Genetic analysis of innate immunity and its contribution to disease resistance in the Brassicaceae family

Yalcin, Hicret (2020) Genetic analysis of innate immunity and its contribution to disease resistance in the Brassicaceae family. Doctoral thesis, University of East Anglia.

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Abstract

Brassicas are important crops susceptible to significant losses caused by disease. Breeding resistant lines can mitigate the effects of pathogens. The first layer of active defence in plants is based on the perception of pathogen- (or microbe-) associated molecular patterns (PAMPs/MAMPs) leading to PAMP-triggered immunity (PTI). In this study I studied the response to various PAMPs including Necrosis & Ethylene-inducing peptide 1-like proteins (NLPs) in 3 different plant species from Brassicaceae.

This PhD research investigates the immune system of Brassicas in different aspects, and how it is contributing to quantitative disease resistance (QDR). I developed a segregating population from a cross between two NLP responsive and non-responsive Brassica napus accessions and revealed that recognition of NLP induces the resistance against Botrytis cinerea. In silico mapping of the region associated with NLP-recognition on B. napus genome was accomplished with an improved BSA pipeline and the most significant peak was identified on chromosome A04 spread over a 2.5Mbp region. KASP markers were designed and tested on F2 individuals of the BSA population to narrow down the region and to reduce the number of the candidate genes. I identified 4 KASP markers tightly linked to the phenotype. I also genetically mapped the locus responsible for high NLP-induced ROS burst, and show that BnaBSK1.A01 is involved in modulating the NLP response, and further supported by functional tests of the gene in A. thaliana.

The genetic tolerance under drought stress conditions is another agronomically important trait for the changing climate conditions in the world. The effect of environmental conditions, including drought stress, on the PTI responses of the plants observed quite a lot during the study. To investigate the effect of abiotic stress conditions, I optimised reproducible drought stress conditions to enable further mapping of induced QTL on Brassica oleracea genome and design and RNA-Seq experiment to reveal underlying genes. As a result, I showed that drought stress induces both PTI and disease resistance against B. cinerea in B. oleracea. The work will provide new insight into crop improvement, enabling more reliable QDR for controlling Brassica diseases to be developed.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Chris White
Date Deposited: 08 Feb 2021 11:41
Last Modified: 08 Feb 2021 11:41
URI: https://ueaeprints.uea.ac.uk/id/eprint/79184
DOI:

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