The growth and development of skeletal muscle also determine the meat production of yak, ultimately affecting the economic benefits.  Hence, improving growth performance is a top priority in the yak industry.  Skeletal muscle development is a complex process involving the regulation of several genes, including microRNAs (miRNAs).  However, the transcription of miRNAs in yak skeletal muscle during prenatal to postnatal stages is unknown.  We used small RNA sequencing (small RNA-Seq) to determine the global miRNAs of longissimus dorsi muscle from yak (the samples were collected from three fetuses and three adults).  Totally 264 differently expressed miRNAs (|log₂(fold change)|>1 and P-value≤0.05) were detected between the two groups.  Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that differently expressed miRNAs-targeted genes participated in pathways associated with muscle development, such as MAPK, PI3K-Akt, and Hippo signaling pathways, etc.  MiR-652, which was up-regulated in the fetal group, was transfected into C2C12 myoblasts to examine its role.  miR-652 promoted (P≤0.05) proliferation and differentiation, but inhibited (P≤0.001) apoptosis at early period.  Furthermore, miR-652 reduced (P≤0.001) the proportion of C2C12 myoblasts in the G1 phase while increasing (P≤0.01) the proportion of cells in the S and G2 phases.  Dual-luciferase reporter assays indicated that ISL1 served as a target of miR-652.  In general, these findings expand our understanding of yak skeletal muscle miRNAs, and suggested that miR-652 probably regulated myogenesis by regulating ISL1.

Viral diseases are among the most critical damaging factors that impose a global threat to the cucurbit industry.  China is the world’s leading country for the production and consumption of cucurbits.  Guangdong, a province in southern China dominated by the tropical and subtropical climate, favors the survival of different plant viruses and their vectors.  Five main cucurbit crops showing various disease symptoms were surveyed and collected to identify viruses infecting cucurbits in Guangdong during 2018–2020.  In the field, the incidence ranged from 5–30%, or even 60–100% in the case of severely infected cucurbits.  A total of 357 symptomatic samples were collected and subsequently screened for cucurbit viruses by small RNA deep sequencing and assembly (sRSA).  Seventeen virus species belonging to 10 genera were identified in the five main cucurbit crops.  The most common viruses were papaya ringspot virus (PRSV; Potyvirus), zucchini tigre mosaic virus (ZTMV; Potyvirus), zucchini yellow mosaic virus (ZYMV; Potyvirus), and watermelon silver mottle virus (WSMoV; Orthotospovirus), with infection rates of 24.4, 19.0, 17.1, and 14.3%, respectively.  Notably, the most prevalent viruses were melon yellow spot orthotospovirus (MYSV) in cucumber, PRSV in squash, cucumber green mottle mosaic virus (CGMMV; Tobamovirus) in bottle gourd, WSMoV in white gourd, and ZYMV in luffa.  Mixed infections were prevalent, and the types of mixed infections varied substantially in different cucurbit crops.  Moreover, the full-length nucleotide sequences of watermelon green mottle mosaic virus (WGMMV), CGMMV, and watermelon virus A (WVA; Wamavirus) identified in bottle gourd were cloned and analyzed.  This study is the first reporting WGMMV infecting bottle gourd in China mainland.  In summary, the results demonstrate that in Guangdong, the most prevalent viruses belong to potyviruses, orthotospoviruses, and tobamoviruses groups.  The findings will facilitate agricultural researchers and farmers to plan and implement effective disease control strategies aiming at timely detection and management of cucurbit-infecting viral pathogens.

Maize (Zea mays), as a staple food and an important industrial raw material, has been widely cultivated for centuries especially by smallholder farmers. Maize lethal necrosis disease (MLND) is a serious disease infecting maize, which caused devastating damage in the African region recently. MLND is induced by co-infection of maize chlorotic mottle virus and one of several cereal-infecting viruses in the Potyviridae family, with the symptoms ranging from chlorotic mottle to plant death at different infection stages. Integrated pest management for MLND needs strengthening detection, focusing on prevention and effective control. Early detection system of MLND has been successfully established by serological methods, nucleic acid-based methods, next-generation sequencing et al. The practices, such as using certified seeds, sanitary measures, crop rotation, tolerant or resistant varieties etc., have been considered as the effective, economical and eco-friendly way to prevent and control MLND.

