Characterization of a Begomovirus-Betasatellite Complex, Producing Defective Molecules in Spinach (Spinacia oleracea L.), a New Host for Begomovirus and Betasatellite Complex in Pakistan

Tahir, Muhammad Nouman,Hameed, Amir,Amin, Imran,Mansoor, Shahid The Korean Society of Plant Pathology 2017 Plant Pathology Journal Vol.33 No.5

Spinach is a vegetable crop which is widely grown over a large area especially in Punjab province of Pakistan. Leaf curling and enations on spinach plant collected shown to be associated with the begomovirus Pedilanthus leaf curl virus (PeLCV) and Shahdadpur strain of Cotton leaf curl Multan betasatellite ($CLCuMB^{Sha}$). Defective molecules of half and quarter size derived from monopartite begomoviruses are usually generated by the deletion of virion-sense sequences. Characterization of defective molecules of PeLCV from spinach revealed that the molecules of half the size are derived from the deletion of complementary-sense genes while quarter size molecule appears to have evolved by further deletion. This is the first report of the begomovirus-betasatellite complex on spinach and unusual defective molecules derived from deletion of complementary-sense genes in Pakistan.

Detection of Multiple Potato Viruses in the Field Suggests Synergistic Interactions among Potato Viruses in Pakistan

Hameed, Amir,Iqbal, Zafar,Asad, Shaheen,Mansoor, Shahid The Korean Society of Plant Pathology 2014 Plant Pathology Journal Vol.30 No.4

Viral diseases have been a major limiting factor threating sustainable potato (Solanum tuberosum L.) production in Pakistan. Surveys were conducted to serologically quantify the incidence of RNA viruses infecting potato; Potato virus X (PVX), Potato virus Y (PVY), Potato virus S (PVS), Potato virus A (PVA), Potato virus M (PVM) and Potato leaf roll virus (PLRV) in two major potato cultivars (Desiree and Cardinal). The results suggest the prevalence of multiple viruses in all surveyed areas with PVY, PVS and PVX dominantly widespread with infection levels of up to 50% in some regions. Co-infections were detected with the highest incidence (15.5%) for PVX and PVS. Additionally the data showed a positive correlation between co-infecting viruses with significant increase in absorbance value (virus titre) for at least one of the virus in an infected plant and suggested a synergistic interaction. To test this hypothesis, glasshouse grown potato plants were challenged with multiple viruses and analyzed for systemic infections and symptomology studies. The results obtained conclude that multiple viral infections dramatically increase disease epidemics as compared to single infection and an effective resistance strategy in targeting multiple RNA viruses is required to save potato crop.

Detection of Multiple Potato Viruses in the Field Suggests Synergistic Interactions among Potato Viruses in Pakistan

Amir Hameed,Zafar Iqbal,Shaheen Asad,Shahid Mansoor 한국식물병리학회 2014 Plant Pathology Journal Vol.30 No.4

Viral diseases have been a major limiting factor threatingsustainable potato (Solanum tuberosum L.) productionin Pakistan. Surveys were conducted to serologicallyquantify the incidence of RNA viruses infectingpotato; Potato virus X (PVX), Potato virus Y (PVY),Potato virus S (PVS), Potato virus A (PVA), Potato virusM (PVM) and Potato leaf roll virus (PLRV) in twomajor potato cultivars (Desiree and Cardinal). Theresults suggest the prevalence of multiple viruses in allsurveyed areas with PVY, PVS and PVX dominantlywidespread with infection levels of up to 50% in someregions. Co-infections were detected with the highestincidence (15.5%) for PVX and PVS. Additionally thedata showed a positive correlation between co-infectingviruses with significant increase in absorbance value(virus titre) for at least one of the virus in an infectedplant and suggested a synergistic interaction. To testthis hypothesis, glasshouse grown potato plants werechallenged with multiple viruses and analyzed for systemicinfections and symptomology studies. The resultsobtained conclude that multiple viral infections dramaticallyincrease disease epidemics as compared tosingle infection and an effective resistance strategy intargeting multiple RNA viruses is required to save po-tato crop.

Characterization of a Begomovirus-Betasatellite Complex, Producing Defective Molecules in Spinach (Spinacia oleracea L.), a New Host for Begomovirus and Betasatellite Complex in Pakistan

Muhammad Nouman Tahir,Amir Hameed,Imran Amin,Shahid Mansoor 한국식물병리학회 2017 Plant Pathology Journal Vol.33 No.5

Spinach is a vegetable crop which is widely grown over a large area especially in Punjab province of Pakistan. Leaf curling and enations on spinach plant collected shown to be associated with the begomovirus Pedilanthus leaf curl virus (PeLCV) and Shahdadpur strain of Cotton leaf curl Multan betasatellite (CLCuMBSha). Defective molecules of half and quarter size derived from monopartite begomoviruses are usually generated by the deletion of virion-sense sequences. Characterization of defective molecules of PeLCV from spinach revealed that the molecules of half the size are derived from the deletion of complementary-sense genes while quarter size molecule appears to have evolved by further deletion. This is the first report of the begomovirusbetasatellite complex on spinach and unusual defective molecules derived from deletion of complementarysense genes in Pakistan.

