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Gene expression in rice roots after Pythium arrhenomsnes infection versus mock infection

ABSTRACT: Next to their essential roles in plant growth and development, phytohormones play a central role in plant immunity against pathogens. In this study we examined the role of hormones in the antagonism of the plant-pathogenic oomycete Pythium arrhenomanes against the root-knot nematode Meloidogyne graminicola in rice roots. Hormone measurements and gene expression analyses showed that the jasmonate (JA) pathway is induced early upon P. arrhenomanes infection. Exogenous application of methyl-jasmonate (MeJA) on the plant confirmed that JA is needed for basal defence against both P. arrhenomanes and M. graminicola in rice. Whereas M. graminicola suppresses root JA levels to increase host susceptibility, Pythium inoculation boosts JA accumulation up to levels that can no longer be repressed by the nematode in double-inoculated plants. Exogenous MeJA supply phenocopied the defence-inducing capacity of P. arrhenomanes against the root-knot nematode, whereas the antagonism was weakened in JA-insensitive mutants. Transcriptome analysis confirmed upregulation of JA biosynthesis and signalling genes upon P. arrhenomanes infection, and additionally revealed induction of genes involved in biosynthesis of diterpenoid phytoalexins, consistent with strong activation of the gene encoding the JA-inducible transcriptional regulator DITERPENOID PHYTOALEXIN FACTOR. Next to that, our results provide evidence for induced expression of genes encoding ERF83, and related PR proteins, as well as auxin depletion in P. arrhenomanes infected rice roots, which potentially further contributes to the reduced nematode susceptibility seen in double-infected plants.

ORGANISM(S): Oryza sativa

PROVIDER: GSE133268 | GEO | 2019/10/21

REPOSITORIES: GEO

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Project description:Biotrophic plant pathogens have evolved sophisticated strategies to manipulate their host. They derive all of their nutrients from living plant tissues, by making intimate contact with their host while avoiding a resistance response. Rice is one of the most important crop plants worldwide and an excellent model system for studying monocotyledonous plants. Estimates of annual yield losses due to plant-parasitic nematodes on this crop range from 10 to 25% worldwide. One of the agronomically most important nematodes attacking rice is the rice root knot nematode Meloidogyne graminicola. Attack of plant roots by sedentary plant parasitic nematodes, like the root knot nematodes (RKN; Meloidogyne spp.) involves the development of specialized feeding cells in the vascular tissue. The second stage juvenile of the RKN punctures selected vascular cells with its stylet, injects pharyngeal secretions, and this ultimately leads to the reorganisation of these cells into typical feeding structures called giant cells (GCs), from which the nematode feeds for the remainder of its sedentary life cycle (Gheysen & Mitchum, 2011). Morphological and physiological reprogramming of the initial feeding cell leads to nucleus enlargement, proliferation of mitochondria and plastids, metabolic activation, cell cycle alterations and cell wall changes (Gheysen and Mitchum, 2011). The hyperplasia and hypertrophy of the surrounding cells leads to the formation of a root gall, which is typically formed at the root tips in the case of the rice RKN M. graminicola. In comparison with other RKN, M. graminicola has a very fast life cycle, with swelling of the root tips observed as early as 1 day after infection (dai). At 3 dai, terminal hook-like galls are clearly visible (Bridge et al., 2005). After 3 moults the nematodes are mature, around 10 dai. The M. graminicola females lay their eggs inside the galls, while most other RKN deposit egg masses at the gall surface, and hatched juveniles can reinfect the same or adjacent roots. In well-drained soil at 22-29 degrees C the life cycle of M. graminicola is completed in 19 days. 2 biological replicates of nematode infected giant cells and control vascular cells were sampled at two time points: 7 and 14 dai

Project description:Biotrophic plant pathogens have evolved sophisticated strategies to manipulate their host. They derive all of their nutrients from living plant tissues, by making intimate contact with their host while avoiding a resistance response. Rice is one of the most important crop plants worldwide and an excellent model system for studying monocotyledonous plants. Estimates of annual yield losses due to plant-parasitic nematodes on this crop range from 10 to 25% worldwide. One of the agronomically most important nematodes attacking rice is the rice root knot nematode Meloidogyne graminicola. Attack of plant roots by sedentary plant parasitic nematodes, like the root knot nematodes (RKN; Meloidogyne spp.) involves the development of specialized feeding cells in the vascular tissue. The second stage juvenile of the RKN punctures selected vascular cells with its stylet, injects pharyngeal secretions, and this ultimately leads to the reorganisation of these cells into typical feeding structures called giant cells (GCs), from which the nematode feeds for the remainder of its sedentary life cycle (Gheysen & Mitchum, 2011). Morphological and physiological reprogramming of the initial feeding cell leads to nucleus enlargement, proliferation of mitochondria and plastids, metabolic activation, cell cycle alterations and cell wall changes (Gheysen and Mitchum, 2011). The hyperplasia and hypertrophy of the surrounding cells leads to the formation of a root gall, which is typically formed at the root tips in the case of the rice RKN M. graminicola. In comparison with other RKN, M. graminicola has a very fast life cycle, with swelling of the root tips observed as early as 1 day after infection (dai). At 3 dai, terminal hook-like galls are clearly visible (Bridge et al., 2005). After 3 moults the nematodes are mature, around 10 dai. The M. graminicola females lay their eggs inside the galls, while most other RKN deposit egg masses at the gall surface, and hatched juveniles can reinfect the same or adjacent roots. In well-drained soil at 22-29ºC the life cycle of M. graminicola is completed in 19 days.

Project description:affy_meloidogyne_rice - affy_meloidogyne_rice - Plant-parasitic nematodes cause profound economic losses to global agriculture with the obligate sedentary endoparasitic varieties; amongst them the cyst and Root Knot Nematode (RKN) species are the most damaging. Meloidogyne graminicola is a RKN mainly found in the monocotyledous plants. In the compatible interaction with Oryza sativa, M. graminicola induces the characteristic formation of hook-like galls resulting from the redifferentiation of root cells into multinucleate giant cells. In order to understand the global transcriptome changes occurring during infection, several recent microarray studies on root knots have demonstrated complex changes in host plant gene expression in response to infection. However, to our knowledge, all these transcriptome studies were performed on dicotyledous plants. A histological study enabled us to observe hyperplasia and hypertrophy of the surrounding cells leading to the formation of hook-like galls. We also investigated the plant response to M. graminicola by carrying out a global analysis of gene expression during gall formation in rice, using giant cell-enriched root tissues at an early stage (2dpi) and a latter stage (4dpi) of gall development.-Oryza sativa (var. Nipponbare) seedlings were grown on 6 cm3 SAP substrate completed with diluted Hoaglands solution (Reversat et al., 1999). Culture units were placed in a growth chamber illuminated with fluorescent tubes 9/24 h and maintained at 23°C for 5 days before being inoculated with a 100 J2-stage juveniles M. graminicola. One day after inoculation (dai), the rice seedlings were immersed in de-ionised water to remove all J2s that had not penetrated the roots and allowing synchronization of the infection. Each seedling was transferred to a hydroponic mini chamber (Reversat et al., 2004). Sampling was performed at 2 and 4 dai and each of them contained galls from 70 infected plants, they were then hand-dissected, frozen in liquid-nitrogen and stored at -80°C. As reference samples, uninfected meristematic root fragments were dissected from seedlings grown under the same conditions. Each sample was replicated 3 times. Keywords: normal vs disease comparison,time course 9 arrays - rice

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Gene expression in rice roots after Pythium arrhenomsnes infection versus mock infection

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