Stomatal Penetration of Wheat Seedlings by Stem and Leaf Rust: Effect of Light and Carbon Dioxide

Yirgou, Dagnatchew; Caldwell, Ralph M.

doi:10.1126/science.141.3577.272

Cited by 29 publications

(21 citation statements)

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“…According to our histological analysis in Bd1-1 (Figure 4), the growth of Pg-tr , Pg-lo and Pg-pp in Brachypodium during the first 12 hpi (under dark, wet conditions) is comparable to that of Pg-tr in susceptible or resistant wheat cultivars [16]. Under comparable experimental conditions, the formation of substomatal vesicles and primary hyphae of Pg-lo and Pg-pp follow a time course similar to that reported in compatible and incompatible interactions between Pg-tr and wheat [16], [17], [18], [19] or barley [59], [60]. However, compared to Pg-tr in its natural hosts, Pg-lo and Pg-pp in Brachypodium display a delay in the formation of first haustoria (16 to 20 hpi in wheat and 18 hpi in barley vs. 32 hpi in Brachypodium ) [16], [60] and emergence of secondary infection hyphae (24 to 36 hpi in wheat and barley vs. 42 hpi in Brachypodium ) [16], [17], [60].…”

Section: Discussionsupporting

confidence: 72%

“…The formation of appressoria can be detected at 6 hpi [17] and maximum appressorium development is reached by 12 hpi [16]. Subsequent to appressorium formation, light and photosynthesis-associated O 2 reduction stimulate the growth of a penetration peg and a substomatal vesicle in the mesophyll space [18]. Substomatal vesicles form within 1.5 h after light exposure [19] and a primary infection hypha emerges from the vesicle, and eventually differentiates a haustorial mother cell.…”

Section: Introductionmentioning

confidence: 99%

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Infection of Brachypodium distachyon by Formae Speciales of Puccinia graminis: Early Infection Events and Host-Pathogen Incompatibility

et al. 2013

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Puccinia graminis causes stem rust, a serious disease of cereals and forage grasses. Important formae speciales of P. graminis and their typical hosts are P. graminis f. sp. tritici (Pg-tr) in wheat and barley, P. graminis f. sp. lolii (Pg-lo) in perennial ryegrass and tall fescue, and P. graminis f. sp. phlei-pratensis (Pg-pp) in timothy grass. Brachypodium distachyon is an emerging genetic model to study fungal disease resistance in cereals and temperate grasses. We characterized the P. graminis-Brachypodium pathosystem to evaluate its potential for investigating incompatibility and non-host resistance to P. graminis. Inoculation of eight Brachypodium inbred lines with Pg-tr, Pg-lo or Pg-pp resulted in sporulating lesions later accompanied by necrosis. Histological analysis of early infection events in one Brachypodium inbred line (Bd1-1) indicated that Pg-lo and Pg-pp were markedly more efficient than Pg-tr at establishing a biotrophic interaction. Formation of appressoria was completed (60–70% of germinated spores) by 12 h post-inoculation (hpi) under dark and wet conditions, and after 4 h of subsequent light exposure fungal penetration structures (penetration peg, substomatal vesicle and primary infection hyphae) had developed. Brachypodium Bd1-1 exhibited pre-haustorial resistance to Pg-tr, i.e. infection usually stopped at appressorial formation. By 68 hpi, only 0.3% and 0.7% of the Pg-tr urediniospores developed haustoria and colonies, respectively. In contrast, development of advanced infection structures by Pg-lo and Pg-pp was significantly more common; however, Brachypodium displayed post-haustorial resistance to these isolates. By 68 hpi the percentage of urediniospores that only develop a haustorium mother cell or haustorium in Pg-lo and Pg-pp reached 8% and 5%, respectively. The formation of colonies reached 14% and 13%, respectively. We conclude that Brachypodium is an apt grass model to study the molecular and genetic components of incompatiblity and non-host resistance to P. graminis.

