Plant pathology is the scientific study of diseases in plants caused by pathogens and environmental conditions. Organisms that cause infectious disease include fungi, oomycetes, bacteria, viruses, viroids, virus-like organisms, phytoplasmas, protozoa, nematodes and parasitic plants. Not included are ectoparasites like insects, mites, vertebrate, or other pests that affect plant health by eating plant tissues. Plant pathology also involves the study of pathogen identification, disease etiology, disease cycles, economic impact, plant disease epidemiology, plant disease resistance, how plant diseases affect humans and animals, pathosystem genetics, and management of plant diseases.
Bunyavirales is an order of segmented negative-strand RNA viruses with mainly tripartite genomes. Member viruses infect arthropods, plants, protozoans, and vertebrates. It is the only order in the class Ellioviricetes. The name Bunyavirales derives from Bunyamwera, where the original type species Bunyamwera orthobunyavirus was first discovered. Ellioviricetes is named in honor of late virologist Richard M. Elliott for his early work on bunyaviruses.
Closteroviridae is a family of viruses. Plants serve as natural hosts. There are four genera and 59 species in this family, seven of which are unassigned to a genus. Diseases associated with this family include: yellowing and necrosis, particularly affecting the phloem.
A leaf spot is a limited, discoloured, diseased area of a leaf that is caused by fungal, bacterial or viral plant diseases, or by injuries from nematodes, insects, environmental factors, toxicity or herbicides. These discoloured spots or lesions often have a centre of necrosis. Symptoms can overlap across causal agents, however differing signs and symptoms of certain pathogens can lead to the diagnosis of the type of leaf spot disease. Prolonged wet and humid conditions promote leaf spot disease and most pathogens are spread by wind, splashing rain or irrigation that carry the disease to other leaves.
Closterovirus, also known as beet yellows viral group, is a genus of viruses, in the family Closteroviridae. Plants serve as natural hosts. There are 17 species in this genus. Diseases associated with this genus include: yellowing and necrosis, particularly affecting the phloem. This genus has a probably worldwide distribution and includes among other viral species the Beet yellows virus and Citrus tristeza virus, rather economically important plant diseases. At least some species require vectors such as aphids or mealybugs for their transmission from plant to plant.
Idaeovirus is a genus of positive-sense ssRNA viruses that contains two species: Raspberry bushy dwarf virus (RBDV) and Privet idaeovirus. RBDV has two host-dependent clades: one for raspberries; the other for grapevines. Infections are a significant agricultural burden, resulting in decreased yield and quality of crops. RBDV has a synergistic relation with Raspberry leaf mottle virus, with co-infection greatly amplifying the concentration of virions in infected plants. The virus is transmitted via pollination with RBDV-infected pollen grains that first infect the stigma before causing systemic infection.
Alternanthera mosaic virus (AltMV) is a plant pathogenic virus. AltMV belongs to the virus genus Potexvirus and the virus family Alphaflexiviridae.
Fig mosaic emaravirus (FMV) is a segmented, negative sense, single-stranded RNA virus that is determined to be the causal agent of fig mosaic disease (FMD) in fig plants, Ficus carica. It is a member of the genus Emaravirus and order Bunyavirales and is transmitted mainly by the eriophyid mite Aceria ficus. FMV can cause a range of symptoms varying in severity, including leaf chlorosis, deformity, and mosaic or discoloration patterns, as well as premature fruit drop.
Emaravirus is a genus of negative-strand RNA viruses which infect plants. The plant virus group is the sole genus in the family Fimoviridae. The genus has 21 species.
Grapevine virus A (GVA) is a moderately common genetic virus that affects Vitis vinifera and American Vitis grapevine species throughout the world and can be fatal if not treated. Grapevine virus A is in the family Betaflexiviridae and genus Vitivirus. The common name for this virus is grapevine closterovirus. Common symptoms in infected grapevines include stem pitting. Although there is a treatment available to cure infected grapevines, it is not one hundred percent effective, so preventative measures are the best solution to the virus. Every inhabited continent on the globe has had breakouts of grapevine closterovirus due to the complex genetic makeup of the virus. Grapevine virus A has a single-stranded RNA genome, which is similar to that of Grapevine virus B. There are multiple strains of the virus that vary both molecularly and biologically which account for the slightly different symptoms exhibited by infected plants.
Genomoviridae is a family of single stranded DNA viruses that mainly infect fungi. The genomes of this family are small. The genomes are circular single-stranded DNA and encode rolling-circle replication initiation proteins (Rep) and unique capsid proteins. In Rep-based phylogenies, genomoviruses form a sister clade to plant viruses of the family Geminiviridae. Ten genera are recognized in this family.
Chilli leaf curl virus(ChiLCV) is a DNA virus from the genus Begomovirus and the family Geminiviridae. ChiLCV causes severe disease especially in pepper, but also affects other crops such as tomato. It can be found in tropical and subtropical regions primarily in India, but has also been detected in countries such as Indonesia and Sri Lanka. This virus is transmitted by an insect vector from the family Aleyrodidae and order Hemiptera, the whitefly Bemisia tabaci. The primary host for ChiLCV are several Capsicum spp., but host species also include tomato and amaranth. ChiLCV has been responsible for several epidemics and causes severe economic losses. It is the focus of research trying to understand the genetic basis of resistance. Currently, a few sources of resistance have been discovered and used to breed resistant varieties.
Tomato yellow leaf curl China virus (TYLCCNV) is a virus which contains 25 isolates. It infects plants as different as tobacco and tomato, as well as genetically modified plants. Petunias can be infected, but show no symptoms. The microbiology of the virus has been studied in the Chinese province of Yunnan. Tomato yellow leaf curl China virus belongs to the genus Begomovirus, which also contains the tomato leaf curl China virus.
Solemoviridae is a family of non-enveloped, positive-strand RNA viruses which infect plants. Solemoviridae is a member of the order Sobelivirales.
Plantain virus X is a species of virus, part of the Potexvirus viral family. It infects the weed plaintain. DNA sequencing has shown it to be synonymous with Actinidia virus X, infecting kiwifruit and blackcurrants. The same research also found Plantain virus X infecting Capsicum annuum and the ornamental flower Browallia americana.
Onion yellow dwarf virus (OYDV) is a plant virus in the genus Potyvirus that has been identified worldwide and mainly infects species of Allium such as onion, garlic, and leek. The virus causes mild to severe leaf malformation, and bulb reduction up to sixty percent has been observed in garlic.
Tomato mottle mosaic virus is a Tobamovirus which infects Solanum lycopersicum. First detected in Mexico in 2013 from S. lycopersicum samples taken in 2009, ToMMV has since been found throughout the world. In 2014 some S. lycopersicum samples from Florida in 2010 and 2012 and a Nicotiana tabacum 'Xanthi nc' sample were retested using an assay that distinguishes ToMMV from other Tobamoviruses, especially the closely related Tomato mosaic virus and Tobacco mosaic virus. These samples tested positive for ToMMV, showing that ToMMV was widespread and had been for several years earlier than previously known.
Leek yellow stripe virus (LYSV) belongs to the genus Potyvirus. It was first detected in leek but also infects garlic and onion worldwide. Economically less important Allium spp., such as Allium angulosum, Allium caeruleum, Allium cyathophorum, Allium nutans, Allium scorodoprasum, Allium senescens subsp. montanum were also found to harbor the virus.
