Publications by authors named "Dilip K Lakshman"

stalk rot (FSR), caused by the species complex, is an economic threat to maize cultivation all over the world. We investigated the population structure and genetic diversity of species obtained from five major maize-growing regions in India. The locus was used for phylogenetic analysis of geographically distinct isolates of , , , , and causing FSR.

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There are fewer studies on Trichoderma diversity in agricultural fields. The rhizosphere of 16 crops was analyzed for Trichoderma species in 7 districts of Rajasthan state of India. Based on DNA sequence of translation elongation factor 1α (tef-1α), and morphological characteristics, 60 isolates were identified as 11 species: Trichoderma brevicompactum, species in Harzianum clade identified as T.

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Background: Wheat streak mosaic virus (WSMV) and Triticum mosaic virus (TriMV) are components of the wheat streak mosaic virus disease complex in the Great Plains region of the U.S.A.

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Cercospora leaf spot (CLS) is the most destructive foliar disease in sugar beet (). It is caused by Sacc., a fungal pathogen that produces toxins and enzymes which affect membrane permeability and cause cell death during infection.

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Post flowering stalk rot (PFSR) of maize caused by the species complex is a serious threat to maize production worldwide. The identification of species causing PFSR based on morphology traditionally relies on a small set of phenomic characteristics with only minor morphological variations among distinct species. Seventy-one isolates were collected from 40 sites in five agro-climatic zones of India to assess the diversity of spp.

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Rhizoctonia solani is a collective group of genetically and pathologically diverse basidiomycetous fungi that damage economically important crops. Its isolates are classified into 13 Anastomosis Groups (AGs) and subgroups having distinctive morphology and host ranges. The genetic factors driving the unique features of pathology are not well characterized due to the limited availability of its annotated genomes.

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Gray bulb rot of tulips and bulbous iris is caused by the soil-borne fungal pathogen, (). Sclerotia present in infected bulbs, as well as overwintering sclerotia in soil and field debris, are the primary sources of infection. A method for accurate and sensitive detection of from soil and infected bulbs, and estimation of inoculum threshold levels, is needed for the management of disease caused by this pathogen.

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Article Synopsis
  • Foliar diseases of maize lead to significant economic losses globally, with maize leaf blight (MLB) worsening in India over the past decade, prompting the need for detailed research on its pathogens for better resistance breeding and management strategies.
  • A study collected 350 symptomatic leaf samples from MLB hotspots across nine Indian states between 2016 and 2018, identifying and characterizing 20 fungal isolates linked to MLB symptoms through various methods.
  • Results indicated that 13 of the isolates were newly identified pathogens in India, including several species that caused more severe symptoms, offering crucial baseline data for future research on MLB management and diagnosis.
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Maize brown sheath spot (MBSS), a new disease of maize, was discovered while surveying for maize leaf and sheath blight diseases in the Indian states of Assam, Jharkhand, Meghalaya, Manipur, and Odisha. Maize is the third most important cereal after rice and wheat in India. Unlike banded leaf and sheath blight disease caused by , MBSS symptoms on maize were discrete and limited to sheaths only.

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Ethanol extract of cell mass of Serratia marcescens strain N4-5, when applied as a treatment to cucumber seed, has been shown to provide control of the oomycete soil-borne plant pathogen Pythium ultimum equivalent to that provided by a seed-treatment chemical pesticide in some soils. Two dominant compounds in this extract, prodigiosin and the serratamolide serrawetin W1, were identified based on mass and collision induced dissociation mass fragmentation spectra. An additional four compounds with M+H masses (487, 541, 543, and 571) consistent with serratamolides reported in the literature were also detected.

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The root nodules are a unique environment formed on legume roots through a highly specific symbiotic relationship between leguminous plants and nodule-inducing bacteria. Previously, Rhizobia were presumed to be the only group of bacteria residing within nodules. However, recent studies discovered diverse groups of bacteria within the legume nodules.

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Long-term preservation of experimental fungi without genetic, morphological, and pathogenic changes is of paramount importance in mycological and plant pathological investigations. Several cryogenic and non-cryogenic methods are available for the preservation of fungi, but the methods can be cumbersome, hazardous, expensive, and often not suitable for long-term storage of non-spore-forming (sterile) fungi. A method of preservation of spore-forming fungi in commercially available porous beads (Micrbank™) under cryogenic condition was successfully tested for three non-spore-forming basidiomycetes genera: Rhizoctonia solani (teleomorph: Thanatephorus cucumeris) (n = 19), Ceratobasidium species (n = 1), and Waitea circinata (n = 3), and a non-spore forming ascomycetes, Sclerotinia sclerotiorum (n = 1).

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Background: The biological control agent Aspergillus aculeatus Asp-4 colonizes and degrades sclerotia of Sclerotinia sclerotiorum resulting in reduced germination and disease caused by this important plant pathogen. Molecular mechanisms of mycoparasites underlying colonization, degradation, and reduction of germination of sclerotia of this and other important plant pathogens remain poorly understood.

Results: An RNA-Seq screen of Asp-4 growing on autoclaved, ground sclerotia of S.

