Wikipedia

Peronospora

Peronosporais a genus ofoomycetesthat are obligate plant pathogens of manyeudicots.[1]Most species in this group produce a downy mildew disease, which can cause severe damage to many different cultivated crops, as well as wild and ornamental plants.[2]There are 19 genera that produce downy mildew, andPeronosporahas been placed alongsidePseudoperonosporain the group ofdowny mildewswith colouredconidia.[3]Peronosporahas far more species than any other genus of the downy mildews.[3]However, many species have been moved from this genus to be reclassified to other or new genera.[4]Among these was the most famousPeronosporaspecies, formerly known asPeronospora parasitica,and now known asHyaloperonospora parasitica.[4]Now, thePeronosporaspecies of most importance is likely thePeronospora tabacina.[5]Peronospora tabacinacauses blue mold on tobacco plants and can severely reduce yields of this economically important crop to the point where it has been classified as a bioweapon.[5][3]

Peronospora
P. manshuricaon soybean leaf
Scientific classificationEdit this classification
Domain: Eukaryota
Clade: Diaphoretickes
Clade: SAR
Clade: Stramenopiles
Phylum: Oomycota
Order: Peronosporales
Family: Peronosporaceae
Genus: Peronospora
Corda

History

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Peronosporawas first described in 1837 by August Carl Joseph Corda, a Czech mycologist and physician, in his first of six volumes of hisIcones fungorum hucusque cognitorum.[6]Since then, many of the species originally placed inPeronosporahave been allocated to other genera or given rise to new genera based on new techniques such as molecular genetics.[4]

There was an epidemic in 1960 ofPeronospora tabacinaaffecting tobacco plants leading to $25 million in losses across eleven countries, which was about 30 percent of the tobacco plants.[5]Another epidemic that was caused byPeronospora destructorreduced the yield of sweet onions by 25 percent in Georgia, USA in 2012, and led to an estimated $18.2 million in losses.[7]

Habitat and ecology

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Most of thePeronosporaspecies are highly specific to their hosts and can generally be found anywhere the host plant grows, or is being cultivated.[3]A large portion of their life cycle is spent inside their host plant. Many species ofPeronosporaare seedborne pathogens, so the worldwide spread ofPeronosporacrop-plant pathogens is likely to be a result of unknowingly trading infected seeds to new areas.[3]There are also manyPeronosporaspecies that are spread by wind currents, which allows them to disperse over large distances.[3]Peronosporaspecies prefer humid air and cool temperatures.[5]

General form and structure

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The first stage in thePeronosporalife history is the sporangia.[5]The sporangia are small spore-like structures about 65 um long that germinate a germ-tube when they are near a leaf stoma.[8][5]A germ tube will come from the sporangium and penetrate the leaf cell where it will form a haustorium.[5]The haustorium absorbs nutrients from the leaf, while hyphae invade the intercellular space, and the leaf will eventually develop a lesion.[5]These lesions often start out yellow and then turn brown as the leaf starts to undergo necrosis.[5]From here,Peronosporacan undergo either asexual reproduction or sexual reproduction.[5]Asexual reproduction occurs when the air outside is moist making for favourable conditions.[5]During asexual reproduction, hyphae on the host plant will form sporangiophores, which will produce conidia.[5]The conidia will be dispersed by the wind is able to infect other plants.[5]The asexual cycle only takes five to seven days to complete.[5]Sexual reproduction occurs when the conditions are unfavourable and it needs to withstand harsh environmental conditions.[5]During sexual reproduction, the hyphae will undergo meiosis forming antheridia and oogonia, the only haploid structures in thePeronosporalife history.[5]The antheridia will fuse to the oogonia, initiating plasmogamy and then karyogamy, and will result in the production of many oospores.[5]The oospores can then be dispersed by the wind to infect more plants.[5]

BothPeronosporaandPseudoperonosporaare characterized by their ability to produce melanized sporangia, butPseudoperonosporaproduces zoospores whereasPeronosporacannot.[3]

Practical importance

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The model oomycete pathogen,Peronospora parasitica,used to be included in this genus, however it has been reclassified to the genusHyaloperonospora.[3]

Some species ofPeronosporahave been considered for their use as a bioweapon or have been classified as potential bioweapons.[3]Peronspora somniferiwas considered for its ability to devastate fields of the opium poppy, which could have targeted areas that depend on the crop.[3]The United States has classifiedPeronospora tabacinaas a possible bioweapon, because if it were used to target the US tobacco industry, it would lead to major economic loss.[3]

