michal shoresh - Academia.edu (original) (raw)

Papers by michal shoresh

Springer eBooks, May 16, 2007

Page 1. 7. THE MECHANISMS AND APPLICATIONS OF SYMBIOTIC OPPORTUNISTIC PLANT SYMBIONTS Gary E. Har... more Page 1. 7. THE MECHANISMS AND APPLICATIONS OF SYMBIOTIC OPPORTUNISTIC PLANT SYMBIONTS Gary E. Harman ∗ and Michal Shoresh Department of Horticultural Sciences, Cornell University, Geneva, NY 14456, USA ... Page 2. 132 GE HARMAN AND M. SHORESH ...

BMC Plant Biology, 2010

Background: The interaction of plants with endophytic symbiotic fungi in the genus Trichoderma al... more Background: The interaction of plants with endophytic symbiotic fungi in the genus Trichoderma alters the plant proteome and transcriptome and results in enhanced plant growth and resistance to diseases. In a previous study, we identified the numerous chitinolytic enzyme families and individual enzymes in maize which are implicated in plant disease resistance and other plant responses. Results: We examined the differential expression of the entire suite of chitinolytic enzymes in maize plants in the presence and absence of T. harzianum. Expression of these enzymes revealed a band of chitinolytic enzyme activity that had greater mass than any known chitinase. This study reports the characterization of this large protein. It was found to be a heretofore undiscovered heterodimer between an exo-and an endo-enzyme, and the endo portion differed between plants colonized with T. harzianum and those grown in its absence and between shoots and roots. The heterodimeric enzymes from shoots in the presence and absence of T. harzianum were purified and characterized. The dimeric enzyme from Trichoderma-inoculated plants had higher specific activity and greater ability to inhibit fungal growth than those from control plants. The activity of specific chitinolytic enzymes was higher in plants grown from Trichoderma treated seeds than in control plants. Conclusions: This is the first report of a dimer between endo-and exochitinase. The endochitinase component of the dimer changed post Trichoderma inoculation. The dimer originating from Trichoderma inoculated plants had a higher antifungal activity than the comparable enzyme from control plants.

Genetics, Sep 1, 1998

LIM domains function as bridging modules between different members of multiprotein complexes. We ... more LIM domains function as bridging modules between different members of multiprotein complexes. We report the cloning of a LIM-containing gene from Drosophila, termed Dlmo, which is highly homologous to the vertebrate LIM-only (LMO) genes. The 3Ј untranslated (UTR) of Dlmo contains multiple motifs implicated in negative post-transcriptional regulation, including AT-rich elements and Brd-like boxes. Dlmo resides in polytene band 17C1-2, where Beadex (Bx) and heldup-a (hdp-a) mutations map. We demonstrate that Bx mutations disrupt the 3ЈUTR of Dlmo, and thereby abrogate the putative negative control elements. This results in overexpression of Dlmo, which causes the wing scalloping that is typical of Bx mutants. We show that the erect wing phenotype of hdp-a results from disruption of the coding region of Dlmo. This provides molecular grounds for the suppression of the Bx phenotype by hdp-a mutations. Finally, we demonstrate phenotypic interaction between the LMO gene Dlmo, the LIM homeodomain gene apterous, and the Chip gene, which encodes a homolog of the vertebrate LIM-interacting protein NLI/Ldb1. We propose that in analogy to their vertebrate counterparts, these proteins form a DNAbinding complex that regulates wing development.

Plant Physiology, Sep 1, 2006

The fungal biocontrol agent Trichoderma asperellum has been recently shown to induce systemic res... more The fungal biocontrol agent Trichoderma asperellum has been recently shown to induce systemic resistance in plants through a mechanism that employs jasmonic acid and ethylene signal transduction pathways. Mitogen-activated protein kinase (MAPK) proteins have been implicated in the signal transduction of a wide variety of plant stress responses. Here we report the identification and characterization of a Trichoderma-induced MAPK (TIPK) gene function in cucumber (Cucumis sativus). Similar to its homologs, wound-induced protein kinase, MPK3, and MPK3a, TIPK is also induced by wounding. Normally, preinoculation of roots with Trichoderma activates plant defense mechanisms, which result in resistance to the leaf pathogen Pseudomonas syringae pv lachrymans. We used a unique attenuated virus vector, Zucchini yellow mosaic virus (ZYMV-AGII), to overexpress TIPK protein and antisense (AS) RNA. Plants overexpressing TIPK were more resistant to pathogenic bacterial attack than control plants, even in the absence of Trichoderma preinoculation. On the other hand, plants expressing TIPK-AS revealed increased sensitivity to pathogen attack. Moreover, Trichoderma preinoculation could not protect these AS plants against subsequent pathogen attack. We therefore demonstrate that Trichoderma exerts its protective effect on plants through activation of the TIPK gene, a MAPK that is involved in signal transduction pathways of defense responses.

