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Hyaloperonospora parasitica is an oomycete from the family Peronosporaceae.[1] It has been considered for a long time to cause downy mildew of a variety of species within the Brassicaceae, on which the disease can cause economically important damage by killing seedlings or affecting the quality of produce intended for freezing.[2] Hyaloperonospora parasitica[3] causes downy mildew on a wide range of many different plants. It belongs to the Kingdom Chromista, the phylum Oomycota, and the family Peronosporaceae. The former name for H. parasitica was Peronospora parasitica until it was reclassified and put in the genus Hyaloperonospora. It is an especially vicious disease on crops of the family Brassicaceae. It is most famous for being a model pathogen of Arabidopsis thaliana which is a model organism used for experimental purposes.[4][5][6] Accordingly, the former Hyaloperonospora parasitica has been split into a large number of species. For instance, the taxonomically correct name of the parasite of the well-known model organism Arabidopsis thaliana is Hyaloperonospora arabidopsidis, not H. parasitica, whereas the pathogen of Brassica has to be called Hyaloperonospora brassicae.[7][8]
The infection first appears as conidiophores covering the upper and lower leaf surfaces.[4] Other symptoms include lesions on spikelet, fungal growth on leaves, and necrosis on stems and leaves. Hyaloperonospora Parasitica has a very wide host range. It can infect garlic mustard, horseradish, cruciferous vegetables, Shepherd's purse, Cheiranthus spp., Cucurbits, purple vein rocket, treacle mustard, wallflower, spurges, candytuft, mustard plants, radish, and sweet alyssum.[3] Although it is not significantly damaging on any one specific plant, the damage of H. parasitica can cause major economic losses if not managed properly. The recommendation for management is weekly fungicide application.[9]
This is a polycyclic pathogen with a sexual and an asexual stage. It thrives in cool moist environments. Over winter in the soil, oospores survive and wait for spring.[4] In warmer conditions when it gets to about 47–53 degrees F the oospores will germinate and produce an appressorium or form a short germ tube. The mycelium grows intracellularly and haustoria penetrate through the host cells when the temperature is around 60 degrees F. After about 1–2 weeks when the temperature is between 60 and 64 degrees F, conidiophores (the asexual stage) will form out of the plant stomata bearing conidia. Sporulation occurs at night. The conidia disseminate in high humidity mornings when it's about 50–60 degrees.[4] Meanwhile, during the sexual stage, the antheridia (the male sex organ) fertilizes the oogonium (the female sex organ) with a fertilization tube and an oospore is developed.[4]
Hyaloperonospora parasitica is an obligate biotroph, meaning it lives off a host obtaining nutrients.[3] The pathogen infects about six hours after landing on a plant surface.[4] The spores produce an appressorium which in turn produces a penetration peg. This hypha grows from bottom of the appressorium and works its way through an intercellular junction of two epidermal cells. As the penetration peg grows between cells, haustoria grow into the cells to gain nutrients.[4] The oomycete grows until it has penetrated through the entire leaf where conidiophores are then grown out of the stomata and disseminated by wind and rain.
Synonyms:[10]
Hyaloperonospora parasitica is an oomycete from the family Peronosporaceae. It has been considered for a long time to cause downy mildew of a variety of species within the Brassicaceae, on which the disease can cause economically important damage by killing seedlings or affecting the quality of produce intended for freezing. Hyaloperonospora parasitica causes downy mildew on a wide range of many different plants. It belongs to the Kingdom Chromista, the phylum Oomycota, and the family Peronosporaceae. The former name for H. parasitica was Peronospora parasitica until it was reclassified and put in the genus Hyaloperonospora. It is an especially vicious disease on crops of the family Brassicaceae. It is most famous for being a model pathogen of Arabidopsis thaliana which is a model organism used for experimental purposes. Accordingly, the former Hyaloperonospora parasitica has been split into a large number of species. For instance, the taxonomically correct name of the parasite of the well-known model organism Arabidopsis thaliana is Hyaloperonospora arabidopsidis, not H. parasitica, whereas the pathogen of Brassica has to be called Hyaloperonospora brassicae.
Hyaloperonospora parasitica est une espèce d'oomycète phytopathogène de la famille des Peronosporaceae. C'est l'un des agents pathogènes du mildiou. Il a pour hôtes les crucifères telles que le chou et Arabidopsis thaliana. À l'heure actuelle, c'est un organisme à hôte obligatoire, c'est-à-dire qu'on ne parvient pas à le cultiver sur milieu de culture artificiel.
En agriculture, il génère des pertes non négligeables sur les récoltes de colza, du chou et autres brassicacées.
Il est utilisé dans le monde de la recherche en phytopathologie, car son développement est ni trop rapide ni trop lent (de l'ordre d'une semaine de conidiospore à conidiospore), et ses effets ne sont en général pas létaux pour la plante. Ainsi, il permet une mesure fine des degrés de résistance de la plante hôte en fonction des traitements appliqués[1].
Selon NCBI (28 août 2014)[2] :
Hyaloperonospora parasitica est une espèce d'oomycète phytopathogène de la famille des Peronosporaceae. C'est l'un des agents pathogènes du mildiou. Il a pour hôtes les crucifères telles que le chou et Arabidopsis thaliana. À l'heure actuelle, c'est un organisme à hôte obligatoire, c'est-à-dire qu'on ne parvient pas à le cultiver sur milieu de culture artificiel.