Crop production and livelihoods of smallholder farmers are often threatened by crop insect pests and diseases worsening the insecurity of food.  Globalization has rapidly increased the introduction and threats of invasive pests.  Climate change results in a changed suitability of landscapes to pests, further increasing the threat and uncertainty of their impact.  Providing innovative technologies for sustainable pest management to smallholder farmers is urgently needed for food security and eliminating poverty.  

The most devasting diseases and insect pests to major crops such as rice, wheat, maize and potato contribute to the largest yield losses in the world.  Under the support of the Food and Agriculture Organization (FAO), Chinese plant protection scientists, in collaboration with experts of different regions, carried out a specific project to prioritize top crop diseases and insect pests that affect smallholder farmers’ production globally.  After evaluation by relevant global experts, top 10 crop diseases and insect pests have been assessed as six crop diseases and four insect pests, namely cereal blast disease, potato late blight, wheat rust disease, Fusarium head blight, maize lethal necrosis disease, banana Fusarium wilt (TR4), rice planthopper, wheat aphid, whitefly, and oriental fruit fly.  Integrated pest management (IPM) guidelines for the identified diseases and insect pests have been formulated, and will be shared through a global knowledge platform.  To share the knowledge with more researchers, the IPM of four major diseases including cereal blast disease, Fusarium head blight, maize lethal necrosis disease and potato late blight were further reviewed and presented in this special focus.  

The first case study is cereal blast disease caused by fungal pathogen Magnaporthe oryzae (Zhang et al. 2022), which is a destructive filamentous fungus that infects many plants including most economically important food crops, rice, wheat, pearl millet and finger millet (Chakraborty et al. 2021; Hossain 2022).  Different pathovars of M. oryzae often infect different host plants with high specificity.  The rice blast disease caused by the Oryza pathotype (MoO) of M. oryzae can result in 10–30% yield loss in rice-growing countries, posing a major threat to rice production, especially in the small-scale farming system (Mutiga et al. 2021).  The Triticum pathotype (MoT), causing wheat blast disease, was first found in Brazil in 1985.  It has now spread to other countries in South America, and also Asian countries such as Bangladesh (Islam et al. 2016).  Wheat blast disease can result in an average yield loss of 51% in the affected field, becoming one of the most fearsome wheat diseases (Islam et al. 2020).  Because of low fungicide efficacy against the blast diseases and lack of availability of resistant varieties, control of rice and wheat blast diseases is difficult.  A combination of management strategies including early detection and utilization of biopesticides was proposed (Zhang et al. 2022), providing some helpful insights for fighting these devasting cereal blast diseases.  

The second case study is the fusarium head blight (FHB) caused by FHB pathogens, which are mainly the Fusarium graminearum species complex (Chen et al. 2022).  FHB is one of the most important diseases that affects wheat production worldwide (Summerell 2019).  In general, a severe FHB epidemic occurred every four or five years in the most of wheat production regions.  Since 2010, the outbreaks of FHB have become more frequent in China.  Besides causing yield loss in affected crop field, FHB also produces mycotoxin contaminating the harvested grains, which are harmful to humans and livestock (Stepien and Chelkowski 2010).  According to the economic importance and toxicity of FHB, F. graminearum is considered as one of the world’s top 10 fungal phytopathogens (Dean et al. 2012).  Breeding resistant cultivars has been considered as the most effective strategy against FHB (Wegulo et al. 2015).  Rational use of chemical pesticides, and potential biopesticides, and good agronomic practices are also important components in the IPM programme for FHB.   