Vaccine, Feb 1, 1999

Administration of vaccinia immune globulin (VIG), derived from vaccinated healthy adult volunteer... more Administration of vaccinia immune globulin (VIG), derived from vaccinated healthy adult volunteers, is the treatment-ofchoice for patients suering from severe complications following smallpox vaccination. The present study was aimed to determine the time interval after vaccination, at which the highest titer of neutralizing antibodies is obtained. Ninety-nine 18year-old soldiers, immunized with vaccinia virus at birth, participated in the study, 87 of whom had detectable antibodies against vaccinia virus prior to re-vaccination. Their initial average neutralizing antibodies titer (NT 50) was 27. Fourteen days after re-vaccination the titer reached 152 and then dropped to 136, 119, 110 and 87 at 21, 30, 45 and 60 d, respectively. The titers of vaccinia antibodies induced in vaccinees without detectable antibodies at the start of the study, were signi®cantly lower and the titers observed after re-vaccination were: 62, 56, 66, 38 and 34, at 14, 21, 30, 45 and 60 d, respectively. In an additional study, 65 volunteers vaccinated at birth and again at the age of 8 years old were re-vaccinated. Fourteen days later their NT 50 was higher than those vaccinated only at birth. It can be concluded that bleeding of vaccinees 14 d following re-vaccination is the preferable time for the preparation of VIG.

Israel Journal of Plant Sciences, Dec 1, 2011

ABSTRACT

Molecular Genetics and Genomics, 2002

Congenic lines that differ in a single defined chromosome segment are useful for the study of com... more Congenic lines that differ in a single defined chromosome segment are useful for the study of complex phenotypes, as they allow isolation of the effect of a particular quantitative trait locus (QTL) from those of the entire genome. We conducted high-resolution QTL mapping of a 9-cM introgression, originating from the wild tomato species Lycopersicon pennellii, in two extremely different genetic and physiological backgrounds. In the "indeterminate" glasshouse background we identified only a single QTL ( Brix9-2-5) that affects the total soluble solids of the fruit [mainly sugars, measured in Brix units (B)]. This QTL was previously delimited within the gene for an apoplastic invertase, Lin5, that modulates sugar partitioning to the fruit. Analysis of the effects of the same chromosome segment in "determinate", open-field tomatoes, revealed two QTLs, 0.3 cM apart: the fruit-specific Brix9-2-5 that affects B only, and the shoot-specific PW9-2-5, which accounts for an altered growth habit resulting in increases in plant weight, yield, and B. This study highlights the power of the congenic approach for dissecting developmental pathways leading to complex phenotypes.

Growing awareness of the environmental damage caused by the use of chemical substances for plant ... more Growing awareness of the environmental damage caused by the use of chemical substances for plant disease control in agriculture has raised the need to study biological alternatives, such as activating the defense response of plant crops by inducers not toxic to the environment. Trichoderma spp. are effective biocontrol agents for a number of soilborne pathogens, and are also known for their ability to enhance plant growth and to induce systemic resistance (ISR) in plants.