Hyaloperonospora parasitica (Pers.) Constant. – gatunek grzybopodobnych lęgniowców z rodziny wroślikowatych[1]. Grzyb mikroskopijny, pasożyt roślin z rodziny kapustowatych (Brassicaceae) i czystkowatych (Cistaceae). Wywołuje u nich chorobę zwaną mączniakiem rzekomym[2].
Pozycja w klasyfikacji według Index Fungorum: Hyaloperonospora, Peronosporaceae, Peronosporales, Peronosporidae, Peronosporea, Incertae sedis, Oomycota, Chromista[1].
Po raz pierwszy zdiagnozował go w 1796 r. Christiaan Hendrik Persoon nadając mu nazwę Botrytis parasitica. Obecną, uznaną przez Index Fungorum nazwę nadał mu Ovidiu Constantinescu w 2002 r.[1] Jest gatunkiem typowym rodzaju Hyaloperonospora[2].
Ma ponad 30 synonimów, w tym 27 to wyróżnione dawniej formy, odmiany i podgatunki. Pozostałe to[3]:
Dawniej był uważany za sprawcę choroby zwanej mączniakiem rzekomym kapustowatych. Obecnie jednak takson ten rozbito na kilka innych i za sprawcę tej choroby uważa się utworzony w 2003 r. gatunek Hyaloperonospora brassicae[4].
Endobiont, rozwijający się wewnątrz tkanek roślin. Tworzy pomiędzy ich komórkami hialinowe, bezprzegrodowe strzępki, z których wyrastają duże, płatowate ssawki wnikające do komórek[2], oraz dichtonomicznie rozgałęzione sporangiofory, na których powstają zarodniki sporangialne. Sporangiospory te wraz z powstającymi na nich zarodnikami tworzą na dolnej stronie liści porażonych roślin biały nalot. Zarodniki mają wymiary 22– 27 × 12– 22 μm. W obumarłych, porażonych częściach roślin tworzy żółtobrunatne, kuliste oospory o średnicy 26– 45 μm. Oospory te są źródłem infekcji pierwotnej. Infekują rośliny poprzez korzenie. W sezonie wegetacyjnym natomiast wytwarzane na nadziemnych częściach roślin zarodniki sporangialne dokonują infekcji wtórnych rozprzestrzeniając chorobę. Roznoszone są przez wiatr[5].
Poza Antarktydą występuje na wszystkich kontynentach i na niektórych wyspach (m.in. na Nowej Zelandii, Haiti, Tahiti)[6].
Głównym żywicielem jest tasznik pospolity (Capsella bursa-pastoris), ale patogen ten pasożytuje także na wielu innych rodzajach roślin kapustowatych, m.in. na pieprzyczniku (Cardaria), pieprzycy (Lepidium), rezedzie (Reseda), tobołkach (Thlaspi), a także niektórych gatunkach z rodziny czystkowatych.
Hyaloperonospora parasitica (Pers.) Constant. – gatunek grzybopodobnych lęgniowców z rodziny wroślikowatych. Grzyb mikroskopijny, pasożyt roślin z rodziny kapustowatych (Brassicaceae) i czystkowatych (Cistaceae). Wywołuje u nich chorobę zwaną mączniakiem rzekomym.
Hyaloperonospora parasitica é uma espécie da família Peronosporaceae. É desde há muito considerada a causadora do míldio penugento numa variedade de espécies da família Brassicaceae, como a colza e a couve-flor, nas quais a doença pode provocar danos economicamente importantes, matando as plântulas ou afectando a qualidade de plantas destinadas a congelação.[1] Contudo, pesquisas filogenéticas recentes mostraram que Hyaloperonospora parasitica restringe-se a Capsella bursa-pastoris como hospedeiro vegetal. Na verdade, em regra as espécies de Hyaloperonospora são genética e biologicamente bastante distantes entre si. Cada espécie de Hyaloperonospora é altamente especializada e parasita apenas alguns poucos hospedeiros, ou até mesmo apenas um.[2][3] Assim, a antiga Hyaloperonospora parasitica foi dividida num grande número de espécies. Por exemplo, o nome taxonomicamente correcto do parasita do bem conhecido organismo modelo Arabidopsis thaliana é Hyaloperonospora arabidopsidis, e não H. parasitica, enquanto que o patógeno de Brassica chama-se Hyaloperonospora brassicae.[4][5]
Sinónimos[6]:
Hyaloperonospora parasitica é uma espécie da família Peronosporaceae. É desde há muito considerada a causadora do míldio penugento numa variedade de espécies da família Brassicaceae, como a colza e a couve-flor, nas quais a doença pode provocar danos economicamente importantes, matando as plântulas ou afectando a qualidade de plantas destinadas a congelação. Contudo, pesquisas filogenéticas recentes mostraram que Hyaloperonospora parasitica restringe-se a Capsella bursa-pastoris como hospedeiro vegetal. Na verdade, em regra as espécies de Hyaloperonospora são genética e biologicamente bastante distantes entre si. Cada espécie de Hyaloperonospora é altamente especializada e parasita apenas alguns poucos hospedeiros, ou até mesmo apenas um. Assim, a antiga Hyaloperonospora parasitica foi dividida num grande número de espécies. Por exemplo, o nome taxonomicamente correcto do parasita do bem conhecido organismo modelo Arabidopsis thaliana é Hyaloperonospora arabidopsidis, e não H. parasitica, enquanto que o patógeno de Brassica chama-se Hyaloperonospora brassicae.
Sinónimos:
Botrytis parasitica Pers., 1796 ...