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Rice blast and bacterial leaf blight, are major disease, significantly threatens rice yield in all rice growing regions under favorable conditions and identification of resistance genes and their superior haplotypes is a potential strategy for effectively managing and controlling this devastating disease. In this study, we conducted a genome-wide association study (GWAS) using a diverse set of 147 rice accessions for blast and bacterial blight diseases in replications. Results revealed 23 (9 for blast and 14 for BLB) significant marker-trait associations (MTAs) that corresponded to 107 and 210 candidate genes for blast and BLB, respectively. The haplo-pheno analysis of the candidate genes led to the identification of eight superior haplotypes for blast,with an average SES score ranging from 0.00 to 1.33, and five superior haplotypes for BLB, with scores ranging from 1.52cm to 4.86cm superior haplotypes. Among these, superior haplotypes LOC_OS12G39700-H4 and LOC_Os06g30440-H33 were identified with the lowest average blast scores of 0.00-0.67, and superior haplotype LOC_Os02g12660-H39 exhibited the lowest average lesion length (1.88 - 2.06cm) for BLB. A total of ten accessions for blast and eight accessions for BLB were identified carrying superior haplotypes were identified. These haplotypes belong to aus and indx subpopulations of five countries (Bangladesh, Brazil, India, Myanmar, and Pakistan). For BLB resistance, eight accessions from six countries (Bangladesh, China, India, Myanmar, Pakistan, and Sri Lanka) and four subpopulations (aus, ind1A, ind2, and ind3) were identified carrying superior haplotypes. Interestingly, four candidate genes, LOC_Os06g21040, LOC_Os04g23960, LOC_Os12g39700, and LOC_Os01g24640 encoding transposon and retrotransposon proteins were among those with superior haplotypes known to play a crucial role in plant defense responses. These identified superior haplotypes have the potential to be combined into a single genetic background through haplotype-based breeding for a broader resistance spectrum against blast and bacterial blight diseases. [ABSTRACT FROM AUTHOR]

Rice blast and bacterial leaf blight, are major disease, significantly threatens rice yield in all rice growing regions under favorable conditions and identification of resistance genes and their superior haplotypes is a potential strategy for effectively managing and controlling this devastating disease. In this study, we conducted a genome-wide association study (GWAS) using a diverse set of 147 rice accessions for blast and bacterial blight diseases in replications. Results revealed 23 (9 for blast and 14 for BLB) significant marker-trait associations (MTAs) that corresponded to 107 and 210 candidate genes for blast and BLB, respectively. The haplo-pheno analysis of the candidate genes led to the identification of eight superior haplotypes for blast, with an average SES score ranging from 0.00 to 1.33, and five superior haplotypes for BLB, with scores ranging from 1.52cm to 4.86cm superior haplotypes. Among these, superior haplotypes LOC_OS12G39700-H4 and LOC_Os06g30440-H33 were identified with the lowest average blast scores of 0.00-0.67, and superior haplotype LOC_Os02g12660-H39 exhibited the lowest average lesion length (1.88 - 2.06cm) for BLB. A total of ten accessions for blast and eight accessions for BLB were identified carrying superior haplotypes were identified. These haplotypes belong to aus and indx subpopulations of five countries (Bangladesh, Brazil, India, Myanmar, and Pakistan). For BLB resistance, eight accessions from six countries (Bangladesh, China, India, Myanmar, Pakistan, and Sri Lanka) and four subpopulations (aus, ind1A, ind2, and ind3) were identified carrying superior haplotypes. Interestingly, four candidate genes, LOC_Os06g21040, LOC_Os04g23960, LOC_Os12g39700, and LOC_Os01g24640 encoding transposon and retrotransposon proteins were among those with superior haplotypes known to play a crucial role in plant defense responses. These identified superior haplotypes have the potential to be combined into a single genetic background through haplotype-based breeding for a broader resistance spectrum against blast and bacterial blight diseases.

Riee is one of the primarily grown eereals in the universe and is eaten by 60% of the world population as a staple food. Three indigenous extra long grain riee varieties grown in Punjab, Pakistan were analyzed for their eooking, ehemieal and physieal properties. A eomparison of newly developed varieties was done with the existing Basmati 515, super Basmati. Among all studied traits, varieties differ eonsiderably atP > 0.001 value for paddy yield, plant height, grain dimensions, elongation/expansion ratio, gel uniformity, temperature for gelatinization, alkaline spread value and aroma on sensory pereeption. The volume expansion ratio varied from 4.5 to 5.5. The highest volume expansion ratio was aequired for Kissan Basmati. Grain elongation after eooking ranged between 14.7 to 16.6 mm. The values for the amylose ranged between 22.50 to 24.0% and amylopeetin ranged between 76-77.5%. The range of AGL of extra long grain ranged from 8.10to 8.23 mm, L/B ratio from 4.47 to 5.47. All verified varieties showed resistanee against BLS, blast and BLB ineidenee. [ABSTRACT FROM AUTHOR]

An investigation was carried out with the aim to study the interactive effect of Pseudomonas fluorescens (PF9) and Rhizophora apiculata for the management of bacterial leaf blight disease of rice. In both pot and field trials, application of P. fluorescens as seed treatment (10 ml/kg seed) and foliar spray of R. apiculata @ 15% at 35 and 50 DAT significantly reduced the bacterial leaf blight incidence with maximum plant height, number of productive tillers per hill, panicle length, grains per panicle of paddy and recorded on par results with that of streptomycin (100 ppm) treatment. Untreated control treatment recorded the maximum per cent disease incidence and minimum plant height, number of productive tillers per hill, panicle length as well as grains per panicle of rice. [ABSTRACT FROM AUTHOR]

The System of Rice Intensification (SRI), an innovation that was first emerged in Madagascar in the 1980s and has now diffused to more than 50 countries. The present study was conducted as field experiment in the central farm of Sher-e-Bangla Agricultural University (SAU) using RCBD design and the lab experiment was carried out in Molecular Biology and Plant Virology Laboratory under the Department of Plant Pathology, Sher-e-Bangla Agricultural University, Dhaka-1207. The experiment was carried out to adopt SRI as an alternative approach for management of major rice diseases in Bangladesh, during the period of November, 2020 to June, 2021. From the study it was revealed that all the selected planting methods gave the significantly effect on percent disease incidence (% DI) and severity (% DS) of major rice diseases viz. blast, brown spot, sheath blight and bacterial leaf blight in selected Boro rice varieties (BRRI dhan 28, BRRI dhan 89, BRRI dhan 92 and purple rice). The highest disease incidence and severity was recorded in conventional planting method and the lowest in basic SRI method. The moderate disease incidence and severity was recorded in modern SRI method which was statistically non-significant with Basic SRI method but significant with conventional method. However, it is necessary for further trial in different variety and AEZs as field experiment. So, it may be recommended that the System of Rice Intensification (SRI) may be alternative for management of major rice diseases. [ABSTRACT FROM AUTHOR]

