Molecular identification of blast resistance genes in rice landraces from northeastern India

Rice blast disease caused by the fungus Magnaporthe oryzae is one of the most devastating diseases causing huge losses worldwide. In the present study, major blast resistance genes were investigated in landraces originating from northeastern India. Based on phenotypic evaluation, 288 landraces were classified into three distinct groups: resistant (75), moderately resistant (127) and susceptible (86). The genetic frequencies of the 18 major blast resistance genes were between 6.2% and 27.4%, with only two genotypes possessing a maximum of nine blast resistance genes. The cluster and population structure analysis grouped the landraces into two groups. Through principal coordinate analysis, the scatter plots partitioned the resistant and moderately resistant landraces into different groups. Analysis of molecular variance showed maximum (96%) diversity within populations and least (4%) diversity between populations. Association analysis identified six markers, CRG4_2, RM72, tk59-2, pi21_79-3, RM1233 and RM6648, that are significantly associated with blast disease and explained a phenotypic variance of 1.1–6.5%. The associated genes could be used in marker-assisted rice breeding programmes for gene pyramiding to develop rice varietal resistance against blast disease. The present study represents a valuable blast resistance genetic resource that could be used for identification of new R genes, donors for blast resistance, and genomic studies.     

Assessment of the ideal ratios of digestible essential amino acids for pacu,Piaractus mesopotamicus,juveniles by the amino acid deletion method

The present study aimed to determine the ideal ratios of digestible essential amino acids (EAAs) for pacu (Piaractus mesopotamicus) juveniles by the amino acid (AA) deletion method. A completely randomized design which consisted of 11 treatments and three replicates each was used. The treatments included a control diet (CD) containing 55% of nonpurified natural ingredients and 45% of purified synthetic amino acids and ingredients, and other ten isonitrogenous and isoenergetic EAA limiting diets (LDs), each being deficient in 44.4 ± 0.02% of the respective EAA. Pacu juveniles with initial average body weight of 6.22 ± 0.09 g were distributed among 33 fiber glass tanks. Fish were fed with semipurified and extruded diets for 113 days two times a day until apparent satiation. The ideal ratio of each dietary EAA was calculated on the basis of the relationship between body N retention and amount of EAA deleted from the respective EAA LD. Based on the AA deletion method, the ideal ratios of digestible EAAs for pacu juveniles, relative to lysine requirement of 100% were estimated as: methionine 14.6%, threonine 35.0%, tryptophan 6.6%, arginine 62.8%, histidine 13.6%, isoleucine 26.3%, leucine 43.7%, phenylalanine 27.2%, and valine 35.8%.     

Geostatistical and fuzzy clustering approach for delineation of site-specific management zones and yield-limiting factors in irrigated hot arid environment of India

Precision Agriculture - Delineation of management zones (MZs) are needed to manage fields in order to maximize economic return, minimize environmental impact, and improve soil and crop management....     

Utilizing a DUALEM‐421 and inversion modelling to map baseline soil salinity along toposequences in the Hunter Valley Wine district

In the oldest commercial wine district of Australia, the Hunter Valley, there is the threat of soil salinization because marine sediments underlie the area. To understand the risk requires information about the spatial distribution of soil properties. Electromagnetic (EM) induction instruments have been used to identify and map the spatial variation of average soil salinity to a certain depth. However, soils vary with depth dependent on soil forming factors. We collected data from a single‐frequency and multiple‐coil DUALEM‐421 along a toposequence. We inverted this data using EM4Soil software and evaluated the resultant 2‐dimensional model of true electrical conductivity (σ – mS/m) with depth against electrical conductivity of saturated soil pastes (EC_p – dS/m). Using a fitted linear regression (LR) model calibration approach and by varying the forward model (cumulative function‐CF and full solution‐FS), inversion algorithm (S1 and S2), damping factor (λ) and number of arrays, we determined a suitable electromagnetic conductivity image (EMCI), which was optimal (R² = 0.82) when using the full solution, S2, λ = 3.6 and all six coil arrays. We conducted an uncertainty analysis of the LR model used to estimate the electrical conductivity of the saturated soil‐paste extract (EC_e – dS/m). Our interpretation based on estimates of EC_e suggests the approach can identify differences in salinity, how these vary with parent material and how topography influences salt distribution. The results provide information leading to insights into how soil forming factors and agricultural practices influence salinity down a toposequence and how this can guide soil management practices.     

