The influence of polyploidy on mutation rates in the oil crop Brassica napus

• Applicant: Professorin Dr. Sarah Schießl-Weidenweber
• Subject Area: Plant Breeding and Plant Pathology
• Term: from 2018 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 405304351

Many of the world’s most important crops are recent polyploids. Understanding the mechanisms underlying the advantages of polyploidy can therefore help to further improve crop diversity and performance. The major hypothesis of this project is that polyploidy affects mutation rates. Mutation rate is an absolutely critical parameter in evolution and breeding research. Based on preliminary research findings, I hypothesise that mutation rate will be dramatically increased by polyploidy and hybridisation processes. The hypothesized influence is assumed to differ between recent and ancient polyploids. To study this differential influence, I decided to use Brassica napus, because it is both a well-characterised recent polyploid and a major crop. In this project, I want to quantify the influence of both polyploidisation and polyploidy on the mutation rate in B. napus. Whole exome sequencing on different generations of resynthesised vs. natural B. napus will be used to capture not only genome-wide SNP and InDel variation, but also structural variants like duplications and deletions. Sanger sequencing data from selected genes will be used to validate and improve the bioinformatic pipelines for the sequence capture data. By comparing resynthesised and natural B. napus, we will be able to separate spontaneous effects in the first generations after polyploidisation from longer-term, ongoing effects of polyploidy. Moreover, including the diploid parents of the resynthesised plants will allow us to directly follow the effect of increased redundancy. To study the influence of gene copy number and subfunctionalisation, I want to perform a gene clustering approach as well as an RNAseq experiment to provide data about differential expression patterns between the different levels of ploidy. This project will study the immediate influence of polyploidy on mutation rates in B. napus, and the persistence of mutations in later generations, in order to develop hypotheses about crop selection and evolution in polyploid plants.

• DFG Programme: Research Grants