Bacterial leaf blight caused by Xanthomonas oryzae pv. oryzae (Xoo) is a catastrophic bacterial disease of rice, and researchers are facing difficulties in developing the management practices, whereas the continued use of bactericides viz, streptomycin, copper oxychloride leads to the development of resistant Xoo strains. As a consequence, the development of an environmentally safe bactericide for the management of this devastating disease is needed. The present study focused on identification of effective synthetic activators against bacterial leaf blight in rice during their interaction. Survey was conducted to collect different isolates of Xoo and their morphological characters and biochemical properties were determined. All the 10 isolates exhibited circular to flattened slimy yellow colour colonies of the pathogen and showed positive reaction for citrate utilization, lysine utilization and ornithine utilization test. All the ten isolates showed negative reaction for sorbitol utilization. The collected isolates were subjected to PCR for the amplification of 16S-23S intergenic regionwith the species specific primer and obtained amplicon at 470 bp for the confirmation at molecular level. The virulentisolate wasidentified by measuring biofilm formation and xanthomonadin pigment which revealed that the isolate ADT 53 strain T3 with the accession number OR121377 recorded maximumOD value of 0.356 for biofilm formation at 570 nm and 0.686 for xanthomonadin pigment at 445 nm. In planta studies revealed that salicylic acid at 100 ppm has the maximum inhibitory effect against bacterial leaf blight disease with the minimal lesion size of 0.7 cmcompared to negative control (water). [ABSTRACT FROM AUTHOR]

Abstract Rice is a widely consumed staple food for a large part of the world’s human population. Approximately 90% of the world’s rice is grown in Asian continent and constitutes a staple food for 2.7 billion people worldwide. Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae is one of the devastating diseases of rice. A field experiment was conducted during the year 2016 and 2017 to investigate the influence of different meteorological parameters on BLB development as well as the computation of a predictive model to forecast the disease well ahead of its appearance in the field. The seasonal dataset of disease incidence and environmental factors was used to assess five rice varieties/ cultivars (Basmati-2000, KSK-434, KSK-133, Super Basmati, and IRRI-9). The accumulated effect of two year environmental data; maximum and minimum temperature, relative humidity, wind speed, and rainfall, was studied and correlated with disease incidence. Average temperature (maximum & minimum) showed a negative significant correlation with BLB disease and all other variables; relative humidity, rainfall, and wind speed had a positive correlation with BLB disease development on individual varieties. Stepwise regression analysis was performed to indicate potentially useful predictor variables and to rule out incompetent parameters. Environmental data from the growing seasons of July to October 2016 and 2017 revealed that, with the exception of the lowest temperature, all environmental factors contributed to disease development throughout the cropping season. A disease prediction multiple regression model was developed based on two-year data (Y = 214.3-3.691 Max T-0.508 Min T + 0.767 RH + 2.521 RF + 5.740 WS), which explained 95% variability. This disease prediction model will not only help farmers in early detection and timely management of bacterial leaf blight disease of rice but may also help reduce input costs and improve product quality and quantity. The model will be both farmer and environmentally friendly.

Bacterial Bight profoundly affects global rice-growing regions. Breeding resistant cultivars is a reliable, effective, and eco-friendly way to control bacterial blight. The study was conducted during 2021–2022 to evaluate the resistance of rice genotypes to bacterial blight under glasshouse conditions. A total of 137 rice genotypes were screened for their resistance against two Xanthomonas oryzae pv. oryzae strains (TXO01 and TXO08) using the leaf clipping method. The results revealed diverse disease reactions among the genotypes, with some exhibiting high levels of resistance characterized by hypersensitive reactions and shorter lesion lengths. To further investigate the genetic basis of resistance, we screened moderately resistant and resistant genotypes for major bacterial blight resistance genes, including Xa21, xa5, and xa13, using gene-specific markers. Five genotypes viz., ADT55, CB MAS 13056, CB MAS 13060, CB MAS 13066, and ACM 18234 confirmed the presence of all R genes in a homozygous state, indicating a potentially robust resistance background. In addition, we examined the expression patterns of five defense-related genes involved in the salicylic acid (SA) and jasmonic acid (JA) signaling pathways using quantitative real-time PCR (qRT-PCR). The resistant genotypes exhibited significantly elevated expression levels of OsNPR1, OsWRKY45, OsPAL1, OsPR1a, and OsPR10a, ranging from 2 to 20-fold changes compared with the susceptible genotype. In conclusion, our findings suggest that the resistant genotypes not only harbor multiple bacterial blight resistance genes but also manifest up regulated defense responses against Xanthomonas oryzae pv. oryzae , possibly substantiating their elevated level of disease resistance. • Phenotypic screening conducted with two Xoo strains in rice genotypes. • Out of 137, five genotypes exhibited greater resistance to Xoo. • The presence of three major BB-R genes were identified in resistant genotypes. • The upregulation of defense response in resistant genotypes were studied through qRT-PCR. [ABSTRACT FROM AUTHOR]

Marker-assisted selection and gene pyramiding are very important breeding strategies for conferring broad spectrum and durable resistance against diseases causing yield loss in rice. One such disease causing major set backs in rice production is bacterial leaf blight (BLB) caused by the pathogen Xanthomonas oryzae pv. oryzae. Molecular markers are very essential in both marker-assisted selection and pyramiding of genes, hence, many molecular marker techniques have already been developed. Presently, the most commonly used ones are DNA-based markers also known as molecular markers. The molecular markers are classified into two major categories based on the techniques used for detecting them. These are hybridization and polymerase chain reaction-based markers. Other types of markers available include the morphological (traditionally based) and biochemical (enzyme-based) markers. Host plant/varietal resistance is the most suitable means for controlling BLB disease of rice. Marker-assisted gene pyramiding has the potential to accelerate the breeding programmes and guarantee the durability of resistance conferred in the host plant. Therefore, this paper uncovers the utilization, economic importance, limitations and future prospects of marker-assisted selection and gene pyramiding for resistance to BLB disease of rice.