Isolation of infectious microalga Prototheca wickerhamii from a carp (Cyprinus carpio) – a first confirmed case report of protothecosis in a fish

Protothecosis is a rare infection caused by environmentally ubiquitous achlorophyllic microalgae of the genus Prototheca. Here, we describe a first case of protothecosis in a carp (Cyprinus carpio), which is at the same time the first case of protothecosis in a fish, confirmed by phenotype‐ and molecular‐based methods, including PCR sequencing of the rDNA cluster and protein profiling using matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry.     

Phosphorus utilization in juvenile Clarias gariepinus fed phytase-supplemented diets based on soya bean (oil-extracted) and full-fat (roasted): A comparison

The effect of microbial phytase on phosphorus utilization in juvenile Clarias gariepinus (initial fish body weight 11.55 ± 0.2 g) was tested on two different diets based on oil-extracted soya bean (Experiment 1) and roasted soya bean meal (Experiment 2) using a 5 × 5 experimental design for 84 days. The basal isonitrogenous and isocaloric diets for oil-extracted and roasted soya bean were formulated to replace fish meal at 25% (S1E), 50% (S2E), 75% (S3E), 100% (S4E); and 25% (S1), 50% (S2), 75% (S3), 100% (S4), respectively. Each treatment was replicated four times. Microbial phytase was supplemented in each replicate at 250 FTU/g (P1), 500 FTU/g (P2), 750 FTU/g (P3), and 1,000 FTU/g (P4). Basal controls, which included a fish meal-based diet (S0), were not supplemented with phytase (P0). The result in Experiment 1 showed that there was a significant increase in whole-body protein and reduction in fat with phytase compared to a diet without phytase (P < 0.05). Serum total protein declined significantly with phytase supplementation (P < 0.05). Serum phosphorus and glucose were higher with phytase supplementation compared to control (P < 0.05). Bone minerals declined significantly with increasing level of soya bean compared to fish meal diet (P < 0.05). In Experiment 2, serum phosphorus was improved with phytase compared to control with no phytase (P > 0.05). A significant reduction in whole-body protein and increase in fat was observed for fish fed phytase diets compared to diets with no phytase, regardless of soya bean level (P < 0.05); however, ash content was improved with phytase (250 FTU/g) compared to control (P < 0.05). Phytase supplementation improved bone phosphorus (250 FTU/g), calcium (250 FTU/g), magnesium (250–500 FTU/g), and zinc (250–1,000 FTU/g) compared to control (P < 0.05). In conclusion, the research has demonstrated that improved bone phosphorus (P) and growth could be achieved with the supplementation of dietary phytase.     

Influence of crop establishment methods on yield,economics and water productivity of rice cultivars under upland and lowland production ecologies of Eastern Indo-Gangetic Plains

