Please use this identifier to cite or link to this item: http://krishikosh.egranth.ac.in/handle/1/5810146613
Authors: Ramandeep Kaur
Advisor: Joshi, Neelam
Title: Elucidating the role of whitefly heat shock proteins and endosymbiont in transmission of cotton leaf curl virus
Publisher: Punjab Agricultural University, Ludhiana
Language: en
Type: Thesis
Pages: 86
Keywords: Antibiotics, arboreum, bioformulations haplotype, heat shock proteins, endosymbionts
Abstract: Bemisia tabaci is a cryptic species complex, which poses a major threat to agricultural crops worldwide. To unravel its genetic diversity and endosymbiont composition across Punjab, sampling of whiteflies was done from fifteen different locations. Based on mitochondrial cytochrome oxidase I (mtCOI) sequencing and phylogenetic analysis, two major B. tabaci groups i.e Asia II-1 and Asia- 1group were identified and the prevalence of endosymbionts within these groups was described. The south western region of Punjab was dominated by AsiaII-1group, while Asia-1group was predominant in the northern region. Infection status of endosymbionts in individual whitefly were analyzed using specific primers corresponding to 16S/23S rDNA region of bacterial gene. The primary endosymbiont Portiera aleyrodidarum and secondary endosymbiont Arsenophonus was present across all populations of Punjab. The infection percent of Cardinium was 100 % in Asia II-1 group, while its presence in Asia-1 group was variable across these locations. Presence of Rickettsia could not be associated with any haplotype as its infection was varied within the same population. Wolbachia was restricted to only Asia -1 group; however Hamiltonella was not detected from any of the tested populations. The present study evidenced the predominance Arsenophonus in AsiaII-1 group, which might be implicated with higher incidences of cotton leaf curl disease (CLCuD) in southwestern Punjab. The role of Arsenophonus in transmission of cotton leaf curl virus (CLCuV) by whitefly was investigated after its selective elimination with rifampicin and tetracycline @90μg/ml in sucrose diet. Virus transmission assays showed that Arsenophonus-ve B. tabaci poorly transmits CLCuV in cotton plants compared to control whiteflies. The functional role of Heat shock proteins, Knottin and Cyclophilin in transmission of CLCuV was studied through knockdown of these genes in whitefly using RNAi. To have an enhanced RNAi efficiency dsRNA (dsdsRNases) against gut nuclease gene (dsRNases) was co administered with the target genes. Whiteflies were given feeding access to 400 ng/μl of dsRNA against target gene along with dsdsRNase (400ng/μl) in sucrose diet for 48 h knockdown of Hsp and knottin-1 resulted in increased viral load in the host vector and its high transmission ability in cotton host plants compared to control whiteflies. On the contrary, cyclophilin knockdown led to decreased viral load in vector and ultimately lower transmission of CLCuV in cotton plants compared to sucrose fed whiteflies. Comparative study on fate of virus particle in two cotton species (Gossypium arboreum and G. hirsutum) showing variable response to CLCuD revealed that the immunity in arboreum cotton may possibly be due to the degradation of CLCuV particles after gaining entry in plant phloem through vector feeding. The RT-PCR based detection assays (Syber green and Taq man) suggest that the virus may be restricted to plant phloem for up to seven days and thereafter it degrades. No detection of virus from cDNA synthesized from total RNA of inoculated leaf of arboreum compared to hirsutum also suggest that there is a possibility that virus degrades or is trapped after gaining entry into the arboreum cell. Bioformulation of Lecanicillium lecanii MTCC956 at middle and lower dose (10and 12g/liter) was effective in reducing whitefly population on cotton under screenhouse conditions.
Subject: Microbiology
Theme: Elucidating the role of whitefly heat shock proteins and endosymbiont in transmission of cotton leaf curl virus
Research Problem: Elucidating the role of whitefly heat shock proteins and endosymbiont in transmission of cotton leaf curl virus
These Type: Ph.D
Issue Date: 2020
Appears in Collections:Thesis

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