Towards a better molecular and physiological understanding of spikelet fertility in barley (Hordeum vulgare L.)

• Applicant: Professor Dr. Thorsten Schnurbusch
• Subject Area: Plant Breeding and Plant Pathology
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 251169880

This research proposal we will focus on the molecular elucidation of spikelet fertility in barley. It largely consists of two major parts: The first area of interest deals with the molecular analysis of a developmental mutant, six-rowed-spike2 (vrs2); whereas part two focuses on the molecular and physiological characterization of putative down-stream genes of Vrs4.1) Through genetic mapping we identified a vrs2-candidate chromosomal region containing two predicted gene models in the barley physical map. However, for the vrs2 locus only one known allele has been found so far (vrs2.e), which makes analysis of this locus difficult. Hence, we propose to search for, or create new vrs2 alleles using different genetic and molecular approaches. New alleles shall be found through (I) SANGER-sequencing of intermedium-barleys (H. vulgare convar. intermedium), and (II) TILLING analyses of the two candidate genes. (III) Putatively new alleles shall be tested for being allelic to vrs2.e. (IV) Transgenic approaches shall include a complementation of the vrs2.e mutant using the two wild type candidate genes; but similarly to create new alleles through TALEN technology. (V) Finally, vrs2.e and other putative alleles shall undergo a detailed phenotypic analysis as well as metabolic and hormonal profiling to reveal functional links to one of the two vrs2 candidate genes.2) In our very recent study (Koppolu et al. 2013)* we showed that Vrs4 regulates transcripts of genes belonging to the trehalose biosynthesis pathway. Trehalose-6-phosphate (T6P) has been implicated to control meristem determinacy and generally has been considered as an important signaling metabolite that is involved in the regulation of plant growth and development in response to carbon availability. T6P levels are potentially governed by a group of trehalose-6-phosphate synthase (TPS) and trehalose-6-phosphate phosphatase (TPP) homologs. Here we would like to propose a detailed functional characterization of these two enzyme classes in barley inflorescences to elucidate their phylogenetic relationships, copy number, tissue-specificity, mRNA expression pattern and catalytic activities (i.e. TPS, ability to synthesize T6P; TPP, ability to dephosphorylate T6P).This research proposal aims at a deeper molecular, genetic and physiological insight into spikelet and floret fertility of barley for improving future yields of small grain cereals.

• DFG Programme: Research Grants