Heterologous expression and characterization of ToxA1 haplotype from India and its interaction with Tsn1 for spot blotch susceptibility in spring wheat.

BACKGROUND: ToxA, a necrotrophic effector protein, is present in the genome of fungal species like Parastagnospora nodorum, Pyrenophora tritici-repentis and Bipolaris sorokiniana. Tsn1 is the sensitivity gene in the host whose presence indicates more susceptibility to ToxA carrying pathogen, and ToxA-Tsn1 interaction follows an inverse gene-for-gene relationship. METHODS AND RESULTS: The present study involved cloning and expressing the ToxA1 haplotype from B. sorokiniana. It was found that the amplicon exhibited an expected product size of 471 bp. Sequence analysis of the ToxA1 nucleotide sequence revealed the highest identity, 99.79%, with P. tritici-repentis. The protein expression analysis showed peak expression at 16.5 kDa. Phylogenetic analysis of the ToxA1 sequence from all the Bipolaris isolates formed an independent clade along with P. tritici-repentis and diverged from P. nodorum. ToxA-Tsn1 interaction was studied in 18 wheat genotypes (11 Tsn1 and 7 tsn1) at both seedling and adult stages, validating the inverse gene-for-gene relationship, as the toxin activity was highest in the K68 genotype (Tsn1) and lowest in WAMI280 (tsn1). CONCLUSION: The study indicates that the haplotype ToxA1 is prevailing in the Indian population of B. sorokiniana. It would be desirable for wheat breeders to select genotypes with tsn1 locus for making wheat resistant to spot blotch.

Validation of Novel spot blotch disease resistance alleles identified in unexplored wheat (Triticum aestivum L.) germplasm lines through KASP markers.

BACKGROUND: During the last few decades, the diverse sources of resistance, several genes and QTLs for spot blotch resistance have been identified. However, a large set of germplasm lines are still unexplored that have the potential to develop highly resistant wheat cultivars for the target environments. Therefore, the identification of new sources of resistance to spot blotch is essential for breeding programmes to develop spot blotch resistant cultivars and sustain wheat production. The association mapping panel of 294 diverse bread wheat accessions was used to explore new sources of spot blotch disease resistance and to identify genomic regions using genome wide association analysis (GWAS). The genotypes were tested in replicated trials for spot blotch disease at three major hot spots in India (Varanasi in UP, Pusa in Bihar, and Cooch Behar in West Bengal). The area under the disease progress curve (AUDPC) was calculated to assess the level of resistance in each genotype. RESULTS: A total of 19 highly and 76 moderately resistant lines were identified. Three accessions (EC664204, IC534306 and IC535188) were nearly immune to spot blotch disease. The genotyping of all accessions resulted in a total of 16,787 high-quality polymorphic SNPs. The GWAS was performed using a Compressed Mixed Linear Model (CMLM) and a Mixed Linear Model (MLM). A total of seven significant MTAs, common in both the models and consistent across the environment, were further validated to develop KASP markers. Four MTAs (AX-94710084, AX-94865722, AX-95135556, and AX-94529408) on three chromosomes (2AL, 2BL, and 3BL) have been successfully validated through the KASP marker. CONCLUSIONS: The new source of resistance was identified from unexplored germplasm lines. The genomic regions identified through GWAS were validated through KASP markers. The marker information and the highly resistant sources are valuable resources to rapidly develop immune or near immune wheat varieties.

Genomic selection for spot blotch in bread wheat breeding panels, full-sibs and half-sibs and index-based selection for spot blotch, heading and plant height.

KEY MESSAGE: Genomic selection is a promising tool to select for spot blotch resistance and index-based selection can simultaneously select for spot blotch resistance, heading and plant height. A major biotic stress challenging bread wheat production in regions characterized by humid and warm weather is spot blotch caused by the fungus Bipolaris sorokiniana. Since genomic selection (GS) is a promising selection tool, we evaluated its potential for spot blotch in seven breeding panels comprising 6736 advanced lines from the International Maize and Wheat Improvement Center. Our results indicated moderately high mean genomic prediction accuracies of 0.53 and 0.40 within and across breeding panels, respectively which were on average 177.6% and 60.4% higher than the mean accuracies from fixed effects models using selected spot blotch loci. Genomic prediction was also evaluated in full-sibs and half-sibs panels and sibs were predicted with the highest mean accuracy (0.63) from a composite training population with random full-sibs and half-sibs. The mean accuracies when full-sibs were predicted from other full-sibs within families and when full-sibs panels were predicted from other half-sibs panels were 0.47 and 0.44, respectively. Comparison of GS with phenotypic selection (PS) of the top 10% of resistant lines suggested that GS could be an ideal tool to discard susceptible lines, as greater than 90% of the susceptible lines discarded by PS were also discarded by GS. We have also reported the evaluation of selection indices to simultaneously select non-late and non-tall genotypes with low spot blotch phenotypic values and genomic-estimated breeding values. Overall, this study demonstrates the potential of integrating GS and index-based selection for improving spot blotch resistance in bread wheat.