The third case study is the maize lethal necrosis disease (MLND), which is a relatively new viral disease on maize (Zhan et al. 2022).  The MLND is caused by the co-infection of maize chlorotic mottle virus (MCMV) and one of cereal-infecting potyviruses, and the symptoms on maize include leaf necrosis, premature aging, small cobs and even plant death (Redinbaugh and Stewart 2018).  First reported in Americas in 1970s and 1980s, the MLND has now spread to more than fifteen countries in the Americas, Asia and Africa (Wangai et al. 2012).  The outbreaks of MLND in several Asian and African countries caused devastating damage to maize production with large impacts on smallholder farmers (Mahuku et al. 2015).  Integrated management of MLND involves effective detection methods such as serological methods, nucleic acid-based methods, and next-generation sequencing.  The practices, such as using certified seeds, sanitary measures, crop rotation, and tolerant or resistant varieties, have been considered as the effective, economical and eco-friendly approach to prevent and control MLND.

The fourth case study is the potato late blight (PLB) disease (Dong and Zhou 2022).  PLB, caused by the fungal-like oomycete pathogen Phytophthora infestans, is a devastating disease worldwide that led to the infamous Irish potato famine of the 1840s.  Besides the primary host potato, P. infestans also infects other solanaceous plants such as tomato, petunia and nightshade.  These infected plants can become pathogen inoculum to potato (Kirk et al. 2003).  Originated from Central Mexico or South America, this disease has spread to almost all major potato-producing countries including the United States, Canada, China, and India (Fry et al. 2015).  Up to now, PLB remains the most important biotic constraint to potato production worldwide and presents a major threat to global food security, especially for under-developed areas that heavily depend on potato as the major source of food (Cucak et al. 2021).  Careful agronomic practices, such as using pathogen-free seed, serve as the good start for the successful management of PLB.  Chemical fungicides remain the most effective means to control the pathogen.  However, these chemical fungicides should be used more scientifically to avoid over-dosage and high cost.  Some potential environmental-friendly biopesticides have been identified (He et al. 2021).  Additionally, new technologies which may bring some innovative solutions to control PLB are also proposed.  

The desert locust (Schistocerca gregaria), the most destructive migratory insect pest in the world, was also selected in the special focus (Li et al. 2022).  Desert locust is an omnivorous insect, feeding on more than 300 various host plants including many cultivated crops and wild plants (Li et al. 2021).  Formation of desert locust swarms and the outbreak of desert locusts are induced by a combination of environmental stimuli.  During its outbreak and migration, desert locust can cause serious damage to cultivated crops, such as cotton, alfalfa, beans, wheat, barley, corn, flax, tobacco, tomato, potato, and melons, posing a major threat to food security and rural livelihoods.  Since the 20th century, there have been 15 outbreaks of the desert locust, affecting about 30 million km² of Africa and Asia continents and the lives of 850 million people in 65 countries (Ceccato et al. 2007; Divi 2020).  Studies demonstrate the correlation between poor early childhood health and the desert locust swarm outbreak (Kien and Nguyen 2022).  To date, much research has been conducted regarding the ecology and management of desert locusts.  Climate change resulted in more favorable conditions, which is a major factor contributing to the recent outbreak of desert locust in 2020 (Peng et al. 2020).  A critical component of preventive management programs is being able to locate significant infestations rapidly.  The FAO provides forecasts, early warning and alerts on the timing, scale and location of invasions and breeding through its global Desert Locust Information Service (DLIS).  Integrated management of desert locust, mainly including physical control methods, chemical insecticides, microbial pesticides, and biocontrol methods, are summarized in ths review (Li et al. 2022).  

Occurrence of plant diseases and insect pests have been worsened by climate change in many aspects.  Prevention of yield loss of major crops is critical for achieving global food security.  Not only the IPM strategies should be adopted, but also the inter-government cooperation should be encouraged to share knowledge, information and innovative solutions, and to jointly tackle with challenges caused by transboundary pests.  All these efforts are needed to achieve the United Nations Sustainable Development Goals (SDGs) of 2030 Agenda for Sustainable Development.