The present study was undertaken to assess the genetic variability existed among 114 rice germplasm for BLB resistance. In field level screening, the genotypes PY5 and Kadaikannan showed immune against rice BLB. The rice germplasm were subjected to 𝐷2 analysis for nine quantitative traits viz., plant height, number of productive tillers per plant, days to fifty per cent flowering, panicle length, number of grains per panicle, thousand grain weight, single plant yield, grain length and grain breadth. On the basis of Mahalanobis 𝐷2 statistics, the 114 genotypes were grouped into eighteen clusters.

The use of resistant (R) genes is the most effective strategy to manage bacterial leaf blight (BLB) disease of rice. Several attempts were made to incorporate R genes into susceptible rice cultivars using marker-assisted backcross breeding (MABB). However, MABB relies exclusively on PCR for foreground selection of R genes, which requires expensive equipment for thermo-cycling and visualization of results; hence, it is limited to sophisticated research facilities. Isothermal nucleic acid amplification techniques such as loop-mediated isothermal amplification (LAMP) assay do not require thermo-cycling during the assay. Therefore, it will be the best alternative to PCR-based genotyping. In this study, we have developed a LAMP assay for the specific and sensitive genotyping of seven BLB resistance (R) genes viz., Xa1, Xa3, Xa4, Xa7, Xa10, Xa11, and Xa21 in rice. Gene-specific primers were designed for the LAMP assay. The LAMP assay was optimized for time, temperature, and template DNA concentration. For effective detection, incubation at 60 °C for 30 min was optimum for all seven R genes. A DNA intercalating dye ethidium bromide and a calorimetric dye hydroxynaphthol blue was used for result visualization. Further, sensitivity assay revealed that the LAMP assay could detect R genes at 100 fg of template DNA compared to 1 ng and 10 pg, respectively, in conventional PCR and q-PCR assays. The LAMP assay developed in this study provides a simple, specific, sensitive, robust, and cost-effective method for foreground selection of R genes in the resistance breeding programs of resource-poor laboratory. [ABSTRACT FROM AUTHOR]

Bacterial leaf blight (BLB) is caused by Xanthomonas oryzae pv. oryzae and is a major cause of rice yield reductions around the world. When diseased, plants produce a variety of metabolites to resist pathogens. In this study, the various defense metabolites were quantified using high-performance liquid chromatography (HPLC) after Xoo inoculation in a 120 Cheongcheong/Nagdong double haploid (CNDH) population. Quantitative trait locus (QTL) mapping was conducted using the concentration of the plant defense metabolites. HPLC analyzes the concentration of substances according to the severity of disease symptoms. Searching for BLB resistance candidate genes by applying this analysis method is very effective when mapping related genes. These resistance genes can be mapped directly to the causative pathogens. A total of 17 metabolites were detected by means of HPLC analysis after Xoo inoculation in the 120 CNDH population. QTL mapping of the metabolite concentrations resulted in the detection of the BLB resistance candidate gene, OsWRKYq6, in RM3343 of chromosome 6. OsWRKYq6 has a very high homology sequence with WRKY transcription factor 39, and when inoculated with Xoo, the relative expression level of the resistant population was higher than that of the susceptible population. Resistance genes have previously been detected using only phenotypic change data. In this study, resistance candidate genes were detected using the concentration of metabolites produced in plants after inoculation with pathogens. This newly developed analysis method can be used to effectively detect and identify genes directly involved in disease resistance for future studies.

An investigation was carried out to evaluate the susceptibility of rice cultivation to major field diseases like brown spot, sheath blight and bacterial leaf blight under middle Indo Gangetic Plain. The disease incidence and disease severity were observed at three different growth stages namely flowering, milk and maturity in boro seasons during 2015-16. The incidence of brown spot ranged from 8.93 to 17.83%, 16.67 to 25.67% and 18.33 to 28.33% at flowering, milk and maturity stages, respectively. The severity of brown spot in grade (0-9 scale) ranged from 5.13 to 10.33, 9.33 to 20.00 and 11.57 to 22.67, respectively at flowering, milk and maturity stages. The incidence of sheath blight of paddy ranged from 7. 03 to 16.50%, 13.13 to 22.67% and 19.67 to 35.67% at flowering, milk and maturity stages, respectively. The severity of sheath blight in grade (0-9 scale) ranged from 4.00 to 8.60, 8.33 to 13.93 and 18.33 to 34.33, respectively at flowering, milk and maturity stages. The incidence of bacterial leaf blight ranged from 5.00 to 14.00%, 11.43 to 21.00% and 17.00 to 34.00% at flowering, milk and maturity stages, respectively. The severity of bacterial leaf blight in grade (0-9 scale) ranged from 2.00 to 8.00%, 6.33 to 12.05% and 14.47 to 20.17%, respectively at flowering, milk and maturity stages. Among the varieties, the highest incidence and severity of Brown spot was recorded on Rajendra Bhagawati whereas it was lowest on 27P31 at all growth stages. In the case of Sheath blight, highest incidence and severity was recorded on Sambha Mahsuri whereas it was the lowest on CRL 193. Beside this in the case of Bacterial leaf blight, the highest incidence and severity was recorded on Kranti whereas the lowest was recorded on CRL 193. In general, it was observed that the incidence and severity of diseases increased gradually from flowering to maturity stage and the genotypes with the minimum incidence and severity of diseases gave the maximum yield.

