本研究旨在明确侵染广东省瓜类作物病毒种类，为瓜类作物病毒病防控提供理论依据。2018-2020年，我们针对黄瓜、南瓜、葫芦、冬瓜、丝瓜等5种广东主要瓜类作物的病毒病进行了调查与监测，并采集了357个疑似病毒侵染的瓜类作物样品。将采集的样品提取总RNA后进行小RNA深度测序与组装分析，然后根据小RNA测序分析结果设计病毒特异引物进行RT-PCR验证，得出每个瓜类样品中的病毒种类，最后对结果进行统计分析。广东瓜类作物病毒病的田间病株率一般为5%-30%，在一些发病严重地块的病株率高达60%，甚至100%。在采集的5种瓜类作物样品中总共鉴定出归属于10个病毒属的17种病毒，其中检出率最高的病毒是番木瓜环斑病毒 (PRSV)、小西葫芦虎纹花叶病毒 (ZTMV)、小西葫芦黄花叶病毒 (ZYMV)、西瓜银斑驳病毒 (WSMoV)，检出率分别是24.4%、19.0%、17.1%、14.3%。5种瓜类作物样品中病毒种类不同，且优势病毒也明显不同，黄瓜上检出率最高的病毒是甜瓜黄化斑点病毒 (MYSV)，南瓜上是PRSV，葫芦上是黄瓜绿斑驳花叶病毒 (CGMMV)，冬瓜上是WSMoV，丝瓜上是ZYMV。一个样品中检测出多种病毒的复合侵染很普遍，不同的瓜类作物样品中复合侵染的形式也不一样。进一步分析发现CGMMV、西瓜绿斑驳花叶病毒 (WGMMV)、西瓜病毒A (WVA) 在葫芦上的复合侵染率很高。我们克隆了CGMMV、WGMMV、和WVA的基因组全长序列，遗传进化分析表明WGMMV与CGMMV的亲缘关系较近。本研究首次在中国大陆发现了WGMMV。广东最流行的瓜类作物病毒是马铃薯Y病毒属病毒 (potyvirus)、正番茄斑萎病毒属病毒 (orthotospovirus)、烟草花叶病毒属病毒 (tobamovirus)，其主要传播途径分别是蚜虫、蓟马及种子带毒。本研究为瓜类作物病毒病防控策略及防控措施的制订奠定了理论基础。
玉米作为重要的粮食作物和工业原料，几个世纪以来一直被人们广泛种植。玉米致命性坏死病（maize lethal necrosis disease，MLND）是一种严重制约玉米生产的病毒，于1971年首次在秘鲁被发现，近年来在肯尼亚、卢旺达、刚果等非洲国家对玉米的生产造成了毁灭性危害，尤其给小农户造成了严重的经济损失。MLND是由番茄丛矮病毒科玉米褪绿斑驳病毒属的玉米褪绿斑驳病毒和马铃薯Y病毒科的1种或多种病毒复合侵染引起的，危害玉米引起发病植株的叶片产生褪绿、斑驳到局部坏死等症状，严重时叶片枯死甚至全株死亡，严重影响玉米产量甚至造成绝收。深入了解MLND的病原、加强MLND病原的早期检测以及有效防控对切实阻截MLND的扩散蔓延具有重要意义。本文就引起MLND的病原及其基因组结构与功能、分布与危害、传播扩散方式等进行了综述；探讨了已经建立的基于病毒单克隆抗体的酶联免疫吸附等血清学方法、基于核酸检测的PCR和逆转录-环介导等温扩增等分子生物学方法和高通量测序等技术在MLND病原早期检测中的应用；提出了利用种子检疫、推广健康种子、作物轮作、种植抗病或耐病品种等经济、环境友好型的防治措施有效控制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.
马铃薯A病毒（potato virus A，PVA）是马铃薯种植区域侵染马铃薯的常见且经济重要的病毒之一，建立快速、灵敏、高通量的PVA检测技术对防控该病毒病害具有重要意义。本研究利用感染PVA的马铃薯植物中提纯的PVA病毒粒子为免疫原，免疫BALB/c小鼠，经杂交瘤技术获得4株能分泌抗PVA单克隆抗体的杂交瘤细胞株(2D4、8E11、14A6和16H10)。Western blot分析发现，4株单抗均与PVA的假定外壳蛋白亚基有特异性免疫反应。以4株杂交瘤细胞分泌的单抗为核心相继建立了检测马铃薯叶片和马铃薯块茎等中PVA的抗原包被板子酶联免疫吸附试验（antigen-coated plate enzyme-linked immunosorbent assay，ACP-ELISA）、斑点酶联免疫吸附试验（Dot-ELISA）和组织印迹酶联免疫吸附试验（Tissue print-ELISA）三种血清学方法。特异性分析结果表明，ACP-ELISA和Dot-ELISA检测感染PVA马铃薯病叶的灵敏度达到1:327680倍和1:10240倍稀释 (w/v, g/mL)。Tissue print-ELISA是这三种血清学检测方法中最快、最简便的检测技术，更适合现场大规模样品检测。利用建立的三种血清学方法对2019年从云南省和浙江省田间采集的22个马铃薯样品进行检测，发现有3个样品感染PVA。进一步通过RT-PCR检测和PVA CP基因的克隆测序及核酸序列比对证实3种PVA血清学检测方法在马铃薯田间样品调查上的准确性。我们的研究结果表明，灵敏、特异PVA单抗的创制及血清学检测方法的建立在PVA田间检测、病害流行病学的研究、马铃薯无毒种薯的生产方面具有巨大应用潜力。
