High intraspecific diversity of Restorer‐of‐fertility‐like genes in barley. (9th November 2018) - Melonek, Joanna
SUMMARY : Nuclear restorer of fertility ( Rf ) genes suppress the effects of mitochondrial genes causing cytoplasmic male sterility (CMS), a condition in which plants fail to produce viable pollen. Rf genes, many of which encode RNA‐binding pentatricopeptide repeat (PPR) proteins, are applied in hybrid breeding to overcome CMS used to block self‐pollination of the seed parent. Here, we characterise the repertoire of restorer‐of‐fertility‐like (RFL) PPR genes in barley ( Hordeum vulgare ). We found 26 RFL genes in the reference genome ('Morex') and an additional 51 putative orthogroups (POGs) in a re‐sequencing data set from 262 barley genotypes and landraces. Whereas the sequences of some POGs are highly conserved across hundreds of barley accessions, the sequences of others are much more variable. High sequence variation strongly correlates with genomic location – the most variable genes are found in a cluster on chromosome 1H. A much higher likelihood of diversifying selection was found for genes within this cluster than for genes present as singlets. This work includes a comprehensive analysis of the patterns of intraspecific variation of RFL genes. The RFL sequences characterised in this study will be useful for the development of new markers for fertility restoration loci. Significance statement: Restorer of fertility genes are applied in plant breeding to overcome mitochondrially conditioned male sterility in hybrid crop production. Although these genes are known to vary between related species, intraspecific variation in the gene family has not been comprehensively studied. By systematic analysis of restorer of fertility‐like sequences across hundreds of barley accessions, we show that a huge diversity of these RNA‐binding proteins exists within a single species, with strong diversifying selection on the residues known to determine binding specificity.