Free Radical Biology and Medicine, Jan 1, 2011

Salinity reduces Ca(2+) availability, transport, and mobility to growing regions of the plant and... more Salinity reduces Ca(2+) availability, transport, and mobility to growing regions of the plant and supplemental Ca(2+) is known to reduce salinity damages. This study was undertaken to unravel some of the ameliorative mechanisms of Ca(2+) on salt stress at the cellular and tissue levels. Zea mays L. plants were grown in nutrient solution containing 1 or 80 mM NaCl with various Ca(2+) levels. Measurements of growth and physiological parameters, such as ion imbalance, indicated that the Ca(2+)-induced alleviation mechanisms differed between plant organs. Under salinity, H(2)O(2) levels increased in the leaf-growing tissue with increasing levels of supplemental Ca(2+) and reached the levels of control plants, whereas superoxide levels remained low at all Ca(2+) levels, indicating that Ca(2+) affected growth by increasing H(2)O(2) but not superoxide levels. Salinity completely abolished apoplastic peroxidase activity. Supplemental Ca(2+) increased its activity only slightly. However, under salinity, polyamine oxidase (PAO) activity was shifted toward the leaf base probably as an adaptive mechanism aimed at restoring normal levels of reactive oxygen species (ROS) at the expansion zone where NADPH oxidase could no longer provide the required ROS for growth. Interestingly, addition of Ca(2+) shifted the PAO-activity peak back to its original location in addition to its enhancement. The increase in PAO activity in conjunction with low levels of apoplastic peroxidase is supportive of cellular growth via nonenzymatic wall loosening derived by the increase in H(2)O(2) and less supportive of the peroxidase-mediated cross-linking of wall material. Thus extracellular Ca(2+) can modulate ROS levels at specific tissue localization and developmental stages thereby affecting cellular extension.

Israel Journal of Plant …, Jan 1, 2011

Shortage of water in Israel necessitates utilization of increasing volumes of marginal water for ... more Shortage of water in Israel necessitates utilization of increasing volumes of marginal water for irrigation. Marginal water is characterized by higher concentrations of heavy metals then the potable water from which they were derived. Over time, irrigation with treated water ...

Viral …, Jan 1, 1998

A colorimetric assay for titration of neutralizing antibodies against vaccinia virus was develope... more A colorimetric assay for titration of neutralizing antibodies against vaccinia virus was developed. The test is based on the ability of live cells in culture to reduce the yellow tetrazolium salt MTT (thiazolyl-blue), to its blue formazan derivative. Antisera from individuals vaccinated with vaccinia virus against smallpox were serially diluted, incubated with 100 plaque-forming units (PFU) of vaccinia virus for 1 hour at 37 degrees C, and then transferred to a 96-well plate containing monolayers of B-SC-1 cells. After incubation for 3 to 4 days at 37 degrees C, when more than 80% of the control infected cultures exhibited high degree of cytopathogenic effect, MTT was added. The absorbance of the formazan formed and extracted by dimethylsulfoxide was read at 492 nm by an automatic microplate spectrophotometer. A good correlation was found between the results obtained using this newly developed method and those of the plaque-reduction assay.

BMC plant biology, Jan 1, 2010

Background: The interaction of plants with endophytic symbiotic fungi in the genus Trichoderma al... more Background: The interaction of plants with endophytic symbiotic fungi in the genus Trichoderma alters the plant proteome and transcriptome and results in enhanced plant growth and resistance to diseases. In a previous study, we identified the numerous chitinolytic enzyme families and individual enzymes in maize which are implicated in plant disease resistance and other plant responses.

Outlooks on Pest …, Jan 1, 2008

Free Radical Biology and …, Jan 1, 2010

Sensitivity to salinity varies between plant organs and between cells of different developmental ... more Sensitivity to salinity varies between plant organs and between cells of different developmental stages within a single organ. The physiological and molecular bases for the differential responses are not known. Exposure of plants to salinity is known to induce formation of reactive oxygen species (ROS), which are involved in damage mechanisms but also in cell growth processes. The objective of this study was to elucidate developmental-stage-specific and organ-specific involvement of oxidative defense in the plant response to salinity in maize (Zea mays L.). Plants were grown in nutrient solution containing 1mM NaCl (control) or 80mM NaCl. The oxidative stress response and damage symptoms along the cell developmental gradient in growing and mature tissue of leaves and roots were examined. Unlike leaves, roots did not suffer oxidative damage in either growing or mature cells and demonstrated reduced antioxidant response. This may reflect different requirements of ROS for growth mechanisms of leaf and root cells. In leaves, growing tissue demonstrated higher stimulation of superoxide dismutase (SOD) and ascorbate peroxidase (APX) activity under salinity than mature tissue, whereas mature tissue demonstrated higher stimulation of catalase. These results indicate differential roles for these ROS-scavenging enzymes at different cell developmental stages. Because ROS are required for cell expansion, the higher increase in SOD and APX activities in the growing leaf cells that resulted in reduction of ROS content under salinity could lead to the inhibition of cell growth under salinity.

