Estimates of direct and maternal (co)variance components as well as genetic parameters of growth traits in Nellore sheep

In the present study, (co)variance components and genetic parameters in Nellore sheep were obtained by restricted maximum likelihood (REML) method using six different animal models with various combinations of direct and maternal genetic effects for birth weight (BW), weaning weight (WW), 6-month weight (6MW), 9-month weight (9MW) and 12-month weight (YW). Evaluated records of 2075 lambs descended from 69 sires and 478 dams over a period of 8 years (2007–2014) were collected from the Livestock Research Station, Palamaner, India. Lambing year, sex of lamb, season of lambing and parity of dam were the fixed effects in the model, and ewe weight was used as a covariate. Best model for each trait was determined by log-likelihood ratio test. Direct heritability for BW, WW, 6MW, 9MW and YW were 0.08, 0.03, 0.12, 0.16 and 0.10, respectively, and their corresponding maternal heritabilities were 0.07, 0.10, 0.09, 0.08 and 0.11. The proportions of maternal permanent environment variance to phenotypic variance (Pe²) were 0.07, 0.10, 0.07, 0.06 and 0.10 for BW, WW, 6MW, 9MW and YW, respectively. The estimates of direct genetic correlations among the growth traits were positive and ranged from 0.44(BW-WW) to 0.96(YW-9MW), and the estimates of phenotypic and environmental correlations were found to be lower than those of genetic correlations. Exclusion of maternal effects in the model resulted in biased estimates of genetic parameters in Nellore sheep. Hence, to implement optimum breeding strategies for improvement of traits in Nellore sheep, maternal effects should be considered.     

Virulence and mycotoxic effects of Metarhizium anisopliae on Mahogany shoot borer, Hypsipyla robusta (Lepidoptera: Pyralidae)

Developing appropriate control measures for the Mahogany shoot borer,Hypsipyla robusta Moore has become increasingly important due to the severe damaging effect of the pest on the establishment of the saplings of Swietenia mahagoni Jacq(Sapindales:Meliaceae).Existing management methods are largely limited to silvicultural practices and spraying of chemical insecticides.To identify a potential fungal biocontrol agent,we compared the virulence of six native and two standard ARSEF isolates of Metarhizium anisopliae Metsch.against this pest.The average survival time and conidial yield of IWST-Ma7 was higher(6.2 to 7.3 days and 4.9 to 4.7 × 10 5 conidia/ml) than the standards.Significant difference in sporulation on the cadavers between isolates,doses and incubation periods were substantiated for the selection of potential strain.The mycotoxic effects of crude soluble protein extract when incorporated in the artificial diet,the ARSEF 2596 and ARSEF 3603 showed LD 50 value of 3.7% and 5.6%.However,IWST-Ma7 was highly lethal with significant lowest LD 50 value of 2.6%.The enzyme activity of IWST-Ma7 was highest for chitinase,CDA,protease and lipase viz.,1.90 U/mg,1.80 U/mg,0.98 U/mg and 0.80 U/mg respectively.However the enzyme activity of chitinase and Chitin deacetylase assay for all the isolates was significantly higher than protease and lipase activity.The ITS regions(5.8S rDNA and 28S rDNA) of seven isolates of M.anisopliae were amplified using the ITS1 and ITS4 primers which was a unique fragment of approximately 550 bp.Based on ITS regions,phylogenetic tree have been constructed and the isolates have been grouped in to 5 clades.The virulence and mycotoxic effects of different isolates could rationally be used to employ them for the management of the mahogany borer.     

