Evidence and Consequence of a Highly Adapted Clonal Haplotype within the Australian Ascochyta rabiei Population

Mehmood, Yasir; Sambasivam, Prabhakaran Thanjavur; Kaur, Sukhjiwan; Davidson, J. A.; Leo, Audrey E.; Hobson, Kristy; Linde, Celeste C.; Moore, Kevin; Brownlie, Jeremy C.; Ford, Rebecca

doi:10.3389/fpls.2017.01029

Cited by 27 publications

(46 citation statements)

References 55 publications

(67 reference statements)

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“…Five chickpea genotypes with known disease reactions were used as a differential host set to assess the aggressiveness of the Australian A. rabiei population: ICC3996, Genesis 090, PBA HatTrick , PBA Seamer and Kyabra ( Fungal materials, inoculation and disease assessment 201 single spored A. rabiei isolates were selected for phenotyping, representative of the years, regions and host genotype origins sampled within the 2016-2017 collection as described in Mehmood et al (2017). The full list of isolates and their available passport data (place of collection, year of collection, and host genotype) is provided in the additional material (Online source 1).…”

Section: Plant Materialsmentioning

confidence: 99%

“…Seed of genotypes ICC3996, Genesis 090, PBA HatTrick and Kyabra were grown as described above. Single spored isolates were chosen from PG 0-4 within the 2013-2015 populations ( Table 3), as was determined based on the symptomology on the host set (Mehmood et al, 2017). The experiments were conducted in a complete randomised design with four replicates sown at each time point/isolate and one leaflet from each replicate used to assess the development of infection structures.…”

Section: Plant Material Fungal Materials and Inoculum Preparationmentioning

confidence: 99%

“…Genetic variation and concomitant adaptation within A. rabiei populations has led to the erosion of resistance (Peever et al, 2012;Mahiout et al, 2015;Vafaei et al, 2015;Mehmood et al, 2017;Tekin et al, 2017). This has created highly aggressive isolates that are able to cause significant disease on commonly deployed cultivars (Varshney et al, 2007;Mehmood et al, 2017). Selection for stable and durable resistance to prevailing isolates within a growing region, requires an understanding of the pathogenic structure in the population and identification of isolates for deployment in future resistance breeding strategies.…”

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confidence: 99%

“…Whilst breeders have moved away from single source resistance to employing pyramided polygenic resistance (Thabuis et al, 2004;Reeves et al, 2013), longevity of newly deployed "resistant" cultivars remains dependent on the speed of isolate evolution and population adaptation (Moore et al, 2015;Mehmood et al, 2017). Accordingly, to assess this risk, variation in isolate aggressiveness has been assessed in many global regions including India (Vir and Grewal, 1974), the Palouse region of USA (Chen et al, 2004) Spain (Navas-Cortes et al, 1998), Pakistan (Jamil et al, 2000;Iqbal et al, 2004;Ali et al, 2012), Canada (Chongo et al, 2004), Syria (Atik et al, 2013;Imtiaz et al, 2015) and Australia (Mehmood et al, 2017). Within these studies, groups of isolates that interact in a differential manner with a host genotype set have been identified possessing a range of aggressiveness within the populations.…”

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confidence: 99%

“…Worryingly, only low levels of resistance were identified in advanced breeding material screened against the pathotype IV isolate at the International Center for Agricultural Research in the Dry Areas (ICARDA) (Imtiaz et al, 2015). Most recently in Australia, a broad range of aggressiveness was observed including several highly pathogenic isolates (Mehmood et al, 2017). These were not associated with a host genotype or growing region, however under controlled environmental conditions, they were able to cause severe disease symptoms on moderately resistant PBA HatTrick and "resistant" Genesis 090 (Moore et al, 2016), two pillar cultivars of the Australian chickpea industry.…”

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confidence: 99%

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Evidence of recent increased pathogenicity within the AustralianAscochyta rabieipopulation

Sambasivam

Mehmood

Bar

et al. 2020

Preprint

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AbstractAscochyta Blight (AB), caused by Ascochyta rabiei (syn Phoma rabiei), is the major endemic foliar fungal disease affecting the Australian chickpea industry, resulting with potential crop loss and management costs. This study was conducted to better understand the risk posed by the Australian A. rabiei population to current resistance sources and to provide informed decision support for chemical control strategies. Recent changes in the pathogenicity of the population were proposed based on disease severity and histopathological observations on a host set. Controlled environment disease screening of 201 isolates on the host set revealed distinct pathogenicity groups, with 41% of all isolates assessed as highly aggressive and a significant increase in the proportion of isolates able to cause severe damage on resistant and moderately resistant cultivars since 2013. In particular, the frequency of highly aggressive isolates on the widely adopted PBA HatTrick cultivar rose from 18% in 2013 to 68% in 2017. In addition, isolates collected since 2016 caused severe disease on Genesis 090, another widely adopted moderately resistant cultivar and on ICC3996, a commonly used resistance source. Of immediate concern was the 10% of highly aggressive isolates able to severely damage the recently released resistant cultivar PBA Seamer (2016). Histopathology studies revealed that the most aggressive isolates were able to germinate, develop appressoria and invade directly through the epidermis faster than lower aggressive isolates on all hosts assessed, including ICC3996. The fungal invasion triggered a common reactive oxygen species (ROS) and hypersensitive response (HR) on all assessed resistant genotypes with initial biochemical and subsequent structural defence responses initiated within 24 hours of inoculation by the most highly aggressive isolates. These responses were much faster on the less resistant and fastest on the susceptible check host, indicating that speed of recognition was correlated with resistance rating. This will inform fungicide application timing so that infected crops are sprayed with prophylactic chemistries prior to invasion and with systemic chemistries after the pathogen has invaded.

