Infection processes of Sclerospora graminicola on Pennisetum glaucum lines resistant and susceptible to downy mildew

Sharada, M. S.; Shetty, Sudheer A.; Shetty, H. Shekar

doi:10.1016/s0953-7562(09)80905-2

Cited by 19 publications

(10 citation statements)

References 8 publications

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“…If such pathogenic microorganisms are disseminated throughout the plant, then it would be misleading to expect that defenses are only induced at the site of entry. For instance, the fungal pathogen Sclerospora graminicola infects root tissue, but most of the pathogen is subsequently localized in the shoot region (Sharada et al 1995). Therefore, when assessing optimal defenses of plants to herbivory, one must consider the possibility that the response measured may not necessarily be elicited by the herbivore.…”

Section: Herbivore-induced Plant Defenses In Foliar Vs Root Tissuesmentioning

confidence: 99%

Constitutive and Induced Defenses to Herbivory in Above- And Belowground Plant Tissues

Kaplan

Halitschke

Kessler

et al. 2008

Ecology

256

237

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A recent surge in attention devoted to the ecology of soil biota has prompted interest in quantifying similarities and differences between interactions occurring in above- and belowground communities. Furthermore, linkages that interconnect the dynamics of these two spatially distinct ecosystems are increasingly documented. We use a similar approach in the context of understanding plant defenses to herbivory, including how they are allocated between leaves and roots (constitutive defenses), and potential cross-system linkages (induced defenses). To explore these issues we utilized three different empirical approaches. First, we manipulated foliar and root herbivory on tobacco (Nicotiana tabacum) and measured changes in the secondary chemistry of above- and belowground tissues. Second, we reviewed published studies that compared levels of secondary chemistry between leaves and roots to determine how plants distribute putative defense chemicals across the above- and belowground systems. Last, we used meta-analysis to quantify the impact of induced responses across plant tissue types. In the tobacco system, leaf-chewing insects strongly induced higher levels of secondary metabolites in leaves but had no impact on root chemistry. Nematode root herbivores, however, elicited changes in both leaves and roots. Virtually all secondary chemicals measured were elevated in nematode-induced galls, whereas the impact of root herbivory on foliar chemistry was highly variable and depended on where chemicals were produced within the plant. Importantly, nematodes interfered with aboveground metabolites that have biosynthetic sites located in roots (e.g., nicotine) but had the opposite effect (i.e., nematodes elevated foliar expression) on chemicals produced in shoots (e.g., phenolics and terpenoids). Results from our literature review suggest that, overall, constitutive defense levels are extremely similar when comparing leaves with roots, although certain chemical classes (e.g., alkaloids, glucosinolates) are differentially allocated between above- and belowground parts. Based on a meta-analysis of induced defense studies we conclude that: (1) foliar induction generates strong responses in leaves, but much weaker responses in roots, and (2) root induction elicits responses of equal magnitude in both leaves and roots. We discuss the importance of this asymmetry and the paradox of cross-system induction in relation to optimal defense theory and interactions between above- and belowground herbivory.

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Section: Herbivore-induced Plant Defenses In Foliar Vs Root Tissuesmentioning

confidence: 99%

Constitutive and Induced Defenses to Herbivory in Above- And Belowground Plant Tissues

Kaplan

Halitschke

Kessler

et al. 2008

Ecology

256

237

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“…The investigation on nature of disease control mechanisms has indicated that it is due to induction of systemic resistance [40]. Although pearl millet roots and coleoptiles regions are easily available for S. graminicola infection, majority of the pathogenic microbes are inhabitants of mesocotyl and shoot regions in seedling stage [41]. In northern analysis, detectable RGPM 213 transcript signals were not observed in root region and hence coleoptile region was selected for immnolocalization studies.…”

Section: Discussionmentioning

confidence: 99%

Chitosan and ß-amino butyric acid up-regulates transcripts of resistance gene analog RGPM213 in pearl millet to infection by downy mildew pathogen

2016

J App Biol Biotech

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Plants are hosts to a diverse group of pathogens belonging to different kingdoms of life. In absence of active immune system, plants have evolved several layers of defense to combat individual pathogen strain and evolving pathogen populations. Management of various plant pathogen infections necessitates the use of multiple resistance (R) genes, which requires efficient and accurate practices for identification, isolation and characterization of R genes. This knowledge helps to probe R gene(s) in a host plant and sort out their functional redundancy and specificity. Pearl millet [Pennisetum glaucum (L.) R. Br.] is highly nutritive, summer-annual forage crop, drought tolerant cereal, staple food crop of the semi-arid tropics but is highly susceptible to the downy mildew disease caused by oomycetous Sclerospora graminicola (Sacc.) schroet. Earlier studies have identified several resistance gene analogues (RGAs) in pearl millet which may be involved in resistance against downy mildew. Of these, a clone RGPM213 was shown to encode resistant protein having serine threonine kinase domain and its transcript was upregulated following S. graminicola infection and β-amino butyric acid an abiotic inducer treatment. Here we have shown the accumulation of transcripts of RGPM 213 in pearl millet during treatment with Chitosan, a chitin derivative, a known inducer of plant defense which is completely safe, characterized by unique properties, like bioactivity and biocompatibility.

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“…One reaction of the plant to the formation of haustoria (which must, in any case, include a large number of complex biochemical responses) is the formation of a callose collar or ring round the entry point of the haustorium (Figure 4), which remains as a callose papilla if haustorial penetration fails (Sharada et al, 1995). Perhaps not surprisingly, electron microscopic studies have shown that changes occur in plastid size and structure, the plasma membrane, cell wall, mitochondria, ribosomes and polyribosomal density following haustorial penetration both within infected and in adjacent uninfected cells.…”

Section: Physiology and Biochemistrymentioning

confidence: 99%

The Compatible Interaction in Downy Mildew Infections

Spencer‐Phillips

2004

Advances in Downy Mildew Research — Volume 2

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Infection processes of Sclerospora graminicola on Pennisetum glaucum lines resistant and susceptible to downy mildew

Cited by 19 publications

References 8 publications

Constitutive and Induced Defenses to Herbivory in Above- And Belowground Plant Tissues

Constitutive and Induced Defenses to Herbivory in Above- And Belowground Plant Tissues

Chitosan and ß-amino butyric acid up-regulates transcripts of resistance gene analog RGPM213 in pearl millet to infection by downy mildew pathogen

The Compatible Interaction in Downy Mildew Infections

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