Pyramiding of genes for grain protein content, grain quality, and rust resistance in eleven Indian bread wheat cultivars: a multi-institutional effort.

Improvement of grain protein content (GPC), loaf volume, and resistance to rusts was achieved in 11 Indian wheat cultivars that are widely grown in four different agro-climatic zones of India. This involved use of marker-assisted backcross breeding (MABB) for introgression and pyramiding of the following genes: (i) the high GPC gene Gpc-B1; (ii) HMW glutenin subunits 5 + 10 at Glu-D1 loci, and (iii) rust resistance genes, Yr36, Yr15, Lr24, and Sr24. GPC increased by 0.8 to 3.3%, although high GPC was generally associated with yield penalty. Further selection among high GPC lines allowed identification of progenies with higher GPC associated with improvement in 1000-grain weight and grain yield in the backgrounds of the following four cultivars: NI5439, UP2338, UP2382, and HUW468. The high GPC progenies (derived from NI5439) were also improved for grain quality using HMW glutenin subunits 5 + 10 at Glu-D1 loci. Similarly, progenies combining high GPC and rust resistance were obtained in the backgrounds of following five cultivars: Lok1, HD2967, PBW550, PBW621, and DBW1. The improved pre-bred lines developed following multi-institutional effort should prove a valuable source for the development of cultivars with improved nutritional quality and rust resistance in the ongoing wheat breeding programmes. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-022-01277-w.

ToxA-Tsn1 Interaction for Spot Blotch Susceptibility in Indian Wheat: An Example of Inverse Gene-for-Gene Relationship.

The ToxA-Tsn1 system is an example of an inverse gene-for-gene relationship. The gene ToxA encodes a host-selective toxin (HST) which functions as a necrotrophic effector and is often responsible for the virulence of the pathogen. The genomes of several fungal pathogens (e.g., Pyrenophora tritici-repentis, Parastagonospora nodorum, and Bipolaris sorokiniana) have been shown to carry the ToxA gene. Tsn1 is a sensitivity gene in the host, whose presence generally helps a ToxA-positive pathogen to cause spot blotch in wheat. Cultivars lacking Tsn1 are generally resistant to spot blotch; this resistance is attributed to a number of other known genes which impart resistance in the absence of Tsn1. In the present study, 110 isolates of B. sorokiniana strains, collected from the ME5A and ME4C megaenvironments of India, were screened for the presence of the ToxA gene; 77 (70%) were found to be ToxA positive. Similarly, 220 Indian wheat cultivars were screened for the presence of the Tsn1 gene; 81 (36.8%) were found to be Tsn1 positive. When 20 wheat cultivars (11 with Tsn1 and 9 with tsn1) were inoculated with ToxA-positive isolates, seedlings of only those carrying the Tsn1 allele (not tsn1) developed necrotic spots surrounded by a chlorotic halo. No such distinction between Tsn1 and tsn1 carriers was observed when adult plants were inoculated. This study suggests that the absence of Tsn1 facilitated resistance against spot blotch of wheat. Therefore, the selection of wheat genotypes for the absence of the Tsn1 allele can improve resistance to spot blotch.

Effect of heat stress during flowering and pod formation in pea (Pisum sativum L.).

