Explore the vast range of titles available.

Groundnut bud necrosis virus (GBNV), a member of the genus Orthotospovirus, is the most devastating pathogen causing bud blight of tomato and causes substantial crop losses in India. Current management strategies rely upon the use of virus tolerant cultivars, control of insect vectors, and other cultural practices. Under field conditions, these methods are ineffective in reducing the disease. Control can be achieved with RNA silencing, which regulates the homologous specific degradation of targeted genes, resulting in reduced virus multiplication. In the present study, virus infected tomato plant samples were collected from different parts of Tamil Nadu, and infection was confirmed through DAC-ELISA using a polyclonal antibody specific to GBNV. The virus inoculum was propagated on the local lesion host, cowpea (Vigna unguiculata), resulting in the production of chlorotic and necrotic spots on inoculated primary leaves. Our results demonstrated that the complete nucleotide sequence of the replicase gene identified using PCR shared an identity of 94.7 to 97.7% with other isolates of GBNV. To investigate the virus suppression mechanism, an effective RNAi construct was developed with the conserved sequence of the replicase gene for GBNV. A 3674 bp hpRNA cassette, comprising the sense and antisense fragments of 357 bp along with the flanking sequence, inserted in a pHANNIBAL vector, generated transgenic tomato plants using shoot apical meristem explants through Agrobacterium harboring the gene construct. The presence of the transgene in the developed putative transformants was assessed by PCR analysis using nptII and Rep genes and dot blot hybridization using a DIG luminescent detection kit. The expression of the replicase hpRNA construct revealed reduced symptom development upon artificial inoculation of GBNV. Further analysis of the transgenic tomato plants using DAC-ELISA confirmed the reduced level of virus titer. We propose that the RNAi construct, established with a conserved sequence of the replicase gene, showed a gene silencing mechanism as evidenced by reduced virus accumulation in putative transgenic lines, and this could be used as an effective strategy in the management of GNBV in tomato.

Since 2008, spruce bud blight (Gemmamyces piceae (Borthw.) Casagr.) has been spreading epidemically in forest stands of the Czech Republic’s Ore Mountains. This fungus, with a disjunct Holarctic range, injures buds, especially of Colorado blue spruce (Picea pungens Engelm.). Damaged buds do not sprout, and, in case of a stronger attack, the tree does not recover its assimilation apparatus and may die. Within the past few years, there has been a huge spread of this fungus throughout the mountain range. This paper summarizes the biology of G. piceae, its host plants, and presents the first findings from the massive outbreak of G. piceae. In 2015, an increase in damage was detected on Norway spruce (Picea abies (L.) Karst). The course of the G. piceae epidemic had been monitored in 25 permanent research plots over the course of 11 years. In the case of Colorado blue spruce, stands aged 10–60 years were attacked, with 60% of buds damaged on average. The intensity of damage to Norway spruce buds was around 25%. Norway spruce infestation varied significantly depending upon the age of the stand (GLMM: p < 0.01). In the age class of 31–60 years, on average 80% of individuals were infested. In older stands, only 42% of trees were infested, and no infestation was found in individuals younger than 15 years. In Colorado blue spruce, the distribution of the pathogen was continuous, whereby all individuals in the research plots were affected, and, with the exception of a few trees, the infestation was lethal or resulted in a significant reduction of the assimilation apparatus. The development of damage on Colorado blue spruce can be characterized as continuous growth.

Dendrobium officinale is an important traditional Chinese medicine (TCM). A disease causing bud blight in D. officinale appeared in 2021 in Yueqing city, Zhejiang Province, China. In this paper, 127 isolates were obtained from 61 plants. The isolates were grouped into 13 groups based on collected areas and morphological observations. Four loci (ITS, LSU, tub2 and rpb2) of 13 representative isolates were sequenced and the isolates were identified by constructing phylogenetic trees with the multi-locus sequence analysis (MLSA) method. We found the disease to be associated with three strains: Ectophoma multirostrata, Alternaria arborescens and Stagonosporopsis pogostemonis, with isolates frequencies of 71.6%, 21.3% and 7.1%, respectively. All three strains are pathogenic to D. officinale. A. arborescens and S. pogostemonis isolated from D. officinale were reported for the first time. Iprodione (50%), 33.5% oxine-copper and Meitian (containing 75 g/L pydiflumetofen and 125 g/L difenoconazole) were chosen to control the dominant pathogen E. multirostrata, with an EC50 value of 2.10, 1.78 and 0.09 mg/L, respectively. All three fungicides exhibited an effective inhibition of activities to the growth of the dominant pathogen E. multirostrata on potato dextrose agar (PDA) plates, with Meitian showing the strongest inhibitory effect. We further found that Meitian can effectively control D. officinale bud blight disease in pot trial.

