See pages 590–598 by Xie et al. for more details.
Spatially accurate soil information is critical for precision agriculture, environmental protection and climate mitigation. Unfortunately, the conventional soil maps that were produced by soil survey and traditional mapping techniques, are often inaccessible, coarse and inconsistency at scales, and with limited attribute data. Moreover, these maps require long time in preparation and can hardly be updated over time. Thus, new technologies are urgently needed to fill the gaps between the coarse soil information and the development of data-driven modern agriculture. Digital soil mapping (DSM) is a useful tool to infer the spatial and temporal variations of both qualitative and quantitative soil data in a particular area, and produces maps using related environmental variables. Since last decade, major progresses have been made in different aspects of DSM including soil data sources, predictive models, environmental covariates, and the applications. The Special Focus of “Digital mapping in agriculture and environment” brings together updates on different aspects with focus in agriculture and the environment. Cover photo is provided by Dr. TENG Hong-fen from College of Environmental and Resource Sciences, Zhejiang University, China. See pages 251–264 by Teng et al. for more details.
Somatic embryogenesis (SE) plays a vital role in genetic transformation and massive propagation of important agronomicaland economical crops. In this study, we conducted a systematic assessment of the morphological, cytochemical, and cytogenetical characteristics of six culture strains with various embryogenic/regenerative potential during SE process in cotton. Results indicated that the six cell culture strains had stable ploidy levels, and did not reveal any relationship between the cytogenetic state and their morphogenetic potential. Moreover, the six culture strains were compared via double staining with Evans blue and Acetocarmine to efficiently distinguish embryogenic and nonembryogenic cells and determine the embryogenic nature of the calli. In addition, the kind of auxins added in medium affected not only growth property, color, size of cell clumps but also ploidy level and regeneration ability. By combining analysis of morphological, cytochemical, and cytogenetical characteristics of the cell cultures, we are able to obtain and maintain homogeneous cell population with high morphogenic and regeneration ability and establish efficient somatic embryogenesis and regeneration system from short-term cell cultures in upland cotton, which highlight the application of biotechnological approaches in crop breeding, and above all, to better understand totipotency of cells in higher plants. The photo here shows high-regenerative somatic embryos under light microscope, provided by Prof. Zeng Fanchang from the State Key Laboratory of Crop Biology, Ministry of Science and Technology/College of Agronomy, Shandong Agricultural University, China. See pages 1–8 by Guo et al. in details.
It is important to identify resistance genetic sources for identification of the genes underlying resistance to the devastating pathogen, soybean cyst nematode (SCN, Heterodera glycines Ichinohe), on soybean (Glycine max (L.) Merr.), for management of this pathogen. In this study, two ethane methylsulfonate (EMS)- mutagenesis populations of soybean PI 437654 and Zhonghuang 13 were developed, from which many types of morphological phenotypes were observed. Thirteen mutants were identified to display alteration of resistance to SCN race 4 through forward genetic screening of 400 PI 437654 mutants. These identified mutants did not show any changes in the genomic sequences of the three known SCN-resistant genes and were still resistant to SCN race 3 similar to the wild-type soybean. Thus, the thirteen identified mutants carry the mutations of the new gene(s) contributing to the resistance to SCN race 4 in PI 437654 and can be potentially used as the genetic soybean sources to further identify the novel SCN-resistant gene(s). Photos showed here were the two representative morphological phenotypes (short but high yield (right on top panel) and coat color change (left on bottom panel)), SCN infection (left on top panel) and cysts on soybean roots (right on bottom panel) of EMS-mutagenized soybean mutants. The photos were provided by Liu Shiming, Zhang Liuping, Ge Fengyong and Peng Deliang, the Institute of Plant Protection, Chinese Academy of Agricultural Science. See pages 2734–2744 by Ge et al. in details.
Rusts are severe fungal diseases threatening the global wheat production. Our current knowledge on systemic acquired resistance (SAR) and pathogenesis-related (PR) protein in cereal crops of wheat and barley may provide valuable clues for improving their resistance in novel ways. These photos show the possible model of SAR-like responses in wheat and barley (1), symptom of wheat leaf rust (2), stripe rust (3), urediniospore (4) and uredium (5) of stripe rust. The presented issue summarizes specific features of the SAR-like responses and PR proteins in wheat and barley. The photos were provided by Prof. Kang Zhensheng from Northwest A&F University, China (2, 3, 4, and 5) and Associate Prof. Wang Xiaodong from Hebei Agricultural University, China (1), respectively. See pages 2467–2491 in details.
Silicon is a beneficial element for the healthy growth and development of a wide range of plant species, especially under various forms of abiotic and biotic stress. All plants take up Si, but Si content ranges from ca. 0.1 to 10% (w/w), depending largely on plant species and external Si concentration. Rice is a typical Si-accumulator. If Si2O content in rice straw at mature stage is below 10%, Si deficiency symptoms such as willow-shaped leaf blades occur. Under Si deficiency, lodging and disease susceptibility increases in rice. LSi1 (left) is a rice mutant defective in LSi1 gene (Si influx) responsible for Si uptake and transport from solution to root cells. The Si content of the mutant is only about 10% that of its wide type (WT, right). The rice mutant is extremely low in biomass, fertility and yield with severe grain discoloration and disease infection as compared to its WT. Cover photos were provided by Prof. LIANG Yong-chao from College of Environmental and Resource Sciences, Zhejiang University, China. See pages 2138–2150 by Yan et al. for more details.
