Responses of maize × teosinte derived backcross inbred lines (BILs) to maydis leaf blight (MLB) disease

Euphytica - Rice growth and productivity are greatly affected by cold stress, which is likely to become more of a hindrance for high and stable rice yields. To identify cold tolerance at the...     

Genetic diversity assessment in Pandanus amaryllifolius Roxb. populations of India

Pandanus amaryllifolius is cultivated in home gardens in coastal regions of India. Leaves of P. amaryllifolius are scented and exploited commercially by flavour industry. In the present attempt, 40 clonal populations were used for genetic diversity assessment using ISSR and AFLP molecular marker. In ISSR based diversity analysis, out of 38 scorable primers, only one primer showed polymorphism and most of the polymorphic fragments were found in clonal populations from Thailand locality only. In AFLP based diversity analysis all clonal populations from India showed very low genetic distance except Kolkata and Amtala but these populations showed more similarity with Sri Lanka clones and these two localities showed more similarity with Thailand population. Present study confirms that the species has very low level of genetic variation even though it is exposed to a wide range of environmental conditions across peninsular India. Thus, the genome of P. amaryllifolius is said to be highly conserved and remained unaffected through its spread. As per previous report P. amaryllifolius has been introduced in Kolkata, India in 1798 from Indonesia, the similarity is shown by the populations of West Bengal with Thailand population which is close to Indonesia. The populations from Sri Lanka showed similarity with the populations from east and west coast of India suggests that Sri Lanka may be the another source of introduction of P. amaryllifolius in India.     

Understanding the effects of intramuscular injection and feed withdrawal on Salmonella Typhimurium shedding and gut microbiota in pullets

Background:Gut microbiota plays a key role in health,immunity,digestion,and production in layers.Factors such as environment,diet,diseases,stress,and flock management significantly affect gut microbiota;however,it is not known how potential stressors such as intramuscular injections or feed withdrawal alter the composition of gut microbiota that result in increased the shedding level of foodborne pathogens.In the current study,the effects of intramuscular corticosterone injection and feed withdrawal were evaluated to understand their role in Salmonella Typhimurium shedding and changes in the composition of gut microbiota in layers.Results:Salmonella shedding was observed for 8 weeks post-infection.There was a significant increase in Salmonella Typhimurium count after intramuscular injection and feed withdrawal.The Salmonella infected and the negative control groups showed significant differences in the abundance of different genera in gut microbiota at week 1 and up to week 7 post infection.The infected group showed a significant reduction in alpha diversity of gut microbiota.Firmicutes reduced significantly(P<0.05)after intramuscular injection,while the feed withdrawal groups did not cause any significant changes in Proteobacteria-Firmicutes ratio.Furthermore,intramuscular injection resulted in a significant change in alpha diversity of gut microbiota.Conclusions:Exposure of chicks to relatively low dose of Salmonella Typhimurium can lead to persistent shedding in pullets.The Salmonella Typhimurium infection disrupted the gut microbiota composition immediately after infection.The potential stress of intramuscular injection and feed withdrawal significantly increased the Salmonella Typhimurium count in faeces.The intramuscular injection also resulted in a significant alteration of the Proteobacteria-Firmicutes ratio,which could increase the risk of dysbiosis.     

Dietary zinc potentiates thermal tolerance and cellular stress protection of Pangasius hypophthalmus reared under lead and thermal stress

