M Sc

The research work entitled “Evaluation of beneficial fungal root endophyte,
Piriformospora indica for the management of Tomato leaf curl virus” was done at the
Department of Plant Pathology, College of Agriculture, Vellayani,
Thiruvananthapuram during the academic year 2019-2021 with the objectives of
evaluation of the beneficial fungal root endophyte Piriformospora indica for the
management of Tomato leaf curl virus (ToLCV) in tomato; and elucidating the role of
reactive oxygen species (ROS) and antioxidant enzymes in the tripartite interaction.
ToLCV symptoms were assessed and maintained in insect proof nets from the
various field at College of Agriculture, Vellayani, Thiruvananthapuram. The major
symptoms observed includes mild curling with yellow speckles, severe leaf curling
with blisters on leaf, stunted growth and reduced leaf size with flower abortion.
Tomato variety Vellayani Vijay showed a disease incidence of 72.3 to 100 per cent
with vulnerability index of 68.5 to 71.0 at different fields, while Anagha variety
recorded an incidence of 67.0 per cent and vulnerability index of 54. The presence of
ToLCV was confirmed using the universal primers viz., Deng and AV/AC that
amplifies the coat protein of Begomovirus which produce amplicons of 520 bp and
575 bp respectively under specified conditions.
P. indica-colonization in tomato variety Vellayani Vijay was done in portray
mixture amended with 2 per cent gram flour. P. indica spores were observed from 3
day after colonization (DAC) and the spore size increased by subsequent days.
P.indica-colonization enhanced the growth parameters including plant height, shoot
height, and root and shoot biomass. The tomato plants colonized with P. indica
showed an increase in shoot height, number of branches, number of leaves, number of
flower, fresh shoot weight, dried shoot weight, fresh root weight and dried shoot
weight by 34, 117, 96, 86, 45, 66, 45 and 120 per cent respectively compared to the
control at 60 DAC. The days taken for flowering in P. indica-colonized plants were
decreased by 12 days and the yield per plant in P. indica-colonized was 892.46 g
against 449.51g.
P.indica-colonization decreased incidence and severity of fungal and bacterial
diseases under field conditions. Moreover, it recorded a drastic reduction in the
severity of ToLCD by 58 percent. Tomato plants were subjected to pre- and postcolonization of P. indica challenged with ToLCV through wedge grafting at 2, 5, 10
and 15 days interval. Pre-colonized tomato plants decreased the severity of ToLCD by
66 per cent, while post-colonization decreased the severity by 26 per cent at various
intervals of treatments. Further, P. indica-colonization promoted flowering and fruit
set against complete flower abortion in non-colonized plants challenged with ToLCV
under pot studies. The best treatments selected from pre- and post- inoculation of the
fungus include P. indica-colonization followed by graft transmission of the virus after
15 days, and graft transmission of the virus followed by P. indica-colonization after 2
days respectively. Amplification of the virus by polymerase chain reaction (PCR)
using Deng and AV/AC primers also revealed that the virus titer was the least in P.
indica-pre-colonized plants that were inoculated with the virus after 45 DAC,
followed by post-colonized plants that were inoculated with the virus.
Nitro blue tetrazolium (NBT) for superoxides and diamino benzidine (DAB)
for H2O2 staining recorded a reduction in ROS production in both pre- and post- P.
indica-colonized tomato plants artificially inoculated with ToLCV against the virus
alone. The decrease in ROS production and disease severity in the fungus colonized
plants inoculated with the virus were attributed to the increased total soluble proteins
and enhanced activities of antioxidant enzymes. The substantial increase in
antioxidant enzymes viz., peroxidase, phosphatase, superoxide dismutase, catalase and
glutathione reductase and glutamate synthase were observed in P. indica-colonized
plants against the control; and for both pre- and post- P. indica-colonized plants
artificially inoculated with ToLCV against the virus alone.
Thus, the present study reveals that P. indica can be exploited for the
management of ToLCV on prophylactic and curative bases with the best results in the
former. P. indica colonized plants enhanced the over all growth and productivity; and
drastically reduced the severity of ToLCD under both controlled and open field
conditions.