A mapping population was created to detect quantitative trait loci (QTL) for resistance to stem rust caused by Puccinia graminis subsp. graminicola in Lolium perenne. A susceptible and a resistant plant were crossed to produce a pseudo-testcross population of 193 F1 individuals. Markers were produced by the restriction-site associated DNA (RAD) process, which uses massively parallel and multiplexed sequencing of reduced-representation libraries. Additional simple sequence repeat (SSR) and sequence-tagged site (STS) markers were combined with the RAD markers to produce maps for the female (738 cM) and male (721 cM) parents. Stem rust phenotypes (number of pustules per plant) were determined in replicated greenhouse trials by inoculation with a field-collected, genetically heterogeneous population of urediniospores. The F1 progeny displayed continuous distribution of phenotypes and transgressive segregation. We detected three resistance QTL. The most prominent QTL (qLpPg1) is located near 41 cM on linkage group (LG) 7 with a 2-LOD interval of 8 cM, and accounts for 30–38% of the stem rust phenotypic variance. QTL were detected also on LG1 (qLpPg2) and LG6 (qLpPg3), each accounting for approximately 10% of phenotypic variance. Alleles of loci closely linked to these QTL originated from the resistant parent for qLpPg1 and from both parents for qLpPg2 and qLpPg3. Observed quantitative nature of the resistance may be due to partial-resistance effects against all pathogen genotypes, or qualitative effects completely preventing infection by only some genotypes in the genetically mixed inoculum. RAD markers facilitated rapid construction of new genetic maps in this outcrossing species and will enable development of sequence-based markers linked to stem rust resistance in L. perenne.

Mapping with RAD (restriction-site associated DNA) markers to rapidly identify QTL for stem rust resistance in Lolium perenne

Genetic improvement programs for livestock and pasture plants have been central to the development of the New Zealand (NZ) pastoral industry Although genetic improvement of livestock is easily shown to improve animal production on-farm, the link between genetic improvement of pasture plants and animal production is less direct For several reasons, gains in farm output arising from improved plant performance are more difficult to confirm than those arising from livestock improvement, which has led to some debate in the livestock industries about which plant traits to prioritise in future breeding programs to deliver the greatest benefit This review investigates this situation, with the aim of understanding how genetic improvement of perennial ryegrass (Lolium perenne L), the predominant pasture grass, may more directly contribute towards increased productivity in the NZ dairy industry The review focuses on the dairy industry, since it is the largest contributor to the total value of NZ agricultural exports Also, because rates of pasture renewal are greater in the dairy industry compared with the sheep and beef industries, genetic gain in pasture plants is likely to have the greatest impact if the correct plant traits are targeted The review highlights that many aspects of ryegrass growth and ecology have been manipulated through breeding, with evidence to show that plant performance has been altered as a result However, it is not clear to what extent these gains have contributed to the economic development of the NZ dairy industry There are opportunities for breeders and scientists to work together more closely in defining economic traits that positively influence pasture performance and to translate this information to objectives for breeding programs, systematically linking information on the measured traits of ryegrass cultivars to economic values for those traits to assist farmer decision-making regarding the most appropriate cultivars to use in their farm system, and better defining genotype × environment interactions in key productivity traits of modern ryegrass cultivars Changes in priorities for investment of public- and industry-good funds in forage improvement research and development will be needed if these opportunities are to be captured

https://bioone.org/journals/crop-and-pasture-science/volume-63/issue-2/CP11282/Perennial-ryegrass-breeding-in-New-Zealand--a-dairy-industry/10.1071/CP11282.pdf

Perennial ryegrass breeding in New Zealand: a dairy industry perspective

A large number of expressed sequence tags (ESTs) in public databases have provided an opportunity for the systematic development of simple sequence repeat (SSR) markers. EST-SSRs derived from conserved coding sequences show considerable cross-species transferability in related species. In the present study, we assessed the utility of cereal EST-SSRs in ryegrass (Lolium spp.). A total of 165 cereal EST-SSRs were tested; a high rate of transferability (57%) and polymorphism (67% of functional EST-SSRs) was demonstrated between cereals and ryegrass. A total of 46 segregating loci derived from 37 EST-SSRs were mapped on an existing ryegrass genetic map. The mapped loci were uniformly dis- tributed across all seven linkage groups without significant clustering at the distal regions of linkage groups. Sequences of ryegrass amplicons generated by randomly selected 16 EST-SSRs were aligned with reference sequences of cereal EST- SSRs. The SSR motifs and repeat lengths of the cereal EST-SSR markers were different from the majority of ryegrass am- plicons. Furthermore, a majority of EST-SSRs amplified different flanking sequences of SSRs in ryegrass than the original cereal sequences. Our results suggest that the high degree of cereal EST-SSR transferability to ryegrass can be a useful en- hancement to the molecular database of PCR-based markers but sequence analysis is essential before transferring genetic information using comparative mapping.