A survey was carried out in 2013–2019 on the life cycle of the bud blight Gemmamyces piceae (Borthw.) Casagrande and the trend assessment in the infestation of the Colorado blue spruce Picea pungens Engelm. stands. Four ecologically different plots were chosen in the Fláje region in the Eastern part of the Krušné hory Mountains. The pycnidia were formed at the beginning of June on buds infested the previous year. Later, in the second half of June, they formed on the spring attack buds. Conidia occurred in the first week of July on the buds of the old infestation, or later in the case of the spring attack buds, in the middle of July. The production of conidia lasted till the end of September. Ascospores occurred in the middle of July and were produced until the end of September. The ability of host trees to sprout became continually weaker, along with the defoliation progress. A distinct decline in the sprouting ability was noticed on stands with a dense crown canopy and on stands with competition of broad-leaved trees – with an admixture of birch.

Norway spruce is often considered to have a negative impact on a site, yet it is native to many mountain regions of Europe. The relative influence of Norway spruce on site properties has frequently been compared with that of both broadleaved and other coniferous tree species. In our study, growth, as well as needle, forest floor, and topsoil chemistry were compared between Norway spruce and introduced spruce species (white, black, red, Serbian, Sitka, and blue spruce), all growing on the same, formerly polluted mountain site. There were few differences in needle nutrient status between the introduced spruce species and native Norway spruce. The chemistry of forest floor horizons beneath some of the non-native species showed less acidity and better conditions of the soil sorption complex. There were no significant differences in the nutrient pools, indicating that the influence of the various spruce species on the site was comparable. Given the small differences observed in the various nutritional characteristics, it appears that, under the conditions of the study site, the alternative spruces had substituted for the role of Norway spruce before its recovery in the 2000s. The six spruces grew quite consistently during 2001-2012, while the mean height of Norway spruce shifted from the lowest 176 cm (2001) to one of the tallest. At 710 cm (2012), its height had become comparable with that of Sitka. The poorest performing were black spruce (due to bark beetle attack) and blue spruce (due to bud blight infestation and decline).

The present study on magnitude and spatial distribution of bud blight disease of tomato caused by Peanut bud necrosis virus in major tomato growing area of North Eastern Karnataka through GPS approach during 2014-15, revealed that disease was found to occur at all the stages of the crop with characteristic symptoms such as necrotic rings with green or yellow hallow spots on leaves, later tip necrosis and die back. Further, presence of longitudinal brown necrotic streaks on petioles, stem and characteristic brown ring and chlorotic ring spots on green and red ripened tomatoes respectively. GPS based survey indicated that the % disease incidence varied from location to location (spatial variation), with the mean incidence ranging from 14.52 to 62.13 per cent. Among the six districts, highest incidence of 62.13 per cent was recorded in Kalaburgi district followed by Raichur, Bidar, Yadgir and Koppal with 60.35, 57.96, 45.68 and 37.13 per cent incidence, respectively and the least disease incidence of 14.52 per cent was recorded in Ballari district. The GPS maps plotted based on PDI scale (0-4) represents high risk areas of the disease in North Eastern Karnataka and higher magnitude of disease was recorded in many of the location surveyed were the tomato fields surrounded by alternate hosts of PBNV. The study signifies PBNV diagnostic symptoms and its prevalence in North Eastern Karnataka

Tobacco ringspot virus (TRSV, genus Nepovirus), causes severe diseases in soybean and tobacco plants. TRSV-induced bud blight disease significantly reduced both the yield and quality of soybeans. The function of the encoded viral gene product involved in TRSV infection was unclear due to the limitation of reverse genetics studies on the viral genome. Here, we represent the successful construction of infectious full-length cDNA clones of TRSV genome (RNA1 and RNA2). The cDNAs of TRSV RNA1 and RNA2 were cloned into the binary vector pPZP211 immediately downstream of a double cauliflower mosaic virus 35S promoter and upstream of the nopaline synthase terminator. Seven days after agrobacterium-mediated co-inoculation of these two constructs, Nicotiana benthamiana plants developed a systemic infection with necrotic ringspot symptoms and weak stunting of the leaves, similar to that induced by natural TRSV. The systemic infection was confirmed by transmission electron microscopy and Western blot analysis. Simultaneously, soybean, tomato, and Arabidopsis ecotype Estland were mechanically inoculated with sap prepared from TRSV-agroinfiltrated N. benthamiana leaves, showing typical symptoms of bud blight, necrotic spots, and lethal systemic necrosis, respectively. The system developed herein will be an appealing way to determine TRSV viral gene functions and study host–TRSV interactions.

