Thumbnail Image

Thesis

Browse

20231
Reset filters
Author: Belludi, Rakesh × Start date: 1990 × Type: Thesis × Thesis Type: Ph.D ×
Reset filters

Search Results

Now showing 1 - 1 of 1
  • Thumbnail Image
    ThesisItemEmbargo
    Detection, variability and translocation of Potato virus Y (PVY) infecting potato in Punjab and identification of host plant resistance
    (Punjab Agricultural University, 2023) Belludi, Rakesh; Sharma, Abhishek
    This study aimed to investigate the variability of Potato virus Y (PVY) infecting potato crop of Rabi season in Punjab, encompassing symptomatology, serology and molecular aspects. The study revealed prevalent symptoms, such as mild mosaic, chlorotic patches, interveinal chlorosis, puckering, veinal necrosis and stem necrosis, on potato plants caused by various potato viruses including PVY. ELISA tests confirmed the presence of six out of seven viruses in potato samples. Among them, PVX exhibited the highest incidence (78.08%), followed by PVYN (51.37%), PVM (20.55%), PVYO/C and PVS (13.01%). PLRV exhibited a lower incidence (2.74%) and no samples tested positive for PVA. Notable regional variations noticed, with Ludhiana showing high incidences of PVYN (78.43%), PVYO/C (31.37%), PVM (33.3%) and PVS (35.29%). Conversely, Kapurthala displayed a 100% PVX incidence, while Jalandhar had the highest PLRV (19.05%) incidence. In nucleic acid-based detection through RT-PCR, the primer NIb2F/3R effectively amplified the desired ~350bp amplicon in all PVYN and PVYO/C seropositive samples. Whereas, the qPVY NIb F2/CP R2 primer generated the ~1.5kb fragment in only 24 out of 67 samples, further confirmed via BLASTn sequence analysis as PVYO, PVYNTN and PVYN-Wi strains. Further virus translocation studies revealed a wide range of carryover rates, spanning from 40% to 92.46%, from infected mother plants to daughter tubers, exhibiting significant variation in viral titre across genotypes and among tubers. Spatial translocation within the tuber's root zone revealed that the bottommost tuber displayed a relatively lower PVY titre. Interestingly, freshly harvested tubers exhibited a higher viral titre at the heel end (stem end) compared to the rose end eyes in all examined tubers. After storage, a contrasting trend emerged in sprouted tubers, where the highest PVY titre was found in rose end eyes and the lowest in heel end eyes. In germplasm screening against resistance to PVY, one germplasm (KP -16-19-14) displayed high resistance (HR), while 16 exhibited resistant (R), 20 moderately resistant (MR), 22 moderately susceptible (MS), 10 susceptible (S) and two were highly susceptible (HS) to PVY. Following PVY inoculation, significant reduction was observed in chlorophyll fluorescence parameters, viz., Fv/Fm, Y(II), qP, and qL values in susceptible cultivars, accompanied by notable increases in NPQ, Y(NO) and qN values. Susceptible genotypes displayed yield losses ranging from 13.64 to 58.84% with viral titre ranging from 0.014 mc to 419.673 mc. Finally, a farmer-friendly and cost-effective vertical flow assay (VFA) was developed for rapid PVY detection in potato leaf samples. The sensitivity of the developed assay was equivalent to commercially utilized ELISA. Specificity test confirmed assays precision for prevalent PVY strains and its non-specificity to other potato viruses. Developed assay exhibited 95% accuracy compared to RT-PCR.