Nitrogen management improves lodging resistance and production in maize (Zea mays L.) at a high plant density

Lodging in maize leads to yield losses worldwide.  In this study, we determined the effects of traditional and optimized nitrogen management strategies on culm morphological characteristics, culm mechanical strength, lignin content, root growth, lodging percentage and production in maize at a high plant density.  We compared a traditional nitrogen (N) application rate of 300 kg ha^–1 (R) and an optimized N application rate of 225 kg ha^–1 (O) under four N application modes: 50% of N applied at sowing and 50% at the 10th-leaf stage (N1); 100% of N applied at sowing (N2); 40% of N applied at sowing, 40% at the 10th-leaf stage and 20% at tasseling stage (N3); and 30% of N applied at sowing, 30% at the 10th-leaf stage, 20% at the tasseling stage, and 20% at the silking stage (N4).  The optimized N rate (225 kg ha^–1) significantly reduced internode lengths, plant height, ear height, center of gravity height and lodging percentage.  The optimized N rate significantly increased internode diameters, filling degrees, culm mechanical strength, root growth and lignin content.  The application of N in four split doses (N4) significantly improved culm morphological characteristics, culm mechanical strength, lignin content, and root growth, while it reduced internode lengths, plant height, ear height, center of gravity height and lodging percentage.  Internode diameters, filling degrees, culm mechanical strength, lignin content, number and diameter of brace roots, root volume, root dry weight, bleeding safe and grain yield were significantly negatively correlated with plant height, ear height, center of gravity height, internode lengths and lodging percentage.  In conclusion, treatment ON4 significantly reduced the lodging percentage by improving the culm morphological characteristics, culm mechanical strength, lignin content, and root growth, so it improved the production of the maize crop at a high plant density.     

Silicon-mediated genotoxic alterations in Brassica juncea under arsenic stress: A comparative study of biochemical and molecular markers

Arsenic (As), one of the most harmful toxicant at the global level, severely affects plant metabolism when taken up. Interestingly, the presence of silicon (Si) as a fertilizer in As-contaminated soil is an effective strategy to decrease As accumulation in plants. Brassica juncea (var. Varuna) were grown hydroponically to investigate the role of Si at biochemical and molecular levels under arsenite (As³⁺) stress. Seedlings of B. juncea were exposed to As³⁺, Si, and a combination of both elements. Our data demonstrated that seedlings exposed to As³⁺ showed an inhibition in shoot length, chlorophyll, carotenoid, and protein, while co-application of Si improved these growth parameters. Silicon supplementation reduced As accumulation in shoot. Increase/decrease was observed in stress-related parameters (cysteine and proline), antioxidant enzymes (superoxide dismutase, ascorbate peroxidase, and catalase), and oxidative stress markers (malondialdehyde and H₂O₂), which were improved upon co-application of Si as compared to As³⁺ alone treatment. Random amplified polymorphic DNA (RAPD) is a suitable biomarker assay for plants for assessing the genotoxicity. Seven RAPD primers produced a total of 39 and 48 bands in the leaves of the untreated and treated seedlings, respectively. The RAPD band-profiles and genomic template stability were consistent with other growth and physiological parameters. In conclusion, the genotoxic alterations along with the biochemical parameters indicate that the exposure to Si mitigates As³⁺-induced oxidative stress by improving the stress-related parameters and antioxidant system in B. juncea.     

Genome-wide association analysis for stripe rust resistance in spring wheat(Triticum aestivum L.) germplasm

Stripe rust is a continuous threat to wheat crop all over the world. It causes considerable yield losses in wheat crop every year. Continuous deployment of adult plant resistance(APR) genes in newly developing wheat cultivars is the most judicious strategy to combat this disease. Herein, we dissected the genetics underpinning stripe rust resistance in Pakistani wheat germplasm. An association panel of 94 spring wheat genotypes was phenotyped for two years to score the infestation of stripe rust on each accession and was scanned with 203 polymorphic SSRs. Based on D' measure, linkage disequilibrium(LD) exhibited between loci distant up to 45 c M. Marker-trait associations(MTAs) were determined using mixed linear model(MLM). Total 31 quantitative trait loci(QTLs) were observed on all 21 wheat chromosomes. Twelve QTLs were newly discovered as well as 19 QTLs and 35 previously reported Yr genes were validated in Pakistani wheat germplasm. The major QTLs were QYr.uaf.2 AL and QYr.uaf.3 BS(PVE, 11.9%). Dissection of genes from the newly observed QTLs can provide new APR genes to improve genetic resources for APR resistance in wheat crop.     

Herd-level prevalence of Mycobacterium avium subspecies paratuberculosis by bulk-tank milk PCR in Fars province (southern Iran) dairy herds

A cross-sectional study was conducted from March to August 2006 in dairy herds in Fars province, southern Iran to determine the herd-level prevalence of Mycobacterium avium subspecies paratuberculosis (MAP) infection. Bulk-tank milk samples were collected from 110 dairy herds in the 3 districts (Shiraz, Marvdasht and Sepidan) of the province. Among study populations, 12 herds (11%, 95%CI: 5-17%) were positive for MAP infection based on IS900 nested PCR. The prevalence of positive milk samples in the three districts of Fars province was different ranging from 8.6% to 23% which was not statistically significant (P=0.19). It is recommended to conduct further epidemiologic studies to determine cow-level prevalence and risk factors for infection, and to evaluate the economic consequences of the MAP infection in the region.     