Marker-assisted selection and gene pyramiding are very important breeding strategies for conferring broad spectrum and durable resistance against diseases causing yield loss in rice. One such disease causing major set backs in rice production is bacterial leaf blight (BLB) caused by the pathogen Xanthomonas oryzae pv. oryzae. Molecular markers are very essential in both marker-assisted selection and pyramiding of genes, hence, many molecular marker techniques have already been developed. Presently, the most commonly used ones are DNA-based markers also known as molecular markers. The molecular markers are classified into two major categories based on the techniques used for detecting them. These are hybridization and polymerase chain reaction-based markers. Other types of markers available include the morphological (traditionally based) and biochemical (enzyme-based) markers. Host plant/varietal resistance is the most suitable means for controlling BLB disease of rice. Marker-assisted gene pyramiding has the potential to accelerate the breeding programmes and guarantee the durability of resistance conferred in the host plant. Therefore, this paper uncovers the utilization, economic importance, limitations and future prospects of marker-assisted selection and gene pyramiding for resistance to BLB disease of rice. [ABSTRACT FROM AUTHOR]

Bacterial leaf blight (BLB) is one of the most important diseases that limit overall rice productivity. To investigate the effects of row spacing on incident of bacterial leaf blight (BLB) in rice, field experiments were conducted at Agronomic Research Area, Department of Agronomy, University of Agriculture Faisalabad during 2013 and 2014. Two rice cultivars i.e., Super Basmati (V1) and Basmati-515 (V2) were sown at three different row spacings i.e., 15, 22.5 and 30 cm regarded as S1, S2, and S3, respectively. Results depicted that the lowest disease incidence i.e., 4.00 and 4.09% was recorded for Basmati-515 sown at 30 and 22.5 cm apart rows, respectively. The maximum productive tillers m-2 was recorded in V1S2, whilst the panicle length, kernels per panicle, and normal kernels per panicle were recorded in V1S3. The 1000 grain weight was found highest in V2S2. The maximum paddy yield i.e., 3.99 t ha-1 was recorded in V1S2 which were statistically similar to V2S2, whereas the harvest index was also found significantly higher in V2S2 than all other interactions. Among both rice cultivars, Basmati-515 was found less prone to BLB as compare Super Basmati. Hence, wider row spacing significantly reduced bacterial leaf blight severity. Thus, it can be concluded that BLB can be managed by growing early maturing short duration genotypes at wider row spacing. [ABSTRACT FROM AUTHOR]

The objective of this work was to study the virulence of 15 Xanthomonas oryzae pv. oryzae (Xoo) isolates collected in three provinces in Indonesia (North Sumatra, South Sumatra, and South Sulawesi) based on five Indonesian differential rice genotypes and 10 near isogenic lines (NILs) that have been known to differ in their resistance to bacterial leaf blight (BLB), in a greenhouse assessment. In addition, this study also aims to monitor the responses of 31 rice genotypes (21 NILs, five differentials, five improved cultivars) to BLB disease in a field experiment. The 15 isolates showed different virulence patterns on the NILs’genotypes with a single resistance gene indicating the pathogen diversity. Eight different pathotypes were present, as demonstrated by a particular virulence pattern of each isolate on the genotypes. Determination of Xoo pathotype revealed that Xoo pathotypes responded differently based on their reaction to NILs and Indonesian differential genotypes. The field assessment demonstrated the incidence and severity of BLB disease on rice genotypes ranging from 25% to 100% and 5.5% to 72.91%, respectively, while the mean disease index ranged from 1.15% to 72.9%. The disease response varied among rice genotypes. IRBB50 (Xa4+xa5), IRBB51 (Xa4+xa13), IRBB52 (Xa4+Xa21), IRBB53 (Xa4+Xa21), IRBB56 (Xa4+xa5+xa13), IRBB57 (Xa4+xa5+Xa21), IRBB59 (Xa4+xa13+Xa21), IRBB64 (Xa4+xa5+Xa7+Xa21), IRBB66 (Xa4+xa5+Xa7+xa13+Xa21), IRBB7(Xa7), Angke (Xa4+xa5) and Code (Xa4+Xa7) were revealed to be highly resistant to the BLB pathogen. These genotypes have potential as genetic material for the pyramiding of several resistance genes for the development of rice resistance to BLB disease in Indonesia

Amongst serious biotic factors deteriorating crop yield, the most destructive pathogen of rice is Xanthomonas oryzae pv. oryzae (Xoo), which causes bacterial leaf blight (BLB) disease. This study involved targeted use of biogenic silver nanoparticles (AgNPs) to control BLB in order to cope with the disadvantages of chemical disease control. AgNPs were biologically synthesized from natively isolated Bacillus cereus strain SZT1, which was identified through 16S rRNA gene sequence analysis. Synthesis of AgNPs in bacterial culture supernatant was confirmed through UV-VIS spectroscopy. Fourier transform infrared spectroscopy (FTIR) confirmed that the existence of AgNPs was stabilized with proteins and alcoholic groups. X-ray diffraction (XRD) data revealed the crystalline nature and imaging with scanning electron microscopy (SEM) and transmission electron microscopy (TEM), showing the spherical shape of AgNPs with particle sizes ranging from 18 to 39 nm. The silver presence in AgNPs was further confirmed by energy dispersive spectra. Biogenic AgNPs showed substantial antibacterial activity (24.21 ± 1.01 mm) for Xoo. In a pot experiment, AgNPs were found to be effective weapons for BLB by significantly increasing the plant biomass with a decreased cellular concentration of reactive oxygen species and increased concentration of antioxidant enzyme activity.

Xanthomonas oryzae pv. oryzae (Xoo) is widely prevalent and causes Bacterial Leaf Blight (BLB) in Basmati rice grown in different areas of Pakistan. There is a need to use environmentally safe approaches to overcome the loss of grain yield in rice due to this disease. The present study aimed to develop inocula, based on native antagonistic bacteria for biocontrol of BLB and to increase the yield of Super Basmati rice variety. Out of 512 bacteria isolated from the rice rhizosphere and screened for plant growth promoting determinants, the isolate BRp3 was found to be the best as it solubilized 97 μg/ mL phosphorus, produced 30 μg/mL phytohormone indole acetic acid and 15 mg/ L siderophores in vitro. The isolate BRp3 was found to be a Pseudomonas aeruginosa based on 16S rRNA gene sequencing (accession no. HQ840693). This bacterium showed antagonism in vitro against different phytopathogens including Xoo and Fusarium spp. Strain BRp3 showed consistent pathogen suppression of different strains of BLB pathogen in rice. Mass spectrometric analysis detected the production of siderophores (1-hydroxy-phenazine, pyocyanin, and pyochellin), rhamnolipids and a series of already characterized 4-hydroxy-2-alkylquinolines (HAQs) as well as novel 2,3,4-trihydroxy-2-alkylquinolines and 1,2,3,4-tetrahydroxy-2-alkylquinolines in crude extract of BRp3. These secondary metabolites might be responsible for the profound antibacterial activity of BRp3 against Xoo pathogen. Another contributing factor toward the suppression of the pathogen was the induction of defense related enzymes in the rice plant by the inoculated strain BRp3. When used as an inoculant in a field trial, this strain enhanced the grain and straw yields by 51 and 55%, respectively, over non-inoculated control. Confocal Laser Scanning Microscopy (CLSM) used in combination with immunofluorescence marker confirmed P. aeruginosa BRp3 in the rice rhizosphere under sterilized as well as field conditions. The results provide evidence that novel secondary metabolites produced by BRp3 may contribute to its activity as a biological control agent against Xoo and its potential to promote the growth and yield of Super Basmati rice.

