The oxidative burst is a critical early event in plant-pathogen interactions that leads to a localized, programmed cell death (PCD) called the hypersensitive response (HR). The HR and associated PCD retard infection b...The oxidative burst is a critical early event in plant-pathogen interactions that leads to a localized, programmed cell death (PCD) called the hypersensitive response (HR). The HR and associated PCD retard infection by biotrophic pathogens, but can, in fact, enhance infection by necrotrophic pathogens like Botrytis cinerea. In addition to signaling the induction of the HR, reactive oxygen species (ROS) produced during the oxidative burst are?antimicrobial. We hypothesize that pathogens such as B. cinerea survive the antimicrobial effects of ROS, at least partially by secreting the antioxidant mannitol during infection. This is supported by the previous observation that overexpression of the catabolic enzyme mannitol dehydrogenase (MTD) can decrease a plants susceptibility to mannitol-secreting pathogens like B. cinerea. To extend the above hypothesis, and test the general utility of this approach in an important horticultural crop, we overexpressed celery MTD in tomato (Solanum lycopersicum cv. “Moneymaker”). In these studies, we observed a significant increase (up to 90%) in resistance to B. cinerea in transgenic tomatoes expressing high amounts of MTD.展开更多
Late blight (LB), caused by the oomycete Phytophthora infestans, is one of the most devastating diseases of tomato. Three major genes Ph-1, Ph-2 and Ph-3 conferring resistance to LB have been identified and mapped to ...Late blight (LB), caused by the oomycete Phytophthora infestans, is one of the most devastating diseases of tomato. Three major genes Ph-1, Ph-2 and Ph-3 conferring resistance to LB have been identified and mapped to the chromosomes 7, 10 and 9, respectively. However, PCR-based molecular markers associated with these genes are limited. Molecular markers are extremely useful in the screening and selection of tomato lines for the development of LB resistant genotypes. The objective of this study was to identify molecular markers associated with Ph-3 gene conferring LB resistance in tomato. Four co-dominant markers were found to be associated with Ph-3, all of which were sequence characterized amplified region (SCAR) type. Breeding lines and cultivars were inoculated with a field isolate of Phytophthora infestans to collect phenotypic data on disease resistance. Genotypic data from molecular markers associated with Ph-3 were in close agreement with the phenotypic data for the lines tested. With the verification of genotypic data from novel molecular markers in known genotypes supported by phenotypic data, the novel molecular markers may be useful in screening tomato populations aiming to develop LB resistant genotypes or cloning the LB resistant genes.展开更多
Lycopene is a red pigment in tomato with purported antioxidant properties. As the amount of lycopene has been reported to differ in different colored tomatoes or even absent in non-red tomatoes, the objective of this ...Lycopene is a red pigment in tomato with purported antioxidant properties. As the amount of lycopene has been reported to differ in different colored tomatoes or even absent in non-red tomatoes, the objective of this study was to investigate the inheritance of lycopene content and the color parameters of hybrids using a 10 parent diallel excluding reciprocals. Parents differed in general combining ability (GCA) for lycopene and color parameters. “Chocolate Stripe” (purple and brown striped) had the highest lycopene content followed by NC 1CS (red colored with the crimson gene) with the best general combining ability among parental lines. Hybrids differed in lycopene content and color parameters across two summer and greenhouse experiments, with no interaction between experiments indicating that the lycopene content was consistent. Narrow-sense heritability for lycopene was only 9% whereas broad-sense heritability was estimated to be 25%. The order of dominance for lycopene content was found as purple-brown > red > blue > yellow > green. Heritability estimates for color parameters were close to those for lycopene. This information may be useful in developing specialty type tomatoes or increasing lycopene content in tomatoes.展开更多
文摘The oxidative burst is a critical early event in plant-pathogen interactions that leads to a localized, programmed cell death (PCD) called the hypersensitive response (HR). The HR and associated PCD retard infection by biotrophic pathogens, but can, in fact, enhance infection by necrotrophic pathogens like Botrytis cinerea. In addition to signaling the induction of the HR, reactive oxygen species (ROS) produced during the oxidative burst are?antimicrobial. We hypothesize that pathogens such as B. cinerea survive the antimicrobial effects of ROS, at least partially by secreting the antioxidant mannitol during infection. This is supported by the previous observation that overexpression of the catabolic enzyme mannitol dehydrogenase (MTD) can decrease a plants susceptibility to mannitol-secreting pathogens like B. cinerea. To extend the above hypothesis, and test the general utility of this approach in an important horticultural crop, we overexpressed celery MTD in tomato (Solanum lycopersicum cv. “Moneymaker”). In these studies, we observed a significant increase (up to 90%) in resistance to B. cinerea in transgenic tomatoes expressing high amounts of MTD.
文摘Late blight (LB), caused by the oomycete Phytophthora infestans, is one of the most devastating diseases of tomato. Three major genes Ph-1, Ph-2 and Ph-3 conferring resistance to LB have been identified and mapped to the chromosomes 7, 10 and 9, respectively. However, PCR-based molecular markers associated with these genes are limited. Molecular markers are extremely useful in the screening and selection of tomato lines for the development of LB resistant genotypes. The objective of this study was to identify molecular markers associated with Ph-3 gene conferring LB resistance in tomato. Four co-dominant markers were found to be associated with Ph-3, all of which were sequence characterized amplified region (SCAR) type. Breeding lines and cultivars were inoculated with a field isolate of Phytophthora infestans to collect phenotypic data on disease resistance. Genotypic data from molecular markers associated with Ph-3 were in close agreement with the phenotypic data for the lines tested. With the verification of genotypic data from novel molecular markers in known genotypes supported by phenotypic data, the novel molecular markers may be useful in screening tomato populations aiming to develop LB resistant genotypes or cloning the LB resistant genes.
文摘Lycopene is a red pigment in tomato with purported antioxidant properties. As the amount of lycopene has been reported to differ in different colored tomatoes or even absent in non-red tomatoes, the objective of this study was to investigate the inheritance of lycopene content and the color parameters of hybrids using a 10 parent diallel excluding reciprocals. Parents differed in general combining ability (GCA) for lycopene and color parameters. “Chocolate Stripe” (purple and brown striped) had the highest lycopene content followed by NC 1CS (red colored with the crimson gene) with the best general combining ability among parental lines. Hybrids differed in lycopene content and color parameters across two summer and greenhouse experiments, with no interaction between experiments indicating that the lycopene content was consistent. Narrow-sense heritability for lycopene was only 9% whereas broad-sense heritability was estimated to be 25%. The order of dominance for lycopene content was found as purple-brown > red > blue > yellow > green. Heritability estimates for color parameters were close to those for lycopene. This information may be useful in developing specialty type tomatoes or increasing lycopene content in tomatoes.
