In field conditions, plants are often simultaneously exposed to multiple biotic and abiotic stresses resulting in substantial yield loss. Plants have evolved various physiological and molecular adaptations to protect themselves under... more
In field conditions, plants are often simultaneously exposed to multiple biotic and abiotic stresses resulting in substantial yield loss. Plants have evolved various physiological and molecular adaptations to protect themselves under stress combinations. Emerging evidences suggest that plant responses to a combination of stresses are unique from individual stress responses. In addition, plants exhibit shared responses which are common to individual stresses and stress combination. In this review, we provide an update on the current understanding of both unique and shared responses. Specific focus of this review is on heat-drought stress as a major abiotic stress combination and, drought-pathogen and heat-pathogen as examples of abiotic-biotic stress combinations. We also comprehend the current understanding of molecular mechanisms of cross talk in relation to shared and unique molecular responses for plant survival under stress combinations. Thus, the knowledge of shared responses o...
Nutrients are indispensable elements required for the growth of all living organisms including plants and pathogens. Phyllosphere, rhizosphere, apoplast, phloem, xylem, and cell organelles are the nutrient niches in plants that are the... more
Nutrients are indispensable elements required for the growth of all living organisms including plants and pathogens. Phyllosphere, rhizosphere, apoplast, phloem, xylem, and cell organelles are the nutrient niches in plants that are the target of bacterial pathogens. Depending upon nutrients availability, the pathogen adapts various acquisition strategies and inhabits the specific niche. In this review, we discuss the nutrient composition of different niches in plants, the mechanisms involved in the recognition of nutrient niche and the sophisticated strategies used by the bacterial pathogens for acquiring nutrients. We provide insight into various nutrient acquisition strategies used by necrotrophic, biotrophic, and hemibiotrophic bacteria. Specifically we discuss both modulation of bacterial machinery and manipulation of host machinery. In addition, we highlight the current status of our understanding about the nutrient acquisition strategies used by bacterial pathogens, namely tar...
Nonhost disease resistance of plants against bacterial pathogens is controlled by complex defense pathways. Understanding this mechanism is important for developing durable disease-resistant plants against wide range of pathogens.... more
Nonhost disease resistance of plants against bacterial pathogens is controlled by complex defense pathways. Understanding this mechanism is important for developing durable disease-resistant plants against wide range of pathogens. Virus-induced gene silencing (VIGS)-based forward genetics screening is a useful approach for identification of plant defense genes imparting nonhost resistance. Tobacco rattle virus (TRV)-based VIGS vector is the most efficient VIGS vector to date and has been efficiently used to silence endogenous target genes in Nicotiana benthamiana. In this manuscript, we demonstrate a forward genetics screening approach for silencing of individual clones from a cDNA library in N. benthamiana and assessing the response of gene silenced plants for compromised nonhost resistance against nonhost pathogens, Pseudomonas syringae pv. tomato T1, P. syringae pv. glycinea, and X. campestris pv. vesicatoria. These bacterial pathogens are engineered to express GFPuv protein and their green fluorescing colonies can be seen by naked eye under UV light in the nonhost pathogen inoculated plants if the silenced target gene is involved in imparting nonhost resistance. This facilitates reliable and faster identification of gene silenced plants susceptible to nonhost pathogens. Further, promising candidate gene information can be known by sequencing the plant gene insert in TRV vector. Here we demonstrate the high throughput capability of VIGS-mediated forward genetics to identify genes involved in nonhost resistance. Approximately, 100 cDNAs can be individually silenced in about two to three weeks and their relevance in nonhost resistance against several nonhost bacterial pathogens can be studied in a week thereafter. In this manuscript, we enumerate the detailed steps involved in this screening. VIGS-mediated forward genetics screening approach can be extended not only to identifying genes involved in nonhost resistance but also to studying genes imparting several biotic and abiotic stress tolerances in various plant species.
