Genomic Scan of Male Fertility Restoration Genes in a 'Gülzow' Type Hybrid Breeding System of Rye (Secale cereale L.).

Nikolaj Meisner Vendelbo,Jihad Orabi,Khalid Mahmood,Peter Skov Kristensen,Ahmed Jahoor,Pernille Sarup

doi:10.3390/ijms22179277

Nikolaj Meisner Vendelbo, Jihad Orabi + Show 4 more

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https://doi.org/10.3390/ijms22179277

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Abstract

Efficient and stable restoration of male fertility (Rf) is a prerequisite for large-scale hybrid seed production but remains an inherent issue in the predominant fertility control system of rye (Secale cereale L.). The ‘Gülzow’ (G)-type cytoplasmic male sterility (CMS) system in hybrid rye breeding exhibits a superior Rf. While having received little scientific attention, one major G-type Rf gene has been identified on 4RL (Rfg1) and two minor genes on 3R (Rfg2) and 6R (Rfg3) chromosomes. Here, we report a comprehensive investigation of the genetics underlying restoration of male fertility in a large G-type CMS breeding system using recent advents in rye genomic resources. This includes: (I) genome-wide association studies (GWAS) on G-type germplasm; (II) GWAS on a biparental mapping population; and (III) an RNA sequence study to investigate the expression of genes residing in Rf-associated regions in G-type rye hybrids. Our findings provide compelling evidence of a novel major G-type non-PPR Rf gene on the 3RL chromosome belonging to the mitochondrial transcription termination factor gene family. We provisionally denote the identified novel Rf gene on 3RL RfNOS1. The discovery made in this study is distinct from known P- and C-type systems in rye as well as recognized CMS systems in barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.). We believe this study constitutes a stepping stone towards understanding the restoration of male fertility in the G-type CMS system and potential resources for addressing the inherent issues of the P-type system.

Highlights

In recent years, hybrids have become the predominant class of cultivated winter rye (Secale cereale L.) in Northern Europe [1]
Breeding of hybrids relies on the existence of cytoplasmic male sterility (CMS) and restoration of male fertility (Rf) genes that reside in genetically distinct parental populations [3,4]
We report an investigation of the genetics underlying male fertility restoration in G-type CMS-based hybrid rye breeding systems

Summary

Introduction

Hybrids have become the predominant class of cultivated winter rye (Secale cereale L.) in Northern Europe [1]. Breeding of hybrids relies on the existence of cytoplasmic male sterility (CMS) and restoration of male fertility (Rf) genes that reside in genetically distinct parental populations [3,4]. This system efficiently enables control of parental crossing in the field, which is a prerequisite for large-scale hybrid seed production [5]. CMS systems exist, of which the most predominant is the Pampa (P) type [6] In this system, five major P-type Rf genes have been identified on 1RS, 4RL (Rfp, Rfp, Rfp3), and 6R (dominant modifier) chromosomes, and three minor genes on 3RL, 4RL, and 5R chromosomes [7,8,9,10]. In the G-type CMS system, one major gene has been identified on 4RL (Rfg1) and two minor genes on 3R (Rfg2) and 6R (Rfg3) chromosomes [15]

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