1a.Objectives (from AD-416)
Collaborate with ARS researchers to provide germplasm for Cotton Leaf Curl Virus (CLCuV) screening and transfer resistance identified into adapted cotton lines. Transferring traits from diploid to cultivated tetraploid cotton is a difficult process. ARS at Stoneville, MS, and Texas A&M University, College Station, TX, are the two locations in the U.S. successfully transferring genes from diploid lines into tetraploid cotton. These groups will cooperate to transfer the resistance genes as quickly and efficiently as possible. The lines will be advanced more rapidly by using DNA markers to verify successful transfer of the resistance gene(s) in each generation of the introgression process. The efficiency will be improved by cytogenetic analyses to confirm the lines produced are cytogenetically stable with a complete set of chromosomes.
1b.Approach (from AD-416)
The university collaborator will work with ARS to increase seed of exotic diploid species and provide technical support for increase of germplasm and preparation of seed for CLCuV resistance screening. Lines identified as resistant will be used as donor parents in crosses to transfer the resistant trait (genes) into adapted cotton lines. The transfer of the trait will be tracked using DNA markers and resistant progeny from the crosses will be cytogenetically evaluated to select lines with a complete set of chromosomes and no chromosomal abnormalities.
To prepare for the arrival of resistant diploid parental material, the synthetic hexaploids to be used as bridging parents between the resistant diploid lines and the target tetraploid varieties were increased. The bridging parents will be used in hybridizations with diploid lines identified as carrying Cotton Leaf Curl Virus (CLCuV) resistance. Preliminary crosses are planned as a means for system development prior to the point where those CLCuV-resistant types are identified. In preparation for installation of our flow cytometer, in-house training was provided for two research team members in principles and methods of flow cytometry, as well as ploidy and chromosome manipulations. These will facilitate the subsequent assimilation and proper usage of this technology as part of our efforts. We also explored several KASP assays for Single Nucleotide Polymorphism (SNP) detection in genomes prospectively to be used in this project, since these could be convenient quality control tools for wide-hybridization and backcrossing as part of this project.
Research activities during this reporting period were monitored by the ADODR through email communications with the cooperator and through in-person discussions with the cooperator at professional society meetings.