Research Interests:
In nature, plants are simultaneously exposed to a combination of biotic and abiotic stresses that limit crop yields. Only recently, researchers have started understanding the molecular basis of combined biotic and abiotic stress... more
In nature, plants are simultaneously exposed to a combination of biotic and abiotic stresses that limit crop yields. Only recently, researchers have started understanding the molecular basis of combined biotic and abiotic stress interactions. Evidences suggest that under combined stress plants exhibit tailored physiological and molecular responses, in addition to several shared responses as part of their stress tolerance strategy. These tailored responses are suggested to occur only in plants exposed to simultaneous stresses and this information cannot be inferred from individual stress studies. In this review article, we provide update on the responses of plants to simultaneous biotic and abiotic stresses, in particular drought and pathogen. Simultaneous occurrence of drought and pathogen during plant growth provokes complex pathways controlled by different signaling events resulting in positive or negative impact of one stress over the other. Here, we summarize the effect of combined drought and pathogen infection on plants and highlight the tailored strategies adapted by plants. Besides, we enumerate the evidences from pathogen derived elicitors and ABA response studies for understanding simultaneous drought and pathogen tolerance.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Finger millet is susceptible to abiotic stresses, especially drought and salinity stress, in the field during seed germination and early stages of seedling development. Therefore developing stress tolerant finger millet plants combating... more
Finger millet is susceptible to abiotic stresses, especially drought and salinity stress, in the field during seed germination and early stages of seedling development. Therefore developing stress tolerant finger millet plants combating drought, salinity and associated oxidative stress in these two growth stages is important. Cellular protection through osmotic adjustment and efficient free radical scavenging ability during abiotic stress are important components of stress tolerance mechanisms in plants. Mannitol, an osmolyte, is known to scavenge hydroxyl radicals generated during various abiotic stresses and thereby minimize stress damage in several plant species. In this study transgenic finger millet plants expressing the mannitol biosynthetic pathway gene from bacteria, mannitol-1-phosphate dehydrogenase (mtlD), were developed through Agrobacterium tumefaciens-mediated genetic transformation. mtlD gene integration in the putative transgenic plants was confirmed by Southern blot. Further, performance of transgenic finger millet under drought, salinity and oxidative stress was studied at plant level in T1 generation and in T1 and T2 generation seedlings. Results from these experiments showed that transgenic finger millet had better growth under drought and salinity stress compared to wild-type. At plant level, transgenic plants showed better osmotic adjustment and chlorophyll retention under drought stress compared to the wild-type. However, the overall increase in stress tolerance of transgenics for the three stresses, especially for oxidative stress, was only marginal compared to other mtlD gene expressing plant species reported in the literature. Moreover, the Agrobacterium-mediated genetic transformation protocol developed for finger millet in this study can be used to introduce diverse traits of agronomic importance in finger millet.
Research Interests:
RNA interference (RNAi), mediated by short interfering RNAs (siRNAs), is one of the widely used functional genomics method for suppressing the gene expression in plants. Initially, gene silencing by RNAi mechanism was believed to be... more
RNA interference (RNAi), mediated by short interfering RNAs (siRNAs), is one of the widely used functional genomics method for suppressing the gene expression in plants. Initially, gene silencing by RNAi mechanism was believed to be specific requiring sequence homology between siRNA and target mRNA. However, several recent reports have showed that non-specific effects often referred as off-target gene silencing can occur during RNAi. This unintended gene silencing can lead to false conclusions in RNAi experiments that are aimed to study the functional role of a particular target gene in plants. This especially is a major problem in large-scale RNAi-based screens aiming for gene discovery. Hence, understanding the off-target effects is crucial for minimizing such effects to better conclude gene function analyzed by RNAi. We discuss here potential problems of off-target gene silencing and focus on possibilities that favor this effect during post-transcriptional gene silencing. Suggestions to overcome the off-target effects during RNAi studies are also presented. We believe that information available in present-day plant science literature about specificity of siRNA actions is inadequate. In-depth systematic studies to understand their molecular basis are necessary to enable improved design of more specific RNAi vectors. In the meantime, gene function and phenotype results from present-day RNAi studies need to be interpreted with caution.
Research Interests:
Research Interests:
Virus-induced gene silencing (VIGS) is an efficient tool for gene function studies. It has been used to perform both forward and reverse genetics to identify plant genes involved in several plant processes. However, this technology has... more
Virus-induced gene silencing (VIGS) is an efficient tool for gene function studies. It has been used to perform both forward and reverse genetics to identify plant genes involved in several plant processes. However, this technology has not yet been used to its full potential. This can be attributed to several of its limitations such as inability to silence genes during seed germination and the non-stable nature of silencing. However, several recent studies have shown that these limitations can now be overcome. In this review, we will discuss the limitations of VIGS and suitable solutions. In addition, we also describe the recent improvements and future prospects of using VIGS in plant biology.
