While viroids were initially identified by their association with specific diseases, we now know that not all viroid-infected plants exhibit obvious signs of disease. In some cases, a viroid may be latent in one host yet cause severe symptoms in another host. Most viroid causes plantdiseases and about 33 viroids have been identified. The human disease caused by a viroid is hepatitis D. After reading this article you will be able to write a short note on Viroids and understand the viroids structure, characteristics, and types of viroids. The diseases that are caused by viroidsinplants are citrus exocortis, cucumber pale fruit, chrysanthemum stunt, etc.The common symptoms of viroiddiseasesinplants include stunting of growth, deformation of leaves and fruit, stem necrosis and finally, death of the plant. Viroiddiseasesinplants are caused by 29 viroids in only two families: Pospiviroidae and Avsunviroidae. Better-known viroidplantdiseases include The diagnostic methods for plant virus and viroiddiseases are being continuously improved. Virus diagnosis by bioassay on indicator hosts to prove the pathogenicity is well established but tedious and requires long time for symptom expression. This paper provides a comprehensive overview of viroid classification, structural properties, and their implications in various plantdiseases, emphasizing the need for further research to understand their biology and impact on agriculture. Viroids are the smallest autonomously replicating subviral pathogens presently known. So far, they have been found only in higher plants where they may cause economically important diseases especially in potato, tomato, citrus, horticulturists chrysanthemum, coconut palms... Many plant virus outbreaks have been recorded in the last two decades around the world and the ultimate aim of the applied plant virologist is to devise measures for combating the virus and viroiddiseases. Citrus exocortis disease: Citrus Exocortis Viroid (CEVd) leads to this disease that affects citrus plants. It often results in yellow discoloration and stunting of the tree, and the peeling or cracking of the tree's bark. In the first volume, the author Dr. K Subramanya Sastry, has provided up-to-date information on different aspects of plant virus and viroiddiseases of crop plants of South East Asia, Africa, South American countries in five chapters, which are interlinked and exhaustive. TL;DR: The basis for TuMV- and other virus-induced diseaseinplants may be explained, at least partly, by interference with miRNA-controlled developmental pathways that share components with the antiviral RNA-silencing pathway. Little is known about epidemiology of this diseasein hemp or hop, but in hop, the viroid is reportedly spread mechanically during propagation, field operations, and to a limited degree by plant-to-plant contact and seed transmission. Some viral and viroiddiseases of plants.potato spindle tuber viroid (PSTV). potato and tomato. stunted growth; tubers are spindle-shaped and smaller than healthy tubers. the first identified viroid infection inplants; can cause major reduction in crop yield. What is a viroid? Viroids are the smallest agents known to cause serious diseasesinplants. They are extremely simple virus-like microorganisms. Like viruses, they multiply only in living plant cells. · 品牌型号：华为MateBook D14 系统版本：WIndows11家庭中文版23H2 软件版本：剪映专业版 5.5.0.11332
