If you want a long term project….
Project Methods
1. Development of Parental Lines: Various tobacco cultivars and germplasm lines have been utilized as initial sources of resistance to develop segregating breeding populations with multiple disease resistance. The incorporation of desirable genetic traits into tobacco breeding lines will be accomplished primarily by the backcross breeding method, modified to include selfing and selection during early generations. These materials will continue to be developed as inbred lines for use in hybrid tobacco cultivars. Screening for black root rot, wildfire, TMV, TVMV, and TEV will be done in greenhouses and field nurseries by inoculating with the appropriate pathogens. Screening for black shank and fusarium wilt resistance will be conducted in Kentucky and Tennessee field nurseries having very high levels of these soil-borne pathogens. As parental breeding lines reach the F5 to F6 generation, they will be evaluated in two locations in Tennessee and three locations in Kentucky. Breeding lines will be compared to commercial varieties in these performance trials; lines that perform well in comparison to the commercial varieties will be used as pollinators onto existing male sterile lines to allow the production of new hybrids. Male sterility will also be incorporated into the best new lines via back crossing so that they can be used as females in future hybrid combinations. 2. Development of Improved Burley Hybrids: Hybrid combinations of parental lines that provide the highest level of disease resistance and also exhibit acceptable performance characteristics will be identified. The yield and quality of the experimental hybrids will be determined in field trials conducted at two locations in Tennessee and three locations in Kentucky. Disease resistance of the experimental hybrids will be verified in field nurseries and/or greenhouse disease inoculation studies. Hybrid lines that have superior performance and disease resistance in advanced testing will be considered for release as commercial cultivars. Prior to release, they will be evaluated in the Regional Variety Minimum Standards Program. Experimental lines that are approved in this program are then eligible for release as commercial cultivars.3. Marker assisted selection techniques and the early flowering FT trait will be utilized to introgress the three Zyvert alleles (CYP82E4, CYP82E5v2 and CYP82e10) into burley and dark dark tobacco varieties. The incorporation of the Zyvert alleles into the fertile varieties and breeding lines will require initial crosses to the burley line FT 2002Z, followed by five to six backcrosses to the appropriate dark male parental line. In each backcross generation, plants heterozygous for all three alleles will be verified via genetic marker analyses. Two self-pollinated generations will then be needed to produce genetically stable homozygous lines for commercial seed production. For male sterile parental lines, the first cross with its fertile Zyvert counterpart will take place using heterozygous BC5 pollen, followed by a second backcross with homozygous BC5 pollen, and a final backcross with homozygous BC6 pollen. After the final self for the fertile lines and the final backcross for the male sterile lines, seed will be collected only from normal flowering plants that are verified by marker analyses to be homozygous for all three low nornicotine alleles. At that point, the new Zyvert dark tobacco varieties will be non-transgenic and available for commercial seed production and release to growers.
Tobacco Breeding and Genetics - UNIVERSITY OF KENTUCKY
Burley and dark tobacco production is an important component of the farm economy of Kentucky and Tennessee. Development of high yielding, disease resistant cultivars has played a major role in tripling the average yield of burley tobacco from 1920 to 2015. However, in order for United States...
portal.nifa.usda.gov
Project Methods
1. Development of Parental Lines: Various tobacco cultivars and germplasm lines have been utilized as initial sources of resistance to develop segregating breeding populations with multiple disease resistance. The incorporation of desirable genetic traits into tobacco breeding lines will be accomplished primarily by the backcross breeding method, modified to include selfing and selection during early generations. These materials will continue to be developed as inbred lines for use in hybrid tobacco cultivars. Screening for black root rot, wildfire, TMV, TVMV, and TEV will be done in greenhouses and field nurseries by inoculating with the appropriate pathogens. Screening for black shank and fusarium wilt resistance will be conducted in Kentucky and Tennessee field nurseries having very high levels of these soil-borne pathogens. As parental breeding lines reach the F5 to F6 generation, they will be evaluated in two locations in Tennessee and three locations in Kentucky. Breeding lines will be compared to commercial varieties in these performance trials; lines that perform well in comparison to the commercial varieties will be used as pollinators onto existing male sterile lines to allow the production of new hybrids. Male sterility will also be incorporated into the best new lines via back crossing so that they can be used as females in future hybrid combinations. 2. Development of Improved Burley Hybrids: Hybrid combinations of parental lines that provide the highest level of disease resistance and also exhibit acceptable performance characteristics will be identified. The yield and quality of the experimental hybrids will be determined in field trials conducted at two locations in Tennessee and three locations in Kentucky. Disease resistance of the experimental hybrids will be verified in field nurseries and/or greenhouse disease inoculation studies. Hybrid lines that have superior performance and disease resistance in advanced testing will be considered for release as commercial cultivars. Prior to release, they will be evaluated in the Regional Variety Minimum Standards Program. Experimental lines that are approved in this program are then eligible for release as commercial cultivars.3. Marker assisted selection techniques and the early flowering FT trait will be utilized to introgress the three Zyvert alleles (CYP82E4, CYP82E5v2 and CYP82e10) into burley and dark dark tobacco varieties. The incorporation of the Zyvert alleles into the fertile varieties and breeding lines will require initial crosses to the burley line FT 2002Z, followed by five to six backcrosses to the appropriate dark male parental line. In each backcross generation, plants heterozygous for all three alleles will be verified via genetic marker analyses. Two self-pollinated generations will then be needed to produce genetically stable homozygous lines for commercial seed production. For male sterile parental lines, the first cross with its fertile Zyvert counterpart will take place using heterozygous BC5 pollen, followed by a second backcross with homozygous BC5 pollen, and a final backcross with homozygous BC6 pollen. After the final self for the fertile lines and the final backcross for the male sterile lines, seed will be collected only from normal flowering plants that are verified by marker analyses to be homozygous for all three low nornicotine alleles. At that point, the new Zyvert dark tobacco varieties will be non-transgenic and available for commercial seed production and release to growers.
