Identification and Characterisation of the Barley Row-Type Gene VRS3

Abstract

Barley row-type describes the number of grains present at a node on the barley spike. Two forms exist amongst cultivated barley: two-rowed with only the central of three spikelets fertile producing a single grain at a node and six-rowed with all three spikelets fertile, producing three grain at a node. Twelve regions of the barley genome have been associated with the row-type character with specific genes identified at three loci, VRS1, VRS4 and INT-C. Advancements in the understanding of the genetic control underpinning barley row-type enables the identification of potential mechanisms for improving yield and yield architecture within the cereals. 
This study used genetic linkage mapping in segregating F2 populations to refine the genetic location of the row-type locus, VRS3, to 16 candidate genes on barley chromosome 1H. Sequencing candidate loci in 32 vrs3 induced mutant alleles identified VRS3 to be a highly conserved JmjC histone demethylase, with two natural alleles within European cultivated barley. VRS3 was further characterised as a potential means of improving grain uniformity within cultivated six-rowed barley, through phenotypic assessment of grain size in varying allele combinations of VRS3, VRS1 and INT-C. The addition of six-rowed alleles at these loci was found to improve balance between central and lateral grain parameters, resulting in a more uniform grain sample. Analysis of gene expression found Vrs3 to be constitutively expressed across a diverse panel of barley tissues. Moreover, detailed study within the developing inflorescence suggests a role for Vrs3 in the regulation of the row-type genes VRS1 and INT-C.

Date of Award	2015
Original language	English
Supervisor	Andrew Flavell (Supervisor), Robbie Waugh (Supervisor) & Bill Thomas (Supervisor)