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Not AvailableBackground: Castor (Ricinus communis L.) is cultivated for seed oil and to feed (leaves) Eri silkworm, Samia ricini (Donovan) Hutt. Alternaria blight affects castor cultivation resulting substantial yield loss (~30%). Uses of synthetic fertilizers and agrochemicals for disease management have serious concerns as the castor leaves are fed to eri silkworms for rearing. Application of plant growth promoting rhizobacteria for disease suppression and to enhance plant growth will be a healthier choice in castor cultivation. The aim of this study was to assess the efficacy of Alternaria blight disease suppression by native rhizobacteria isolated from wasteland castor and their ability on plant growth promotion. Methodology: We isolated 50 bacterial antagonists from castor rhizosphere using the dilution plate method and evaluated their antagonistic activity against the castor blight pathogen, Alternaria ricini. Based on antimicrobial bioassay and plant growth promotion (PGP) traits (phosphate solubilization, ACC deaminase activities, production of IAA, GA3, HCN, NH3 and siderophore), salt and acid tolerance; we have chosen ten potential isolates and identified them through 16SrRNA gene sequencing and analysis. Disease suppression and plant growth studies were evaluated in pot experiments. Results and conclusion: Three isolates namely, Enterobacter hormaechei (LRP-2), Bacillus mycoides (HF-1) and B. aryabhattai (UR-6) showed potential antagonistic activities and PGP traits which were selected for disease suppression and PGP studies. Application of PGPR consortia (LRP-2þHF-1) could suppress the plants from A. ricini infection in challenged inoculation. Mix inoculation of LRP-2 and UR-6 showed synergistic effect and enhanced plant growth in pot experiments. Combinations of E. hormaechei (LRP-2), B. mycoides (HF-1) and B. aryabhattai (UR-6) can be applied as bio-control and bio-fertilizer formulation to protect castor from Alternaria blight and also to enhance plant growth.Not Availabl

Investigation on Pathological Aspects, Mode of Transmission, and Tissue Tropism of Antheraea proylei Nucleopolyhedrovirus Infecting Oak Tasar Silkworm

The temperate oak tasar silkworm, Antheraea proylei, is frequently infested with Antheraea proylei nucleopolyhedrovirus (AnprNPV) causing tiger band disease. This disease is one of the key factors that obstructs production and productivity of oak tasar sericulture. The current study aimed to investigate the pathogenicity of AnprNPV, its mode of transmission, and detection of AnprNPV in different tissues. Transmission electron micrographs of AnprNPV showed single rod-shaped bodies and occlusion derived virus (ODV) enclosed within multiple envelopes. The infecting AnprNPV displayed tissue tropism with higher copy numbers detected in the insect fat body and ovary. The virus was observed to multiply in all developmental stages of the silkworm such as egg, larva, pupa, and moth, confirming its ability to spread throughout the silkworm lifecycle. Baculovirus isolated from infected A. proylei showed cross-infectivity in other Saturniidae wild silkworm species such as Antheraea pernyi, A. frithi, and Samia ricini, widening their probable host range for infection. Baculoviruses generally display a horizontal mode of transmission, mainly through ingestion of occlusion bodies (OBs); however, the present study revealed a trans-ovum vertical mode of transmission in addition to a horizontal mode. The observations made in this study aid a detailed understanding of the tiger band disease and its causative pathogen AnprNPV, which will support future studies and disease management in oak tasar sericulture