Phytophthora

Phytophthora de Bary, J. Roy. Agric. Soc. England, ser. 2 12: 240 (1876)

Background

Phytophthora is classified in the kingdom Straminipila within the diploid, alga-like Oomycetes in the Stramenopile clade of the Kingdom Chromista (Cavalier-Smith 1986; Dick 1995; Yoon et al. 2002; Wijayawardene et al. 2020). Phytophthora consists of about 130 described species with many important plant pathogens. The Oomycota are biologically different from main fungal groups within the Kingdom Fungi (Corliss 1994; Cavalier-Smith 1998). For example, their cell walls are made primarily of cellulose instead of chitin as in most fungi and they cannot synthesize β-hydroxysterols, which is vital for synthesizing hormones that regulate sexual reproduction (Hyde et al. 2014). Another important difference is that oomycetes are diploid throughout their life cycle. One similarity between Phytophthora species and Eumycotan fungi is that they both produce hyphae.

Classification – Oomycota, Peronosporales, Peronosporacae

Type speciesPhytophthora infestans (Mont.) de Bary

Distribution – worldwide

Disease symptoms – blight, canker, dieback, root rots and wilt

Species can have a large impact on agriculture (e.g. Phytophthora infestans, potato late blight), arbiculture (e.g. Phytophthora ramorum, sudden oak death) and whole ecosystems (e.g. Phytophthora cinnamomi in Australia). Phytophthora species damage plants by killing the tissues and resulting necrosis can be seen in leaves, stems or roots. Some species can cause multiple symptoms on a single host, or cause different symptoms on different hosts (Jung and Blaschke 1996).

Blight: Initial symptom is the development of a “water-soaked” appearance, which progresses into brown or black irregular-shaped spots or wedge-shaped lesions. These lesions are usually not surrounded by a yellow halo (Babadoost 2004; Pande et al. 2011; Ali et al. 2017).

Canker: A dark discoloured necrotic lesion in the inner bark of a tree can be seen often on the stem or branches. However, generally, cankers are visible once the outer bark is removed. Cankers are often seen with a reddish-brown liquid that oozes through the bark (Davidson et al. 2002; Jung et al. 2018). 

Dieback: Death of shoot tips, twigs and branch tips can be observed. The infection progresses towards the main stem accompanied by a loss of foliage (Kuske and Benson 1983; Akilli et al. 2013).

Decline and Death: This is a gradual process that will take place over several years. Plants fail to grow and the canopy becomes thin due to loss of foliage. Then the whole canopy or sections of the canopy may die (Marais 1980; Belisario et al. 2004; González et al. 2020).

Rot: Dark discoloured rotten tissues that are common on roots, but sometimes extend above the soil surface. However, collar rot occurs at the base of the trunk and extends just below the soil line (Jung and Blaschke 1996; Graham et al. 2011; Summerell and Liew 2020).

Wilting: This is the first above-ground symptom of root rot. Foliage becomes flaccid due to lack of water intake (Vettraino et al. 2009; Xiong et al. 2019).

Phytophthora causes disease in important agricultural and ecological plants. Phytophthora infestans was responsible for the Irish potato famine from 1845 to 1852, causing the death of over 1 million people. Phytophthora ramorum has resulted in the death of millions of coast live oak, tanoak and Japanese larch trees, thus altering the forest ecosystems in California and Oregon, USA (Goheen et al. 2002; Rizzo et al. 2002, 2005).

Hosts Phytophthora agathidicida (commonly known as kauri dieback), which causes kauri death, is considered as one of the world’s most feared fungi (Hyde et al. 2018a). An extensive survey in previously unexplored ecosystems such as natural forests (Rea et al. 2010; Vettraino et al. 2011; Jung et al. 2011, 2017; Reeser et al. 2013), streams (Reeser et al. 2007; Bezuidenhout et al. 2010; Yang et al. 2016; Brazee et al. 2017), riparian ecosystems (Brasier et al. 2003, 2004; Hansen et al. 2012), and irrigation systems (Hong et al. 2010, 2012; Yang et al. 2014a, b) has led an exponential increase in the number of species.

