Cotton TILLING Project: Development and testing of cotton TILLING populations as a resource for the plant genetic improvement

Functional Genomics

oral

Aslam, Usman; Cheema, Hafiza Masooma Naseer; Khan, Asif Ali

Aslam, Usman; Cheema, Hafiza Masooma Naseer

Khan, Asif Ali

Upland cotton is the chief source of white fiber around the world. Unfortunately its vulnerability to various biological and a biological stresses arrest its yield and production for the last several years especially in Pakistan. Besides the improvement of this vital crop regarding the fiber quality traits and productivity has always been hard to be manipulated either by using the classical breeding approaches or by advanced molecular genetic approaches. The recent progress in the area of plant molecular biology and plant genomics has the potential to initiate a new Green Revolution. However, these discoveries are to be implemented in the development of new cultivars to realize that potential. Genetic mutation is a powerful tool to create the genetic variability. TILLING (Target Induced Local Lesions In Genomes) is a reverse genetic approach for mutation based crop improvement that combines conventional mutagenesis with DNA level mutation identification. It has been used successfully by researchers as a functional genomic discovery platform in model organisms. But now it has proven effectively as a crop improvement tool. Besides genetic engineering approaches are hindered mainly by non-availability of tissue culture in elite cotton cultivars, cost of producing the transgenic plants, behavior of the transgene and the ethical questions associated with GMO’s. In contrast, TILLING provides a non-transgenic genetic therapy for cotton genome to deal with the prevailing problems. Cotton TILLING project at the Department of Plant Breeding and Genetics, University of Agriculture Faisalabad, Pakistan is the initiative towards the creation and functionally characterization of the cotton TILLING populations. The major objective of this project is the development and testing of cotton TILLING populations for disease and fiber related genes with theme to circumvent the inferior fiber quality and unrestrained epidemic Cotton Leaf Curl Disease (CLCuD) in subcontinent. We targeted fiber related gene families like pectin methyl esterase, actin, sucrose synthase, and defense related gene families including resistance gene analogues (RGAs) and defense gene analogues (DGAs). Two cotton cultivars “PB-899 and PB-900” were mutagenized on the calculated optimum doses of EMS and raised up to their M2 populations. A total of 8000 to 10,000 M2 plants were screened for mutations in targeted genes. The phenotyping presented a number of mutants including branching pattern, leaf morphology, disease resistance, photosynthetic lesions and flower sterility. The molecular screening of point mutations was performed by TILLING PCR aided with CEL1 mismatch cleavage assay that also showed significant proportion of induced mutations in TILLING populations that verifies it an efficient tool in improvement of cotton.