Tomato (Solanum lycopersicum) plants exhibiting severe leaf distortion, mottle and systemic crinkling symptoms were identified in Hainan province in China in 2016.  To survey and control the disease, it is necessary to identify and characterize the pathogen causing the disease.  Dot enzyme-linked immunosorbent assay showed that the crude saps of the infected tomato samples reacted positively with the monoclonal antibody against Tobacco mosaic virus which indicated that one or more tobamoviruses are likely associated with the disease.  RT-PCR and DNA sequence analysis results further elucidated that Tomato mottle mosaic virus (ToMMV) in Tobamovirus was the pathogen causing the mottle disease in tomato.  We amplified and sequenced the full-length sequence of the genome which showed the highest nucleotide identity with ToMMV YYMLJ and ToMMV TiLhaLJ isolates.  The putative virus isolate was named ToMMV Hainan.  Biological indexing studies showed that ToMMV Hainan can infect Nicotiana benthamiana, Capsicum annuum and Solanum lycopersicum showing serious symptoms.  This was the first identification and characterization of ToMMV infecting tomato in Hainan of China.

Being a major class of single-stranded DNA viruses, geminiviruses are mostly studied due to their catastrophic infectious effect on crops.  These DNA viruses are characteristic for their ability in quickly multiplying viral genetic materials without integrating into the genome of plants, which makes them ideal for developing viral vectors for plants bioengineering.  Geminivirus-derived vectors can be classified into expression vectors and virus-induced gene silencing (VIGS) vectors.  Details of the design, construction, application and improvements of these geminivirus vectors are summarized and discussed.  

Citrus yellow vein clearing virus (CYVCV) is considered as the causal agent of Citrus yellow vein clearing disease and belongs to the genus Mandarivirus in the family Alphaflexiviridae.  Capsid protein (CP) of CYVCV Chongqing isolate (CYVCV-CQ) was produced using a prokaryotic expression system and used as the immunogen for monoclonal antibody (MAb) production.  Four highly specific and sensitive murine MAbs and one polyclonal antibody were prepared in this study.  Titers of the four MAbs in ascites fluids ranged from 10^–6 to 10^–7 as determined by indirect enzyme-linked immunosorbent assay (ELISA).  Three serological assays, including dot enzyme-linked immunosorbent assay (dot-ELISA), tissue blot-ELISA, and double-antibody sandwich (DAS)-ELISA, were developed for quick and reliable detections of CYVCV in citrus samples.  The developed dot-ELISA and DAS-ELISA methods could detect CYVCV in the infected citrus leaf crude extracts diluted at 1:2 560 and 1:10 240 (w/v, g mL^–1), respectively.  The detection result of 125 citrus leaf samples collected from citrus groves in Yunnan Province and Chongqing Municipality of China showed that approximately 36% samples were positive for CYVCV.  This virus was, however, not detected in any sample collected from Zhejiang or Jiangxi Province, China.