Heat stress is a major constraint of yield in grain legumes including peas. Increasing global warming and human population now urge to develop climate resilient varieties. The present experiment was conducted over 2 years to evaluate the heat tolerance of 211 pea genotypes. In the present study, the field pea genotypes showed a wide variation for reproductive stage heat stress (RSHS) quantitative traits. Significant positive correlations were found between no. of seeds per plant and no. of pods per plant; seed diameter (mm) and 25-seed weight (g) in heat tolerant as well as heat susceptible genotypes. Principal component analysis revealed two major principal components contributed approximately 91% of total variations and heat tolerant and susceptible genotypes separately formed two major clusters. Stepwise multiple regression analysis revealed that no. of seeds per plant was the best predictor for no. of pods per plant. On the basis of four RSHS traits, the most prominent heat tolerant pea genotypes identified in the present study JP-625, IARI-2877, PMR-38 II, EC-318760, EC-328758 and IARI-2904 would better combat RSHS and provide yield stability under changing climatic conditions.

Variations in straw fodder quality and grain-Straw relationships in a mapping population of 287 diverse spring wheat lines.

A wheat association mapping population consisting of 287 diverse spring wheat lines were evaluated for three years in one location (Varanasi) and out of these for one year across three locations (Karnal, Dharwad and Varanasi) in India. Straw fodder quality traits analyzed were nitrogen (N) content, neutral (NDF) and acid (ADF) detergent fiber, acid detergent lignin (ADL), ash (ASH), in vitro organic matter digestibility (IVOMD) and metabolizable energy (ME) content. Grain yield (GY) and straw yield (SY) were also recorded. Highly significant (P < 0.0001) differences among lines were observed for all traits except for ADF and ADL in the three years trials conducted at Varanasi. However, year and location had strong (P < 0.0001) effects on all traits. Compared to line-dependent variations in GY and SY variation in straw fodder quality traits were small. Proportionally greatest variations between lines were observed for straw N where lowest and highest N varied by about 30%. Difference for NDF and ADF between lines were at most 4% units and below 3% units for IVOMD. Grain yield and straw yield were positively correlated (P < 0.0001) with GY accounting for 26% of the variation in SY. Straw N, IVOMD and ME were weakly but significantly (P < 0.05) negatively associated with GY and SY. Straw NDF and ADF were significantly (P < 0.05) positively correlated with GY but the association was again weak. Straw NDF, ADF and ADL were also weakly but significantly positively correlated with SY. Genome-wide association studies (GWAS) were applied to detect significant marker- straw fodder quality trait associations. Five genomic regions contributed for six traits (ADF, ADL, ASH, IVOMD, ME and NDF). ADF and ADL mapped in the common QTL region on chromosome 2B. Similarly, for the IVOMD and ME QTLs on chromosome 5B were associated with SNP marker, wsnp_Ku_c35090_44349517. While some associations were detected for ADF, ALD, ASH, IVOMD, ME and NDF on chromosomes 1A, 2B, 3A, 5A and 5B, the phenotypic variation explained was low to medium by individual QTL. A likely contributing factor was the comparatively small difference in straw fodder quality traits among the lines. It is interesting to note that line dependent variations in GY and SY were about two-fold. In other words, strong genotypic variations of GY and SY do exist. The lack of any similar variations in straw fodder quality traits is intriguing and requires further research.

Pulmonary and Regional Deposition of Nebulized and Dry Powder Aerosols in Ferrets.

The utilization of ferrets as a non-clinical model for disease is rapidly increasing within drug development. Many of these models include respiratory diseases that involve targeted drug delivery via nose-only inhalation. While the deposition patterns within other non-clinical models (mice, rats, canines, and non-human primates) have been well studied, the local and regional deposition of aerosols in ferrets has not been well characterized. Therefore, inhalation aerosols were developed, radiolabeled and the radiolabeling methods validated to support SPECT-CT imaging and quantification of regional deposition within ferrets. The studies were conducted with one liquid formulation and one dry powder formulation (two concentrations of dry powder). Additionally, both aerosols were polydisperse and therefore reflect the majority of pharmaceutical aerosols. Overall, the studies showed lung deposition fractions between 5 and 10% with median aerodynamic particle sizes of 2.5 and 2.8 µm. The lung deposition fraction of the liquid aerosol was ~ 9%, nearly double observed in rats with a similarly sized aerosol. Analysis of respiratory tract (oropharynx, laryngopharynx, trachea, bifurcation area, and lung) deposition indicates increased deposition of the liquid aerosol compared to the dry powder aerosol, however, when this analysis was refined to the pulmonary region (trachea, bifurcation, and lung) the deposition was similar between formulations. These data provide the first description of the regional deposition of inhalation aerosols in ferrets with standard nose-only inhalation procedures. These data can be used for calculations of both total and regional doses within ferret inhalation drug delivery.

