Cotton leafroll dwarf disease: An enigmatic viral disease in cotton

Abstract

Taxonomy: Cotton leafroll dwarf virus (CLRDV) is a member of the genus Polerovirus, family Solemoviridae. Geographical Distribution: CLRDV is present in most cotton‐producing regions worldwide, prominently in North and South America. Physical Properties: The virion is a nonenveloped icosahedron with T = 3 icosahedral lattice symmetry that has a diameter of 26–34 nm and comprises 180 molecules of the capsid protein. The CsCl buoyant density of the virion is 1.39–1.42 g/cm3 and S20w is 115–127S. Genome: CLRDV shares genomic features with other poleroviruses; its genome consists of monopartite, single‐stranded, positive‐sense RNA, is approximately 5.7–5.8 kb in length, and is composed of seven open reading frames (ORFs) with an intergenic region between ORF2 and ORF3a. Transmission: CLRDV is transmitted efficiently by the cotton aphid (Aphis gossypii Glover) in a circulative and nonpropagative manner. Host: CLRDV has a limited host range. Cotton is the primary host, and it has also been detected in different weeds in and around commercial cotton fields in Georgia, USA. Symptoms: Cotton plants infected early in the growth stage exhibit reddening or bronzing of foliage, maroon stems and petioles, and drooping. Plants infected in later growth stages exhibit intense green foliage with leaf rugosity, moderate to severe stunting, shortened internodes, and increased boll shedding/abortion, resulting in poor boll retention. These symptoms are variable and are probably influenced by the time of infection, plant growth stage, varieties, soil health, and geographical location. CLRDV is also often detected in symptomless plants. Control: Vector management with the application of chemical insecticides is ineffective. Some host plant varieties grown in South America are resistant, but all varieties grown in the United States are susceptible. Integrated disease management strategies, including weed management and removal of volunteer stalks, could reduce the abundance of virus inoculum in the field.

Functional Characterization of RNA Silencing Suppressor Encoded by Cotton Leafroll Dwarf Virus

“…Cotton leafroll dwarf virus (CLRDV) is a newly emerging virus in the United States that has had a significant impact on cotton production in other countries [1][2][3][4][5]. CLRDV belongs to the family Solemoviridae and the genus Polerovirus, which consists of plant viruses expressing their proteins via a monopartite, positive-sense, single-stranded RNA genome comprising seven open reading frames (ORFs; Figure 1A) (reviewed in [6][7][8][9][10][11]).…”

Discovery and Analyses of Caulimovirid-like Sequences in Upland Cotton (Gossypium hirsutum)

“…Upland cotton is cultivated worldwide because of its high-yield potential, while Pima cotton is known for its superior fiber quality. As with other agricultural crops, cotton is affected by various pathogens, including viruses, some of which may cause serious economic losses (for example, in the cases of begomoviruses in Pakistan and India or the cotton leafroll dwarf virus in South America) [ 22 , 23 , 24 ]. The evolution of cotton has been well studied and its phylogeny has been described through morphological traits and genomic evaluation.…”

Cotton blue disease from Africa and its de facto relationship with cotton leafroll dwarf virus: a misleading etiological discrepancy

“…A disease of cotton associated with multiple alternative names [cotton blue disease; (CBD), cotton vein mosaic disease (CVMD), and cotton leafroll dwarf disease (CLRDD)] has been reported from countries throughout Africa, South America, North America and Asia. CBD is believed to have originated from central Africa in 1949 (1)(2)(3). The disease has been variably characterized throughout the aforementioned regions.…”

“…However, the same etiological agent, cotton leafroll dwarf virus (CLRDV), has been associated with all of these diseases reported in different continents, even in the cases where only symptomology has been reported. In many, if not all, recent writings on the subject, the assumption is made that the CBD reported in Africa shares the same etiological agent as the CVMD, later renamed to CBD, reported from South America or CLRDD reported from the United States (US) (1)(2)(3). South American CBD and CLRDD from the US have been confirmed biologically and at the molecular level to have the same etiological agent based on numerous independent confirmations from multiple sequence reports (2).…”

“…In many, if not all, recent writings on the subject, the assumption is made that the CBD reported in Africa shares the same etiological agent as the CVMD, later renamed to CBD, reported from South America or CLRDD reported from the United States (US) (1)(2)(3). South American CBD and CLRDD from the US have been confirmed biologically and at the molecular level to have the same etiological agent based on numerous independent confirmations from multiple sequence reports (2). Additionally, while CLRDV sequences have been reported from a variety of hosts in different countries, there has not been a reported viral sequence of CLRDV associated with CBD in cotton from Africa, especially from the Central African Republic, where CBD was first documented (Table 1) (2).…”