Zinc micronutrient is the second most abundant trace element in the animal body, as it could not be stored in the body; hence, regular dietary zinc is required for animals. With this backdrops a 60 days feeding trial was conducted to study the effect of dietary zinc on the thermal tolerance and cellular metabolic stress of Pangasius hypophthalmus reared under Pb (1/21th of LC₅₀, 4 ppm) and elevated temperature (34°C). Three isocaloric and isonitrogenous diets with Zn‐0, 10 and 20 mg/kg were prepared. Two hundred seventy‐three fish were randomly distributed into seven treatments in triplicate in completely randomized forms. Dietary zinc supplementation had remarkable (p < .01) changes on thermal tolerance of P. hypophthalmus viz. CTmin (critical temperature minima) and LTmin (lethal temperature minima), CTmax (critical temperature maxima) and LTmax (lethal temperature maxima). The positive correlations were also observed between CTmin and LTmin (Y = ?0.707 + 6.59x, R², 0.875) and CTmax and LTmax (Y = ?0.923 + 2.45x, R², 0.960). The oxidative stress (catalase, superoxide dismutase and glutathione‐s‐transferase) and lipid peroxidation were significantly reduced and neurotransmitter enzyme (AChE) was significantly enhanced with zinc supplementation at the end of the thermal tolerance. The present study concluded that thermal tolerance of P. hypophthalmus enhanced by zinc supplementation through CTmax LTmax and CTmin LTmin and also by strengthening the antioxidative status along with neurotransmitter enzymes.     

Identification and characterization of sources for photo‐ and thermo‐insensitivity in Vigna species

Cultivation of the same varieties of mungbean and blackgram across different seasons and locations is constrained by their photo‐ and thermo‐sensitive behaviour. Developing insensitive genotypes, which can fit well across all seasons, requires robust donors which would provide genes imparting this trait. This study was undertaken to identify such donors in the Vigna species. Forty‐eight accessions belonging to 13 Vigna species and eight released cultivars were evaluated under natural field conditions. Among these, two accessions, viz. V. umbellata (IC251442) and V. glabrescens (IC251372) were found photo‐ and thermo‐insensitive as these were able to flower and set pods at temperatures as high as 43.9°C and as low as 2.7°C. Pollen viability studies indicated viable pollen (>75% at 2.7°C and >85% at 41.9°C) and normal pollen tube growth at both the extremes of temperature. The identified V. glabrescens accession has long, constricted pods and dark green, mottled seeds while V. umbellata has smooth, curved pods and shining, oval, large seeds. Both these accessions can be utilized in developing photo–thermo insensitive genotypes in cultivated Vigna species.     

Heat stress in crop plants: its nature,impacts and integrated breeding strategies to improve heat tolerance

Increasing severity of high temperature worldwide presents an alarming threat to the humankind. As evident by massive yield losses in various food crops, the escalating adverse impacts of heat stress (HS) are putting the global food as well as nutritional security at great risk. Intrinsically, plants respond to high temperature stress by triggering a cascade of events and adapt by switching on numerous stress‐responsive genes. However, the complex and poorly understood mechanism of heat tolerance (HT), limited access to the precise phenotyping techniques, and above all, the substantial G × E effects offer major bottlenecks to the progress of breeding for improving HT. Therefore, focus should be given to assess the crop diversity, and targeting the adaptive/morpho‐physiological traits while making selections. Equally important is the rapid and precise introgression of the HT‐related gene(s)/QTLs to the heat‐susceptible cultivars to recover the genotypes with enhanced HT. Therefore, the progressive tailoring of the heat‐tolerant genotypes demands a rational integration of molecular breeding, functional genomics and transgenic technologies reinforced with the next‐generation phenomics facilities.     

Kernel morphometric traits in hexaploid wheat (Triticum aestivum L.) are modulated by intricate QTL × QTL and genotype × environment interactions

Wheat kernel size and shape influence its flour yield and market price. A hexaploid wheat population of 185 recombinant inbred lines was evaluated for five kernel morphometric traits namely, 1000-kernel weight, kernel length, width, length–width ratio and factor form density in two diverse agro-climatic regions in India in five to eight year–location combinations. Additive main effects and multiplicative interaction analysis revealed significant contributions from genotype (G) and genotype × environment (G × E) effects for these traits. Quantitative trait locus (QTL) analysis by composite interval mapping (CIM) was performed using a linkage map of 251 SSR markers and 59 QTLs distributed on 16 chromosomes were identified. The majority of the QTLs were located on the D genome (44.07%) and the homeologous chromosomes of Group 2 (38.98%). Stable QTLs detected in three or more year–location combinations were identified for four traits. Multi-trait CIM showed 10 chromosomal regions harboring putative pleiotropic loci. Complexity in the genetic effects was further revealed by QTL analysis based on mixed-linear model that indicated 19 QTLs with significant individual effects (main-effect QTLs) and 14 QTL × QTL interactions. Five of these nineteen main-effect QTLs and one of the fourteen QTL × QTL interactions showed environmental influence.     

