Thumbnail Image

Theses

Browse

20211
Reset filters
Subject: Plant Pathology × Author: Gogoi, Shankar Hemanta × End date: 2022 × Start date: 2020 × Type: Thesis × Thesis Type: Ph.D ×
Reset filters

Search Results

Now showing 1 - 1 of 1
  • Thumbnail Image
    ThesisItemOpen Access
    Biochemical, histopathological and molecular characterization of sesamum phyllody disease in Assam
    (2021) Gogoi, Shankar Hemanta; Nath, P. Deb
    The field of phytoplasma diseases witnessed a new height of systematic study and research works throughout the world. An effort was made for biochemical, histopathological and molecular characterization of the sesamum phyllody disease. Sixteen (16) different alternate hosts were identified by molecular technique and out of that 9 were characterized. Three different groups of phytoplasma viz., aster yellows (16SrI), clover proliferation (16SrVI) and stolbur phytoplasma (16Sr XII) were identified to be associated with the phytoplasma alternate host samples. By using iPhyClassifier tool Brinjal phytoplasma isolate was grouped into the subgroup level 16SrVI-D. Exitinus indicus was detected for phytoplasma presence; characterization was done and it was found that it may play a new role for sesamum phyllody phytoplasma transmission. Ten (10) sesamum cultivars were grown in the field and pot conditions to observe the disease reactions and the cultivars were found moderately resistant (MR) to moderately susceptible (MS). The sesamum phyllody disease was successfully transmitted from infected to healthy sesamum plants by graft transmission (80%). Membrane-bound, phytoplasma-like bodies were detected in Transmission electron microscopy. Total chlorophyll content was reduced by 41.02 per cent in severely infected plants, while in mildly infected plant it was reduced by 28.20 per cent. Ratio between chlorophyll “a” and chlorophyll “b” progressively reduced as a result of infection. The ratio was 1.02 in healthy plants, while it was 1.01 and 0.96 in case of mild infection and severe infection, respectively. Phyllody disease considerably increased the dry matter content in the infected plant. Increase in dry matter content was 12.41 per cent and 19.85 per cent in mildly infected and severely infected plants, respectively. However, no considerable difference in moisture content was observed in both mildly and severely infected plants compared to the healthy ones. Phyllody disease decreased the total nitrogen as well as protein content. The reduction in protein content was 8.50 per cent in mildly infected leaves and 13.29 per cent in severely infected leaves. Phenol content was increased as disease advanced from milder to severe symptoms stage from 2.24 mg/g to 2.68 mg/g, respectively, as compared to healthy leaves i.e., 1.85 mg/g. Molecular characterization of Sesamum phyllody phytoplasma was done from all the agro-climatic zones of Assam and all the phytoplasma isolates were grouped into 16SrI-B. Restriction Fragment Length Analysis (RFLP) was done with three restriction enzymes viz., BamHI, EcoRI and RsaI. Sequence analysis, iPhyClassifier and the comparison between virtual and actual RFLP pattern revealed that there is no genetic difference among the Sesamum phyllody phytoplasma isolates of Assam.