Pathogen biology, disease cycle and epidemiology

Fig. 1 Disease cycle of Phytophthora infestans (redrawn from Bengtsson 2013)

Morphological based identification and diversity

             Species-level classification is based on the morphological characterization of reproductive structures including the sporangium (asexual) and oospore (sexual) as well as the production of chlamydospores (Martin et al. 2012). Characteristics that are important for species classification include the diameter of the oogonium and oospore, thickness of the oospore wall, whether or not the oospore fills the oogonium, ornamentation on the oogonial wall, and mode of attachment of the antheridium (Hyde et al. 2014). Identification and classification of Phytophthora species into morphological groups based on several characteristics was initially based on the key provided by Waterhouse (1963), which was later updated by Stamps et al. (1990).

Molecular based identification and diversity

             Phytophthora has been historically placed in the Pythiales with Pythium and related genera, however recent phylogenetic analysis with the large (LSU) or small (SSU) rDNA sequences or cox2 gene has indicated a closer relationship with downy mildew and white rusts (Albugo.) in the Peronosporales (Beakes and Sekimoto 2009; Thines et al. 2009). Additional multigene analyses are vital to clarify the relationship between the Peronosporales and Pythium. Early efforts focusing on the phylogenetic relationships in Phytophthora used nuclear-encoded rDNA, primarily the ITS region (Crawford et al. 1996; Cooke and Duncan 1997; Förster et al. 2000). The first comprehensive study was based on the phylogenetic study of the ITS region (Cooke et al. 2000). The study by Kroon et al. (2004) was based on analysis using two nuclear (tef1, tub2) and two mitochondrial (cox1 and nad1) genes. Subsequent phylogenetic analysis was based on sequences of seven nuclear genetic markers (60S ribosomal protein L10, tub2, enolase, heat shock protein90, large subunit rDNA, TigA gene fusion and tef1) which divided the species into 10 well-supported clades (Blair et al. 2008). The phylogenetic study by Martin et al. (2014) was based on seven nuclear and four mitochondrial genes (cox2, nad9, rps10 and secY). More recently, an extensive study of the genus by Yang et al. (2017) was based on sequences of seven nuclear genetic markers as in Blair et al. (2008).

             The number of described species in Phytophthora was approximately 55 in 1999, but since then there has been a significant increase in the number of species nearly doubling the number of described species to 105 (Brasier 2007), and over 128 species (Hyde et al. 2014). Additional species have since been described, for example, P. cocois (Weir et al. 2015), P. crassamura (Scanu et al. 2015), P. attenuata, P. xheterohybrida, P. xincrassata (Jung et al. 2017) bringing the total to over 150 species (Jung et al. 2019). The phylogenetic tree constructed is presented in Fig. 2 and the accepted species are given in table 1.

Recommended genetic markers (genus level) – LSU, SSU and cox2

Recommended genetic markers (species level) – LSU, tub2 and cox2

Accepted number of species– There are 317 epithets listed in Index Fungorum (2020), however only 162 species have DNA sequence data (Table 1).

References – Waterhouse 1963, Stamps et al. 1990 (morphology); Crawford et al. 1996, Cooke and Duncan 1997, Cooke et al. 2000, Förster et al. 2000, Brasier 2007, Blair et al. 2008 (morphology and phylogeny); Hyde et al. 2014 (phylogeny and accepted species).

Table 1 DNA barcodes available for Phytophthora. Ex-type/ex-epitype/ex-neotype/ex-lectotype strains and voucher strains are in bold. Species confirmed with pathogenicity studies are marked with #. (VdPN) are strains used by Van der Plaäts-Niterink (1981) for descriptions.

