Progress 07/01/06 to 06/30/08
Outputs
OUTPUTS: Utilization of potato varieties resistant to late blight is the most cost-effective and environmentally sound method to controlling this disease. Resistant varieties minimize crop injuries and the environmental impact of fungicide applications. Full immunity has been derived from at least 11 resistance (R) genes derived from the wild species Solanum demissum and S. andigena. These R genes have been incorporated into numerous potato varieties. However, this resistance breaks down in the presence of a different race of this oomycete. Moreover, at least one race of P. infestans, represented by the US8 strain, the most widely distributed in the US can overcome all these 11 R genes. In a study of 147 cultivars and breeding lines evaluated against the US8 genotype of P. infestans, two thirds classified as very susceptible. Thus, no potato cultivar grown in the U.S. has an adequate level of resistance to late blight. Recently, resistance to the US8 genotype was discovered in S. bulbocastanum, conferring resistance to all known races of the late blight pathogen. The development of varieties with durable, broad scope resistance was the main focus of this project. In 2007 several studies were undertaken: 1. Marker Assisted Selection for Resistance to Late Blight: In 2007, 276 clones that were previously confirmed in Dr. Jiming Jiang's laboratory to carry RB late blight resistance gene were planted in the field and selected for adaptation, maturity and tuber traits. A small percentage of these lines are targeted for additional evaluations for use as parents and potential variety development. 2. Selection of Progenies for Late Blight Resistance: In 2007, 167 clones were field evaluated for adaptation. These clones were screened by detached leaf assays in collaboration with Dr. Terese Barta (UW-Stevens Point) under controlled conditions. We submitted 160 early stage lines carrying different late blight sources of resistance to the Oregon breeding program for unreplicated evaluations (4 hills). In addition, 40 advanced lines were evaluated for late blight resistance in collaboration with this breeding program. Incidence of late blight in the field is highly dependent on weather conditions. Therefore, to assess late blight resistance under uniformly favorable conditions, a detached leaf assay was developed and tested in 2008. For this purpose potato plants were grown in a greenhouse and excised leaves were exposed to Phytophtora infestans (strain ME9382). Leaves will be scored seven days after inoculation by estimating the percent surface area of the leaf with watersoaking or necrosis, and for the presence of sporangia. We plan to use this assay in future studies aimed at screening potato breeding lines for late blight resistance. PARTICIPANTS: Terese Barta and Felix Navarro TARGET AUDIENCES: Potato Growers, Breeders and Scientists PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Growers will benefit with the development and use of resistant potato cultivars due to a decrease in the cost of production due to a reduction in the use of fungicides including mancozeb, dimethomorph, cymoxanil, zoxamide, fluazinam, propamocarb, maneb, chlorothalonil, azoxystrobin, metiram, triphenyltin hydroxide, famoxadone, trifloxystrobin that are applied every year as a preventive measure irrespective of the incidence or the severity of this disease. The pre-emptive applications are done in all US potato growing areas because, once the late blight appears it is too late to contain or control it. In addition, farms and related agribusinesses will also benefit with the development and use of resistant potato cultivars by having sustainable and more secure investments and benefits through years. During the 1995 late blight epidemics that affected the US Columbia Basin, the number of fungicide applications increased from 2.5 to 10. This represented a $30 million expenses in this region alone reported in 1995 and $70-140 countrywide to control late blight reported in 2003. In relation to the improvement of the quality of life, the public will benefit from the development and adoption of varieties with a broad scope of resistance to different late blight strains due to a reduction of pollution caused by the deposition of fungicides into the environment every year. In 2008, we developed an excised leaf assay to screen potato breeding lines for late blight resistance. This assay worked satisfactorily and will be used in future studies.
Publications
- No publications reported this period
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: Utilization of potato varieties resistant to late blight is the most cost-effective and environmentally sound method to controlling this disease. Resistant varieties minimize crop injuries and the environmental impact of fungicide applications. Full immunity has been derived from at least 11 resistance (R) genes derived from the wild species Solanum demissum and S. andigena. These R genes have been incorporated into numerous potato varieties. However, this resistance breaks down in the presence of a different race of this oomycete. Moreover, at least one race of P. infestans, represented by the US8 strain, the most widely distributed in the US can overcome all these 11 R genes. In a study of 147 cultivars and breeding lines evaluated against the US8 genotype of P. infestans, two thirds classified as very susceptible. Thus, no potato cultivar grown in the U.S. has an adequate level of resistance to late blight. Recently, resistance to the US8 genotype was discovered in S.
bulbocastanum, conferring resistance to all known races of the late blight pathogen. The development of varieties with durable, broad scope resistance is main focus of this project. The specific objectives of this project are: i. to produce backcross progenies by crossing available lines with RB genes against cultivated types. ii. to precisely screen backcross progenies for resistance to late blight combining marker assisted selection with desired agronomic and quality traits (yield, grade, fresh market or processing). iii. to screen selected potato accessions from the US Potato Gene Bank at Sturgeon Bay for the RB and other genes as possible alternate sources of resistance. iv. to develop a collaborative effort between UW-Madison, UW-Stevens Point and US Potato Gene Bank at Sturgeon Bay. In 2007 several studies were undertaken: 1. Marker Assisted Selection for Resistance to Late Blight: In 2007, 276 clones that were previously confirmed in Dr. Jiming Jiang's laboratory to carry RB
late blight resistance gene were planted in the field and selected for adaptation, maturity and tuber traits. A small percentage of these lines are targeted for additional evaluations for use as parents and potential variety development. 2. Selection of Progenies for Late Blight Resistance: In 2007, 167 clones were field evaluated for adaptation. These clones were screened by detached leaf assays in collaboration with Dr. Terese Barta (UW-Stevens Point) under controlled conditions. We submitted 160 early stage lines carrying different late blight sources of resistance to the Oregon breeding program for unreplicated evaluations (4 hills). In addition, 40 advanced lines were evaluated for late blight resistance in collaboration with this breeding program.