Precision phenotyping of contrasting potato(Solanum tuberosum L.) varieties in a novel aeroponics system for improving nitrogen use efficiency: In search of key traits and genes

With increasing population, degrading soil health, limited arable land area, and high cost of nitrogen(N) fertilizers, improving nitrogen use efficiency(NUE) of potato is an inevitable approach to save the environment and achieve sufficient tuber yields with less N fertilizer supply. Recently, we have developed an aeroponics system to study NUE in potato using genomics, physiology, and breeding approaches. This study aims on precision phenotyping of plants of two distinct potato varieties(Kufri Gaurav, N efficient; Kufri Jyoti, N inefficient) in the novel aeroponics system. Plants were grown in aeroponics under controlled conditions with low N(0.75 mmol L~(-1) NO_3~-) and high N(7.5 mmol L~(–1) NO_3~-) levels. Plant biomass, root traits, total chlorophyll content, and plant N were increased with increasing N supply, whereas higher NUE parameters namely NUE, agronomic NUE(Ag NUE), N uptake efficiency(NUp E), harvest index(HI), and N harvest index(NHI) were observed at low N. An NUE efficient cv. Kufri Gaurav showed higher tuber dry weight, fresh tuber yield, tuber number per plant, early start of tuber harvesting, root traits, stolon traits, NUE parameters, and higher amino acid(aspartic acid and asparagine) content at low N supply. Higher expression of nitrate reductase(NR), nitrite reductase(NIR), and asparagine synthetase(AS) genes was observed in the leaf tissues of Kufri Gaurav at high N. Thus, aeroponics-based precision phenotyping enables identification of NUE efficient genotypes based on key traits and genes involved in improving NUE in potato. Further, this study suggests that the potential of aeroponics can be utilized to investigate N biology in potato under different N regimes.     

Potential of Azotobacter spp. as biocontrol agents against Rhizoctonia solani and Fusarium oxysporum in cotton (Gossypium hirsutum), guar (Cyamopsis tetragonoloba) and tomato (Lycopersicum esculentum)

During the current investigation, 51 bacterial isolates/mutants of Azotobacter chroococcum, Azospirillum spp. and Gluconacetobacter diazotrophicus were tested for antifungal activity against three fungal pathogens, namely Rhizoctonia solani cotton, Rhizoctonia solani rice and Fusarium oxysporum tomato using a dual-culture technique under laboratory conditions. Ten isolates/mutants were found to be inhibitory against R. solani cotton, six against R. solani rice and twelve against F. oxysporum tomato. Nearly 50% of the isolates/mutants were siderophore positive. The antimicrobial substance was found to be extracellular and proteinaceous in nature, but in some strains it was found to be associated with other complex material also. Almost all the positive isolates/mutants showed production of antibiotic and antifungal compounds. On the basis of this study, in vitro results under laboratory conditions were reproduced in pot experiments in the greenhouse and chosen isolates/mutants of A. chroococcum were found to be effective biocontrol agents against R. solani cotton (disease index 16.7%) and R. solani rice (2.5%) in cotton crop, whereas in guar, the crop disease index was 2.5% against R. solani cotton, 13.3% against R. solani rice and 0% against F. oxysporum tomato in tomato crop compared with their respective checks.     

Pathogenicity of Metarhizium anisopliae (Deuteromycotina: Hyphomycetes) Isolates to the Ailanthus Webworm,Atteva fabriciella (Lepidoptera: Yponomeutidae) Under Laboratory and Field Conditions

The virulence of 25 Metarhizium anisopliae isolates was tested under laboratory conditions and the two most effective isolates were evaluated in the field for control of the Ailanthus defoliator, Atteva fabriciella. A bioassay was carried out to determine the dose and time mortality responses. The LC₅₀ of the isolates ranged from 3.16 to 647.81?×?10⁵ conidia mL^?1. Toxicity tests of the isolates MIS7 and MIS13 and 0.5% Pongamia pinnata seed oil, individually and in different combinations, indicated improved efficacy of the isolates when used in combination and also when combined with seed oil. Evaluation of these formulations in the field showed 66.36% reduction of infestation with MIS7 + MIS13 + 0.5% P. pinnata seed oil and 61.15% reduction with MIS7 + MIS13. The study indicated a possibility of employing combined formulations of M. anisopliae and also combination with P. pinnata seed oil for augmenting the effectiveness of the fungus.     