Species Strain 60S tub2 tef1 Enl HSP90 28S TigA
Phytophthora ×alni 47A8 KX251595 KX251596 KX251597 KX251598 KX251599 KX251600 KX251601
P. ×heterohybrida 67C1 KX251637 KX251638 KX251639 KX251640 KX251641 KX251642 KX251643
P. ×incrassata 67C2 KX251644 KX251645 KX251646 KX251647 KX251648 KX251649 KX251650
P. ×stagnum# 36J7 KX251368 KX251369 KX251370 KX251371 KX251372 KX251373 KX251374
P. acerina# 61H1=CBS 133931 KX250712 KX250713 KX250714 KX250715 KX250716 KX250717 KX250718
P. aff. brassicae# CBS 112968 EU079880 EU079881 EU079882 EU079883 EU079884 EU079885 EU079886
P. aff. citrophthora# IMI 342898 EU080384 EU080385 EU080386 EU080387 EU080388 EU080389 EU080390
P. aff. erythroseptica 33A1=P207 KX251979 KX251980 KX251981 KX251982 KX251983 KX251984 KX251985
P. aff. hedraiandra# 33F4=P226 KX250411 KX250412 KX250413 KX250414 KX250415 KX250416 KX250417
P. aff. himalsilva 61G4=CBS 128754 KX250621 KX250622 KX250623 KX250624 KX250625 KX250626 KX250627
P. aff. parsiana# 47C8 KX252397 KX252398 KX252399 KX252400 KX252401 KX252402 N/A
P. agathidicida# 67D5=ICMP 17027 KX251076 KX251077 KX251078 KX251079 KX251080 KX251081 KX251082
P. alticola 47G5=CBS 121939 KX251006 KX251007 KX251008 KX251009 KX251010 KX251011 KX251012
P. amnicola 61G6=CBS 131652 KX251167 KX251168 KX251169 KX251170 KX251171 KX251172 KX251173
P. andina# P13365 EU080182 EU080183 EU080184 EU080185 EU080186 EU080187 EU080188
P. aquimorbida 40A6=MYA4578 KX252238 KX252239 KX252240 KX252241 KX252242 KX252243 KX252244
P. arenaria 55C2=CBS 127950 KX251013 KX251014 KX251015 KX251016 KX251017 KX251018 KX251019
P. asiatica 45G1=ATCC 90455 KX251651 KX251652 KX251653 KX251654 KX251655 KX251656 KX251657
P. asparagi# 33D7= IMI384046 KX251466 KX251467 KX251468 KX251469 KX251470 KX251471 KX251472
P. attenuata 67C5 KX251609 KX251610 KX251611 KX251612 KX251613 KX251614 KX251615
P. austrocedrae 41B5=MYA4073 KX252161 KX252162 KX252163 KX252164 KX252165 KX252166 KX252167
P. bilorbang# 61G8=CBS 131653 KX251181 KX251182 N/A KX251183 KX251184 KX251185 KX251186
P. bisheria 29D2 KX250873 KX250874 KX250875 KX250876 KX250877 KX250878 KX250879
P. boehmeriae# 45F9=CBS 291.29 EU080161 EU080162 EU080163 EU080164 EU080165 EU080166 EU080167
P. borealis 60B2=CBS 132023 KX251187 KX251188 KX251189 KX251190 KX251191 KX251192 KX251193
P. botryosa# IMI130422=P6945 EU079934 EU079935 EU079936 EU079937 EU079938 EU079939 EU079940
P. brassicae# 29D8=CBS 686.95 KX251993 KX251994 KX251995 KX251996 KX251997 KX251998 KX251999
P. cactorum# 22E6=P10194 KX250369 KX250370 KX250371 KX250372 KX250373 KX250374 KX250375
P. cajani# 45F6=ATCC 44389 KX251679 KX251680 KX251681 KX251682 KX251683 KX251684 KX251685
P. cambivora# 22F6=ATCC 46719 KX251494 KX251495 KX251496 KX251497 KX251498 KX251499 KX251500
P. capensis 62C1=CBS 128319 KX250726 KX250727 KX250728 KX250729 KX250730 KX250731 KX250732
P. capsici# 22F4=ATCC 15399 KX250635 KX250636 KX250637 KX250638 KX250639 KX250640 KX250641
P. captiosa# 46H8=NZFS 430 KX252554 KX252555 KX252556 KX252557 KX252558 KX252559 KX252560
P. castaneae 22H6=MYA4060 KX251083 KX251084 KX251085 KX251086 KX251087 KX251088 KX251089
