TY - BOOK AU - Potluri Navya Rohini AU - Joy, M (Guide) TI - Promising botanicals and piriformospora indica for the management of blackeye cowpea mosaic virus in yard long bean U1 - 632.3 PY - 2023/// CY - Vellayani PB - Department of plant pathology, college of agriculture KW - piriformospora indica KW - mosaic virus KW - plant pathology KW - yard long bean N1 - MSc N2 - The study entitled “Promising botanicals and Piriformospora indica for the management of Blackeye cowpea mosaic virus in yard long bean” was conducted at Department of Plant Pathology, College of Agriculture, Vellayani during 2021-2023, with the objective of field evaluation of potential botanicals and the beneficial fungal root endophyte P. indica for the management of Blackeye cowpea mosaic virus (BlCMV) in yard long bean / vegetable cowpea; and to elucidate its biochemical and molecular mechanisms. BlCMV was maintained in systemic host, yard long bean (Vigna ungiculata var. sesqipedalis (L.) Verdcourt) variety Vellayani Jyothika and local lesion host, Chenopodium amaranticolor through mechanical transmission / sap inoculation. In yard long bean, initial symptoms like mosaic patterns, leaf blistering, vein banding, vein clearing and stunting were observed at seven days after inoculation (DAI) in newly emerged trifoliate leaves; which was followed by mosaic, vein netting, floral deformation, stunting and yield reduction. The artificially inoculated vegetable cowpea plants had a vulnerability index (V. I.) of 79.3. In C. amaranticolor, an average of 26 local lesions of size 2 mm was recorded at five DAI. BICMV, a member of potyviridae, was serologically detected using polyclonal antibodies of potyviruses viz., Cowpea aphid-borne mosaic virus (CABMV) (DSMZ, Germany) through Direct antigen coating - Enzyme linked immuno-sorbent assay (DAC-ELISA) and Dot immuno-binding assay (DIBA) as the polyclonal antibody of BICMV was not commercially available and was molecularly detected through Reverse Transcription – Polymerase Chain Reaction (RT-PCR) with coat protein specific primers of BlCMV. Fungal root endophyte, P. indica culture was obtained from Department of Plant Pathology was maintained by periodical sub-culturing in potato dextrose agar (PDA) and potato dextrose broth (PDB) media. P. indica was mass-multiplied in coir pith-dried farm yard manure (FYM) mixture (1:1) amended with two per cent gram flour and was allowed to colonize the vegetable cowpea seedlings. P. indica-colonization resulted in 14.9 per cent more shoot biomass, 28.9 per cent more root biomass than the control plants at 30 DAI; and also 71 per cent more number of pods per plant and 64 per cent more yield per plant. The fungal colonization enhanced the other biometric characters like shoot length, root length, number of leaves, leaf area and number of tertiary roots at different intervals, compared to the non-colonized control plants at 30 DAI. The days taken for flowering in P. indica-colonized plants were decreased by 14 days and the yield per plot in P. indica-colonized was 10.5 kg against 4.6 kg in the control plots. A pot culture experiment was laid out in CRD with 11 treatments and 5 replications to evaluate the efficiency of prophylactic as well as curative application of 1 per cent of P. niruri and B. diffusa; and P. indica, in managing BlCMV in vegetable cowpea. Pre- and post- application of P. niruri and B. diffusa and P. indica-colonisation significantly reduced the incidence and severity of BlCMV, upon pre- as well as postinoculation of the virus, compared to the control plants. Prophylatic application of the above treatments resulted in better control of the disease and recovered the loss in biomass and yield caused by the virus infection. The highest reduction of the disease with enhanced biomass and yield was recorded in pre-colonization of P. indica. Similarly, a field study laid out in RBD with 6 treatments and 4 replications (with and without P. indica along with botanicals – 1 % P. niruri) to evaluate their efficiency against natural incidence of BlCMV. The disease incidence and severity was less in P. indica-colonised plants with minimal loss of biomass and yield due to the virus infection. In order to evaluate the influence of P. indica in modulating different biochemical process of the plants against BlCMV infection, the activity of various antioxidant defense enzymes viz. peroxidase, catalase and superoxide dismutase were assayed. A significant increase in the activity of above enzymes was observed in the P. indica-colonized plants compared to the control plants, upon post-inoculation of BlCMV; thus the better performance of P. indica-colonized plants upon the virus infection is correlated. BlCMV-infected plants showed increased accumulation of reactive oxygen species like super oxides as evidenced by NBT staining and hydrogen peroxide by DAB staining, which cause oxidative stress in the plants. P. indicacolonization was able to mitigate the increase in ROS concentration caused due to BlCMV infection, thus reducing the symptoms. Moreover, chlorophyll content and phenylalanine ammonia lyase activities were more in P. indica-colonised plants. The differential gene expression of salicylic acid (NPR1 and PR1) and ethylene (ETR1 and EIN1) signaling genes clearly demonstrates its involvement in P. indica-mediated tolerance against BlCMV in vegetable cowpea. Thus, the present study reveals that P. indica-colonisation and spraying of 1 per cent P. niruri in vegetable cowpea at 5 and 25 DAT could significantly and substantially reduce the incidence and severity of BlCMV infection without compromising the biomass and yield of the crop; and is a reliable and chemical-free method to control blackeye cowpea mosaic disease. Bio-protective action of P. indica might be attributed to the increased activity of antioxidant enzymes, which in turn leads to suppression in ROS accumulation in the colonized plants, upon being challenged by the virus. The combined effect of AVPs and P. indica on management of BlCMV in vegetable cowpea needs more studies in future ER -