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Search Results: 1 - 10 of 325367 matches for " Kirankumar?S. Mysore "
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Arabidopsis genome sequence as a tool for functional genomics in tomato
Kirankumar S Mysore, Robert P Tuori, Gregory B Martin
Genome Biology , 2001, DOI: 10.1186/gb-2001-2-1-reviews1003
Abstract: Arabidopsis thaliana is widely used as a model for the study of many aspects of plant biology. Because of its small genome size (125 Mb) it was chosen as the subject of the first plant genome sequencing project, an effort that was recently completed [1,2]. The availability of the Arabidopsis genome sequence will greatly enhance our knowledge of the entire complement of genes expressed by a typical flowering plant and will lead to a thorough analysis of the function of these genes. A comprehensive molecular-marker-based linkage map exists for Arabidopsis, and the map-based cloning of genes conferring specific phenotypes will become even easier with the availability of genomic sequence information [3]. In addition to map-based cloning, several other approaches for isolating and determining the function of specific genes are available in Arabidopsis including T-DNA and activation tagging, transposon tagging, and various gene silencing methods [4,5,6,7,8,9]. The many resources available for the Arabidopsis experimental system also make it an ideal springboard for understanding the function of genes in economically important plants, such as tomato.Tomato is a member of the Solanaceae family, a widely distributed group of plants to which many other economically important species also belong, including potato, pepper, eggplant, tobacco, and Petunia. In addition to its economic importance, several features make tomato an excellent species for understanding basic plant biology. Tomato is diploid, has a relatively small genome (950 Mb), has a moderately short life cycle, tolerates inbreeding yet is easily cross-hybridized, and is easy to grow and maintain. Recently, a miniature tomato variety with an accelerated life cycle has been developed and is gaining favor among tomato researchers [10,11]. As a result of intensive breeding and genetic research over the past 50 years, many resources are available for tomato studies, including extensive germplasm collections of wild and c
Arabidopsis seedling flood-inoculation technique: a rapid and reliable assay for studying plant-bacterial interactions
Yasuhiro Ishiga, Takako Ishiga, Srinivasa R Uppalapati, Kirankumar S Mysore
Plant Methods , 2011, DOI: 10.1186/1746-4811-7-32
Abstract: In this study, we developed a rapid and reliable seedling flood-inoculation method based on young Arabidopsis seedlings grown on MS medium. This method has several advantages over conventional soil-grown plant inoculation assays, including a shorter growth and incubation period, ease of inoculation and handling, uniform infection and disease development, requires less growth chamber space and is suitable for high-throughput screens. In this study we demonstrated the efficacy of the Arabidopsis seedling assay to study 1) the virulence factors of P. syringae pv. tomato DC3000, including type III protein secretion system (TTSS) and phytotoxin coronatine (COR); 2) the effector-triggered immunity; and 3) Arabidopsis mutants affected in salicylic acid (SA)- and pathogen-associated molecular pattern (PAMPs)-mediated pathways. Furthermore, we applied this technique to study nonhost resistance (NHR) responses in Arabidopsis using nonhost pathogens, such as P. syringae pv. tabaci, pv. glycinea and pv. tomato T1, and confirmed the functional role of FLAGELLIN-SENSING 2 (FLS2) in NHR.The Arabidopsis seedling flood-inoculation assay provides a rapid, efficient and economical method for studying Arabidopsis-Pseudomonas interactions with minimal growth chamber space and time. This assay could also provide an excellent system for investigating the virulence mechanisms of P. syringae. Using this method, we demonstrated that FLS2 plays a critical role in conferring NHR against nonhost pathovars of P. syringae, but not to Xanthomonas campestris pv. vesicatoria. This method is potentially ideal for high-throughput screening of both Arabidopsis and pathogen mutants.One of the model pathosystems for the study of plant-pathogen interactions is Arabidopsis thaliana-Pseudomonas syringae interaction [1]. This model system has been widely used to understand a number of dynamic and complex molecular events in both resistance and susceptible interactions. In addition, P. syringae pvs. tomato an
Coronatine inhibits stomatal closure and delays hypersensitive response cell death induced by nonhost bacterial pathogens
Seonghee Lee,Yasuhiro Ishiga,Kristen Clermont,KirankumarS. Mysore
PeerJ , 2013, DOI: 10.7717/peerj.34
Abstract: Pseudomonas syringae is the most widespread bacterial pathogen in plants. Several strains of P. syringae produce a phytotoxin, coronatine (COR), which acts as a jasmonic acid mimic and inhibits plant defense responses and contributes to disease symptom development. In this study, we found that COR inhibits early defense responses during nonhost disease resistance. Stomatal closure induced by a nonhost pathogen, P. syringae pv. tabaci, was disrupted by COR in tomato epidermal peels. In addition, nonhost HR cell death triggered by P. syringae pv. tabaci on tomato was remarkably delayed when COR was supplemented along with P. syringae pv. tabaci inoculation. Using isochorismate synthase (ICS)-silenced tomato plants and transcript profiles of genes in SA- and JA-related defense pathways, we show that COR suppresses SA-mediated defense during nonhost resistance.