RNAi-mediated silencing of endogenous Vlnv gene confers stable reduction of cold-induced sweetening in potato (Solanum tuberosum L. cv. Désirée)

Amir Hameed,Rakhshanda Bilal,Farooq Latif,Joyce Van Eck,Georg Jander,Shahid Mansoor 한국식물생명공학회 2018 Plant biotechnology reports Vol.12 No.3

Potato tubers must be cold-stored to extend their shelf life and maintain an uninterrupted supply chain for food processors. However, a side-effect of low-temperature storage is manifested in terms of cold-induced sweetening (CIS) of potato tubers, which reduces the processing quality and the commercial value of the end-products. RNA interference (RNAi) technology, whereby transgene-derived small interfering RNAs can trigger the homology-based knockdown of cognate host genes and can initiate gene silencing, has been successfully applied in crop improvement through targeted gene knockout in host plants. In the current study, transgenic potato plants (Solanum tuberosum cv. Désirée) were generated, expressing a 300 bp hairpin loop nucleotide sequence targeting the potato vacuolar invertase gene (VInv), under the constitutive Cauliflower mosaic virus 35S promoter. Tubers collected from transgenic lines showed a significant reduction in reducing sugar content after 180 days of cold storage, without showing any measurable off-target effects on plant morphology and tuberization compared to nontransformed control plants. The cold-stored tubers were further assayed for chip color, which showed a fairly light colored quality in the samples originating from RNAi lines. Together with similar effects seen in previously published experiments involving other potato varieties, the Désirée results described here establish the efficacy of using RNAi for the successful reduction of CIS in potato tubers.

Diversity in Betasatellites Associated with Cotton Leaf Curl Disease During Source-To-Sink Movement Through a Resistant Host

Iftikhar Ali Khan,Khalid Pervaiz Akhtar,Fazal Akbar,Ishtiaq Hassan,Imran Amin,Muhammad Saeed,Shahid Mansoor 한국식물병리학회 2016 Plant Pathology Journal Vol.32 No.1

Cotton leaf curl is devastating disease of cotton characterized by leaf curling, vein darkening and enations. The disease symptoms are induced by DNA satellite known as Cotton leaf curl Multan betasatellite (CLCuMuB), dominant betasatellite in cotton but another betasatellite known as Chili leaf curl betasatellite (ChLCB) is also found associated with the disease. Grafting experiment was performed to determine if host plant resistance is determinant of dominant population of betasatellite in cotton (several distinct strains of CLCuMuB are associated with the disease). Infected scion of Gossypium hirsutum collected from field (the source) was grafted on G. arboreum, a diploid cotton species, resistant to the disease. A healthy scion of G. hirsutum (sink) was grafted at the top of G. arboreum to determine the movement of virus/betasatellite to upper susceptible scion of G. hirsutum. Symptoms of disease appeared in the upper scion and presence of virus/betasatellite in the upper scion was confirmed via molecular techniques, showing that virus/betasatellite was able to move to upper scion through resistant G. arboreum. However, no symptoms appeared on G. arboreum. Betasatelites were cloned and sequenced from lower scion, upper scion and G. arboreum which show that the lower scion contained both CLCuMuB and ChLCB, however only ChLCB was found in G. arboreum. The upper scion contained CLCuMuB with a deletion of 78 nucleotides (nt) in the non-coding region between Arich sequence and βC1 gene and insertion of 27 nt in the middle of βC1 ORF. This study may help in investigating molecular basis of resistance in G. arboreum.

Diversity in Betasatellites Associated with Cotton Leaf Curl Disease During Source-To-Sink Movement Through a Resistant Host

Khan, Iftikhar Ali,Akhtar, Khalid Pervaiz,Akbar, Fazal,Hassan, Ishtiaq,Amin, Imran,Saeed, Muhammad,Mansoor, Shahid The Korean Society of Plant Pathology 2016 Plant Pathology Journal Vol.32 No.1

Cotton leaf curl is devastating disease of cotton characterized by leaf curling, vein darkening and enations. The disease symptoms are induced by DNA satellite known as Cotton leaf curl Multan betasatellite (CLCuMuB), dominant betasatellite in cotton but another betasatellite known as Chili leaf curl betasatellite (ChLCB) is also found associated with the disease. Grafting experiment was performed to determine if host plant resistance is determinant of dominant population of betasatellite in cotton (several distinct strains of CLCuMuB are associated with the disease). Infected scion of Gossypium hirsutum collected from field (the source) was grafted on G. arboreum, a diploid cotton species, resistant to the disease. A healthy scion of G. hirsutum (sink) was grafted at the top of G. arboreum to determine the movement of virus/betasatellite to upper susceptible scion of G. hirsutum. Symptoms of disease appeared in the upper scion and presence of virus/betasatellite in the upper scion was confirmed via molecular techniques, showing that virus/betasatellite was able to move to upper scion through resistant G. arboreum. However, no symptoms appeared on G. arboreum. Betasatelites were cloned and sequenced from lower scion, upper scion and G. arboreum which show that the lower scion contained both CLCuMuB and ChLCB, however only ChLCB was found in G. arboreum. The upper scion contained CLCuMuB with a deletion of 78 nucleotides (nt) in the non-coding region between Arich sequence and ${\beta}C1$ gene and insertion of 27 nt in the middle of ${\beta}C1$ ORF. This study may help in investigating molecular basis of resistance in G. arboreum.