Genomics and genetics

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Only one species in the genusPeronosporahas had its genome sequenced and assembled. In 2015, Derevnina et al. performed ade novosequence assembly of the genome of twoPeronospora tabacinaisolates using Illumina sequencing.[9]They estimated the genome size to be 68 Mb with a mitochondrial genome of 43 kb.[9]The two assemblies had 61.8x and 128.9x coverage for the nuclear genomes and 6,824x and 43,225x coverage for the mitochondrial genomes.[9]The mitochondrial genome only differed by seven single nucleotide polymorphisms, three small indels, and one copy number variant.[9]Using a program to predict gene models, they found 18,000 potential protein coding genes.[9]

List of species

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The following species are placed in genusPeronospora:[10]

References

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  1. ^Göker, M., García-Blázquez, G., Voglmayr, H., Tellería, M. T., & Martín, M. P. (2009)."Molecular taxonomy of phytopathogenic fungi: a case study inPeronospora".PLOS ONE.4(7): e6319.Bibcode:2009PLoSO...4.6319G.doi:10.1371/journal.pone.0006319.PMC2712678.PMID19641601.{{cite journal}}:CS1 maint: multiple names: authors list (link)
  2. ^Lee, J. S., Shin, H. D., Lee, H. B., & Choi, Y. J. (2017)."Taxonomy and Phylogeny ofPeronosporaSpecies (Oomycota) Parasitic toStellariaandPseudostellariain Korea, with the Introduction ofPeronospora casparyisp. nov ".Mycobiology.45(4):263–269.doi:10.5941/MYCO.2017.45.4.263.PMC5780358.PMID29371794.{{cite journal}}:CS1 maint: multiple names: authors list (link)
  3. ^abcdefghijkThines, M., & Choi, Y. J. (2015)."Evolution, diversity, and taxonomy of the Peronosporaceae, with focus on the genusPeronospora".Phytopathology.106(1):6–18.doi:10.1094/PHYTO-05-15-0127-RVW.PMID26649784.{{cite journal}}:CS1 maint: multiple names: authors list (link)
  4. ^abcGöker, M., Voglmayr, H., Riethmüller, A., Weiß, M., & Oberwinkler, F. (2003). "Taxonomic aspects of Peronosporaceae inferred from Bayesian molecular phylogenetics".Canadian Journal of Botany.81(7):672–683.doi:10.1139/b03-066.{{cite journal}}:CS1 maint: multiple names: authors list (link)
  5. ^abcdefghijklmnopqrKrsteska, V., Dimeska, V., Stojkov, S., & Stojanoski, P. (2015)."Peronospora tabacinaA. the causing agent of Blue Mold disease on tobacco ".Bulgarian Journal of Agricultural Science.21:132–139.{{cite journal}}:CS1 maint: multiple names: authors list (link)
  6. ^Corda, A. C. J. (1837).Icones fungorum hucusque cognitorum, vol. 1.
  7. ^Parkunan, V., Gitaitis, R. D., Dutta, B., Langston, D. B., & Ji, P. (2013)."An Epidemic of Downy Mildew caused byPeronospora destructoron Vidalia Sweet Onions in Georgia in 2012 ".Plant Health Progress.14:54.doi:10.1094/PHP-2013-0328-01-BR.{{cite journal}}:CS1 maint: multiple names: authors list (link)
  8. ^Langston Jr, D. B., & Sumner, D. R. (2000)."First report of downy mildew (caused byPeronospora destructor) of onion in Georgia ".Plant Disease.84(4): 489.doi:10.1094/PDIS.2000.84.4.489B.PMID30841183.{{cite journal}}:CS1 maint: multiple names: authors list (link)
  9. ^abcdeDerevnina, L., Chin-Wo-Reyes, S., Martin, F., Wood, K., Froenicke, L., Spring, O., & Michelmore, R. (2015)."Genome sequence and architecture of the tobacco downy mildew pathogenPeronospora tabacina".Molecular Plant-Microbe Interactions.28(11):1198–1215.doi:10.1094/MPMI-05-15-0112-R.PMID26196322.{{cite journal}}:CS1 maint: multiple names: authors list (link)
  10. ^"Taxonomy Browser:Peronospora".NCBI taxonomy database.Retrieved7 September2023.
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