Elucidation of defense-related signaling responses to spot blotch infection in bread wheat (Triticum aestivum L.).

Spot blotch disease, caused by Bipolaris sorokiniana, is an important threat to wheat, causing an annual loss of ~17%. Under epidemic conditions, these losses may be 100%, yet the molecular responses of wheat to spot blotch remain almost uncharacterized. Moreover, defense-related phytohormone signaling genes have been poorly characterized in wheat. Here, we have identified 18 central components of salicylic acid (SA), jasmonic acid (JA), ethylene (ET), and enhanced disease susceptibility 1 (EDS1) signaling pathways as well as the genes of the phenylpropanoid pathway in wheat. In time-course experiments, we characterized the reprogramming of expression of these pathways in two contrasting genotypes: Yangmai #6 (resistant to spot blotch) and Sonalika (susceptible to spot blotch). We further evaluated the performance of a population of recombinant inbred lines (RILs) by crossing Yangmai#6 and Sonalika (parents) and subsequent selfing to F10 under field conditions in trials at multiple locations. We characterized the reprogramming of defense-related signaling in these RILs as a consequence of spot blotch attack. During resistance to spot blotch attack, wheat strongly elicits SA signaling (SA biogenesis as well as the NPR1-dependent signaling pathway), along with WRKY33 transcription factor, followed by an enhanced expression of phenylpropanoid pathway genes. These may lead to accumulation of phenolics-based defense metabolites that may render resistance against spot blotch. JA signaling may synergistically contribute to the resistance. Failure to elicit SA (and possibly JA) signaling may lead to susceptibility against spot blotch infection in wheat.

In vitro screening of calli of mungbean to cercosporin, a photoactivated toxin.

Mungbean or Green gram [Vigna radiata (L.) R. Wilczek] is an arid/semiarid pulse crop, native to India, grown mostly as a rotational crop with cereals like wheat, rice, maize, sorghum, etc. It is an affordable source of protein, carbohydrate, vitamins and minerals preferred for its nutrient digestibility, food processing properties and bioavailability. India accounts for 65% of mungbean's world acreage and 54% of its world production. Various pests, diseases and environmental stresses have kept mungbean yield quite unstable over decades and researcher's worldover are looking for resistant varieties to overcome these challenges. Cercospora leaf spot (CLS) caused by Cercospora canescens is one of the most destructive diseases of mungbean and the key polyketide toxin cercosporin plays an important role in pathogenesis. Such toxins as selective agents in the tissue culture medium can help in selecting genotype with suitable levels of resistance to the toxin and/or to the pathogen among the available germplasm. Here, we standardized the dose of cercosporin for in vitro selection of resistant mungbean genotypes and variable expression of peroxidase, catalase and superoxide dismutase. Murashige and Skoog (MS) medium supplemented with 1.0 mg L-1 NAA and 1.0 mg L-1 BAP was standardized for the development of callus from mungbean using hypocotyls as an explant. The calli from six cultivars of mungbean were tested in medium amended with cercosporin (0-40 µg mL-1) and calli survived up to 20 µg mL-1 of cercosporin. The calli from resistant cultivars survived 83.33-93.00%, and showed lower reduction in fresh weight (25.97-28.83%). Calli from the susceptible cultivars survived 50-60% and showed higher reduction in fresh weight. Callus showed browning, exposure to cercosporin (5-20 µg mL-1). Enzymes assay from survived calli of different cultivars showed higher peroxidase activity (7.90-8.91 ∆OD min-1 mg­1 callus), superoxide dismutase (0.96-1.03 ∆OD min-1 mg-1 callus) and a lower catalase (0.35-0.43 µ moles of H2O2 utilized min-1 mg­1 callus) in resistant, followed by moderately resistance and susceptible cultivars. The necrosis in leaves was recorded with 200 µg mL-1 of cercosporin, and no visible necrosis was observed below this concentration. Enzyme assayed from the controlled and cercosporin-treated (100-200 µg mL-1) leaves of mungbean genotypes showed variable activity of peroxidase, catalase and superoxide dismutase.

Metronidazole Induced Encephalopathy.