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Section: Discussionsupporting

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Infection of Brachypodium distachyon by Formae Speciales of Puccinia graminis: Early Infection Events and Host-Pathogen Incompatibility

et al. 2013

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“…Uredinial infection was later found to follow the ecological distribution and the rapid global expansion of perennial ryegrass cultivation (Potter et al, 1990). Following contact with a stoma, a germ-tube ceases to elongate and forms an appressorium over the stoma (Yirgou and Caldwell, 1968). In contrast to cereal leaves, ryegrass leaves have few stomata on the abaxial surface, dramatically reducing the incidence of infection.…”

Section: Biology Of the Crown Rust Pathogen Of Ryegrasses First Obsermentioning

confidence: 99%

Biology and Genetics of Crown Rust Disease in Ryegrasses

et al. 2010

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The most serious foliar disease of perennial ryegrass (Lolium perenne L.) is crown rust (caused by Puccinia coronata Corda f.sp. lolii Brown). Progress in resistance breeding using recurrent selection has been slow, due to lack of genetic knowledge. Puccinia coronata is a basidiomycete fungus with a complex life‐cycle involving both asexual and sexual reproductive modes. Pathotype variation may exist, but confirmation is complicated by the outbreeding nature of the host grass and consequent intrapopulation diversity. Qualitative and quantitative resistance mechanisms may hence be due to either major resistance genes responding to mixed pathogen populations, or minor (quantitative) resistance genes. Advances in molecular biology have permitted analysis of both host and pathogen genetics. Development of pathogen‐derived simple sequence repeat (SSR) genetic markers allowed detailed analysis of genetic variation, as well as generation of homogenized inoculum for detailed trait‐dissection studies. Multiple genomic regions were identified as containing quantitative trait loci (QTLs) for pathogen resistance, and specific single nucleotide polymorphism (SNP) markers for defense response (DR) and disease resistance (R) genes have been evaluated for QTL co‐location. The current knowledge status of the crown rust pathogen and genetics of host resistance is reviewed, as well as future prospects for facilitated rust resistance breeding.

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“…This resumption of development probably depends only indirectly on light through its stimulation of photosynthesis and reduction of CO 2 concentration at stomata in the host plant. Yirgou and Caldwell (1968) showed that penetration of the host by P. graminis is inhibited by CO 2 but will occur nearly equally well in light or dark in CO 2 ‐free air. Penetration by appressoria of P. graminis did not occur on non‐photosynthetic albino wheat plants or etiolated plants in 1% ambient CO 2 .…”

Section: Infection Processmentioning

confidence: 99%

Stem rust of small grains and grasses caused by Puccinia graminis

Leonard

Szabo

2005

Molecular Plant Pathology

283

197

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The host range of P. graminis is very broad compared with that of most Puccinia spp.; it includes at least 365 species of cereals and grasses in 54 genera [Anikster (1984) The Cereal Rusts. Orlando, FL: Academic Press, pp. 115-130]. Wheat stem rust, P. graminis f. sp. tritici, was shown to infect 74 species in 34 genera in artificial inoculations of seedlings, but only 28 of those species belonging to eight genera were known to be natural hosts of the fungus. Other formae speciales of P. graminis have narrower host ranges than P. graminis f. sp. tritici. Disease symptoms: Infections in cereals or grasses occur mainly on stems and leaf sheaths, but occasionally they may be found on leaf blades and glumes as well. The first macroscopic symptom is usually a small chlorotic fleck, which appears a few days after infection. About 8-10 days after infection, a pustule several millimetres long and a few millimetres wide is formed by rupture of the host epidermis from pressure of a mass of brick-red urediniospores produced in the infection. These uredinial pustules are generally linear or diamond shaped and may enlarge up to 10 mm long. The powdery masses of urediniospores appear similar to rust spots on a weathered iron surface. With age, the infection ceases production of brick-red urediniospores and produces a layer of black teliospores in their place, causing the stems of heavily infected plants to appear blackened late in the season.

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Stomatal Penetration of Wheat Seedlings by Stem and Leaf Rust: Effect of Light and Carbon Dioxide

Cited by 29 publications

References 0 publications

Infection of Brachypodium distachyon by Formae Speciales of Puccinia graminis: Early Infection Events and Host-Pathogen Incompatibility

Infection of Brachypodium distachyon by Formae Speciales of Puccinia graminis: Early Infection Events and Host-Pathogen Incompatibility

Biology and Genetics of Crown Rust Disease in Ryegrasses

Stem rust of small grains and grasses caused by Puccinia graminis

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