Jasmonate ZIM-Domain (JAZ) Protein Regulates Host and Nonhost Pathogen-Induced Cell Death in Tomato and Nicotiana benthamiana
Yasuhiro Ishiga, Takako Ishiga, Srinivasa Rao Uppalapati, Kirankumar S. Mysore
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0075728
Abstract: The nonhost-specific phytotoxin coronatine (COR) produced by several pathovars of Pseudomonas syringae functions as a jasmonic acid-isoleucine (JA-Ile) mimic and contributes to disease development by suppressing plant defense responses and inducing reactive oxygen species in chloroplast. It has been shown that the F-box protein CORONATINE INSENSITIVE 1 (COI1) is the receptor for COR and JA-Ile. JASMONATE ZIM DOMAIN (JAZ) proteins act as negative regulators for JA signaling in Arabidopsis. However, the physiological significance of JAZ proteins in P. syringae disease development and nonhost pathogen-induced hypersensitive response (HR) cell death is not completely understood. In this study, we identified JAZ genes from tomato, a host plant for P. syringae pv. tomato DC3000 (Pst DC3000), and examined their expression profiles in response to COR and pathogens. Most JAZ genes were induced by COR treatment or inoculation with COR-producing Pst DC3000, but not by the COR-defective mutant DB29. Tomato SlJAZ2, SlJAZ6 and SlJAZ7 interacted with SlCOI1 in a COR-dependent manner. Using virus-induced gene silencing (VIGS), we demonstrated that SlJAZ2, SlJAZ6 and SlJAZ7 have no effect on COR-induced chlorosis in tomato and Nicotiana benthamiana. However, SlJAZ2-, SlJAZ6- and SlJAZ7-silenced tomato plants showed enhanced disease-associated cell death to Pst DC3000. Furthermore, we found delayed HR cell death in response to the nonhost pathogen Pst T1 or a pathogen-associated molecular pattern (PAMP), INF1, in SlJAZ2- and SlJAZ6-silenced N. benthamiana. These results suggest that tomato JAZ proteins regulate the progression of cell death during host and nonhost interactions.
Virus-induced gene silencing is a versatile tool for unraveling the functional relevance of multiple abiotic-stress-responsive genes in crop plants
Venkategowda Ramegowda,Kirankumar S. Mysore,Muthappa Senthil-Kumar
Frontiers in Plant Science , 2014, DOI: 10.3389/fpls.2014.00323
Abstract: Virus-induced gene silencing (VIGS) is an effective tool for gene function analysis in plants. Over the last decade, VIGS has been successfully used as both a forward and reverse genetics technique for gene function analysis in various model plants, as well as crop plants. With the increased identification of differentially expressed genes under various abiotic stresses through high-throughput transcript profiling, the application of VIGS is expected to be important in the future for functional characterization of a large number of genes. In the recent past, VIGS was proven to be an elegant tool for functional characterization of genes associated with abiotic stress responses. In this review, we provide an overview of how VIGS is used in different crop species to characterize genes associated with drought-, salt-, oxidative- and nutrient-deficiency-stresses. We describe the examples from studies where abiotic stress related genes are characterized using VIGS. In addition, we describe the major advantages of VIGS over other currently available functional genomics tools. We also summarize the recent improvements, limitations and future prospects of using VIGS as a tool for studying plant responses to abiotic stress.