Metronidazole is an antimicrobial used for the treatment of anaerobic bacterial and protozoal infections. Neurological toxicity due to metronidazole use has been a matter of concern and many case reports of neurotoxicity are being published. We report here a case of a 32 years old male chronic alcoholic with multiple liver abscesses and history of 6 weeks use of metronidazole presenting with multiple episodes of seizures, burning sensation of feet and altered sensorium. MRI Brain revealed characteristic and reversible involvement of dentate nuclei and splenium of corpus callosum, typical of metronidazole induced encephalopathy (MIE).

Effect of Tricyclazole on morphology, virulence and enzymatic alterations in pathogenic fungi Bipolaris sorokiniana for management of spot blotch disease in barley.

Bipolaris sorokiniana synthesizes the 1,8-dihydroxynaphthalene (DHN) melanin via pentaketide pathway and promotes the development of aerial mycelia and conidia. A melanin biosynthesis inhibitor Tricyclazole (TCZ), brought changes when applied at 5-100 µg ml(-1) concentration in the colony morphology, radial growth, mycelia weight, melanin content, antioxidant enzymes (SOD and CAT) and extracellular hydrolytic enzymes (cellulase, pectinase, amylase and protease) in black, mixed and white isolates of B. sorokiniana. A significant alteration was recorded in antioxidant enzymes in black and mixed isolates; however, non-significant alteration was recorded in white isolate. Isolates of B. sorokiniana exposed to 100 µg ml(-1) TCZ showed significantly increased formation of superoxide radical (O 2 (·-) ) and hydrogen peroxide (H2O2)·H2O2 was detected significantly high in hyphae and conidia while, O 2 (·-) was found primarily in the conidia. Microscopic results suggest that TCZ damages not only the cell wall but also the cell membrane. The foliar application of TCZ (25, 50 and 100 µg ml(-1)) decreases the area under disease progress curve, lesion development and spore formation on barley leaves thereby reducing potential for the disease development. In conclusion TCZ influences the pathogenic ability by damaging the cell structure of hyphae and conidia and also alters the antioxidant enzyme levels in B. sorokiniana. TCZ may therefore, works against to pathogen for better management of spot blotch disease in barley infected with B. sorokiniana.

Validation of SSR markers associated with rust (Uromyces fabae) resistance in pea (Pisum sativum L.).

Pea rust is a devastating disease of peas especially in the sub-tropical regions of the world and greatly influenced by the environmental conditions during disease development. Molecular markers associated with pea rust resistance would be useful in marker assisted selection (MAS). Utility of molecular markers associated with the pea rust resistance were evaluated in 30 diverse pea genotypes using four SSR markers (AA446 and AA505 flanking the major QTL Qruf; AD146 and AA416 flanking the minor QTL, Qruf1). QTL, Qruf flanking markers were able to identify all the resistant genotypes when used together, except Pant P 31. While, SSR markers AD146 and AA416 flanking the minor QTL, Qruf1 were able to identify all the pea resistant genotypes used for validation, except for HUDP-11 by AD146 and Pant P 31 by AA416. Similarly, SSR markers AA446 and AA505 were able to identify all the susceptible pea genotypes, except IPFD 99-13, HFP 9415 and S- 143. SSR markers AD146 and AA416 were together able to identify all the pea susceptible genotypes used for validation, except KPMR 526, KPMR 632 and IPFD 99-13. On the basis of marker allele analysis it may be concluded that SSR markers (AA446, AA505, AD146 and AA416) can be used in MAS of pea rust resistance.

Role of melanin in release of extracellular enzymes and selection of aggressive isolates of Bipolaris sorokiniana in barley.

Eighteen barley isolates of Bipolaris sorokiniana belonging to wild and clonal type of black, mixed and white subpopulations were quantitatively assayed for their melanin content and aggressiveness with respect to production of some of the extracellular enzymes such as cellulase, pectinase, amylase and protease. Cellulase and pectinase constituted major portion of the enzymes recovered from the black, mixed and white isolates. Enzyme production and aggressiveness were relatively higher in melanin devoid or low melanin isolates. The melanin deficient isolates were also differentiated from black and mixed isolates on the basis of variation in internal transcribed spacer region of the ribosomal DNA. Higher enzyme productions positively correlated with area under disease progress curve (AUDPC) and lesion development. Melanin content was negatively correlated with extracellular enzymes and aggressiveness of the isolates. Based on melanin content, lesion size, AUDPC and extracellular enzymes, the isolates were grouped in two major clusters (I and II) with further division of cluster II into two sub-clusters (II-A and II-B). The results appears to indicate a possible role of melanin in release of extracellular enzymes and hence in evolution and selection of aggressive isolates of B. sorokiniana in barley.

