Abstract
Vast collections of barley germplasm have been established and conserved in various global gene banks. These collections hold tremendous genetic diversity for resistance genes to Puccinia hordei, a causal agent of barley leaf rust. This study was undertaken to discover, characterize and postulate the known Rph genes (resistance to Puccinia hordei) and identify novel sources of ASR (all-stage resistance) and APR (adult plant resistance) to P. hordei. A core set of 315 barley lines were rust-tested as seedlings for their response to eight Australian pathotypes of P. hordei and genotyped with molecular markers linked to the known characterised ASR and APR genes. These tests led to the postulation of ASR leaf rust resistance genes Rph1, Rph2, Rph3, Rph9.am, Rph12, Rph15, Rph19 and Rph25 singly or in combination. Field tests revealed that the vast majority of lines (84%) carried APR. Genotyping of the APR-carrying lines with markers bPb-0837, Ebmac0603 and sun43-44 identified lines that likely carry the known APR genes Rph20, Rph23 and Rph24 singly or in combination. Thirty-nine per cent of the lines were negative for all the three markers and were thus postulated to carry uncharacterized APR. The sources of resistance identified in this study provide a valuable resource to breeders for further utilization and diversifying the genetic basis of leaf rust resistance in barley.
Highlights
Barley (Hordeum species), a founder crop of the Old World Neolithic food production, was first domesticated in the Fertile Crescent ~8000 years ago
The aims of this study were (1) to identify and characterize the genes conferring ASR and adult plant resistance” (APR) to P. hordei in the barley germplasm derived from the Middle East and Central Asia using multi-pathotype greenhouse rust tests and field-based phenotypic screening and (2) to genotype the accessions with the diagnostic molecular markers linked to the APR and ASR genes conferring resistance to P. hordei
Eight lines (AGG-3, AGG-45, AGG-624, AGG-662, AGG-663, AGG-1104, AGG-1124 and AGG-1724) were postulated to carry Rph1 based on the infection type (IT) patterns that matched with the differential line Sudan
Summary
Barley (Hordeum species), a founder crop of the Old World Neolithic food production, was first domesticated in the Fertile Crescent ~8000 years ago. 32 species (diploid and polyploid), and is distributed widely in most temperate areas and grown throughout annual winter cropping systems of the world [1]. With the renaissance of Mendelian work in early 1900s and the sustained efforts of breeding, cultivated barley (Hordeum vulgare L.) is adapted to marginal environments and today ranks as the fourth most important cereal crop after wheat, maize and rice with a global production of more than 150 million tonnes produced from about 60 million hectares [2]. Several biotic and abiotic stresses hamper barley production worldwide. Among the biotic stresses that threaten barley, rust diseases are of significant concern.
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