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941.
V. M. Malathi Sushil Kumar Jalali Vazhakkala Jose Lyju R. Gandhi Gracy Ravi Prabhakar More Rangasamy Anandham Apoothy Thulasi Thiruvengadam Venkatesan 《Phytoparasitica》2017,45(5):683-693
Nilaparvata lugens (Stål) is one of the major pests of rice throughout tropical and temperate Asia. Indiscriminate use of insecticides for suppressing N. lugens has resulted in the development of resistance to multiple insecticide classes, causing frequent control failures in the field. Analysis of gut bacterial diversity within an insect host is the initial step towards understanding the ecological roles of the symbionts. Present study aimed to survey the bacterial diversity associated with laboratory-reared (insecticide-susceptible) and field-collected (insecticide-resistant) populations of N. lugens by culture-dependent and PCR-Denaturing Gradient Gel Electrophoresis (DGGE) methods. Seventeen bacterial isolates were obtained by the culture-dependent method. Molecular characterization using the 16S rRNA gene and phylogenetic analysis revealed that the isolates belonged to Firmicutes and Proteobacteria. Taxonomic assignment placed these isolates into seven families representing 10 genera. Enterobacteriaceae was the most dominant family with its occurrence in four out of the five populations studied. The DGGE profiles indicated a low complex gut bacteria associated with N. lugens with limited number of bands. The Shannon-Wiener index ranged from 0.898 in insecticide-susceptible population to 0.946–1.035 in resistant populations. Sequencing and phylogenetic analysis revealed that the DGGE bands belonged to Firmicutes, Proteobacteria and Bacteriodetes. Results of this study illustrated that gut bacterial community associated with N. lugens is dominated by Proteobacteria and Firmicutes. Present findings could provide the basis for future work on the possible role of the bacterial symbionts in insecticide resistance and to formulate potential resistance management strategies. 相似文献
942.
R. M. Nair M. Götz S. Winter R. R. Giri V. N. Boddepalli A. Sirari T. S. Bains G. K. Taggar H. K. Dikshit M. Aski M. Boopathi D. Swain A. Rathore V. Anil Kumar E. C. Lii L. Kenyon 《European journal of plant pathology / European Foundation for Plant Pathology》2017,147(2):349-364
The segmentation of symptoms during image analysis of diseased plant leaves is an essential process for detection and classification of diseases. However, there are challenges involved in the task, many of them related to the variability of image and host/symptom characteristics and conditions. As a result of those challenges, the methods proposed in the literature so far focus on a specific problem and are usually bounded by tight constraints regarding image capture conditions. This research explores a new automatic method for segmenting disease symptoms on plant leaves that was designed to be applicable in a wide range of situations. The proposed technique employs only color channel manipulations and Boolean operations applied on binary masks, thus being simpler and more robust compared to many previously described automatic methods. Its effectiveness is demonstrated by tests performed over a large database containing images of 77 different diseases of 11 plant species. A comparison with manual segmentation is also presented, further reinforcing the advantages of the proposed approach. 相似文献
943.
Parthenium hysterophorus (Asteraceae) is known as one of the most aggressive invasive weeds, causing severe economic, environmental, human and animal health problems in India and around the world. During a series of extensive surveys for natural enemies of P. hysterophorus, a leaf spot pathogen was isolated from the affected parts of the parthenium following the standard isolation techniques using potato dextrose agar (PDA) and parthenium dextrose agar (PeDA) media. Koch's postulates were performed and found satisfactory for the isolate and proved to be pathogenic to this weed. On the basis of cultural, morphological and molecular characteristics, the pathogen was identified as Alternaria sp. PMK2. The growth of the pathogen was studied on eight selected media and it exhibited varying degrees of growth on different media. Phytotoxicity of fungal cultural filtrates was also confirmed on parthenium leaves in laboratory conditions. Due to the virulent nature of the isolated pathogen, it may be selected for further studies to develop mycoherbicide for control of this devastating weed. 相似文献
944.