Plant Signaling & Behavior, Jan 1, 2008

Trichoderma spp. are effective biocontrol agents for numerous foliar and root phytopathogens, and... more Trichoderma spp. are effective biocontrol agents for numerous foliar and root phytopathogens, and some are also known for their abilities to enhance systemic resistance to plant diseases as well as overall plant growth. Root colonization with T. harzianum strain T22 induces large changes in the proteome of shoots of maize seedlings (Zea mays) even though T22 is present only on roots; changes also were recorded in the roots. In shoots, we identified 91 of 114 upregulated and 30 of 50 downregulated proteins. In roots, 20 upregulated and 11 downregulated proteins were found and 17 and eight, respectively, were identified. Classification of proteins differentially expressed in both shoots and roots revealed that the largest number of upregulated proteins was involved in carbohydrate metabolism; in shoots, some upregulated proteins were involved in photosynthesis. Increases in these protein classifications suggest enhanced respiratory and photosynthetic rates. These changes may be required for the enhanced growth response induced by colonization of Trichoderma following seed or soil treatments. Stress and defense related proteins that were upregulated probably are related to the enhanced resistance conferred by the Trichoderma inoculation. We suggest that Trichoderma induces both increased growth, which is mediated by an increase in photosynthetic and respiratory rates, and systemic induced resistance. These two general effects may be mediated by different elicitors.

Novel Biotechnologies for Biocontrol Agent …, Jan 1, 2007

Page 1. 7. THE MECHANISMS AND APPLICATIONS OF SYMBIOTIC OPPORTUNISTIC PLANT SYMBIONTS Gary E. Har... more Page 1. 7. THE MECHANISMS AND APPLICATIONS OF SYMBIOTIC OPPORTUNISTIC PLANT SYMBIONTS Gary E. Harman ∗ and Michal Shoresh Department of Horticultural Sciences, Cornell University, Geneva, NY 14456, USA ... Page 2. 132 GE HARMAN AND M. SHORESH ...

Springer eBooks, May 16, 2007

Page 1. 7. THE MECHANISMS AND APPLICATIONS OF SYMBIOTIC OPPORTUNISTIC PLANT SYMBIONTS Gary E. Har... more Page 1. 7. THE MECHANISMS AND APPLICATIONS OF SYMBIOTIC OPPORTUNISTIC PLANT SYMBIONTS Gary E. Harman ∗ and Michal Shoresh Department of Horticultural Sciences, Cornell University, Geneva, NY 14456, USA ... Page 2. 132 GE HARMAN AND M. SHORESH ...

BMC Plant Biology, 2010

Background: The interaction of plants with endophytic symbiotic fungi in the genus Trichoderma al... more Background: The interaction of plants with endophytic symbiotic fungi in the genus Trichoderma alters the plant proteome and transcriptome and results in enhanced plant growth and resistance to diseases. In a previous study, we identified the numerous chitinolytic enzyme families and individual enzymes in maize which are implicated in plant disease resistance and other plant responses. Results: We examined the differential expression of the entire suite of chitinolytic enzymes in maize plants in the presence and absence of T. harzianum. Expression of these enzymes revealed a band of chitinolytic enzyme activity that had greater mass than any known chitinase. This study reports the characterization of this large protein. It was found to be a heretofore undiscovered heterodimer between an exo-and an endo-enzyme, and the endo portion differed between plants colonized with T. harzianum and those grown in its absence and between shoots and roots. The heterodimeric enzymes from shoots in the presence and absence of T. harzianum were purified and characterized. The dimeric enzyme from Trichoderma-inoculated plants had higher specific activity and greater ability to inhibit fungal growth than those from control plants. The activity of specific chitinolytic enzymes was higher in plants grown from Trichoderma treated seeds than in control plants. Conclusions: This is the first report of a dimer between endo-and exochitinase. The endochitinase component of the dimer changed post Trichoderma inoculation. The dimer originating from Trichoderma inoculated plants had a higher antifungal activity than the comparable enzyme from control plants.