Transferability of cereal EST-SSR markers to ryegrass

Warm-season grasses are characterized by the C4 photosynthetic pathway. This pathway occurs in 18 families of fl owering plants, and 61% of the species belong to the grass family. C4 plants are usually found between 30° N and 30° S latitudes; however, some species extend beyond this range (Moser et al., 2004). The C4 pathway gives the warm-season grasses an advantage for performing in hot and dry climates and is one reason why these groups of grasses are found mainly in the tropics and subtropics (Clayton and Renvoize, 1986). Developing warm-season grasses for turf is a relatively new concept that began about 60 yr ago. Most of these grasses were used in their native habitat or introduced for use as forages because they could survive under low fertility and in extreme environments (such as drought). Many stoloniferous grasses are somewhat “plastic” and can be changed by management conditions to perform well for diff erent uses (e.g., forage, turf, water conservation, etc.).

Cool‐Season Grasses: Biology and Breeding

In crop species, QTL analysis is commonly used for identification of factors contributing to variation of agronomically important traits. As an important pasture species, a large number of QTLs have been reported for perennial ryegrass based on analysis of biparental mapping populations. Further characterisation of those QTLs is, however, essential for utilisation in varietal improvement programs. A bibliographic survey of perennial ryegrass trait-dissection studies identified a total of 560 QTLs from previously published papers, of which 189, 270 and 101 were classified as morphology-, physiology- and resistance/tolerance-related loci, respectively. The collected dataset permitted a subsequent meta-QTL study and implementation of a cross-species candidate gene identification approach. A meta-QTL analysis based on use of the BioMercator software was performed to identify two consensus regions for pathogen resistance traits. Genes that are candidates for causal polymorphism underpinning perennial ryegrass QTLs were identified through in silico comparative mapping using rice databases, and 7 genes were assigned to the p150/112 reference map. Markers linked to the Lp DGL1, Lp Ph1 and Lp PIPK1 genes were located close to plant size, leaf extension time and heading date-related QTLs, respectively, suggesting that these genes may be functionally associated with important agronomic traits in perennial ryegrass. Functional markers are valuable for QTL meta-analysis and comparative genomics. Enrichment of such genetic markers may permit further detailed characterisation of QTLs. The outcomes of QTL meta-analysis and comparative genomics studies may be useful for accelerated development of novel perennial ryegrass cultivars with desirable traits.

/pdf/quantitative-trait-locus-qtl-meta-analysis-and-comparative-2fypboatua.pdf

Quantitative Trait Locus (QTL) meta-analysis and comparative genomics for candidate gene prediction in perennial ryegrass (Lolium perenne L.)

Sim, S., Diesburg, K., Casler, M., and Jung, G. 2007. Mapping and comparative analysis of QTL for crown rust resistance in an Italian × perennial ryegrass population. Phytopathology 97:767-776. Crown rust (Puccinia coronata f. sp. lolli) is a serious fungal foliar disease of perennial ryegrass (Lolium perenne L.) and Italian ryegrass (L. multiflorum Lam.), which are important forage and turf species. A number of quantitative trait loci (QTL) for crown rust resistance previously were identified in perennial ryegrass under growth chamber or greenhouse conditions. In this study, we conducted a QTL mapping for crown rust resistance in a three-generation Italian × perennial ryegrass interspecific population under natural field conditions at two locations over 2 years. Through a comparative mapping analysis, we also investigated the syntenic relationships of previously known crown rust resistance genes in other ryegrass germplasms and oat, and genetic linkage between crown rust resistance QTL and three lignin genes: LpOMT1, LpCAD2, and LpCCR1. The interspecific mapping population of 156 progeny was developed from a cross between two Italian × perennial ryegrass hybrids, MFA and MFB. Because highly susceptible reactions to crown rust were observed from all perennial ryegrass clones, including two grandparental clones and eight clones from different pedigrees tested in this study, two grandparent clones from Italian ryegrass cv. Floregon appeared to be a source of the resistance. Two QTL on linkage groups (LGs) 2 and 7 in the resistant parent MFA map were detected consistently regardless of year and location. The others, specific to year and location,

https://apsjournals.apsnet.org/doi/pdfplus/10.1094/PHYTO-97-6-0767

Mapping and Comparative Analysis of QTL for Crown Rust Resistance in an Italian x Perennial Ryegrass Population.

Popular Tasks used by Researchers

How can I help with your research?

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

We encountered an error while loading the panel. Please try refreshing the page.

Something went wrong

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

Anyone with the link can view this chat. You can switch it back to private anytime.

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

S. Sim

Author Tools

Chat about Author

Papers

Mapping and Comparative Analysis of QTL for Crown Rust Resistance in an Italian x Perennial Ryegrass Population.