Sana Tabanda Saeed B. Kumar A. K. Shasany A. Samad 《Journal of General Plant Pathology》2017,83(5):333-336
Whitefly-transmitted begomovirus induces leaf curling and stunting of Mentha arvensis (Kosi) and is responsible for heavy economic losses in and around Lucknow, India. The complete genome was amplified, sequenced and assembled as 2759 bp long, with 1376 bp betasatellite molecule. Because no DNA-B amplicon was detected, the virus was classified as “Old World begomovirus” with the characteristic seven ORFs; two ORFs (AV1, AV2) in the V-sense and five ORFs (AC1–AC5) in the C-sense. BLASTn and phylogenetic analysis showed highest similarity (98%) with chilli leaf curl India virus (ChiLCINV). This is the first report of ChiLCINV infection in M. arvensis (Kosi) from India. 相似文献
945.
946.
Qin Ran Delara Akhter Yang Chengcong Ujjal Kumar Nath Jamal Eshag Jin Xiaoli Shi Chunhai 《水稻科学》2018,25(6):297-307
Grain shape is one of the important agronomic traits, which is closely related to the yield of rice. A new rice mutant, named small and round grain (srg1), was isolated from an indica cultivar Zhenong 34 by ethyl methane sulfonate (EMS) mutagenesis. The microscopic analysis showed that the cell length of spikelet in srg1 was decreased compared with that in wild type (WT), which caused the grain length short. Meanwhile, the grains of srg1 were wider than those of WT because of the increased cell layers in spikelet in the lateral direction. Therefore, the inhibition of cell expansion and increased cell proliferation collectively led to the small and round grain. By map-based cloning, the gene SRG1 was located on the short arm of chromosome 9, which encodes a kinesin-4 protein, represented by the gene LOC_Os09g02650. A single nucleotide polymorphism, occurred in the 16th exon of SRG1, led to premature translation stop in mutant. The cell cycle-related genes were up-regulated in srg1, which conferred that SRG1 controlled grain width through the cell proliferation. Since the role of SRG1 in regulating grain shape was not clarified well before, it is valuable to explore the mechanism of grain development. This study could, hence, provide a morphogenesis and molecular basis for elucidating the function of SRG1, as well as a new germplasm resource for the further study of grain development. 相似文献
947.
Alokesh Kumar Ghosh 《Aquaculture International》2018,26(2):405-417
A study was conducted in a recirculating aquaculture system (RAS) to assess the growth performance, body composition, fatty acid profile, and nutrient accumulation in different tissues of shrimp using two feeding levels (10 and 16 g/kg0.8/day). The shrimp PL25 was nursed in the nursing tank for 2 months and stocked in six grow out tanks (ten individuals in each 30 L tank). A commercial feed with 42.7% protein was used over a 16-h period per day. After 4 weeks, the final average weight when fed 16 g/kg0.8/day was 9.7 g which was not significantly different from a final weight of 8.6 g achieved when feeding 10 g/kg0.8/day. The protein and energy content increased in high feeding level whereas moisture, crude fat, and ash content decreased with feeding level (P?>?0.05). With the high feeding level, the fatty acid content increased in the eye, muscle, and whole body, with eye containing the highest concentration. The isotopic ratio of δ13C was enriched with feeding level in the muscle and whole shrimp whereas the ratio of δ13C was depleted in the viscera with feeding level. The fraction of δ15N was enriched with decreasing feeding level and highest value was found in the muscle than in the whole shrimp and viscera. 相似文献
948.
