Search

Cotton leaf curl disease (CLCuD) is a significant constraint to the economies of Pakistan and India. The disease is caused by different begomoviruses (genus Begomovirus, family Geminiviridae) in association with a disease-specific betasatellite. However, another satellite-like molecule, alphasatellite, is occasionally found associated with this disease complex. A quantitative real-time PCR assay for the virus/satellite components causing CLCuD was used to investigate the performance of selected cotton varieties in the 2014–2015 National Coordinated Varietal Trials (NCVT) in Pakistan. The DNA levels of virus and satellites in cotton plants were determined for five cotton varieties across three geographic locations and compared with seed cotton yield (SCY) as a measure of the plant performance. The highest virus titer was detected in B-10 (0.972 ng·µg−1) from Vehari and the lowest in B-3 (0.006 ng·µg−1) from Faisalabad. Likewise, the highest alphasatellite titer was found in B-1 (0.055 ng·µg−1) from Vehari and the lowest in B-1 and B-2 (0.001 ng·µg−1) from Faisalabad. The highest betasatellite titer was found in B-23 (1.156 ng·µg−1) from Faisalabad and the lowest in B-12 (0.072 ng·µg−1) from Multan. Virus/satellite DNA levels, symptoms, and SCY were found to be highly variable between the varieties and between the locations. Nevertheless, statistical analysis of the results suggested that betasatellite DNA levels, rather than virus or alphasatellite DNA levels, were the important variable in plant performance, having an inverse relationship with SCY (−0.447). This quantitative assay will be useful in breeding programs for development of virus resistant plants and varietal trials, such as the NCVT, to select suitable varieties of cotton with mild (preferably no) symptoms and low (preferably no) virus/satellite. At present, no such molecular techniques are used in resistance breeding programs or varietal trials in Pakistan. [ABSTRACT FROM AUTHOR]

Cotton leaf curl disease (CLCuD) is a significant constraint to the economies of Pakistan and India. The disease is caused by different begomoviruses (genus Begomovirus, family Geminiviridae) in association with a disease-specific betasatellite. However, another satellite-like molecule, alphasatellite, is occasionally found associated with this disease complex. A quantitative real-time PCR assay for the virus/satellite components causing CLCuD was used to investigate the performance of selected cotton varieties in the 2014–2015 National Coordinated Varietal Trials (NCVT) in Pakistan. The DNA levels of virus and satellites in cotton plants were determined for five cotton varieties across three geographic locations and compared with seed cotton yield (SCY) as a measure of the plant performance. The highest virus titer was detected in B-10 (0.972 ng·µg−1) from Vehari and the lowest in B-3 (0.006 ng·µg−1) from Faisalabad. Likewise, the highest alphasatellite titer was found in B-1 (0.055 ng·µg−1) from Vehari and the lowest in B-1 and B-2 (0.001 ng·µg−1) from Faisalabad. The highest betasatellite titer was found in B-23 (1.156 ng·µg−1) from Faisalabad and the lowest in B-12 (0.072 ng·µg−1) from Multan. Virus/satellite DNA levels, symptoms, and SCY were found to be highly variable between the varieties and between the locations. Nevertheless, statistical analysis of the results suggested that betasatellite DNA levels, rather than virus or alphasatellite DNA levels, were the important variable in plant performance, having an inverse relationship with SCY (−0.447). This quantitative assay will be useful in breeding programs for development of virus resistant plants and varietal trials, such as the NCVT, to select suitable varieties of cotton with mild (preferably no) symptoms and low (preferably no) virus/satellite. At present, no such molecular techniques are used in resistance breeding programs or varietal trials in Pakistan.

Cotton leaf curl disease (CLCuD) is the major biotic constraint to cotton production in Pakistan and northwestern India. The disease is caused by monopartite begomoviruses in association with a specific DNA satellite, Cotton leaf curl Multan betasatellite. The virus-betasatellite complex is also frequently associated with another DNA satellite-like molecule; an alphasatellite. A quantitative real-time PCR (qPCR) assay to detect all three components of the monopartite begomovirus/betasatellite/alphasatellite complex which causes CLCuD was established. This was used to investigate the relationship between symptoms and virus/satellite titre. Not surprisingly the analysis showed that, overall, there was a reasonable correlation between symptom severity and virus/satellite titre − more severe symptoms usually being associated with more virus/satellite. However, cotton plants were identified with no or very mild symptoms with relatively high virus/satellite titres and plants with severe symptoms but relatively low virus/satellite titres. This may be attributed to the resistance/susceptibility of the cotton variety − tolerant plants being able to sustain a relatively high virus/satellite titre whilst exhibiting mild symptoms. The usefulness of this qPCR procedure in the screening for resistance in cotton against CLCuD is discussed. [ABSTRACT FROM AUTHOR]