P. chrysanthemi# 61F1=CBS 123163 KX252266 KX252267 KX252268 KX252269 KX252270 KX252271 KX252272
P. cichorii 62A8=CBS 115029 KX252007 KX252008 KX252009 KX252010 KX252011 KX252012 KX252013
P. cinnamomi# 23B2=ATCC 15401 KX251804 KX251805 KX251806 KX251807 KX251808 KX251809 KX251810
P. citricola# 33H8=ATCC 60440 KX250747 KX250748 KX250749 KX250750 KX250751 KX250752 KX250753
P. citrophthora# 26H3 KX250551 KX250552 KX250553 KX250554 KX250555 KX250556 KX250557
P. clandestina 32G1=CBS 347.86 EU079866 EU079867 EU079868 EU079869 EU079870 EU079871 EU079872
P. cocois 67D6=ICMP 16948 KX251104 KX251105 KX251106 KX251107 KX251108 KX251109 KX251110
P. colocasiae# 22F8=MYA4159 KX250558 KX250559 KX250560 KX250561 KX250562 KX250563 KX250564
P. constricta 55C3=CBS 125801 KX252561 KX252562 KX252563 KX252564 KX252565 KX252566 KX252567
P. crassamura 66C9=PH094 KX251194 KX251195 KX251196 KX251197 KX251198 KX251199 KX251200
P. cryptogea# 61H9=CBS 113.19 KX251867 KX251868 KX251869 KX251870 KX251871 KX251872 KX251873
P. dauci 32E6=P10728 KX252028 KX252029 KX252030 KX252031 KX252032 KX252033 KX252034
P. drechsleri# P10331 EU079506 EU079507 EU079508 EU079509 EU079510 EU079511 EU079512
P. elongata 33J3=SG11 952 KX250880 KX250881 KX250882 KX250883 KX250884 KX250885 KX250886
P. erythroseptica 61J2=CBS 129.23 KX251895 KX251896 KX251897 KX251898 KX251899 KX251900 KX251901
P. europaea# 62A2=CBS 109049 KX251522 KX251523 KX251524 KX251525 KX251526 KX251527 KX251528
P. fallax# 46J2=P10722 KX252568 KX252569 KX252570 KX252571 KX252572 KX252573 KX252574
P. flexuosa 67C3 KX251616 KX251617 KX251618 KX251619 KX251620 KX251621 KX251622
P. fluvialis 55B6=CBS 129424 KX251208 KX251209 KX251210 KX251211 KX251212 KX251213 KX251214
P. foliorum# 49J8=CBS 121655 KX252112 KX252113 KX252114 KX252115 KX252116 KX252117 KX252118
P. formosa 67C4 KX251623 KX251624 KX251625 KX251626 KX251627 KX251628 KX251629
P. fragariae# 22G6=ATCC 11374 KX251529 KX251530 KX251531 KX251532 KX251533 KX251534 KX251535
P. fragariaefolia 61H4=CBS 135747 KX251853 KX251854 KX251855 KX251856 KX251857 KX251858 KX251859
P. frigida# 47G7 KX250908 KX250909 KX250910 KX250911 KX250912 KX250913 KX250914
P. gallica 50A1=CBS 111474 KX252589 KX252590 KX252591 KX252592 KX252593 KX252594 KX252595
P. gemini 46H1=CBS 123382 KX251125 KX251126 KX251127 KX251128 KX251129 KX251130 KX251131
P. gibbosa 55B7 KX251215 KX251216 KX251217 KX251218 KX251219 KX251220 KX251221
P. glovera 31E5 KX250642 KX250643 KX250644 KX250645 KX250646 KX250647 KX250648
P. gonapodyides# 21J5=ATCC 46726 KX251229 KX251230 KX251231 KX251232 KX251233 KX251234 KX251235
P. gondwanensis 22G7 KX252603 KX252604 KX252605 KX252606 KX252607 KX252608 KX252609
P. gregata# 55B8 KX251243 KX251244 KX251245 KX251246 KX251247 KX251248 KX251249
P. hedraiandra# 38C2 KX250390 KX250391 KX250392 KX250393 KX250394 KX250395 KX250396
P. heveae# 22J1=IMI 180616 KX251111 KX251112 KX251113 KX251114 KX251115 KX251116 KX251117
P. hibernalis# 32F7=CBS 114104 KX252126 KX252127 KX252128 KX252129 KX252130 KX252131 KX252132
P. himalsilva 61G3=CBS 128753 KX250579 KX250580 KX250581 KX250582 KX250583 KX250584 KX250585
P. hydrogena 46A3 KX252280 KX252281 KX252282 KX252283 KX252284 KX252285 KX252286