Aphid-borne Zucchini yellow mosaic virus (ZYMV) is one of the most economically important viruses of cucurbitaceous plants.  To survey and control this virus, it is necessary to develop an efficient detection technique.  Using purified ZYMV virion and the conventional hybridoma technology, three hybridoma cell lines (16A11, 5A7 and 3B8) secreting monoclonal antibodies (MAbs) against ZYMV Zhejiang isolate were obtained.  The working titers of the ascitic fluids secreted by the three hybridoma cell lines were up to 10^–7 by indirect enzyme-linked immunosorbent assay (ELISA).  All MAbs were isotyped as IgG1, kappa light chain.  Western blot analysis indicated that the MAb 3B8 could specifically react with the coat protein of ZYMV while MAbs 5A7 and 16A11 reacted strongly with a protein of approximately 51 kDa from the ZYMV-infected leaf tissues.  According to this molecular weight, we consider this reactive protein is likely to be the HC-Pro protein.  Using these three MAbs, we have now developed five detection assays, i.e., antigen-coated-plate ELISA (ACP-ELISA), dot-ELISA, tissue blot-ELISA, double-antibody sandwich ELISA (DAS-ELISA), and immunocapture-RT-PCR (IC-RT-PCR), for the sensitive, specific, and easy detection of ZYMV.  The sensitivity test revealed that ZYMV could be readily detected respectively by ACP-ELISA, dot-ELISA, DAS-ELISA and IC-RT-PCR in 1:163 840, 1:2 560, 1:327 680 and 1:1 310 720 (w/v, g mL^–1) diluted crude extracts from the ZYMV-infected plants.  We demonstrated in this study that the dot-ELISA could also be used to detect ZYMV in individual viruliferous aphids.  A total of 275 cucurbitaceous plant samples collected from the Zhejiang, Jiangsu, Shandong and Hainan provinces, China, were screened for the presence of ZYMV with the described assays.  Our results showed that 163 of the 275 samples (59%) were infected with ZYMV.  This finding indicates that ZYMV is now widely present in cucurbitaceous crops in China.  RT-PCR followed by DNA sequencing and sequence analyses confirmed the accuracy of the five assays.  We consider that these detection assays can significantly benefit the control of ZYMV in China.  

Bacillus thuringiensis is one of the most widely used bioinsecticides, and cry gene is the major insecticidal gene. Because Cry1Ac protein shows strong toxicity against many lepidopteran species, it has been applied widely in spraying products and transgenic Bt-crops. The preparation of Cry protoxin is the first step in the very important processes of understanding the insecticidal mechanism, resistance screening, and biosafety assessments. The media for crystal production and the method for Cry protoxin preparation were varied, however, it was not clear which was better for preparing a larger amount of Cry protoxin. In this paper, three media for crystal production and the method for Cry1Ac protoxin preparation from HD73 strain were compared to find an efficacious way to prepare a large number of Cry1Ac protoxin. The results showed that the 1/2 LB (Luria-Bertani) medium was the ideal medium for crystal production, because the total yield of Cry1Ac protoxin in 300 mL 1/2 LB medium was (112.38±5.64) mg, the highest one among three media; the repeated crystal solubilization method was better for the preparation of the Cry protoxin comparing with the continuous crystal solubilization method. It will be a reference for other Cry protoxin preparation, especially for larger number.

In order to understand the yield performance and nitrogen (N) response of hybrid rice under different ecological conditions in southern China, field experiments were conducted in Huaiji County of Guangdong Province, Binyang of Guangxi Zhuang Autonomous Region and Changsha City of Hunan Province, southern China in 2011 and 2012. Two hybrid (Liangyoupeijiu and Y-liangyou 1) and two inbred rice cultivars (Yuxiangyouzhan and Huanghuazhan) were grown under three N treatments (N1, 225 kg ha–1; N2, 112.5–176 kg ha–1; N3, 0 kg ha–1) in each location. Results showed that grain yield was higher in Changsha than in Huaiji and Binyang for both hybrid and inbred cultivars. The higher grain yield in Changsha was attributed to larger panicle size (spikelets per panicle) and higher biomass production. Consistently higher grain yield in hybrid than in inbred cultivars was observed in Changsha but not in Huaiji and Binyang. Higher grain weight and higher biomass production were responsible for the higher grain yield in hybrid than in inbred cultivars in Changsha. The better crop performance of rice (especially hybrid cultivars) in Changsha was associated with its temperature conditions and indigenous soil N. N2 had higher internal N use efficiency, recovery efficiency of applied N, agronomic N use efficiency, and partial factor productivity of applied N than N1 for both hybrid and inbred cultivars, while the difference in grain yield between N1 and N2 was relatively small. Our study suggests that whether hybrid rice can outyield inbred rice to some extent depends on the ecological conditions, and N use efficiency can be increased by using improved nitrogen management such as site-specific N management in both hybrid and inbred rice production.

