Phenotypic and genetic diversity of leaf rust resistance in wheat wild relatives

Abstract

Puccinia triticina (Pt), the causal agent of leaf rust evolves through forming new pathotypes that adversely affect the growth and yield of wheat cultivars. Therefore, continued production of resistant varieties through exploring novel sources of resistance in wild relatives which are abundantly found in Iran and the neighbouring regions is a major task in wheat breeding programs. The aim of the present study was to explore 60 wild wheat genotypes selected from the species Triticum monococcum, Aegilops tauschii, Ae. neglecta, Ae. cylindrica, Ae. triuncialis, Ae. umbellulata, Ae. speltoides, Ae. columnaris, Ae. crassa and Ae. ventricosa for resistance to leaf rust. The cultivar ‘Boolani’ and Thatcher near‐isogenic lines were used as controls. Two‐week‐old seedlings were inoculated using 10 Pt pathotypes, and the infection types were recorded. The genotypes were also analysed for polymorphism using six sequence‐tagged sites (STS) and sequence characterized amplified region (SCAR) markers. Forty‐eight genotypes produced high infection types (3+) for two pathotypes, but the remaining genotypes produced low infection types of ‘0; =’ to ‘1+CN’ to all pathotypes. The latter included three accessions of Ae. tauschii, two accessions of each Ae. umbellulata, Ae. columnaris and Triticum monococcum, and one accession from each Ae. triuncialis, Ae. ventricosa and Ae. neglecta. Analysis for STS and SCAR markers suggested several genotypes could carry the genes Lr9, Lr10, Lr19, Lr24, Lr26 and Lr37 or their potential orthologs in addition to unknown resistance genes. In conclusion, the identified resistant genotypes could be further characterized and used in wheat breeding programs for leaf rust resistance.

Molecular analyses in wheat and Aegilops tauschii reveals a new orthologue of the leaf rust resistance gene Lr19 on 7DL chromosome of Ae. tauschii

“…Phenotyping of wheat and Ae. tauschii genotypes supported the results of previous report by Aliakbari et al (2020) as the resistant Ae. tauschii accessions SU442 and SU444 displayed low ITs similar to that of TcLr19 and Agatha.…”

“…Different molecular biology and bioinformatics tools have become instrumental for the analysis of transcriptional pro ling, putative virulence gene identi cation, structural gene annotation, and alternative transcript splicing in host and pathogen. Based on the results of this study and previous reports by Aliakbari et al (2020), it was speculated that an orthologue for Lr19 is responsible for leaf rust resistance in Ae. tauschii genotypes and hence was named AtLr19.…”

“…Though Lr19 was originated from Th. ponticum, Aliakbari et al (2020) observed ITs similar to that of Thatcher+Lr19 (TcLr19) and Lr19corresponding band in few Aegilops tauschii genotypes. Yet, no investigation has performed to con rm this.…”

“…Two Ae. tauschii accessions SU442 and SU444 displaying the same resistance response to P. triticina as the Lr19 carrying genotypes were selected from a larger collection of wheat wild relatives (Aliakbari et al, 2020). Accordingly, for more precise investigation, TcLr19 (RL6040) and Agatha (Agrus/6×Thatcher) as positive controls, and the susceptible accession SU350, and Thatcher as the negative control were included in the experiment.…”

Comparative transcriptome analysis of two contrasting resistant and susceptible Aegilops tauschii accessions to wheat leaf rust (Puccinia triticina) using RNA-sequencing

“…Two resistant and susceptible Ae. tauschii accessions , AT349 (TN-01-1970) and AT350 (TN-01-2017), respectively , were selected from a collection of wheat wild relatives collected from the southern shores of the Caspian Sea (Iran) according to the relevant guidelines and legislations or obtained from the Seed and Plant Improvement Institute (Karaj, Iran) and tested with an array of 10 P. triticina pathotypes 72 . The two above-mentioned accessions were obtained from the National Plant Gene Bank, Seed and Plant Improvement Institute, Iran and inoculated with pathotype CDHLQ (race No.…”