P. hydropathica# 05D1 KX252294 KX252295 KX252296 KX252297 KX252298 KX252299 KX252300
P. idaei 34D4=CBS 971.95 EU080129 EU080130 EU080131 EU080132 EU080133 EU080134 EU080135
P. ilicis# 23A7=ATCC 56615 KX250936 KX250937 KX250938 KX250939 KX250940 KX250941 KX250942
P. infestans# 27A8 KX250474 KX250475 KX250476 KX250477 KX250478 KX250479 KX250480
P. inflata# 28D1 KX250761 KX250762 KX250763 KX250764 KX250765 KX250766 KX250767
P. insolita# 38E1=CBS 691.79 EU080175 EU080176 EU080177 EU080178 EU080179 EU080180 EU080181
P. intercalaris 48A1 KX252617 KX252618 KX252619 KX252620 KX252621 KX252622 KX252623
P. intricata 67B9 KX251630 KX251631 KX251632 KX251633 KX251634 KX251635 KX251636
P. inundata# P8619 EU080202 EU080203 EU080204 EU080205 EU080206 EU080207 EU080208
P. ipomoeae# 31B6=P10227 EU080844 EU080845 EU080846 EU080847 EU080848 EU080849 EU080850
P. iranica# 61J4=CBS 374.72 KX250439 KX250440 KX250441 KX250442 KX250443 KX250444 KX250445
P. irrigata 04E4 KX252308 KX252309 KX252310 KX252311 KX252312 KX252313 KX252314
P. kernoviae 46C8=P10956 EU080041 EU080042 EU080043 EU080044 EU080045 EU080046 KX252631
P. lactucae 61F4 KX252042 KX252043 KX252044 KX252045 KX252046 KX252047 KX252048
P. lacustris# IMI389725=P10337 EU080530 EU080531 EU080532 EU080533 EU080534 EU080535 EU080536
P. lateralis# 22H9 KX252133 KX252134 KX252135 KX252136 KX252137 KX252138 KX252139
P. lilii CBS 135746 AB856779 AB856782 AB856788 AB856791 AB856794 AB856797 AB856800
P. litoralis 55B9=CBS 127953 KX251278 KX251279 KX251280 KX251281 KX251282 KX251283 KX251284
P. macilentosa 58A5 KX252329 KX252330 KX252331 KX252332 KX252333 KX252334 KX252335
P. macrochlamydospora# G231E9=IMI 351473 EU080658 EU080659 EU080660 N/A EU080661 EU080662 EU080663
P. meadii# 22G5 KX250586 KX250587 KX250588 KX250589 KX250590 KX250591 KX250592
P. medicaginis# 23A4 KX251902 KX251903 KX251904 KX251905 KX251906 KX251907 KX251908
P. megakarya# 61J5=CBS 238.83 KX251034 KX251035 KX251036 KX251037 KX251038 KX251039 KX251040
P. megasperma# 62C7=CBS 402.72 KX251285 KX251286 KX251287 KX251288 KX251289 KX251290 N/A
P. melonis# 41B4 KX251700 KX251701 KX251702 KX251703 KX251704 KX251705 KX251706
P. mengei 42B2 KX250656 KX250657 KX250658 KX250659 KX250660 KX250661 KX250662
P. mexicana 45G4=CBS 554.88 KX250670 KX250671 KX250672 KX250673 KX250674 KX250675 KX250676
P. mirabilis 30C2=ATCC 64070 KX250488 KX250489 KX250490 KX250491 KX250492 KX250493 KX250494
P. mississippiae 57J1 KX251291 KX251292 KX251293 KX251294 KX251295 KX251296 KX251297
P. morindae 62B5=CBS 121982 KX252633 KX252634 KX252635 KX252636 KX252637 KX252638 KX252639
P. multivesiculata# 30D4 KX250922 KX250923 KX250924 KX250925 KX250926 KX250927 KX250928
P. multivora# 55C5=CBS 124094 KX250775 KX250776 KX250777 KX250778 KX250779 KX250780 KX250781
P. nagaii 61H5=CBS 133248 KX251860 KX251861 KX251862 KX251863 KX251864 KX251865 KX251866
P. nemorosa 28J3 KX250957 KX250958 KX250959 KX250960 KX250961 KX250962 KX250963
P. nicotianae# 22F9=ATCC 15410 KX250509 KX250510 KX250511 KX250512 KX250513 KX250514 KX250515
P. niederhauserii# 01D5 KX251714 KX251715 KX251716 KX251717 KX251718 KX251719 KX251720