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Section: Plant Materialsmentioning

confidence: 99%

Section: Plant Material Fungal Materials and Inoculum Preparationmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Evidence of recent increased pathogenicity within the AustralianAscochyta rabieipopulation

Sambasivam

Mehmood

Bar

et al. 2020

Preprint

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Seed quality and the effect of introducing Cicer echinospermum to improve disease and pest resistance in desi chickpea

et al. 2019

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The utilisation and consumption of food crops for human nutrition demand acceptable seed quality traits to enable efficient processing into food products. Desi chickpea (Cicer arietinum L.) is a staple food of the Indian subcontinent, and domestication has led to cultivars with seeds that are an acceptable size, colour, and shape, easy to mill, and quick to hydrate and cook. Domestication has also severely restricted the gene pool, so breeders are looking to “wild” chickpea relatives as sources of novel genes that may provide agronomic benefits such as disease and pest resistance. Cicer echinospermum (a“wild” relative of cultivated chickpea with black, echinate seeds) was used in the breeding programme to introgress phytophthora root rot and root‐lesion nematode resistance genes into adapted C. arietinum backgrounds. The resulting C. echinospermum derivative lines were compared with commercial desi cultivars to examine any effects on seed quality attributes. The C. echinospermum derivatives had similar visual seed characteristics to the C. arietinum cultivars with, on average, lower milling performance and quicker cooking times; however, a few individual derivative lines met or exceeded the average cultivar milling performance. This paper shows the quality variation within the C. echinospermum derivatives, compares them with commercial desi cultivars, and confirms their potential to improve disease resistance whilst retaining the basic seed quality traits important for commercialisation and exporting new cultivars.

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Genome-wide SNP discovery for development of high-density genetic map and QTL mapping of ascochyta blight resistance in chickpea (Cicer arietinum L.)

2019

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Key message A high-density linkage map of chickpea using 3430 SNPs was constructed and used to identify QTLs and candidate genes for ascochyta blight resistance in chickpea. Abstract Chickpea cultivation in temperate conditions is highly vulnerable to ascochyta blight infection. Cultivation of resistant cultivars in combination with fungicide application within an informed disease management package is the most effective method to control ascochyta blight in chickpeas. Identifying new sources of resistance is critical for continued improvement in ascochyta blight resistance in chickpea. The objective of this study was to identify genetic loci and candidate genes controlling the resistance to ascochyta blight in recombinant inbred lines derived from crossing cultivars Amit and ICCV 96029. The RILs were genotyped using the genotyping-by-sequencing procedure and Illumina ® GoldenGate array. The RILs were evaluated in the field over three site-years and in three independent greenhouse experiments. A genetic map with eight linkage groups was constructed using 3430 SNPs. Eight QTLs for resistance were identified on chromosomes 2, 3, 4, 5 and 6. The QTLs individually explained 7–40% of the phenotypic variations. The QTLs on chromosomes 2 and 6 were associated with the resistance at vegetative stage only. The QTLs on chromosomes 2 and 4 that were previously reported to be conserved across diverse genetic backgrounds and against different isolates of Ascochyta rabiei were confirmed in this study. Candidate genes were identified within the QTL regions. Their co-localization with the underlying QTLs was confirmed by genetic mapping. The candidate gene-based SNP markers would lead to more efficient marker-assisted selection for ascochyta blight resistance and would provide a framework for fine mapping and subsequent cloning of the genes associated with the resistance. Electronic supplementary material The online version of this article (10.1007/s00122-019-03322-3) contains supplementary material, which is available to authorized users.

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Evidence and Consequence of a Highly Adapted Clonal Haplotype within the Australian Ascochyta rabiei Population

Cited by 27 publications

References 55 publications

Evidence of recent increased pathogenicity within the AustralianAscochyta rabieipopulation

Evidence of recent increased pathogenicity within the AustralianAscochyta rabieipopulation

Seed quality and the effect of introducing Cicer echinospermum to improve disease and pest resistance in desi chickpea

Genome-wide SNP discovery for development of high-density genetic map and QTL mapping of ascochyta blight resistance in chickpea (Cicer arietinum L.)

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