To introgress or not to introgress? Quantifying the expression and effectiveness of the 1RS/1BL introgression in a global sample of modern wheat varieties.

  • Ryan R Biscocho

Student thesis: Master's ThesisMaster of Science (MSc)

Abstract

Bread wheat is an important food source whose low genetic diversity has historically been supplemented with introgressed sequences from a range of different wild grasses. The 1RS/1BL introgression derived from rye is a particularly prevalent introgression that anecdotally provides resistance to several fungal pathogens. However little is known about the expression of these genes and how they behave once introduced into a wheat genetic background, as well as what potential pathways they may be implicated in. To understand this, the transcriptome of various wheat cultivars were studied using an RNA-seq based workflow. Publicly-available RNAseq data, representing a global sample of 38 different varieties, were collated and a subset analysed using a modified RNAseq pipeline to dissect 1RS/1BL expression. As expected, varieties containing the 1RS/1BL introgression showed an upregulation of rye genes and a downregulation of 1B genes, evident of (possible) 1RS introduction and 1BL removal. However these rye genes were expressed at a much lower level relative to wheat genes, which may indicate that these genes are being suppressed, perhaps through homologous co-suppression or by association to nearby transposons. The functional analyses also identified several potential mechanisms by which the 1RS/1BL’s documented disease resistance properties may be realised: the use of NBS-LRR receptors and/or a variant jasmonate signalling pathway are possibilities. Overall the study of the 1RS/1BL introgression is able to glean some important generalisations on the use of introgressions, notably that translocated arms should be treated as heterogeneous collections of diverse genes with dynamic expression that may be much lower in a new crop background. Further research, like a similarly designed experimental study, will help fully determine how useful this introgression will be for wheat cultivars, especially its disease resistance properties that will be increasingly important in a future where crop productivity is likely to be under high threat.
Date of Award11 May 2021
Original languageEnglish
Awarding Institution
  • The University of Bristol
SupervisorGary L A Barker (Supervisor) & Keith J Edwards (Supervisor)

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