Allele mining in wild barley: finding new exotic genes which control flowering time in the barley nested association mapping (NAM) population HEB-25.

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During the second phase of the PP-9 project, we plan to study the function of major genes controlling flowering time, FTi, in the exotic barley population HEB-25 within the following three work packages, WP.WP1, QTL cloning - We will isolate an exotic gene that controls late flowering in HEB-25 at a newly identified locus on chromosome 4H in collaboration with the group of Prof. Dr. Andy Flavell, University of Dundee. Based on exome capture sequencing data of the 1,420 HEB lines, two top candidate genes, which differentiate between early and late flowering pools of recombinant HEB lines, will be selected and subjected to three transgenic approaches. These involve over-expression, knock-out-knock-down and promoter-reporter assays. Whereas the first two approaches will assist to identify the causal gene that causes the late flowering phenotype, the latter approach will be used to characterize the spatial and temporal expression of the candidate genes.WP2, Allele mining - We will study the variation of allelic effects of the 25 exotic HEB donors at four dominant major FTi genes, Ppd-H1, denso, Vrn-H2 and Vrn-H3. For this, 12 exotic haplotypes of the FTi genes will be cloned from HEB lines and used to generate over-expression transformants in the genomic background of the recessive spring barley Golden Promise genotype. The effects of the transformations on FTi will be studied to identify new allelic variants displaying altered FTi phenotypes.WP3, tress tolerance - We will study the flowering effects of FTi genes on yield and their crosstalk with stress tolerance on a global scale. For this, we will select 48 HEB lines, which reveal variation in flowering time, and, which segregate at four major FTi genes, Ppd-H1, denso, VrnH1 and Vrn-H3 on chromosomes 2H, 3H, 5H and 7H, respectively. Those HEB lines will be tested during two years (2015 and 2016) in field plots under two Treatments - stress versus control - and in four replications at five locations world-wide. Based on the subsequent modelling, we will quantify the impact of the studied FTi genes on yield and stress tolerance. Since the tested environments differ along a latitudal gradient, we may also select favorable exotic FTi alleles in response to day length variation.The external partners, their affiliations and the stresses studied are:1. Prof. Dr. Jason Eglinton, University of Adelaide, Australia, drought stress2. Prof. Dr. Mark Tester, King Abdullah University of Science and Technology, Saudi Arabia, salt stress3. Dr. Michael Baum, ICARDA, Jordan, heat stress4. Dr. William Thomas, James Hutton Institute, Dundee, nitrogen deficiency.