Detection and relationships of cotton leaf curl virus and allied whitefly‐transmitted geminiviruses occurring in Pakistan

Abstract

A stock culture of cotton leaf curl virus from Pakistan (CLCuV-PK), was transmitted by whiteflies (Bemisia tabaci) to seven plant species, including French bean, okra, tobacco and tomato, and caused vein thickening and leaf curl symptoms. It was readily detected in triple antibody sandwich ELISA (TAS-ELISA) by 11 out of 3 1 monoclonal antibodies raised against the particles of three other geminiviruses: African cassava mosaic, Indian cassava mosaic and okra leaf curl viruses. Reaction strength was enhanced when the tissue extraction fluid contained sodium sulphite. Minor variations in epitope profile were found among virus isolates from cotton (Gossypium hirsutum) collected from different districts in Pakistan over a 5-year period. These epitope profiles were distinguishable from that of cotton leaf curl virus from G. barbadense in southern India but indistinguishable from the profiles of viruses causing yellow vein disease of okra in India or Pakistan, or leaf curl of okra (Abelmoschus esculentus), Hibiscus tiliaceus, radish or sunflower in Pakistan, suggesting that these plants are putative natural hosts of CLCuV-PK. The viruses in cotton, and in okra with leaf curl or yellow vein symptoms, were also detected by PCR with three pairs of CLCuV-PKspecific primers.Five additional whitefly-transmitted geminiviruses were found among isolates from 11 other naturally-infected species in Pakistan, and were distinguished by their epitope profiles. These viruses were associated, respectively, with tobacco leaf curl, squash yellow blotch, tomato yellow leaf curl, watermelon leaf crinkle and soybean yellow mosaic diseases. The first four of these viruses were detected readily by PCR with geminivirus general primers but only weakly, if at all, with two pairs of CLCuV-PK-specific primers. Pakistani crops are infected with a range of distinguishable but relatively closely related whitefly-transmitted geminiviruses, some of which resemble those found in India.

Genetic Variability of Natural Populations of Cotton Leaf Curl Geminivirus, a Single-Stranded DNA Virus

“…DNA was extracted as described by Harrison et al (1997). Viral double-stranded (ds) DNA in the extract was further purified using a plasmid isolation kit (Boehringer Mannheim, Mannheim, Germany).…”

“…Whitefly-transmitted geminiviruses (WTG) are the best examples of emerging viruses from the plant kingdom, and CLCuV is a good example of emerging WTG. Cotton leaf curl disease has emerged during the last 8 years as the main threat to the cotton (Gossypium hirsutum L.) industry in Pakistan (Ali et al 1995;Harrison et al 1997). The disease is caused by a Bemisia tabacitransmitted geminivirus, CLCuV (Hameed et al 1994), for which only a single DNA component (DNA-A) has been discovered (Nadeem 1995;Zhou et al 1998).…”

Two Novel Mycoviruses Related to Geminivirus Isolated from the Soil-Borne FungiMacrophomina Phaseolina(Tassi) Goid. andMucor RacemosusBull

“…The cotton leaf curl coat protein (CP) specific primers were used for mycovirus detection in the extracted fungal DNA: forward primer, SAf, 5'-GTCGCAGGATTATTCACCG-3'; reverse primer, SAr, 5'-GTATGTAGATCAATATTCAGAAA-3' (14). Ten nanograms of supposedly previously extracted viral nucleic acid was added to a total volume of 25 μL PCR reaction mixture.…”

Assessment of genetic diversity of cotton genotypes for various economic traits against cotton leaf curl disease (CLCuD)

“…During the period 1988 through 2002 more than 7.7 million bales of cotton were lost due to CLCuD (Ahmad et al, 2002). The affected cotton crop was 60 ha in 1988-1989, which increased to 0.9 million ha in 1993-1994(Harrison et al, 1997. During the late 1990s, due to an extensive breeding program, resistant cotton cultivars were developed and released to combat the disease, which helped reducing disease losses (Rahman et al, 2005).…”