Tea (Camellia sinensis (L.) O. Kuntze.) is an economically important crop extensively grown for harvestable shoots in India. In the present study, 40 tea leaf samples (new leaves/buds) showing brown to black water-soaked expanding lesions collected from different commercial tea gardens of North Bengal and Assam, India, in different seasons were analyzed for the associated factor involved in the disease. A total of 40 isolates of bacteria with similar colony appearance on agar plates were isolated from symptomatic leaves/buds. Among the 40 isolates, six representative isolates from different tea gardens including three each from North Bengal (BBN01, BBP01, and BBJ01) and Assam (BBH01, BBD01, and BBA01) were characterized for gram reactions, biochemical tests, and by sequencing the 16S rRNA gene. All the isolates were gram negative, oxidase and catalase positive, and aerobically produced acid from glucose. BLASTn analysis of the obtained sequences revealed that all six isolates were Acidovorax avenae subsp. avenae, sharing a similarity greater than 99% with A. avenae subsp. avenae sequences from the GenBank database. Phylogenetic study also displayed the closest resemblance of these isolates to A. avenae subsp. avenae based on maximum likelihood. Further, six A. avenae subsp. avenae isolates were pathogenic on a tea cultivar TV23 in repeated experiments. Koch's postulates were verified by re-isolating the bacterial pathogen from the inoculated plants showing blight symptoms. In conclusion, this study confirms that A. avenae subsp. avenae is the bacterial pathogen responsible for causing symptoms of blight in tea leaves/buds. As far as we know, this is the first record of A. avenae subsp. avenae on Indian tea plants.

Background - Monilinia blight caused by Monilinia vaccinii-corymbosi (Reade) Honey (M.vc) is a major disease of wild blueberry that can result in severe crop losses in the absence of an integrated disease management programme. The fungus causes blight in the emerging floral and vegetative buds, but the degree of susceptibility varies among the different wild blueberry phenotypes, ranging from the highly susceptible V. a. f. nigrum to the moderately susceptible V. angustifolium and the least susceptible V. myrtilloides. Results - The present study evaluated the defense responses of these major phenotypes during their primary infection (floral buds) with M.vc. The temporal expression profiles of PR genes (PR3 and PR4) and the flavonoid pathway structural genes (CHS, ANS, ANR, DFR and FLS) were analysed. The PR3 and PR4 gene expression profiles revealed that V. myrtilloides responded to M.vc infection by activating the expression of both PR genes. V. a. f. nigrum, on the other hand, failed to activate these genes, while V. angustifolium, exhibited an intermediate response. Our study with the flavonoid pathway genes indicated variability in activation of the genes during post-infection time points with ANS and ANR in V. myrtilloides, FLS in V. angustifolium and no response observed in V. a. f. nigrum. Conclusions - Altogether, this study highlights that the degree of phenotype susceptibility is associated with the timely activation of host defense responsive genes. Data obtained in this study provided a starting point for a better understanding of the wild blueberry- M. vaccinii-corymbosi pathosystem.

Chestnut blight caused by Cryphonectria parasitica is a severe disease worldwide affecting chestnut trees. One pathway for its long-range transmission is grafting by using non-symptomatic scions. The effects of five disinfectants, 80% ethanol, 2.5% NaOCl, 5% H2O2, 2% copper sulphate and Lysol® (Brand III), were evaulated on artificially inoculated scions of 15–20 cm with a spore suspension (1 × 106 conidia/ml) of C. parasitica. Effects of these disinfectants on natural fungal flora and the viability of the scion woods were also investigated in vitro and in vivo conditions. Effectiveness of the disinfectants was evaluated by plating 10 buds taken from five random scions on PDA and counting the growing fungal colonies after 7 days of incubation at 22 °C, with a 12-h lighting period. A total of 40 buds, 10 from each repetition, were cultured for each treatment. The growth of C. parasitica and other fungi were investigated under a stereomicroscope. No growth of C. parasitica was observed on the treated scions while it grew on all of the contaminated control buds (100%). The growth of other fungi was the lowest for the Lysol® treated scions. The effect of the disinfectant treatment on the viability of the scion woods were tested by using 45 scion woods for each treatment and the maximum viability ratio was obtained in distilled water, followed by NaOCl, copper sulphate, ethanol, H2O2 and Lysol® treatment.