QTL for spot blotch resistance in bread wheat line Saar co-locate to the biotrophic disease resistance loci Lr34 and Lr46.

Spot blotch caused by Bipolaris sorokiniana is a major disease of wheat in warm and humid wheat growing regions of the world including south Asian countries such as India, Nepal and Bangladesh. The CIMMYT bread wheat line Saar which carries the leaf tip necrosis (LTN)-associated rust resistance genes Lr34 and Lr46 has exhibited a low level of spot blotch disease in field trials conducted in Asia and South America. One hundred and fourteen recombinant inbred lines (RILs) of Avocet (Susceptible) × Saar, were evaluated along with parents in two dates of sowing in India for 3 years (2007-2008 to 2009-2010) to identify quantitative trait loci (QTL) associated with spot blotch resistance, and to determine the potential association of Lr34 and Lr46 with resistance to this disease. Lr34 was found to constitute the main locus for spot blotch resistance, and explained as much as 55 % of the phenotypic variation in the mean disease data across the six environments. Based on the large effect, the spot blotch resistance at this locus has been given the gene designation Sb1. Two further, minor QTL were detected in the sub-population of RILs not containing Lr34. The first of these was located about 40 cM distal to Lr34 on 7DS, and the other corresponded to Lr46 on 1BL. A major implication for wheat breeding is that Lr34 and Lr46, which are widely used in wheat breeding to improve resistance to rust diseases and powdery mildew, also have a beneficial effect on spot blotch.

Genome sequencing and annotation of Cercospora sesami, a fungal pathogen causing leaf spot to Sesamum indicum.

Cercospora sesami is a plant pathogen that causes leaf spot disease in sesame plants worldwide. In this study, genome sequence assembly of C. sesami isolate Cers 52-10 (MCC 9069) was generated using native paired-end and mate-pair DNA sequencing based on the Illumina HiSeq 2500 platform. The genome assembly of C. sesami is 34.3 Mb in size with an N50 of 26,222 bp and an average GC content of 53.02%. A total number of 10,872 genes were predicted in this study, out of which 9,712 genes were functionally annotated. Genes assigned to carbohydrate-active enzyme classes were also identified during the study. A total of 80 putative effector candidates were predicted and functionally annotated. The C. sesami genome sequence is available at DDBJ/ENA/GenBank, and other associated information is submitted to Mendeley's data. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03468-4.

Rust (Uromyces viciae-fabae Pers. de-Bary) of Pea (Pisum sativum L.): Present Status and Future Resistance Breeding Opportunities.

Uromyces viciae-fabae Pers. de-Bary is an important fungal pathogen causing rust in peas (Pisum sativum L.). It is reported in mild to severe forms from different parts of the world where the pea is grown. Host specificity has been indicated in this pathogen in the field but has not yet been established under controlled conditions. The uredinial states of U. viciae-fabae are infective under temperate and tropical conditions. Aeciospores are infective in the Indian subcontinent. The genetics of rust resistance was reported qualitatively. However, non-hypersensitive resistance responses and more recent studies emphasized the quantitative nature of pea rust resistance. Partial resistance/slow rusting had been described as a durable resistance in peas. Such resistance is of the pre-haustorial type and expressed as longer incubation and latent period, poor infection efficiency, a smaller number of aecial cups/pustules, and lower units of AUDPC (Area Under Disease Progress Curve). Screening techniques dealing with slow rusting should consider growth stages and environment, as both have a significant influence on the disease scores. Our knowledge about the genetics of rust resistance is increasing, and now molecular markers linked with gene/QTLs (Quantitative Trait Loci) of rust resistance have been identified in peas. The mapping efforts conducted in peas came out with some potent markers associated with rust resistance, but they must be validated under multi-location trails before use in the marker-assisted selection of rust resistance in pea breeding programs.

Emerging phytopathogen Macrophomina phaseolina: biology, economic importance and current diagnostic trends.