Strawberry vein banding virus (SVBV) is an important virus infecting strawberry (Fragaria spp.). SVBVinfected strawberry cells contain cytoplasmic inclusions with isometric particles. In this study, SVBV open reading frame (ORF) VI was expressed ectopically in Nicotiana benthamiana. The P6 protein accumulates and forms amorphous, cytoplasmic inclusion bodies (IBs) with different sizes. P6 IBs aligns with microtubules and the endoplasmic reticulum, and trafficks along microfilaments for co-localization with the P1 protein at periphery of cells. In addition, P6 IB formation requires a nuclear localization signal (NLS) located within the C-terminal 25 amino acids of P6, and P6 protein deleted NLS region is also unable to facilitate exogenous green fluorescent protein expression. Photo showed here was the GFP accumulation in leaf discs at 3 days post infiltration after agroinfiltration with P6 and P6 mutant. See pages 2031–2041 by Pan Yuan et al. in detail.
Tree peony is a traditional ornamental plant and its seed oil is now being produced in China.? The unsaturated fatty acids content in peony seed oil is more than 90%, especially α-linolenic acid (ALA), whose content is more than 40%, whereas in other edible oils, the ALA content is commonly lower than 10%.? Paeonia ostii is the most widely used tree peony species for oil extraction, which is commercially called Fengdan and treated as a single cultivar.? Here, 50 P. ostii individuals from the same population in northern China were randomly selected for fatty acid (FA) analysis, and the statistical analysis indicated that most of the individual FA, saturated FA, unsaturated FA, and total FA levels showed significant positive correlations to each other, whereas the seed yield per plant was independent.? Therefore, we suggest that Fengdan cannot be simply treated as one uniform cultivar.? Besides, our results may also help to simplify the resource selection in breeding and accelerate the development of this industry.? See pages 1758–1767 by Wei et al. in details.? Photo showed here was the fully mature seed pod of P. ostii provided by Prof. Zhang Xiuxin from Institute of Vegetables and Flowers, Chinese Academy of Agriculture Sciences, China.
The oriental armyworm, Mythimna separata (Walker), a typical long-distance migratory insect, is a major, polyphagous pest of grain crops in China and other Asian countries. With the recent adjustment in agricultural planting structure in China and global climate change, the regularity of occurrence within regions seems to be changing as well. JIA organized this special focus on the progress of population occurrence and migration regularity, including M. separata closely related species biology, migration energy from nectar plants, trajectory analysis of migration route, and immigrant habitat environment influence and resistance identification. Several related armyworm species often co-infest fields with M. separata, introducing complications in monitoring and forecasting owing to sparse knowledge of their basic biology. Access to nectar plants during migration is a prerequisite for adult long-distance migration and reproduction, and their distribution provides clues to the armyworm migration pathway. Population data and trajectory analysis provide technical support for fine-scale forecasting of outbreaks. Habitat environment such as host plant, weed coverage and temperature affect population abundance and occurrence, and taking them into account can benefit development of new agronomic management tactics. Monitoring insecticide resistance is of immediate importance in developing effective integrated pest management strategies for this insect. Cover photo is provided by Prof. JIANG Xing-fu, Institute of Plant Protection, Chinese Academy of Agricultural Sciences.
Bovine mastitis is one of the most common diseases in dairy farm, which may cause serious harm to dairy cows, including decreasing milk yield and milk quality. How to prevent/control mastitis is one of the largest issues in the whole dairy industry internationally. To enhance the international exchange of information relating to mastitis control and milk quality, the 2017 International Bovine Mastitis Conference & the National Mastitis Council (NMC) Regional in China was successfully held in Beijing on August 25–27, 2017. The conference provided an communication platform for international counterparts, and the content was closely related to all aspects of dairy cow health, including dairy mastitis pathogens, diagnose, therapeutics, management, residue, bacterial resistance and milk safety. Here, we provide a special focus relevant to the conference proceedings. The photo here is provided by Dr. Guo Jiangpeng, Beijing General Station of Animal Husbandry, China.
Peanut is an important oil crop in China which occupies an important position in production, consumption and trade in the world. Currently, there are about 9 000 variety resources and nearly 300 main cultivars in China. The rich variety resources have laid a solid foundation for the development of peanut processing industry. However, till now, few special peanut raw materials for processing have been found due to longterm neglect on raw material characteristics and quality evaluation technology which seriously restricts the peanut processing industry development. Thus, based on the deep study on the raw material characteristics and product qualities, the relationship between raw material and product has been established by mathematical correlation analysis method. Through this processing suitability evaluation model (Y=f(X)), we could easily obtain the best variety for peanut butter processing. See pages 1003–1010 by Gong et al. in detail. The photo here is provided by Prof. WANG Qiang, Institute of Food Science and Technology, Chinese Academy of Agricultural Science.
Duck hepatitis B virus (DHBV) shares many basic characteristics with hepatitis B virus (HBV) and is an attractive model for vaccine development. In this study, DHBV DNA vaccines were designed to express envelope and capsid fusion proteins to enhance the breadth of immune response in ducks. Attenuated Salmonella typhimurium (SL7207) was used as a carrier and adjuvant to boost the magnitude of immune response. The results of this study enriched our knowledge of the antigenicity of envelope and capsid fusion proteins in ducks and demonstrated the value of using attenuated S. typhimurium (SL7207) to deliver DHBV vaccines. In the future, it is worth further exploring DNA vaccines expressing multiple antigen genes delivered by attenuated S. typhimurium, as well as the therapeutic benefits when applied to the duck model of DHBV infection. See pages 928–939 by Liu et al. in details. The photo showed here were ducklings inoculated with DHBV DHA vaccines delivered by attenuated S. typhimurium which was provided by Liu Siyang and Prof. Jia Renyong from the Avian Disease Research Center, Sichuan Agricultural University, China.