Research Interests: Plant Ecology, Genomics, Biotechnology, Plant Biology, Plant Tissue Culture, and 11 morePlant Breeding, Plant Physiology (Biology), Plant biotechnology, Plant breeding and genetics, Plant Molecular Biology, Functional Genomics, Gene Silencing, Plant Physiology, Plants, Plant viruses, and Plant Pathology
Research Interests:
Research Interests: Plant Biology, Oxidative Stress, Abiotic Stress, Functional Genomics, Free Radical, and 18 moreStress response, Animals, Stress tolerance, Light, Osmotic pressure, Glucuronidase, Cell Viability, High Temperature, Paraquat, Enzyme, Model System, Reproducibility of Results, Osmotic Stress, Cold Stress, Chlamydomonas Reinhardtii, Cell Survival, Sodium Chloride, and Planta
Research Interests: Water, Plant Biology, Tobacco, Functional Genomics, Gene Silencing, and 18 moreDisasters, Chlorophyll, Stress response, Flowers, Virus Induced Gene Silencing, Tomato, Transcription Factor, Anthocyanins, Plant viruses, Drought tolerance, Heat Shock Protein, Water Deficit, Arachis Hypogaea, Alcohol Dehydrogenase, Planta, cDNA library, Nucleotides, and Plant Leaves
Research Interests:
Research Interests:
Research Interests:
Bacterial pathogens colonize a host plant by growing between the cells by utilizing the nutrients present in apoplastic space. While successful pathogens manipulate the plant cell membrane to retrieve more nutrients from the cell, the... more
Bacterial pathogens colonize a host plant by growing between the cells by utilizing the nutrients present in apoplastic space. While successful pathogens manipulate the plant cell membrane to retrieve more nutrients from the cell, the counteracting plant defense mechanism against nonhost pathogens to restrict the nutrient efflux into the apoplast is not clear. To identify the genes involved in nonhost resistance against bacterial pathogens, we developed a virus-induced gene-silencing-based fast-forward genetics screen in Nicotiana benthamiana. Silencing of N. benthamiana SQUALENE SYNTHASE, a key gene in phytosterol biosynthesis, not only compromised nonhost resistance to few pathovars of Pseudomonas syringae and Xanthomonas campestris, but also enhanced the growth of the host pathogen P. syringae pv tabaci by increasing nutrient efflux into the apoplast. An Arabidopsis (Arabidopsis thaliana) sterol methyltransferase mutant (sterol methyltransferase2) involved in sterol biosynthesis also compromised plant innate immunity against bacterial pathogens. The Arabidopsis cytochrome P450 CYP710A1, which encodes C22-sterol desaturase that converts β-sitosterol to stigmasterol, was dramatically induced upon inoculation with nonhost pathogens. An Arabidopsis Atcyp710A1 null mutant compromised both nonhost and basal resistance while overexpressors of AtCYP710A1 enhanced resistance to host pathogens. Our data implicate the involvement of sterols in plant innate immunity against bacterial infections by regulating nutrient efflux into the apoplast.
Research Interests:
Research Interests:
Research Interests:
Research Interests: Genetics, Tobacco, Molecular Genetics, Drought Stress, Gene expression, and 19 moreFunctional Genomics, Gene Silencing, DNA, Expressed Sequence Tags, Chlorophyll, Stress response, Water Stress, Virus Induced Gene Silencing, Plant Molecular Genetics and Functional Genomics, Droughts, Gene Selection, Drought tolerance, Dehydration, Water Deficit, Base Sequence, Arachis Hypogaea, cDNA library, Field capacity, and Plant Leaves
Research Interests:
Research Interests: Botany, Plant Biology, Gene expression, Heat Shock Transcription Factor, Stress response, and 14 moreExperimental Botany, Temperature, High Temperature, Methyl Viologen, Heat stress, Inbreeding, Sunflower, Acclimatization, Heat Shock, Helianthus, Heat Shock Protein, Species Specificity, Genetic Variability, and Helianthus annuus L
Research Interests: Water, Plant Biology, Oxidative Stress, Abiotic Stress, Functional Genomics, and 20 moreGene Silencing, Peroxidase, Stress response, Stress tolerance, Gene transfer techniques, Experimental Botany, Virus Induced Gene Silencing, Osmotic pressure, Cell Viability, Tomato, Phenotype, Molecular cloning, Experimental, Very high throughput, Arachis Hypogaea, Cell Survival, PLANT PROTEINS, Osmotic Adjustment, Superoxides, and Lycopersicon esculentum
In contrast to gene-for-gene disease resistance, nonhost resistance governs defense responses to a broad range of potential pathogen species. To identify specific genes involved in the signal transduction cascade associated with nonhost... more
In contrast to gene-for-gene disease resistance, nonhost resistance governs defense responses to a broad range of potential pathogen species. To identify specific genes involved in the signal transduction cascade associated with nonhost disease resistance, we used a virus-induced gene-silencing screen in Nicotiana benthamiana, and identified the peroxisomal enzyme glycolate oxidase (GOX) as an essential component of nonhost resistance. GOX-silenced N. benthamiana and Arabidopsis thaliana GOX T-DNA insertion mutants are compromised for nonhost resistance. Moreover, Arabidopsis gox mutants have lower H(2)O(2) accumulation, reduced callose deposition, and reduced electrolyte leakage upon inoculation with hypersensitive response-causing nonhost pathogens. Arabidopsis gox mutants were not affected in NADPH oxidase activity, and silencing of a gene encoding NADPH oxidase (Respiratory burst oxidase homolog) in the gox mutants did not further increase susceptibility to nonhost pathogens, su...