Genetics, Sep 1, 1998

LIM domains function as bridging modules between different members of multiprotein complexes. We ... more LIM domains function as bridging modules between different members of multiprotein complexes. We report the cloning of a LIM-containing gene from Drosophila, termed Dlmo, which is highly homologous to the vertebrate LIM-only (LMO) genes. The 3Ј untranslated (UTR) of Dlmo contains multiple motifs implicated in negative post-transcriptional regulation, including AT-rich elements and Brd-like boxes. Dlmo resides in polytene band 17C1-2, where Beadex (Bx) and heldup-a (hdp-a) mutations map. We demonstrate that Bx mutations disrupt the 3ЈUTR of Dlmo, and thereby abrogate the putative negative control elements. This results in overexpression of Dlmo, which causes the wing scalloping that is typical of Bx mutants. We show that the erect wing phenotype of hdp-a results from disruption of the coding region of Dlmo. This provides molecular grounds for the suppression of the Bx phenotype by hdp-a mutations. Finally, we demonstrate phenotypic interaction between the LMO gene Dlmo, the LIM homeodomain gene apterous, and the Chip gene, which encodes a homolog of the vertebrate LIM-interacting protein NLI/Ldb1. We propose that in analogy to their vertebrate counterparts, these proteins form a DNAbinding complex that regulates wing development.

Plant Physiology, Sep 1, 2006

The fungal biocontrol agent Trichoderma asperellum has been recently shown to induce systemic res... more The fungal biocontrol agent Trichoderma asperellum has been recently shown to induce systemic resistance in plants through a mechanism that employs jasmonic acid and ethylene signal transduction pathways. Mitogen-activated protein kinase (MAPK) proteins have been implicated in the signal transduction of a wide variety of plant stress responses. Here we report the identification and characterization of a Trichoderma-induced MAPK (TIPK) gene function in cucumber (Cucumis sativus). Similar to its homologs, wound-induced protein kinase, MPK3, and MPK3a, TIPK is also induced by wounding. Normally, preinoculation of roots with Trichoderma activates plant defense mechanisms, which result in resistance to the leaf pathogen Pseudomonas syringae pv lachrymans. We used a unique attenuated virus vector, Zucchini yellow mosaic virus (ZYMV-AGII), to overexpress TIPK protein and antisense (AS) RNA. Plants overexpressing TIPK were more resistant to pathogenic bacterial attack than control plants, even in the absence of Trichoderma preinoculation. On the other hand, plants expressing TIPK-AS revealed increased sensitivity to pathogen attack. Moreover, Trichoderma preinoculation could not protect these AS plants against subsequent pathogen attack. We therefore demonstrate that Trichoderma exerts its protective effect on plants through activation of the TIPK gene, a MAPK that is involved in signal transduction pathways of defense responses.

Vaccine, Feb 1, 1999

Administration of vaccinia immune globulin (VIG), derived from vaccinated healthy adult volunteer... more Administration of vaccinia immune globulin (VIG), derived from vaccinated healthy adult volunteers, is the treatment-ofchoice for patients suering from severe complications following smallpox vaccination. The present study was aimed to determine the time interval after vaccination, at which the highest titer of neutralizing antibodies is obtained. Ninety-nine 18year-old soldiers, immunized with vaccinia virus at birth, participated in the study, 87 of whom had detectable antibodies against vaccinia virus prior to re-vaccination. Their initial average neutralizing antibodies titer (NT 50) was 27. Fourteen days after re-vaccination the titer reached 152 and then dropped to 136, 119, 110 and 87 at 21, 30, 45 and 60 d, respectively. The titers of vaccinia antibodies induced in vaccinees without detectable antibodies at the start of the study, were signi®cantly lower and the titers observed after re-vaccination were: 62, 56, 66, 38 and 34, at 14, 21, 30, 45 and 60 d, respectively. In an additional study, 65 volunteers vaccinated at birth and again at the age of 8 years old were re-vaccinated. Fourteen days later their NT 50 was higher than those vaccinated only at birth. It can be concluded that bleeding of vaccinees 14 d following re-vaccination is the preferable time for the preparation of VIG.