Drought Stress Acclimation Imparts Tolerance to Sclerotinia sclerotiorum and Pseudomonas syringae in Nicotiana benthamiana
Venkategowda Ramegowda,Muthappa Senthil-Kumar,Yasuhiro Ishiga,Amita Kaundal,Makarla Udayakumar,Kirankumar S. Mysore
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms14059497
Abstract: Acclimation of plants with an abiotic stress can impart tolerance to some biotic stresses. Such a priming response has not been widely studied. In particular, little is known about enhanced defense capacity of drought stress acclimated plants to fungal and bacterial pathogens. Here we show that prior drought acclimation in Nicotiana benthamiana plants imparts tolerance to necrotrophic fungus, Sclerotinia sclerotiorum, and also to hemi-biotrophic bacterial pathogen, Pseudomonas syringae pv. tabaci. S. sclerotiorum inoculation on N. benthamiana plants acclimated with drought stress lead to less disease-induced cell death compared to non-acclimated plants. Furthermore, inoculation of P. syringae pv. tabaci on N. benthamiana plants acclimated to moderate drought stress showed reduced disease symptoms. The levels of reactive oxygen species (ROS) in drought acclimated plants were highly correlated with disease resistance. Further, in planta growth of GFPuv expressing P. syringae pv. tabaci on plants pre-treated with methyl viologen showed complete inhibition of bacterial growth. Taken together, these experimental results suggested a role for ROS generated during drought acclimation in imparting tolerance against S. sclerotiorum and P. syringae pv. tabaci. We speculate that the generation of ROS during drought acclimation primed a defense response in plants that subsequently caused the tolerance against the pathogens tested.
Arabidopsis Heterotrimeric G-Proteins Play a Critical Role in Host and Nonhost Resistance against Pseudomonas syringae Pathogens
Seonghee Lee, Clemencia M. Rojas, Yasuhiro Ishiga, Sona Pandey, Kirankumar S. Mysore
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0082445
Abstract: Heterotrimeric G-proteins have been proposed to be involved in many aspects of plant disease resistance but their precise role in mediating nonhost disease resistance is not well understood. We evaluated the roles of specific subunits of heterotrimeric G-proteins using knock-out mutants of Arabidopsis Gα, Gβ and Gγ subunits in response to host and nonhost Pseudomonas pathogens. Plants lacking functional Gα, Gβ and Gγ1Gγ2 proteins displayed enhanced bacterial growth and disease susceptibility in response to host and nonhost pathogens. Mutations of single Gγ subunits Gγ1, Gγ2 and Gγ3 did not alter bacterial disease resistance. Some specificity of subunit usage was observed when comparing host pathogen versus nonhost pathogen. Overexpression of both Gα and Gβ led to reduced bacterial multiplication of nonhost pathogen P. syringae pv. tabaci whereas overexpression of Gβ, but not of Gα, resulted in reduced bacterial growth of host pathogen P. syringae pv. maculicola, compared to wild-type Col-0. Moreover, the regulation of stomatal aperture by bacterial pathogens was altered in Gα and Gβ mutants but not in any of the single or double Gγ mutants. Taken together, these data substantiate the critical role of heterotrimeric G-proteins in plant innate immunity and stomatal modulation in response to P. syringae.