TARGET AUDIENCES: Potato Growers, Breeders and Scientists.
Impacts
Growers will benefit with the development and use of resistant potato cultivars due to a decrease in the cost of production due to a reduction in the use of fungicides including mancozeb, dimethomorph, cymoxanil, zoxamide, fluazinam, propamocarb, maneb, chlorothalonil, azoxystrobin, metiram, triphenyltin hydroxide, famoxadone, trifloxystrobin that are applied every year as a preventive measure irrespective of the incidence or the severity of this disease. The pre-emptive applications are done in all US potato growing areas because, once the late blight appears it is too late to contain or control it. In addition, farms and related agribusinesses will also benefit with the development and use of resistant potato cultivars by having sustainable and more secure investments and benefits through years. During the 1995 late blight epidemics that affected the US Columbia Basin, the number of fungicide applications increased from 2.5 to 10. This represented a $30 million
expenses in this region alone reported in 1995 and $70-140 countrywide to control late blight reported in 2003. In relation to the improvement of the quality of life, the public will benefit from the development and adoption of varieties with a broad scope of resistance to different late blight strains due to a reduction of pollution caused by the deposition of fungicides into the environment every year.
Publications
- No publication yet, the project started in July 2006
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Progress 01/01/06 to 12/31/06
Outputs
Utilization of potato varieties resistant to late blight is the most cost-effective and environmentally sound method to controlling this disease. Resistant varieties minimize crop injuries and the environmental impact of fungicide applications. Full immunity has been derived from at least 11 resistance (R) genes derived from the wild species Solanum demissum and S. andigena. These R genes have been incorporated into numerous potato varieties. However, this resistance breaks down in the presence of a different race of this oomycete. Moreover, at least one race of P. infestans, represented by the US8 strain, the most widely distributed in the US can overcome all these 11 R genes. In a study of 147 cultivars and breeding lines evaluated against the US8 genotype of P. infestans, two thirds classified as very susceptible. Thus, no potato cultivar grown in the U.S. has an adequate level of resistance to late blight. Recently, resistance to the US8 genotype was discovered in
S. bulbocastanum, conferring resistance to all known races of the late blight pathogen. The development of varieties with durable, broad scope resistance is main focus of this project. The specific objectives of this project are: i. to produce backcross progenies by crossing available lines with RB genes against cultivated types. ii. to precisely screen backcross progenies for resistance to late blight combining marker assisted selection with desired agronomic and quality traits (yield, grade, fresh market or processing). iii. to screen selected potato accessions from the US Potato Gene Bank at Sturgeon Bay for the RB and other genes as possible alternate sources of resistance. iv. to develop a collaborative effort between UW-Madison, UW-Stevens Point and US Potato Gene Bank at Sturgeon Bay. Specifically, for 2006 we: 1). Increased and characterized 276 lines carrying the RB gene responsible for late blight resistance and characterized these lines for quality traits and yield
potential. We have now seed available of these lines that will be used to corroborate resistance at the plant and tuber levels. 2). In collaboration with T. Barta, we developed a detached leaf assay for evaluating resistance to the US8 genotype of P.infestans. In this assay we were evaluating the pathogenicity and virulence of four strains of this organism. This assay is giving satisfactory result. 3. We are in the process of selecting breeding lines that will be backcrossed for the fourth time (BC4) to commercial varieties to incorporate more quality and yield traits. Most exceptional BC3 lines that carry the RB gene, superior quality and yield will be multiplied to be included in replicated trials. 4). In collaboration with J. Bamberg, we have identified S. microdontum and S. okadae as other sources of late blight resistance in wild potatoes. These species have been crossed with diploid S. tuberosum types and tubers from these are now available for use in our breeding program.
Impacts
Growers will benefit with the development and use of resistant potato cultivars due to a decrease in the cost of production due to a reduction in the use of fungicides including mancozeb, dimethomorph, cymoxanil, zoxamide, fluazinam, propamocarb, maneb, chlorothalonil, azoxystrobin, metiram, triphenyltin hydroxide, famoxadone, trifloxystrobin that are applied every year as a preventive measure irrespective of the incidence or the severity of this disease. The pre-emptive applications are done in all US potato growing areas because, once the late blight appears it is too late to contain or control it. In addition, farms and related agribusinesses will also benefit with the development and use of resistant potato cultivars by having sustainable and more secure investments and benefits through years. During the 1995 late blight epidemics that affected the US Columbia Basin, the number of fungicide applications increased from 2.5 to 10. This represented a $30 million
expenses in this region alone reported in 1995 and $70-140 countrywide to control late blight reported in 2003. In relation to the improvement of the quality of life, the public will benefit from the development and adoption of varieties with a broad scope of resistance to different late blight strains due to a reduction of pollution caused by the deposition of fungicides into the environment every year.
Publications
- No publication yet, the project started in July 2006
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