Xanthomonas oryzae pv. oryzae (Xoo) is widely prevalent and causes Bacterial Leaf Blight (BLB) in Basmati rice grown in different areas of Pakistan. There is a need to use environmentally safe approaches to overcome the loss of grain yield in rice due to this disease. The present study aimed to develop inocula, based on native antagonistic bacteria for biocontrol of BLB and to increase the yield of Super Basmati rice variety. Out of 512 bacteria isolated from the rice rhizosphere and screened for plant growth promoting determinants, the isolate BRp3 was found to be the best as it solubilized 97 µg/mL phosphorus, produced 30µg/mL phytohormone indole acetic acid and 15 mg/L siderophores in vitro. The isolate BRp3 was found to be a Pseudomonas aeruginosa based on 16S rRNA gene sequencing (accession no. HQ840693). This bacterium showed antagonism in vitro against different phytopathogens including Xoo and Fusarium spp. Strain BRp3 showed consistent pathogen suppression of different strains of BLB pathogen in rice. Mass spectrometric analysis detected the production of siderophores (1-hydroxy-phenazine, pyocyanin, and pyochellin), rhamnolipids and a series of already characterized 4-hydroxy-2-alkylquinolines (HAQs) as well as novel 2,3,4-trihydroxy-2-alkylquinolines and 1,2,3,4-tetrahydroxy-2-alkylquinolines in crude extract of BRp3. These secondary metabolites might be responsible for the profound antibacterial activity of BRp3 against Xoo pathogen. Another contributing factor toward the suppression of the pathogen was the induction of defense related enzymes in the rice plant by the inoculated strain BRp3. When used as an inoculant in a field trial, this strain enhanced the grain and straw yields by 51 and 55%, respectively, over non-inoculated control. Confocal Laser Scanning Microscopy (CLSM) used in combination with immunofluorescence marker confirmed P. aeruginosa BRp3 in the rice rhizosphere under sterilized as well as field conditions. The results provide evidence that novel secondary metabolites produced by BRp3 may contribute to its activity as a biological control agent against Xoo and its potential to promote the growth and yield of Super Basmati rice. [ABSTRACT FROM AUTHOR]

Bacterial leaf blight (BLB) pathogen, Xanthomonas oryzae pv. oryzae (Xoo) is the most devastating bacterial pathogen, which jeopardizes the sustainable rice (Oryza sativa L.) production system. The use of antibiotics and conventional pesticides has become ineffective due to increased pathogen resistance and associated ecotoxicological concerns. Thus, the development of effective and sustainable antimicrobial agents for plant disease management is inevitable. Here, we investigated the toxicity and molecular action mechanisms of bioengineered chitosan‑iron nanocomposites (BNCs) against Xoo using transcriptomic and proteomic approaches. The transcriptomic and proteomics analyses revealed molecular antibacterial mechanisms of BNCs against Xoo. Transcriptomic data revealed that various processes related to cell membrane biosynthesis, antioxidant stress, DNA damage, flagellar biosynthesis and transcriptional regulator were impaired upon BNCs exposure, which clearly showing the interaction of BNCs to Xoo pathogen. Similarly, proteomic profiling showed that BNCs treatment significantly altered the levels of functional proteins involved in the integral component of the cell membrane, catalase activity, oxidation-reduction process and metabolic process in Xoo , which is consistent with the results of the transcriptomic analysis. Overall, this study suggested that BNCs has great potential to serve as an eco-friendly, sustainable, and non-toxic alternative to traditional agrichemicals to control the BLB disease in rice. [Display omitted] • Bioengineered chitosan iron nanocomposites (BNCs) possess antibacterial activity against Xoo. • Genome−enabled approaches revealed the toxicity and action mechanisms of BNC against Xoo. • BNCs altered the expressions of key genes that responsible for bactericidal activity. • BNCs changed the expressions of proteins that involved in metabolic pathways. [ABSTRACT FROM AUTHOR]

Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is a very serious disease in rice growing regions of the world. There are no effective ways of protecting rice from the disease. In this study, the bacteriophage (phage) mixtures infecting Xoo were investigated as biological control agent on BLB. The effects of pH, heat and ultraviolet on the stability of phages were investigated to check and increase the possibility of practical use in the field. Phages were rather stable between pH 5 and pH 10. The infectivity dropped sharply when the phages were incubated at 50℃ and more than 90% of the phages were inactivated after two minutes of ultraviolet treatment. The phages were stable for 7 days at the rice plant leaves, and the phages survived 10 times more than other treatments when mixed with skim milk. Although the skim milk increased the stability of the phages, the control efficacy was not effective. However, the phage mixtures reduced the occurrence of BLB when they were treated with Tecloftalam WP or Acibenzolar-S-methyl simultaneously. The results indicated that the Xoo phages could be used as an alternative control method to increase the control efficacy and reduce the use of agrochemicals.

The study was conducted in the Department of Plant pathology, Faculty of Agricultural Sciences and Technology, Bahauddin Zakariya University, Multan, Pakistan during the year 2012-2015. Stepwise regression model was developed for the devastating pathosystem; bacterial leaf blight of rice caused by Xanthomonas oryzae pv. Oryzae. Three highly susceptible rice cultivars (Basmati Super, IRRI-24 and TN-1) were tested based on the seasonal dataset of disease severity and environmental variables. As the climatic conditions greatly influence the disease developments so datasets for the environmental parameters i.e. maximum and minimum daily temperature of air, relative humidity of morning and evening, rainfall, wind speed and daily sunshine hours were collected and analyzed by correlation for stepwise linear regression model. Stepwise regression analysis was performed to indicate potentially useful predictor variables and to rule out the incompetent parameters. Step wise regression analysis proved that the wind speed and relative humidity in the morning was the most significant (P >0.0001) influential environmental variable for the development of disease. The performance of this model was calculated based on the coefficient of determination (r2) and showed 97 percent variability in disease development. [ABSTRACT FROM AUTHOR]