Israel Journal of Plant Sciences, Dec 1, 2011

ABSTRACT

Molecular Genetics and Genomics, 2002

Congenic lines that differ in a single defined chromosome segment are useful for the study of com... more Congenic lines that differ in a single defined chromosome segment are useful for the study of complex phenotypes, as they allow isolation of the effect of a particular quantitative trait locus (QTL) from those of the entire genome. We conducted high-resolution QTL mapping of a 9-cM introgression, originating from the wild tomato species Lycopersicon pennellii, in two extremely different genetic and physiological backgrounds. In the "indeterminate" glasshouse background we identified only a single QTL ( Brix9-2-5) that affects the total soluble solids of the fruit [mainly sugars, measured in Brix units (B)]. This QTL was previously delimited within the gene for an apoplastic invertase, Lin5, that modulates sugar partitioning to the fruit. Analysis of the effects of the same chromosome segment in "determinate", open-field tomatoes, revealed two QTLs, 0.3 cM apart: the fruit-specific Brix9-2-5 that affects B only, and the shoot-specific PW9-2-5, which accounts for an altered growth habit resulting in increases in plant weight, yield, and B. This study highlights the power of the congenic approach for dissecting developmental pathways leading to complex phenotypes.

Growing awareness of the environmental damage caused by the use of chemical substances for plant ... more Growing awareness of the environmental damage caused by the use of chemical substances for plant disease control in agriculture has raised the need to study biological alternatives, such as activating the defense response of plant crops by inducers not toxic to the environment. Trichoderma spp. are effective biocontrol agents for a number of soilborne pathogens, and are also known for their ability to enhance plant growth and to induce systemic resistance (ISR) in plants.

Free Radical Biology and Medicine, Jan 1, 2011

Salinity reduces Ca(2+) availability, transport, and mobility to growing regions of the plant and... more Salinity reduces Ca(2+) availability, transport, and mobility to growing regions of the plant and supplemental Ca(2+) is known to reduce salinity damages. This study was undertaken to unravel some of the ameliorative mechanisms of Ca(2+) on salt stress at the cellular and tissue levels. Zea mays L. plants were grown in nutrient solution containing 1 or 80 mM NaCl with various Ca(2+) levels. Measurements of growth and physiological parameters, such as ion imbalance, indicated that the Ca(2+)-induced alleviation mechanisms differed between plant organs. Under salinity, H(2)O(2) levels increased in the leaf-growing tissue with increasing levels of supplemental Ca(2+) and reached the levels of control plants, whereas superoxide levels remained low at all Ca(2+) levels, indicating that Ca(2+) affected growth by increasing H(2)O(2) but not superoxide levels. Salinity completely abolished apoplastic peroxidase activity. Supplemental Ca(2+) increased its activity only slightly. However, under salinity, polyamine oxidase (PAO) activity was shifted toward the leaf base probably as an adaptive mechanism aimed at restoring normal levels of reactive oxygen species (ROS) at the expansion zone where NADPH oxidase could no longer provide the required ROS for growth. Interestingly, addition of Ca(2+) shifted the PAO-activity peak back to its original location in addition to its enhancement. The increase in PAO activity in conjunction with low levels of apoplastic peroxidase is supportive of cellular growth via nonenzymatic wall loosening derived by the increase in H(2)O(2) and less supportive of the peroxidase-mediated cross-linking of wall material. Thus extracellular Ca(2+) can modulate ROS levels at specific tissue localization and developmental stages thereby affecting cellular extension.

Israel Journal of Plant …, Jan 1, 2011

Shortage of water in Israel necessitates utilization of increasing volumes of marginal water for ... more Shortage of water in Israel necessitates utilization of increasing volumes of marginal water for irrigation. Marginal water is characterized by higher concentrations of heavy metals then the potable water from which they were derived. Over time, irrigation with treated water ...

Viral …, Jan 1, 1998

A colorimetric assay for titration of neutralizing antibodies against vaccinia virus was develope... more A colorimetric assay for titration of neutralizing antibodies against vaccinia virus was developed. The test is based on the ability of live cells in culture to reduce the yellow tetrazolium salt MTT (thiazolyl-blue), to its blue formazan derivative. Antisera from individuals vaccinated with vaccinia virus against smallpox were serially diluted, incubated with 100 plaque-forming units (PFU) of vaccinia virus for 1 hour at 37 degrees C, and then transferred to a 96-well plate containing monolayers of B-SC-1 cells. After incubation for 3 to 4 days at 37 degrees C, when more than 80% of the control infected cultures exhibited high degree of cytopathogenic effect, MTT was added. The absorbance of the formazan formed and extracted by dimethylsulfoxide was read at 492 nm by an automatic microplate spectrophotometer. A good correlation was found between the results obtained using this newly developed method and those of the plaque-reduction assay.