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Environmentally friendly control measures for soilborne plant pathogens are needed that are effective in different soils when applied alone or as components of an integrated disease control strategy. An ethanol extract of Serratia marcescens N4-5, when applied as a cucumber seed treatment, effectively suppressed damping-off caused by Pythium ultimum in potting mix and in a sandy loam soil. Plant stand associated with this treatment was similar to that of seed treated with the chemical pesticide Thiram in the sandy loam soil.

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Rhizoctonia solani AG 4 is a soilborne necrotrophic fungal plant pathogen that causes economically important diseases on agronomic crops worldwide. This study used a proteomics approach to characterize both intracellular proteins and the secretome of R. solani AG 4 isolate Rs23A under several growth conditions, the secretome being highly important in pathogenesis.

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As shrimp aquaculture has evolved from a subsistent farming activity to an economically important global industry, viral diseases have also become a serious threat to the sustainable growth and productivity of this industry. Parvoviruses represent an economically important group of viruses that has greatly affected shrimp aquaculture. In the early 1980s, an outbreak of a shrimp parvovirus, infectious hypodermal and hematopoietic necrosis virus (IHHNV), led to the collapse of penaeid shrimp farming in the Americas.

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Lactoferrin (LF) is a ubiquitous cationic iron-binding milk glycoprotein that contributes to nutrition and exerts a broad-spectrum primary defense against bacteria, fungi, protozoa, and viruses in mammals. These qualities make lactoferrin protein and its antimicrobial motifs highly desirable candidates to be incorporated in plants to impart broad-based resistance against plant pathogens or to economically produce them in bulk quantities for pharmaceutical and nutritional purposes. This study introduced bovine LF (BLF) gene into tobacco ( Nicotiana tabacum var.

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Rhizoctonia solani is a ubiquitous basidiomycetous soilborne fungal pathogen causing damping-off of seedlings, aerial blights and postharvest diseases. To gain insight into the molecular mechanisms of pathogenesis a global approach based on analysis of expressed sequence tags (ESTs) was undertaken. To get broad gene-expression coverage, two normalized EST libraries were developed from mycelia grown under high nitrogen-induced virulent and low nitrogen/methylglucose-induced hypovirulent conditions.

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The GacS/GacA two-component system functions mechanistically in conjunction with global post-transcriptional regulators of the RsmA family to allow pseudomonads and other bacteria to adapt to changing environmental stimuli. Analysis of this Gac/Rsm signal transduction pathway in phytotoxin-producing pathovars of Pseudmonas syringae is incomplete, particularly with regard to rsmA. Our approach in studying it was to overexpress rsmA in P.

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Background: The development of plant gene transfer systems has allowed for the introgression of alien genes into plant genomes for novel disease control strategies, thus providing a mechanism for broadening the genetic resources available to plant breeders. Using the tools of plant genetic engineering, a broad-spectrum antimicrobial gene was tested for resistance against head blight caused by Fusarium graminearum Schwabe, a devastating disease of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.

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In silico analysis of three Penaeus stylirostris densovirus (PstDNV) promoters, designated P2, P11, and P61, revealed sequence motifs including the TATA box, downstream promoter element (DPE), GC- and A-rich regions, inverted repeat, activation sequence-1 like (ASL) box, and a conserved guanosine (G) at +24. To delineate the regulatory role of these motifs on promoter activity, deletion constructs were made in a promoter assay vector, pGL3 Basic, that contains a luciferase reporter gene. Luciferase assay showed that P2 had the highest promoter activity followed by P11 and P61 in Sf9 cells.

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We have been using mutagenesis to determine how biocontrol bacteria such as Enterobacter cloacae 501R3 deal with complex nutritional environments found in association with plants. E. cloacae C10, a mutant of 501R3 with a transposon insertion in degS, was diminished in growth on synthetic cucumber root exudate (SRE), colonization of cucumber seed and roots, and control of damping-off of cucumber caused by Pythium ultimum.

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Penaeus stylirostris densovirus (PstDNV) genome contains three open reading frames (ORFs), left, middle, and right, which encode a non-structural (NS) protein, an unknown protein, and a capsid protein (CP), respectively. Transcription mapping revealed that P2, P11 and P61 promoters transcribe the left, middle and right ORFs. NS transcript uses the D1/A1 donor/acceptor sites for splicing and has two alternate transcription termination sites (TTS) that were different from the previously predicted TTS.

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A comprehensive investigation of the Taura syndrome virus (TSV) isolate that caused epizootics in shrimp farms in Texas in 2004 (Texas isolate) revealed that this virus was more virulent in laboratory bioassays than the TSV reference isolate, Hawaii 1994, causing severe symptom development and rapid mortality. Histopathology of moribund animals demonstrated epithelial necrosis within the stomach, appendages, general body cuticle and gills, and the surviving animals demonstrated moderate to numerous lymphoid organ spheroids. Purified virions showed icosahedral morphology, with a diameter of 31 nm.

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Rhizoctonia solani (Teleomorph: Thanatephorus cucumeris, T. praticola) is a basidiomycetous fungus and a major cause of root diseases of economically important plants. Various isolates of this fungus are also beneficially associated with orchids, may serve as biocontrol agents or remain as saprophytes with roles in decaying and recycling of soil organic matter.

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