The objective of this work was to study the virulence of 15 Xanthomonas oryzae pv. oryzae (Xoo) isolates collected in three provinces in Indonesia (North Sumatra, South Sumatra, and South Sulawesi) based on five Indonesian differential rice genotypes and 10 near isogenic lines (NILs) that have been known to differ in their resistance to bacterial leaf blight (BLB), in a greenhouse assessment. In addition, this study also aims to monitor the responses of 31 rice genotypes (21 NILs, five differentials, five improved cultivars) to BLB disease in a field experiment. The 15 isolates showed different virulence patterns on the NILs'genotypes with a single resistance gene indicating the pathogen diversity. Eight different pathotypes were present, as demonstrated by a particular virulence pattern of each isolate on the genotypes. Determination of Xoo pathotype revealed that Xoo pathotypes responded differently based on their reaction to NILs and Indonesian differential genotypes. The field assessment demonstrated the incidence and severity of BLB disease on rice genotypes ranging from 25% to 100% and 5.5% to 72.91%, respectively, while the mean disease index ranged from 1.15% to 72.9%. The disease response varied among rice genotypes. IRBB50 (Xa4+xa5), IRBB51 (Xa4+xa13), IRBB52 (Xa4+Xa21), IRBB53 (Xa4+Xa21), IRBB56 (Xa4+xa5+xa13), IRBB57 (Xa4+xa5+Xa21), IRBB59 (Xa4+xa13+Xa21), IRBB64 (Xa4+xa5+Xa7+Xa21), IRBB66 (Xa4+xa5+Xa7+xa13+Xa21), IRBB7(Xa7), Angke (Xa4+xa5) and Code (Xa4+Xa7) were revealed to be highly resistant to the BLB pathogen. These genotypes have potential as genetic material for the pyramiding of several resistance genes for the development of rice resistance to BLB disease in Indonesia. [ABSTRACT FROM AUTHOR]

The experiment was conducted for the evaluation of resistance status of near isogenic lines (IRBB lines) obtained from International Rice Research Institute (IRRI) against bacterial blight caused by Xanthomonasoryzae pv. Oryzae using RCBD design with three replications. For this purpose, 17 near isogenic lines of IR-24(check variety) having resistant genes against bacterial leaf blight of rice were studied for their gene status, resistance behavior and morphological traits. Resistance behavior of these lines was evaluated under natural artificial inoculated conditions. Plant agronomic traits like plant height, number of tillers, panicle length, number of fertile grains/panicle, 1000 grain weight; days to 50% flowering after transplanting (DAT) were also estimated along with the resistant parameters of the lines. The lines IRBB-21(having Xa-21 gene and 4% disease incidence), IRBB-59 (having xa-5, xa-13, Xa-21genes and, 2% disease incidence) and IRBB-66 (having Xa-4, Xa-7, xa-13, Xa-21 genes and, 6% disease incidence), were found to be the best resistant source against bacterial leaf blight of rice (BLB). These lines also have desirable morphological traits. So keeping in view the resistant status of these lines, excellent local breeding programme may be devised. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.), is one of the most important staple food and a life line for thousands of millions of people for their daily requirements especially in Asia and Africa but it's production is threatened by several abiotic and biotic stresses. One of the most devastating diseases for low yield of rice is Bacterial Leaf Blight (BLB) caused by Xanthomonas oryzae pv oryzae which appears at tillering and booting stage and touches its peak at flowering stage as plant grows. To manage this menace, efficacy of three fungicides (Trifloxystrobin + Tubeconazol, copper oxychloride and Bordeux mixture) were tested as foliar spray for their effect on BLB at various locations (farm and farmer fields) of district Sheikhupura during kharif season 2014. The experiment was laid out in randomized complete block design (RCBD) with three replications. Pre and post treatment observations were taken in percentages damage by the disease BLB. Number of filled grains tillers, plant height (cm), grains per spike, thousand grain weight (g) and yield (kgha-1) were recorded at harvesting. Among the test chemicals, copper oxychloride and Trifloxystrobin + Tubeconazole were remained statistically at par. Maximum 63, 50, 73% (cumulative of three locations) decrease over control was observed in copper oxychloride treated plot followed by 44, 41, 70% (three locations) decrease over control from Trifloxystrobin + Tubeconazole. The highest paddy yield at three locations among the test treatments was recorded in copper oxychloride treated plot (4766.7, 3016.0 & 4650.0 kgha-1) followed by Trifloxystrobin + Tubeconazole yielding 4483.0, 2860.0 & 4596.0 kgha-1 against 4036, 2386.7 & 4283.0 kg ha-1 paddy yield in the control at three locations. It is depicted from the results that application of copper based fungicides significantly reduced the impact of disease in rice crop as compared to untreated one. Among the tested chemicals, the use of copper oxychloride played important role from all chemicals for the management of holistic BLB disease of rice. [ABSTRACT FROM AUTHOR]

Bacterial leaf blight (BLB) is a devastating disease of rice caused by Xanthomonas oryzae pv. oryzae (Xoo), severely affects grain quality and reduces yield in all rice-growing areas of Pakistan. The pathogen is highly dynamic and quickly evolves itself when encountered with new resistant genes, hence, the knowledge about existing virulence range within the pathogen population and availability of corresponding resistance gene source is of immense importance. The present study focused on molecular dissection and evaluating the effectiveness of different resistance gene combinations against Xoo isolates collected from seven major rice-growing districts of Punjab Pakistan. Phenotypic characterization of collected Xoo isolates has shown that all of them were rod-shaped Gram-negative bacteria. However, oryzae species and oryzae pathovar were confirmed in only 22 out of 50 isolates using multiplex PCR. Analysis of loop-mediated isothermal amplification validated the lineage and close relatedness of Pakistani Xoo isolates with the already reported Asian Xoo population. Pathogenicity test on susceptible rice variety Super Basmati has shown that out of twenty-two tested Xoo isolates, four isolates from three different districts fell into the most virulent category with an average lesion length of ≥15 cm. Pathotyping of selected resistant rice lines against Xoo isolates distributed 22 isolates into nine pathotypes based on their interaction with R genes. Current molecular and phenotypic profiling of isolated Pakistani Xoo isolates may serve as a valuable reference for global comparison to manage BLB disease of rice in real-time. • Well identified Xoo isolates from Pakistan may use as reference for global comparison. • Findings showed that LAMP and SNP can be harnessed to generate real time data to map disease incidence across a region. • Pathotyping of isolated strains against selected NIL's will pave a way for the development of region specific resistant varieties. [ABSTRACT FROM AUTHOR]