Genetic diversity of Ralstonia solanacearum infecting solanaceous vegetables from India reveals the existence of unknown or newer sequevars of Phylotype I strains

Bacterial wilt is one of the important constraints in the cultivation of solanaceous vegetables in India. The disease is caused by Ralstonia solanacearum, a soil bacterium. We have collected 232 isolates of R. solanacearum infecting solanaceous vegetables (eggplant, tomato and chilli) and other crops from different parts of India. Pathogenicity of the isolates was tested on eggplant, tomato and chilli and the pathogen was confirmed by PCR. Multiplex PCR and biochemical tests indicated that all the isolates were phylotype I and biovar 3. Ninety-five representative isolates selected based on geographical region, host range and pathogenicity were subjected to further phylogenetic and diversity analysis. Sequence analysis of egl, pga and hrpB genes of 95 isolates and genetic diversity of 50 representative isolates was reported and discussed. Indian isolates within the Phylotype I did not group based on the host or geographical location, except clustering of isolates from the Andaman Islands. Indian isolates clustered into two sub groups based on egl and pga trees indicating the presence of two major population groups. Sub group 1 is the dominant group in the data set and consists of unknown/newer sequevars, and sub group 2 consist of mainly the isolates which are designated with sequevar numbers based on egl sequences. In the hrpB based tree, the sub group 2 is the dominant group in the data set and it is the same for the sub group 1 of the egl tree. Indian phylotpe I R. solanacearum strains are phenotypically diverse including the previously described sequevars 14, 17, 44, 47 and 48. Our studies indicated the existence of R. solanacearum isolates with unknown/newer sequevars; the diversity existing among the phylotype I isolates might be due to a continuous evolutionary process. To our knowledge this is the first detailed report on the diversity of phylotype I R. solanacearum strains infecting solanaceous vegetables and the existence of unknown/newer sequevars in India.     

Gene-based analysis of <Emphasis Type="Italic">Puccinia</Emphasis> species and development of PCR-based marker to detect <Emphasis Type="Italic">Puccinia striiformis</Emphasis> f. sp. <Emphasis Type="Italic">tritici</Emphasis> causing yellow rust of wheat

Stripe rust is considered as the current major rust disease affecting winter cereal production across the world. A quick, reliable PCR-based marker was developed here to detect, identify and rapidly monitor Puccinia striiformis f. sp. tritici (Pst) in wheat-growing areas. Three respective sets of primers, designed from β-tubulin, squalene monooxygenase and ketopantoate reductase genes selected from the full genome of Puccinia striiformis f. sp. tritici, amplified sequences of 239, 358 and 1518 bp, respectively, in Pst pathotypes. A fragment of 1518 bp unique to Pst pathotypes was amplified using primer set PstKeto F1_30/Pst KetoR1_1547 and distinguished the pathogen clearly from different Puccinia spp. and other fungal pathogens. The detection limit of the marker (KetoPstRA₁₅₀₀, accession no. KU240073) by conventional PCR assay was 10 pg. This marker could detect the pathogen in the host before symptom expression. The sensitivity and utility of the marker were further enhanced in a qPCR-based assay that was developed with a newly designed primer set PstKeto F1_1246/Pst KetoR1_1547, which amplified a product of 302 bp and detected as little as 10 fg of DNA. This PCR/qPCR based marker is suitable for studying cultivar resistance, which requires accurate quantification of the pathogen in diseased host tissue.     

Technical Comments on Published Research Article “Characterization of Collagen from Different Discarded Fish Species of the West Coast of the Iberian Peninsula”

A research article published in this journal by Sotelo et al. (2016) reported on characterization of collagen from different discarded fish species obtained from the Iberian Peninsula located in the southwest corner of Europe. While the original research contributed new information to the literature, the authors did not provide sufficient details to reproduce the study and adequately interpret the results. This research note provides additional information that may help the reader to understand an important part of the published research study.     

Direct and maternal variance components and genetic parameters for average daily body weight gain and Kleiber ratios in Nellore sheep

Tropical Animal Health and Production - The objective of the present study was to estimate variance components and genetic parameters for average daily gain from birth to weaning (ADGa), birth to...