Amit Ranjan Narottam Prasad Sahu Ashutosh Dharmendra Deo H. Sanath Kumar Sarvendra Kumar Kamal Kant Jain 《Fish physiology and biochemistry》2018,44(4):1037-1049
A 60-day feeding trial was conducted to study the effect of exogenous enzymes (xylanase and phytase) supplementation in the non-fermented and fermented de-oiled rice bran (DORB)-based diet of Labeo rohita. Four test diets (T1-DORB-based diet, T2-fermented DORB-based diet, T3-phytase and xylanase supplemented DORB-based diet, and T4-phytase and xylanase supplemented fermented DORB-based diet) were formulated and fed to the respective groups. Test diets T3 and T4 were supplemented with 0.01% xylanase (16,000 U kg?1) and 0.01% phytase (500 U kg?1) enzymes. One hundred twenty juveniles of L. rohita, with an average weight 5.01?±?0.02 g, were stocked in 12 uniform size plastic rectangular tanks in triplicate with 10 fishes per tank following a completely randomized design (CRD). Exogenous enzyme supplementation to the T3 group significantly improved the growth performance of L. rohita (p?<?0.05). Fermented DORB fed groups registered significantly lower growth irrespective of the supplementation of exogenous enzymes. The carcass composition (except CP %), enzyme activities (except amylase activity), globulin, and A/G ratio did not vary significantly (p?>?0.05). Based on the results of the present study, it is concluded that exogenous enzyme supplementation significantly increases the growth of fish fed with DORB-based diet. 相似文献
949.
Effect of dietary synbiotic on growth performance,body composition,digestive enzyme activity and gut microbiota in Cirrhinus mrigala (Ham.) fingerlings 下载免费PDF全文
A feeding trial of 60 days was conducted to delineate the effect of dietary synbiotic on maximum growth, body composition, digestive enzyme activity and subsequently gut microbiota in Cirrhinus mrigala fingerlings. One hundred and eighty acclimatized fingerlings of mrigal with initial body weight ranging from 2.87 ± 0.01 g to 3.26 ± 0.05 g were randomly distributed in three replicates of each of four experimental groups including control (without probiotic and prebiotic), T1 (high probiotic + low prebiotic), T2 (low probiotic + high prebiotic) and T3 (high probiotic + high prebiotic), using completely randomized design (CRD). Results showed that growth performance parameters, such as specific growth rate (SGR), per cent weight gain, feed conversion ratio (FCR) and protein efficiency ratio (PER), were reported to be higher in the T2 group followed by the T3 group. Maximum gut microbiota activity was found in the T3 group which was significantly different from other treatment groups. Similarly, body composition and digestive enzyme activity varied significantly (p < .05) among the treatment groups. The study showed the possibility of improved nutrient utilization in terms of growth performance and digestive enzyme activity in the group following dietary synbiotic supplementation. 相似文献
950.
Nutritional evaluation of an improved soybean meal as a fishmeal replacer in the diet of Pacific white shrimp,Litopenaeus vannamei 下载免费PDF全文
Richard Hulefeld Habte‐Michael Habte‐Tsion Ramanathan S. Lalgudi Barry McGraw Rob Cain Kristy Allen Kenneth R. Thompson James H. Tidwell Vikas Kumar 《Aquaculture Research》2018,49(4):1414-1422
A 12‐week growth trial was conducted to assess an improved soybean meal (ISBM) in the diet of Pacific white shrimp (PWS). Four isonitrogenous and isolipidic experimental diets were formulated: the control diet (ISBM‐0) contained 30% fishmeal (FM) and three test diets (ISBM‐33, ISBM‐66 and ISBM‐100) were formulated by gradually replacing FM on an isonitrogenous basis. Groups of PWS (3.2 g mean initial weight) were fed their respective experimental diets three times per day. Production performance of PWS was unaffected by diet, except the final weight of shrimp‐fed ISBM‐66 diet was significantly lower than those fed ISBM‐0. Whole‐body moisture was significantly higher and protein was significantly lower in PWS‐fed ISBM‐100 versus shrimp‐fed ISBM‐0. PWS‐fed ISBM‐66 had significantly higher oleic acid than shrimp‐fed ISBM‐0 and linolenic acid versus shrimp‐fed ISBM‐0 and ISBM‐100. The lowest linoleic acid and n‐6 polyunsaturated fatty acids levels were found in shrimp‐fed ISBM‐100. Based on second‐degree polynomial regression analysis of final weight and weight gain, the estimated optimum levels of ISBM to replace FM in PWS diets are 89.13% and 95.56% respectively. Overall, results indicate alternative, sustainable, plant‐based protein sources such as ISBM may potentially replace FM in PWS diets. 相似文献