A field study on assessment of crop establishment methods on yield, economics and water productivity of rice cultivars under upland and lowland production ecologies was conducted during wet seasons (June–November) of 2012 and 2013 in Eastern Indo-Gangetic Plains of India. The experiment was laid-out in a split-plot design (SPD) and replicated four times. The main-plot treatments included three crop establishment methods, viz. dry direct-seeded rice (DSR), system of rice intensification (SRI) and puddled transplanted rice (PTR). In sub-plots, five rice cultivars of different groups like aromatic (Improved Pusa Basmati 1 and Pusa Sugandh 5), inbreds (PNR 381 and Pusa 834) and hybrid (Arize 6444) were taken for their evaluations. These two sets of treatments were laid-out simultaneously in two production ecologies, upland and lowland during both years. In general, lowland ecology was found favourable for rice growth and yield and resulted in 13.2% higher grain yield as compared to upland ecology. Rice grown with SRI method produced 19.4 and 7.0% higher grain yield in 2012 and 20.6 and 7.1% higher in 2013, over DSR and PTR. However, PTR yielded 13.1 and 14.5% higher grain over DSR during 2012 and 2013, respectively. On an average, Arize 6444 produced 26.4, 26.9, 28.9 and 54.7% higher grain yield as compared to PS 5, P 834, PNR 381 and IPB1, respectively. Further, the interaction of production ecologies × crop establishment methods revealed that, in upland ecology, SRI recorded significantly higher grain yield as compared to PTR and DSR, but in lowland, grain yield resulting from SRI was similar to the yield obtained with PTR and significantly higher than DSR. The latter two methods (PTR and DSR) yielded alike in lowland ecology in both study years. The production ecologies × crop establishment methods × cultivars interaction on grain yield showed that the growing of Arize 6444 cultivar using SRI method in upland ecology resulted in the higher grain yield (8.87 t/ha). But the cost of production was also highest in SRI followed by PTR and DSR across production ecologies and cultivars. Cultivation of hybrid (Arize 6444) involved higher cost of production than all other cultivars. Irrespective of crop establishment methods and cultivars, gross returns, net returns and B:C ratio were significantly higher in lowland compared to upland ecology. Owing to higher grain yield, SRI method fetched significantly higher gross returns and net returns over PTR and DSR. Average increase in net return with Arize 6444 was 68.8, 41.0, 37.7 and 33.1% over IPB 1, PNR 381, P 834 and PS 5, respectively. There was a saving of 30.7% water in SRI and 19.9% in DSR over PTR under upland ecology. Similarly in lowland ecology, water saving of 30.2% was observed in SRI and 21.2% in DSR over PTR. Due to higher yield and saving on water, SRI returned significantly higher total water productivity (TWP) (5.9 kg/ha-mm) as compared to DSR (3.5 kg/ha-mm) and PTR (3.6 kg/ha-mm) under upland ecology. In lowland ecology, also SRI (6.2 kg/ha-mm) resulted in higher TWP as compared to other two methods. However, DSR gave significantly higher TWP as compared to PTR. Among cultivars, hybrid Arize 6444 recorded the highest TWP in both upland and lowland production ecologies across crop establishment methods. Hence, growing of hybrid Arize 6444 with SRI method can enhance rice productivity and water-use efficiency in lowland and upland production ecologies of Eastern Indo-Gangetic Plains and in other similar regions.     

Effect of dietary protein content on growth rate,survival and body composition of juvenile cauque river prawn,Macrobrachium americanum (Bate 1868)

We determined the effect of four concentrations of dietary crude protein, 30.7, 37.2, 41.8 and 46.8% on growth rate, survival and body composition of the juvenile cauque river prawn (Macrobrachium americanum). The prawns were hatched in the laboratory from the spawn of one wild ovigerous female. Prawns consuming 37.2% crude protein reached a final weight of 0.58 g (feed conversion ratio of 2.15), which was significantly better than the other treatments. Survival was 100% in all treatments. Protein content in the diets had no significant effect on whole body proximate composition and amino acid profile. Juveniles consuming the 37.2% crude protein diet grew faster than those fed the other diets. Specific growth rate was adjusted to the two‐slope broken‐line regression analysis model to estimate the optimal protein requirement. In conclusion, these results demonstrated that the 37.2% protein level diet is optimal for juvenile cauque river prawn M. americanum in the experimental conditions of this study.     

Pectin purified from pomelo (Citrus maxima) peel as a natural hatching agent for fish embryos

Pectin is a biodegradable polysaccharide, and it has been recently applied as a gene delivery, drug delivery, wound healing and tissue engineering agent. In this study, pectin was extracted from pomelo (Citrus maxima) peel and characterized. The extraction recovery of pectin form pomelo peel was 14.5%, and it had 72.56% degree of esterification, 1,245.56 equivalent weight, 7.82% methoxyl and 68.27% anhydrouronic acid contents. Use of pomelo pectin as a hatching enhancing agent for fish embryos and its effect on hatching enzyme 1 (ZHE1) was investigated. The pectin‐exposed zebrafish embryos (100 µg/ml) showed significantly (p < .05) higher hatching rate (96.6%) compared with untreated (control) embryos (66.6%) at 60 hpf. The mRNA expression of ZHE1 was also significantly (p < .05) elevated up to 55.6‐fold in pectin‐exposed embryos at 24 hpf. In situ hybridization results revealed remarkably strong expression of ZHE1 in pectin‐exposed embryos compared with the control group. In addition, considerably larger size of the hatching gland was observed in pectin‐exposed larvae than that of the unexposed larvae group. These results clearly indicate that pectin isolated from pomelo peel has an ability to enhance the hatching process of zebrafish embryos via upregulation of ZHE1.