BMC plant biology, Jan 1, 2010

Background: The interaction of plants with endophytic symbiotic fungi in the genus Trichoderma al... more Background: The interaction of plants with endophytic symbiotic fungi in the genus Trichoderma alters the plant proteome and transcriptome and results in enhanced plant growth and resistance to diseases. In a previous study, we identified the numerous chitinolytic enzyme families and individual enzymes in maize which are implicated in plant disease resistance and other plant responses.

Outlooks on Pest …, Jan 1, 2008

Free Radical Biology and …, Jan 1, 2010

Sensitivity to salinity varies between plant organs and between cells of different developmental ... more Sensitivity to salinity varies between plant organs and between cells of different developmental stages within a single organ. The physiological and molecular bases for the differential responses are not known. Exposure of plants to salinity is known to induce formation of reactive oxygen species (ROS), which are involved in damage mechanisms but also in cell growth processes. The objective of this study was to elucidate developmental-stage-specific and organ-specific involvement of oxidative defense in the plant response to salinity in maize (Zea mays L.). Plants were grown in nutrient solution containing 1mM NaCl (control) or 80mM NaCl. The oxidative stress response and damage symptoms along the cell developmental gradient in growing and mature tissue of leaves and roots were examined. Unlike leaves, roots did not suffer oxidative damage in either growing or mature cells and demonstrated reduced antioxidant response. This may reflect different requirements of ROS for growth mechanisms of leaf and root cells. In leaves, growing tissue demonstrated higher stimulation of superoxide dismutase (SOD) and ascorbate peroxidase (APX) activity under salinity than mature tissue, whereas mature tissue demonstrated higher stimulation of catalase. These results indicate differential roles for these ROS-scavenging enzymes at different cell developmental stages. Because ROS are required for cell expansion, the higher increase in SOD and APX activities in the growing leaf cells that resulted in reduction of ROS content under salinity could lead to the inhibition of cell growth under salinity.

Plant Signaling & Behavior, Jan 1, 2008

Trichoderma spp. are effective biocontrol agents for numerous foliar and root phytopathogens, and... more Trichoderma spp. are effective biocontrol agents for numerous foliar and root phytopathogens, and some are also known for their abilities to enhance systemic resistance to plant diseases as well as overall plant growth. Root colonization with T. harzianum strain T22 induces large changes in the proteome of shoots of maize seedlings (Zea mays) even though T22 is present only on roots; changes also were recorded in the roots. In shoots, we identified 91 of 114 upregulated and 30 of 50 downregulated proteins. In roots, 20 upregulated and 11 downregulated proteins were found and 17 and eight, respectively, were identified. Classification of proteins differentially expressed in both shoots and roots revealed that the largest number of upregulated proteins was involved in carbohydrate metabolism; in shoots, some upregulated proteins were involved in photosynthesis. Increases in these protein classifications suggest enhanced respiratory and photosynthetic rates. These changes may be required for the enhanced growth response induced by colonization of Trichoderma following seed or soil treatments. Stress and defense related proteins that were upregulated probably are related to the enhanced resistance conferred by the Trichoderma inoculation. We suggest that Trichoderma induces both increased growth, which is mediated by an increase in photosynthetic and respiratory rates, and systemic induced resistance. These two general effects may be mediated by different elicitors.

Novel Biotechnologies for Biocontrol Agent …, Jan 1, 2007

Page 1. 7. THE MECHANISMS AND APPLICATIONS OF SYMBIOTIC OPPORTUNISTIC PLANT SYMBIONTS Gary E. Har... more Page 1. 7. THE MECHANISMS AND APPLICATIONS OF SYMBIOTIC OPPORTUNISTIC PLANT SYMBIONTS Gary E. Harman ∗ and Michal Shoresh Department of Horticultural Sciences, Cornell University, Geneva, NY 14456, USA ... Page 2. 132 GE HARMAN AND M. SHORESH ...