Agrobacterium-Mediated Transformation of Tomato with rolB Gene Results in Enhancement of Fruit Quality and Foliar Resistance against Fungal Pathogens
Waheed Arshad, Ihsan-ul- Haq, Mohammad Tahir Waheed, Kirankumar S. Mysore, Bushra Mirza
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0096979
Abstract: Tomato (Solanum lycopersicum L.) is the second most important cultivated crop next to potato, worldwide. Tomato serves as an important source of antioxidants in human diet. Alternaria solani and Fusarium oxysporum cause early blight and vascular wilt of tomato, respectively, resulting in severe crop losses. The foremost objective of the present study was to generate transgenic tomato plants with rolB gene and evaluate its effect on plant morphology, nutritional contents, yield and resistance against fungal infection. Tomato cv. Rio Grande was transformed via Agrobacterium tumefaciens harbouring rolB gene of Agrobacterium rhizogenes. rolB. Biochemical analyses showed considerable improvement in nutritional quality of transgenic tomato fruits as indicated by 62% increase in lycopene content, 225% in ascorbic acid content, 58% in total phenolics and 26% in free radical scavenging activity. Furthermore, rolB gene significantly improved the defence response of leaves of transgenic plants against two pathogenic fungal strains A. solani and F. oxysporum. Contrarily, transformed plants exhibited altered morphology and reduced fruit yield. In conclusion, rolB gene from A. rhizogenes can be used to generate transgenic tomato with increased nutritional contents of fruits as well as improved foliar tolerance against fungal pathogens.
Local and Systemic Regulation of Plant Root System Architecture and Symbiotic Nodulation by a Receptor-Like Kinase
Emeline Huault,Carole Laffont,Jiangqi Wen,Kirankumar S. Mysore,Pascal Ratet,Gérard Duc,Florian Frugier
PLOS Genetics , 2014, DOI: doi/10.1371/journal.pgen.1004891
Abstract: In plants, root system architecture is determined by the activity of root apical meristems, which control the root growth rate, and by the formation of lateral roots. In legumes, an additional root lateral organ can develop: the symbiotic nitrogen-fixing nodule. We identified in Medicago truncatula ten allelic mutants showing a compact root architecture phenotype (cra2) independent of any major shoot phenotype, and that consisted of shorter roots, an increased number of lateral roots, and a reduced number of nodules. The CRA2 gene encodes a Leucine-Rich Repeat Receptor-Like Kinase (LRR-RLK) that primarily negatively regulates lateral root formation and positively regulates symbiotic nodulation. Grafting experiments revealed that CRA2 acts through different pathways to regulate these lateral organs originating from the roots, locally controlling the lateral root development and nodule formation systemically from the shoots. The CRA2 LRR-RLK therefore integrates short- and long-distance regulations to control root system architecture under non-symbiotic and symbiotic conditions.
Expression of a Finger Millet Transcription Factor, EcNAC1, in Tobacco Confers Abiotic Stress-Tolerance
Venkategowda Ramegowda, Muthappa Senthil-Kumar, Karaba N. Nataraja, Malireddy K. Reddy, Kirankumar S. Mysore, Makarla Udayakumar
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0040397
Abstract: NAC (NAM, ATAF1-2, and CUC2) proteins constitute one of the largest families of plant-specific transcription factors and have been shown to be involved in diverse plant processes including plant growth, development, and stress-tolerance. In this study, a stress-responsive NAC gene, EcNAC1, was isolated from the subtracted stress cDNA library generated from a drought adapted crop, finger millet, and characterized for its role in stress-tolerance. The expression analysis showed that EcNAC1 was highly induced during water-deficit and salt stress. EcNAC1 shares high amino acid similarity with rice genes that have been phylogenetically classified into stress-related NAC genes. Our results demonstrated that tobacco transgenic plants expressing EcNAC1 exhibit tolerance to various abiotic stresses like simulated osmotic stress, by polyethylene glycol (PEG) and mannitol, and salinity stress. The transgenic plants also showed enhanced tolerance to methyl-viologen (MV) induced oxidative stress. Reduced levels of reactive oxygen species (ROS) and ROS-induced damage were noticed in pot grown transgenic lines under water-deficit and natural high light conditions. Root growth under stress and recovery growth after stress alleviation was more in transgenic plants. Many stress-responsive genes were found to be up-regulated in transgenic lines expressing EcNAC1. Our results suggest that EcNAC1 overexpression confers tolerance against abiotic stress in susceptible species, tobacco.
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