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Investigations of self-incompatibility (SI) in perennial ryegrass (Lolium perenne L.)

Yang, Bicheng (2009)
Ph.D. thesis, University of Birmingham.

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Abstract

Perennial ryegrass (Lolium perenne L.) is one of the most economically and environmentally important grass species for the temperate zone. It maintains effective self-incompatibility (SI), which promotes outbreeding as well as limits the efficient production of inbred lines and hybrids. SI in L. perenne is controlled by the S and Z loci, mapping to linkage groups 1 and 2, respectively. None of the gene products has been identified so far. Comparative mapping has identified regions on rice chromosomes 5 (R5) and 4 with synteny to regions of L. perenne genome containing the S and Z loci, respectively. Markers were developed from the syntenic rice genomic region to refine the S and Z maps. The closest flanking markers had a map distance of 2 cM from S and 0.2 cM from Z. SI cDNA libraries were developed from in-vitro pollinated stigma subtracted with unpollinated stigma to identify SI components and SI response related genes. Through a BLAST search, candidates identified from the SI libraries that were orthologous to sequences on the S and Z flanking regions on rice R4 and R5 were the prime candidate SI genes. Altogether ten SI candidate genes were identified with incompatible response associated differentially expression pattern: a rapid increase in expression within two minutes after pollen-stigma contact and reaching a maximum between 2-10 minutes, implying their roles in the SI response. Attempts were carried out to determine the linkage relationships between the identified candidates and the S or Z loci. Large fine scale mapping populations were developed individually for the S and Z loci to generate high resolution maps of S and Z towards map-based cloning. Tightly linked markers were identified mapping at a distance of 1.4 cM from S and 0.9 cM from Z. The studies performed in this project have implications on both the underlying genetic control and the associated biochemical responses involved in L. perenne SI. The closely linked markers for S or Z could be applied in future marker assisted selection breeding programmes and map-based cloning.

Type of Work:Ph.D. thesis.
Supervisor(s):Barth, Susanne and Thorogood, Danny and Armstead, Ian and Franklin, F.C.H.
School/Faculty:Colleges (2008 onwards) > College of Life & Environmental Sciences
Department:School of Biosciences
Subjects:QK Botany
SB Plant culture
Institution:University of Birmingham
Library Catalogue:Check for printed version of this thesis
ID Code:1097
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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