Genome Characterization of Whitefly-Transmitted Geminivirus of Cotton and Development of Virus-Resistant Plants Through Genetic Engineering and Conventional Breeding (CFC/ICAC 07)

摘要

Pakistan is the fourth in global ranking of cotton production (over two million tons produced in 2010/11). Pakistan shared about 8% of world production. Cotton is the backbone of the economy of the country as it accounts for 8.2% of the value added inthe agriculture sector and about 2% to GDP. Nearly 65% of foreign exchange earnings of the country are based on cotton based textile products. Cotton production in Pakistan is however constrained among other common problems with a unique issue of cottonleaf curl virus (CLCuV) disease, which caused an epidemic in 1992-93 season. The first epidemic of cotton leaf curl disease occurred in Africa (Nigeria, 1912; Sudan, 1924; Tanzania, 1926) followed by cotton leaf crumple disease, which broke out in the Southwestern USA in the 1950's, and then cotton leaf curl with enation symptoms in the Punjab region of Pakistan. Despite the somewhat different symptoms observed in each of the locations, it was not known until this project supported by the Common Fund for Cotton was carried out, whether the same or similar viral pathogens caused the disease in all of the locations. The one factor shared in common by all of the outbreaks was the association of the whitefly Bemisia tabaci (Genn.) with symptom development. Based on typical virus symptoms and results from research carried out at the University of Arizona, USA that demonstrated the association of a new type of virus containing ssDNA (Geminiviridae) with cotton leaf crumple disease in the USA, whitefly-transmitted geminiviruses were therefore suspected as the causal agents in Africa and Pakistan.