Rice production is severely affected by the bacterial pathogen, Xanthomonas oryzae pv. oryzae (Xoo), which causes bacterial leaf blight (BLB) disease. Nano-enabled strategies have recently attracted attention as a sustainable platform to improve crop nutrition and protection. Here, we report the bioengineering of chitosan-iron nanocomposites (BNCs) along with their in vitro and in vivo bactericidal activity against Xoo. In addition, the impact of BNCs on the endophytic microbiome of healthy and BLB diseased rice was evaluated using a high-throughput sequencing technique. The BNCs were spherically shaped with an average size of 86 nm. In vitro antibacterial assays showed that BNCs significantly inhibited biological functions of the pathogen (viz., growth, motility, and biofilm formation) at 250 μg mL−1 concentration as compared with respective control. A greenhouse experiment demonstrated that foliar exposure to 250 mg·L−1 BNCs significantly reduced the BLB disease incidence (67.1%) through modulation of antioxidant enzymes viz. , superoxide dismutase (49.2%), peroxidase (38.8%) and ascorbate peroxidase (53.4%); BNCs amendment also improved photosynthesis efficiency by promoting production of total chlorophyll (43.2%) and carotenoids contents (60.0%), and the nutritional profile of rice plants as compared with untreated diseased control. Moreover, BNCs-induced disease resistance response corresponded to an increase in transcript level of defense-related genes, such as OsPRs , OsSOD and OsAPX , in rice plants. High-throughput sequencing results revealed that BNCs amendment decreased the relative abundance of Xanthomonas (87.5%) by reshaping the phyllospheric and root-endophytic bacterial community of rice. In addition, BNCs increased the bacterial community diversity in healthy and diseased plants; significant increases in relative abundance of Ochrobactrum , Allorhizobium , Methylobacterium , Devosia , Pseudolabrys , Sphingomonas and Bradyrhizobium in BNCs-treated diseased and healthy plants was noted. These findings demonstrate that BNCs have potential to serve as non-toxic, sustainable and highly efficient alternative for plant disease management. [Display omitted] • Synthesis and characterization of bioengineered chitosan iron nanocomposites (BNCs) as a bactericidal agent. • In vitro and in vivo antibacterial activity of BNC against rice pathogen Xanthomonas oryzae pv. oryzae (Xoo). • Ultrastructure studies reveal the subcellular localization of BNCs within the rice leaf cells. • High-throughput sequencing revealed the impact of BNCs on the rice endophytic microbiome. • BNCs amendment significantly reduce the Xoo abundance and modulate the rice microbial community composition. [ABSTRACT FROM AUTHOR]

Absence of resistance/tolerance against bacterial leaf blight (BLB), incited by Xanthomonas oryzae pv. oryzae, in famous basmati varieties is one of the main reason for BLB epidemic in Punjab in 2007–2008. For developing resistance against BLB, the response of 26 IRBB lines of IRRI including 10 near isogenic lines (NILs) and 16 gene pyramids carrying two to five resistance genes (Xa series) was evaluated against 61 indigenous Xoo isolates under artificial inoculation field conditions. None of the NILs or gene pyramid provides complete protection against all the isolates. However, Xa21 and xa13 were found resistant against the majority of Xoo isolates, followed by Xa14 and Xa7. Of the 16 gene pyramids used in this study, IRBB-54 (Xa5 + Xa21), IRBB-55 (Xa13 + Xa21) followed by IRBB-58 (Xa4 + Xa13 + Xa21) were found effective against the majority of the Xoo isolates. These resistance genes (individually and in combinations) can be incorporated for the improvement of basmati rice cultivars cultivated in Punjab province of Pakistan. Effectiveness of gene combination supports the strategy of pyramiding appropriate resistance genes. Newly identified resistant genes may also be evaluated for achieving broad spectrum resistance against more Xoo isolates of the area. [ABSTRACT FROM PUBLISHER]

Abstract: BF and BLB genes of chicken major histocompatibility complex (MHC) are responsible for classical antigen processing and presentation; therefore they play a central role in determining the genetic resistance or susceptibility of different MHC-B haplotypes to some infectious diseases. In this study, we developed specific TaqMan probed real-time quantitative reverse transcription PCR (TaqMan qRT-PCR) methods based on the diagnostic nucleotide polymorphisms present in duplicated BF or BLB genes in B2 and B19 haplotypes. The results showed very similar amplification efficiency but no cross-reaction between the duplicated BF or BLB genes of the same haplotype. Spleen mRNA samples of B2 and B19 chickens were used to validate these TaqMan qRT-PCR methods. We observed that BF2 or BLB2 gene was dominantly transcribed in all B2 and B19 chickens. Our findings verified the impact of diversified promoter sequences on the function of duplicated BF or BLB genes. Hence the principles adopted to establish these specific TaqMan qRT-PCR methods in this study can be applied to differentiate the transcripts of duplicated BF or BLB genes of other MHC-B haplotypes in chicken. [Copyright &y& Elsevier]

Conclusion: The results of our research indicate that 125I-labelled basic fibroblast growth factor (125I-bFGF) has some difficulty in getting across the blood–labyrinth barrier (BLB). Therefore, it is necessary to carry out further study on the route of bFGF administration. Objective: To observe whether bFGF could pass through the BLB after intraperitoneal injection and to establish an experimental basis for its clinical applications. Methods: Thirty guinea pigs were divided into three equal groups. Animals in group 1 were administered 125I-bFGF, while animals in groups 2 and 3 were given 125I or saline solution, respectively, via intraperitoneal injection. The animals were sacrificed 2 h later and samples of blood, brain, cochlea, thyroid gland, heart, liver, and kidney were collected and weighed. A radioimmunoassay analyzer was employed to count the CPM values of each sample, and autoradiography was performed on section samples of both cochleae. Results: The CPM value of organ samples in the 125I group was higher than that in other groups, and radioactive grain was observed in cochlear samples of this group. In the 125I-bFGF group, blood demonstrated the highest CPM value, while cochlea and brain demonstrated the lowest CPM value, with no radioactive grain observed in cochlear samples. [ABSTRACT FROM AUTHOR]