Macrophomina phaseolina (Tassi) Goid. is an important phytopathogenic fungus, infecting a large number of plant species and surviving for up to 15 years in the soil as a saprophyte. Although considerable research related to the biology and ecology of Macrophomina has been conducted, it continues to cause huge economic losses in many crops. Research is needed to improve the identification and characterization of genetic variability within their epidemiological and pathological niches. Better understanding of the variability within the pathogen population for traits that influence fitness and soil survival will certainly lead to improved management strategies for Macrophomina. In this context, the present review discusses various biological aspects and distribution of M. phaseolina throughout the world and their importance to different plant species. Accurate identification of the fungus has been aided with the use of nucleic acid-based molecular techniques. The development of PCR-based methods for identification and detection of M. phaseolina are highly sensitive and specific. Early diagnosis and accurate detection of pathogens is an essential step in plant disease management as well as quarantine. The progress in the development of various molecular tools used for the detection, identification and characterization of Macrophomina isolates were also discussed.

Characterization of respiratory deposition of fluticasone-salmeterol hydrofluoroalkane-134a and hydrofluoroalkane-134a beclomethasone in asthmatic patients.

BACKGROUND: Fixed combination fluticasone-salmeterol is the most used anti-inflammatory asthma treatment in North America, yet no studies report the actual respiratory tract dose or the distribution of drug within the lungs. Inflammation due to asthma affects all airways of the lungs, both large and small. Inhaled steroid delivery to airways results from a range of drug particle sizes, with emphasis on smaller drug particles capable of reaching the peripheral airways. Previous studies suggested that smaller drug particles increase pulmonary deposition and decrease oropharyngeal deposition. OBJECTIVES: To characterize the dose of fluticasone-salmeterol hydrofluoroalkane-134a (HFA) (particle size, 2.7 µm) delivered to asthmatic patients and examine the drug distribution within the lungs. The results were compared with the inhalation delivery of HFA beclomethasone (particle size, 0.7 µm). METHODS: A crossover study was conducted in asthmatic patients with commercial formulations of fluticasone-salmeterol and HFA beclomethasone radiolabeled with technetium Tc 99m. Deposition was measured using single-photon emission computed tomography/computed tomography gamma scintigraphy. RESULTS: Two-dimensional planar image analysis indicated that 58% of the HFA beclomethasone and 16% of the fluticasone-salmeterol HFA were deposited in the patient's lungs. The oropharyngeal cavity and gut analyses indicated that 77% of the fluticasone-salmeterol HFA was deposited in the oropharynx compared with 35% of the HFA beclomethasone. CONCLUSIONS: The decreased peripheral airway deposition and increased oropharyngeal deposition of fluticasone-salmeterol HFA was a result of its larger particle size. The smaller particle size of HFA beclomethasone allowed a greater proportion of lung deposition with a concomitant decrease in oropharyngeal deposition.

SNP Discovery Using BSR-Seq Approach for Spot Blotch Resistance in Wheat (Triticum aestivum L.), an Essential Crop for Food Security.

The pathogenic fungus, Bipolaris sorokiniana, that causes spot blotch (SB) disease of wheat, is a major production constraint in the Eastern Gangetic Plains of South Asia and other warm, humid regions of the world. A recombinant inbred line population was developed and phenotyped at three SB-prone locations in India. The single nucleotide polymorphism (SNP) for SB resistance was identified using a bulked segregant RNA-Seq-based approach, referred to as "BSR-Seq." Transcriptome sequencing of the resistant parent (YS#24), the susceptible parent (YS#58), and their resistant and susceptible bulks yielded a total of 429.67 million raw reads. The bulk frequency ratio (BFR) of SNPs between the resistant and susceptible bulks was estimated, and selection of SNPs linked to resistance was done using sixfold enrichments in the corresponding bulks (BFR >6). With additional filtering criteria, the number of transcripts was further reduced to 506 with 1055 putative polymorphic SNPs distributed on 21 chromosomes of wheat. Based on SNP enrichment on chromosomal loci, five transcripts were found to be associated with SB resistance. Among the five SB resistance-associated transcripts, four were distributed on the 5B chromosome with putative 52 SNPs, whereas one transcript with eight SNPs was present on chromosome 3B. The SNPs linked to the trait were exposed to a tetra-primer ARMS-PCR assay, and an SNP-based allele-specific marker was identified for SB resistance. The in silico study of these five transcripts showed homology with pathogenesis-related genes; the metabolic pathway also exhibits similar results, suggesting their role in the plant defense mechanism.