In ovo injection of flavanone on bone quality characteristics,biochemical parameters and antioxidant enzyme status of blood in daily chicks

In ovo injection (IOI) of Naringin (N), flavanone was examined on post‐hatch blood biochemical parameters, antioxidant status and bone characteristics. Fertile eggs (n = 700) were distributed in seven groups with 100 eggs. On 14th and 17.5th days of incubation, four groups were injected using 15 or 30 mg active ingredient levels of naringin/0.5 ml saline/egg, low and high level, into amnion sac. Controls include sham (injected normal saline, 0.5 ml/egg on day 14 and 17.5th) and un‐injected group. IOI of high naringin and saline on 14th day of incubation resulted in lower hatchability and then higher mortality in last week of embryonic life. On day hatch, high levels of injected groups more body weight compared to the control. Chick length was increased at high levels of naringin on day 17.5th compared to control and saline injected. Quality traits of bones were improved in naringin‐injected groups compared to control. IOI of naringin influenced thyroid hormones on 14th day of incubation. Naringin groups influenced the Alkaline phosphatase (ALP), Calcium (Ca), superoxide dismutase (SOD), blood biochemical and lipids. Totally, amniotic IOI of naringin in last days of developing embryo may be useful for hatched chick, development of leg long bone or effect on biochemical metabolites by levels of flavanone that it needs more research.     

The first report on serotyping of bluetongue virus in small ruminants of Khyber Pakhtunkhwa province,Pakistan

Bluetongue virus (BTV), a member of Orbivirus genus (family Reoviridae), is a non-contagious infection of domestic and wild ruminants. The current study was designed to detect various serotypes of BTV in small ruminants of Khyber Pakhtunkhwa (KPK) province of Pakistan, along with their effects on hemato-biochemical parameters. A total of 408 serum samples in four districts (Mansehra, Abbottabad, Swabi, and Kohat) of KPK from small ruminants were screened based on competitive ELISA (cELISA). A total of 204 (50%) samples were found positive for BTV group–specific antibodies. The seropositive samples were processed for the detection of BTV serotypes through real-time polymerase chain reaction (qPCR). Out of 204 cELISA-positive samples, 60 (29.41%) were found positive through qPCR. Three serotypes [6, 8, 9] were detected from Mansehra District and two from Kohat [2, 8] and Abbottabad [6, 8], while only one from Swabi [8]. The serotype “8” was found consistently in all the four study districts. A significant (p?<?0.05) increase in the level of blood urea nitrogen (BUN) and alkaline phosphatase (ALP) was recorded in goats, whereas aspartate aminotransferase (AST) in sheep infected with BTV, compared to healthy animals. The hematological parameters showed significantly (p?<?0.05) raised total leucocyte count (TLC) in both sheep and goats, whereas only hematocrit (HCT) value was increased significantly (p?<?0.05) in infected sheep. This is the first report on serotyping of BTV among small ruminants in Pakistan.

     

Western blot detection of PrP Sc in archived paraffin-embedded brainstem from scrapie-affected sheep

Scrapie is a naturally occurring fatal neurodegenerative disease of adult sheep and goats, one of a group of mammalian diseases known as transmissible spongiform encephalopathies (TSE) or prion diseases. Immunoassays that identify disease-associated prion protein (PrP Sc) are integral to the diagnosis of scrapie and other prion diseases. Results obtained by either immunohistochemistry (IHC) or Western blot (WB) assay are generally adequate for the definitive diagnosis. Approved or accepted methods for WB diagnosis of TSEs requires the use of fresh or frozen nonfixed tissue samples, whereas formalin-fixed, paraffin-embedded tissue is required for the localization of PrP Sc by IHC. Because disparate processing methods are used for these accepted diagnostic techniques, separate tissue samples are collected from the same animal. Occasions arise in which there is either insufficient quantity of tissue available to complete analysis by both techniques or initial tissue processing is incompatible with one of the assays. Also, results between the assays may differ because of the vagaries of sampling, especially in case material that contains moderate-to-low levels of PrP Sc. The present article describes a method to conduct a WB assay from the same paraffin-embedded brainstem sample used for the IHC diagnosis of experimentally induced sheep scrapie.     

Analysis of the Phenylpropanoid Enzyme Activities and Products in the Soft- and Hard-Seeded Pomegranate Genotypes During Fruit Development

To find out more about the biochemical aspects of seed-softness trait in pomegranate (Punica granatum L.), some of the phenylpropanoid pathway enzymes as well as their products were evaluated in the various soft- and hard-seeded genotypes during fruit development. Results showed that peroxidase (POD) activity decreased in all studied genotypes during fruit growth, while increasing at the last stages only in the hard-seeded genotypes. Although laccase (LAC) activity did not show high differences during fruit ripening and in different genotypes, but its general trend was increasing. Phenylalanine ammonia-lyase (PAL) activity decreased during the fruit development and approximately diminished for the hard-seeded genotypes. All genotypes had lignin components in their seeds and amount of lignin increased during the growth season. Total phenolic decreased drastically and antioxidant capacity increased gradually showing an opposite trend and probable competitive effect for the same substrate during fruit development. Considerable differences that were observed in the POD activity at the last sampling stage, and higher activity that was observed in POD than LAC, may indicate that POD is more important for polymerization of lignin in the pomegranate seed and this enzyme might have some role in the development of seed softness trait in pomegranate. Also, this is the first report about lignin detection in the seeds of soft-seeded pomegranate genotypes, and represents a different mechanism (such as monolignol conformation in the final polymer) from lignin content for development of the soft-seeded pomegranate genotype.