Thermoplastic films from wheat proteins

We show that the wheat proteins gluten, gliadin and glutenin can be compression molded into thermoplastic films with good tensile strength and water stability. Wheat gluten is inexpensive, abundantly available, derived from renewable resource and therefore widely studied for potential thermoplastic applications. However, previous reports on developing thermoplastics from wheat proteins have used high amounts of glycerol (30-40%) and low molding temperature (90-120 °C) resulting in thermoplastics with poor tensile properties and water stability making them unsuitable for most thermoplastic applications. In this research, we have developed thermoplastic films from wheat gluten, gliadin and glutenin using low glycerol concentration (15%) but high molding temperatures (100-150 °C). Our research shows that wheat protein films with good tensile strength (up to 6.7 MPa) and films that were stable in water can be obtained by choosing appropriate compression molding conditions. Among the wheat proteins, wheat gluten has high strength and elongation whereas glutenin with and without starch had high strength and modulus but relatively low elongation. Gliadin imparts good extensibility but decreased the water stability of gluten films. Gliadin films had strength of 2.2 MPa and good elongation of 46% but the films were unstable in water. Although the tensile properties of wheat protein films are inferior compared to synthetic thermoplastic films, the type of wheat proteins and compression molding conditions can be chosen to obtain wheat protein films with properties suitable for various applications.     

Tree diversity and carbon stocks of some major forest types of Garhwal Himalaya,India

Four forest stands each of twenty major forest types in sub-tropical to temperate zones (350 m asl–3100 m asl) of Garhwal Himalaya were studied. The aim of the study was to assess the stem density, tree diversity, biomass and carbon stocks in these forests and make recommendations for forest management based on priorities for biodiversity protection and carbon sequestration. Stem density ranged between 295 and 850 N ha⁻¹, while total biomass ranged from 129 to 533 Mg ha⁻¹. Total carbon storage ranged between 59 and 245 Mg ha⁻¹. The range of Shannon–Wiener diversity index was between 0.28 and 1.75. Most of the conifer-dominated forest types had higher carbon storage than broadleaf-dominated forest types. Protecting conifer-dominated stands, especially those dominated by Abies pindrow and Cedrus deodara, would have the largest impact, per unit area, on reducing carbon emissions from deforestation.     

The BamHI site in the Internal Transcribed Spacer Region of Mungbean ribosomal RNA gene is partially methylated

The 18s-5.8s-25s ribosomal gene (18s-25s rDNA) in higher plants is present in multiple copies, on different chromosomes, as tandemly repeated units. Among the multiple BamHI sites that occur in the repeat unit, only the site in the middle of the 25s rRNA coding region is methylated in most cereals and pulses. BamHI restriction enzyme analyses of the mungbean 18s-25s rDNA showed the presence of two populations. Nearly 50% of the 18s-25s rDNA population had BamHI site situated in the internal transcribed spacer region (ITS-BamHI) resistant to cleavage by BamHI. The amplified ITS fragment was completely digestible by BamHI showing that partial cleavage by BamHI is not due to variation in the recognition sequence but most probably due to methylation. The complete cleavage of the ITS-BamHI site by BstYI that recognizes BamHI site but is insensitive to methylation confirms that the ITS-BamHI site is methylated. Methylation is probably due to the presence of a guanosine residue adjacent to the 3′ cytosine in the recognition sequence. This revised version was published online in July 2006 with corrections to the Cover Date.