Phenotypic variation in feeding by the cabbage stem flea beetle (Psylliodes chrysocephala) in white mustard (Sinapis alba), and investigation of its genetic basis

Thursfield, Lucy (2022) Phenotypic variation in feeding by the cabbage stem flea beetle (Psylliodes chrysocephala) in white mustard (Sinapis alba), and investigation of its genetic basis. Doctoral thesis, University of East Anglia.

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Abstract

Oilseed rape (Brassica napus) is one of the worlds most economically important oilseed crops. The cabbage stem flea beetle (CSFB) is a major pest of oilseed rape, and there are currently limited control measures available. Genetic resistance would allow effective management of CSFBs, but no resistance genes have been identified. This thesis utilised a captive colony of CSFBs to screen Brassicaceae for resistance, resulting in the discovery of a potential quantitative trait loci linked to CSFB resistance within a wild relative, white mustard (Sinapis alba).

The dynamics of a captive colony of CSFB were studied which facilitated experimentation utilising the insect. A pipeline was developed to quantify adult CSFB feeding for 49 lines of B. napus and 14 lines of S. alba. While all B. napus were equally susceptible, two S. alba lines had a nine-fold difference in resistance.

No clear resistance mechanisms were observed during the limited characterisation performed, though the defence trait was found to be constitutively expressed. Transcriptome analysis using RNAseq associated wounding and chitin responses with the susceptible line, and salicylic acid catabolism, redox state, and selenium metabolism with the resistant line. Bulked segregant analysis identified a potential quantitative trait loci (QTL) associated with resistance on chromosome 11 containing 56 genes, five of which were differentially expressed. Genes in this region were discussed for their potential roles in resistance.

These results increase knowledge of performing experiments using adult CSFBs, and associate genes and metabolic pathways to CSFB resistance. Future experiments comparing these contrasting varieties could aid in identification of a specific resistance mechanism. Additional experiments for mapping QTL could also substantiate which regions are associated with resistance. In future work, gene candidates can be tested further to understand their mechanism with the aim to eventually develop oilseed rape varieties with increased resistance to the CSFB.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Biological Sciences
Depositing User:	Chris White
Date Deposited:	14 Dec 2023 09:10
Last Modified:	14 Dec 2023 09:10
URI:	https://ueaeprints.uea.ac.uk/id/eprint/93977
DOI:

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