Rice ragged stunt virus (RRSV) is a serious rice disease in Asia, causing serious yield losses on rice. The capsid protein (CP) gene of the major outer capsid protein of RRSV was expressed in Escherichia coli BL21 (DE3) using the pMAL-C2X expression vector. The recombinant protein was used as the immunogen to immunize BALB/c mice. A hybridoma cell line 8A12 secreting monoclonal antibody (MAb) against RRSV was obtained by fusing mouse myeloma cells (Sp 2/0) with spleen cells from the immunized BALB/c mice. Western blot analysis showed that the MAb 8A12 can specifically react with RRSV CP. Using the MAb, an antigen-coated-plate enzyme-linked immunosorbent assay (ACP-ELISA), a dot enzyme-linked immunosorbent assay (dot-ELISA), and immunocapture-RT-PCR (IC-RT-PCR) assay were developed to detect RRSV. The established ACP-ELISA, dot-blot ELISA and IC-RT-PCR methods could detect RRSV in infected rice tissue crude extracts with dilutions of 1:40 960, 1:1280 and 1:655360 (w/v, g mL-1), respectively. The ACP-ELISA and dot-blot ELISA methods could detect RRSV in infected insect vector crude extracts with dilutions of 1:12800 and 1:1600 (an individual planthopper μL-1), respectively. The field survey revealed that Rice ragged stunt disease occurs on rice in Hainan, Yunnan, Guangxi, Sichuan, Guizhou, Fujian, Hunan, Jiangxi and Zhejiang in China.

Horizontal gene transfer (HGT) plays key roles in the evolution of pathogenetic bacteria, especially in pathogenetic associated genes. In this study, the evolutionary dynamics of Xanthomonas at species level were determined by the comparative analysis of the complete genomes of 15 Xanthomonas strains. A concatenated multiprotein phyletic pattern and a dataset with Xanthomonas clusters of orthologous genes were constructed. Mathematical extrapolation estimates that the core genome will reach a minimum of about 1 547 genes while the pan-genome will increase up to 22 624 genes when sequencing 1 000 genomes. The HGT extent in this genus was assessed by using a Markov-based probabilistic method. The reconstructed gene gain/loss history, which contained several features consistent with biological observations, showed that nearly 60% of the Xanthomonas genes were acquired by HGT. A large fraction of variability was in the clade ancestor nodes and “leaves of the tree”. Coexpression analysis suggested that the pathogenic and metabolic variation between Xanthomonas oryzae pv. oryzicola and Xanthomonas oryzae pv. oryzae might due to recently-transferred genes. Our results strongly supported that the gene gain/loss may play an important role in divergence and pathogenicity variation of Xanthomonas species.

Tomato yellow leaf curl virus (TYLCV) is a species of the family Geminiviridae, causing serious yield losses in tomato production. The coat protein (CP) gene of TYLCV isolate SH2 was expressed in Escherichia coli BL21 (DE3) using pET- 32a as the expression vector. The recombinant protein was purified through Ni+-NTA affinity column and used to immunize BALB/c mice. Three hybridoma cell lines (2B2, 2E3 and 3E10) secreting monoclonal antibodies (MAbs) against TYLCV CP were obtained by fusing mouse myeloma cells (Sp 2/0) with spleen cells from the immunized BALB/c mouse. The titers of ascitic fluids of three MAbs ranged from 10-6 to 10-7 in indirect-ELISA. Isotypes and subclasses of all the MAbs belonged to IgG1, κ light chain. Triple antibody sandwich enzyme-linked immunosorbent assay (TAS-ELISA) showed that the MAb 3E10 could react with five begomoviruses infecting tomato, while the other two (2B2 and 2E3) mainly reacted with TYLCV. TAS-ELISA was set up using the MAb 3E10, and the established method could successfully detect virus in plant sap at 1:2 560 (w/v, g mL-1). Detection of field samples showed that begomoviruses were common in tomato crops in Zhejiang Province, China.