The crude extracts of 63 plants were used for testing antibacterial activity against Xanthmonas oryazae Pv. oryzae that causes bacterial leaf blight (BLB) in rice plants. Only ten aqueous extracts of botanicals (Thuja orientalis, Prunus domestica, Citrus limon, Allium sativum, Vitis vinefera, Mangifera indica, Phyllanthus emblica, and Terminalia chebula) showed maximum activity against Xanthmonas oryazae in a plate agar diffusion assay. On a detached leaf, in a glasshouse and in a field assay, two potential plant extracts, namely Allium sativum, and Citrus limon showed maximum efficacy in terms of controlling BLB lesions in rice. After isolation through fractionation of the crude extract of Allium sativum, the bioactive compound was purified and characterized as 8-amino(-8-butoxyoct)-2-(enyldisulfanyl)-3-(2hydroxy-4-methoxyphenylprop-1-enyl) benzene-1,3-diol. [ABSTRACT FROM AUTHOR]

Several genes/QTLs governing resistance/tolerance to abiotic and biotic stresses have been reported and mapped in rice. A QTL for submergence tolerance was found to be co-located with a major QTL for broadspectrum bacterial leaf blight (bs-blb) resistance on the long arm of chromosome 5 in indica cultivars FR13A and IET8585. Using the Nipponbare (japonica) and 93- 11 (indica) genome sequences, we identified, in silico, candidate genes in the chromosomal region [Kottapalli et al. (2006)]. Transcriptional profiling of FR13A and IET8585 using a rice 22K oligo array validated the above findings. Based on in silico analysis and arraying we observed that both cultivars respond to the above stresses through a common signaling system involving protein kinases, adenosine mono phosphate kinase, leucine rich repeat, PDZ/DHR/GLGF, and response regulator receiver protein. The combined approaches suggest that transcription factor EREBP on long arm of chromosome 5 regulates both submergence tolerance and blb resistance. Pyruvate decarboxylase and alcohol dehydrogenase, co-located in the same region, are candidate downstream genes for submergence tolerance at the seedling stage, and t-snare for bs-blb resistance. We also detected up-regulation of novel defense/stress-related genes including those encoding fumaryl aceto acetate (FAA) hydrolase, scramblase, and galactose oxidase, in response to the imposed stresses. [ABSTRACT FROM AUTHOR]

Abstract: An indica rice cultivar IET8585 (Ajaya) resists diverse races of the Xanthomonas oryzae pv oryzae pathogen attack, and is often cultivated as bacterial leaf blight (blb) resistant check in India. Earlier we reported a recessive blb resistance gene mapped to the long arm of chromosome 5 in IET8585. Recessive gene-mediated blb resistance mechanism is not yet clearly understood. Here we analyzed the transcriptional profile of the blb infected resistant cultivar by rice 22K oligo array. Microarray analysis revealed differential expression of numerous genes at both early (6h) and late (120h) stages of infection in the resistant IET8585 cultivar over the susceptible IR24. Some of the differential gene expressions were validated by both RT–PCR and Western blot analysis. Higher expression of ethylene response element binding protein (EREBP) transcription factor along with lower expression of alcohol dehydrogenase gene and reactive oxygen species (ROS) scavenging system may be responsible for hypersensitive cell death in the resistant cultivar upon bacterial infection. Induction of glutathione-mediated detoxification and flavonoid biosynthetic pathways along with up-regulation of defense genes during infection may inhibit pathogen spread in the host tissues. In light of this and previous studies a mechanism of recessive gene-mediated bacterial blight resistance in indica rice is discussed. [Copyright &y& Elsevier]

We found that the Black grouse ( Tetrao tetrix) possess low numbers of Mhc class II B ( BLB) and Y ( YLB) genes with variable diversity and expression. We have therefore shown, for the first time, that another bird species (in this case, a wild lek-breeding galliform) shares several features of the simple Mhc of the domestic chicken ( Gallus gallus). The Black grouse BLB genes showed the same level of polymorphism that has been reported in chicken, and we also found indications of balancing selection in the peptide-binding regions. The YLB genes were less variable than the BLB genes, also in accordance with earlier studies in chicken, although their functional significance still remains obscure. We hypothesize that the YLB genes could have been under purifying selection, just as the mammal Mhc- E gene cluster. [ABSTRACT FROM AUTHOR]

Abstract: Physical mapping and map-based cloning strategies are routinely used for identification of candidate genes for major qualitative traits in rice. Such strategies have enabled mapping and characterization of dominant bacterial leaf blight (blb) resistance genes, but little progress has been made in case of the recessive resistance genes. Two recent studies on map-based cloning of xa5 and xa13 recessive blb resistance genes identified the general transcription factor IIA gamma subunit (TFIIAγ) and the nodulin MtN21 as candidates, respectively. Subsequently, two other reports have raised discussion on whether the identified candidates are indeed recessive resistance genes, and are sufficient to confer blb resistance in rice. Based on published evidence, and our extensive in silico analyses of the genomic environment around xa5 and xa13 regions, we propose that the recessive gene mediated resistance mechanism is more complex and might not be governed by a single gene. [Copyright &y& Elsevier]

Abstract: The cochlear portion of the inner ear converts movements produced by sound waves into electrical impulses. Transcripts enriched in the cochlea are likely to have an important role in hearing. In this paper, we report that microarray analyses of the Soares NMIE inner ear library revealed cochlear enriched expression of apolipoprotein D (apoD), a glycoprotein and member of the lipocalin family that transport small hydrophobic ligands. The cochlear enriched expression of Apod was validated by quantitative real time PCR analysis. To investigate the function of apoD in the inner ear the transcript and protein were localised in the cochlea. Apod messenger RNA (mRNA) expression was localised to the spiral ligament and spiral limbus, particularly in the suprastrial and supralimbral regions. The apoD protein was detected in the spiral ligament, spiral limbus and also in the outer hair cells of the organ of Corti. Investigation of cell lines exhibiting characteristics of hair and supporting cells revealed no Apod mRNA expression in these cells. This suggests transport of the protein within the cochlea, followed by internalisation into outer hair cells. The spiral limbus and ligament contain subpopulations of fibrocytes that are intimately involved in regulation of ion balance in the cochlear fluids and type I, II and III fibrocytes of the spiral ligament were all shown to be positive for apoD protein. On the basis of these results it was hypothesised that apoD could be involved in maintaining cochlear fluid homeostasis. To determine whether the apoD gene product was important for normal auditory function the hearing ability of an apoD knockout mouse was tested. The mouse was found to have a hearing threshold that was not significantly different to the control strain. [Copyright &y& Elsevier]