P. obscura 60E9=CBS 129273 KX252175 KX252176 KX252177 KX252178 KX252179 KX252180 KX252181
P. occultans# 65B9=CBS 101557 KX250600 KX250601 KX250602 KX250603 KX250604 KX250605 KX250606
P. ornamentata 66D2=CBS 140647 KX251319 KX251320 KX251321 KX251322 KX251323 KX251324 KX251325
P. pachypleura# 61H8 KX250796 KX250797 KX250798 KX250799 KX250800 KX250801 KX250802
P. palmivora# 22G9 KX251055 KX251056 KX251057 KX251058 KX251059 KX251060 KX251061
P. parsiana# 47C3=IMI 395329 KX252357 KX252358 KX252359 KX252360 KX252361 KX252362 KX252363
P. parvispora# 30G9 KX251818 KX251819 KX251820 KX251821 KX251822 KX251823 KX251824
P. phaseoli 35B6 KX250502 KX250503 KX250504 KX250505 KX250506 KX250507 KX250508
P. pini# 22F1 KX250803 KX250804 KX250805 KX250806 KX250807 KX250808 KX250809
P. pinifolia 47H1=CBS 122924 KX251333 KX251334 KX251335 KX251336 KX251337 KX251338 KX251339
P. pisi 60A4 KX251735 KX251736 KX251737 KX251738 KX251739 KX251740 KX251741
P. pistaciae# 33D6=IMI 386658 KX251748 KX251749 KX251750 KX251751 KX251752 KX251753 KX251754
P. plurivora# 22E9 KX250817 KX250818 KX250819 KX250820 KX250821 KX250822 KX250823
P. pluvialis# 60B3 KX250971 KX250972 KX250973 KX250974 KX250975 KX250976 KX250977
P. polonica 40G9 KX252532 KX252533 KX252534 KX252535 KX252536 KX252537 KX252538
P. primulae# 29E9=CBS 620.97 KX252063 KX252064 KX252065 KX252066 KX252067 KX252068 KX252069
P. pseudocryptogea# ATCC52402 EU080626 EU080627 EU080628 EU080629 EU080630 EU080631 N/A
P. pseudosyringae# 30A8=CBS 111772 KX250978 KX250979 KX250980 KX250981 KX250982 KX250983 KX250984
P. pseudotsugae ATCC52938 EU080426 EU080427 EU080428 EU080429 EU080430 EU080431 EU080432
P. psychrophila 29J5=CBS 803.95 KX250992 KX250993 KX250994 KX250995 KX250996 KX250997 KX250998
P. quercetorum 15C8 KX251069 KX251070 KX251071 KX251072 KX251073 KX251074 KX251075
P. quercina# 30A4=CBS 783.95 KX252647 KX252648 KX252649 KX252650 KX252651 KX252652 KX252653
P. quininea 45F2=CBS 406.48 EU080107 EU080108 EU080109 N/A KX252522 EU080110 KX252523
P. ramorum# 32G2 KX252147 KX252148 KX252149 KX252150 KX252151 KX252152 KX252153
P. richardiae 45F5=CBS 240.3 KX251923 KX251924 KX251925 KX251926 KX251927 KX251928 KX251929
P. riparia 60B1=CBS 132024 KX251347 KX251348 KX251349 KX251350 KX251351 KX251352 KX251353
P. rosacearum 22J9 KX251431 KX251432 KX251433 KX251434 KX251435 KX251436 KX251437
P. rubi 30D7 KX251550 KX251551 KX251552 KX251553 KX251554 KX251555 KX251556
P. sansomeana# 47H5 KX251944 KX251945 KX251946 KX251947 KX251948 KX251949 KX251950
P. siskiyouensis# 41B7=CBS 122779 KX250677 KX250678 KX250679 KX250680 KX250681 KX250682 KX250683
P. sojae# 22D8=CBS 312.62 KX251762 KX251763 KX251764 KX251765 KX251766 KX251767 KX251768
P. sp. brasiliensis ATCC46705=P0630 EU080419 EU080420 EU080421 EU080422 EU080423 EU080424 EU080425
P. sp. canalensis P10456 EU079569 EU079570 EU079571 EU079572 EU079573 EU079574 N/A
P. sp. citricola VIII 27D9 KX250838 KX250839 KX250840 KX250841 KX250842 KX250843 KX250844
P. sp. cuyabensis P8213 EU080664 EU080665 EU080666 EU080667 EU080668 EU080669 EU080331
P. sp. delaware 63H4 KX251396 KX251397 KX251398 KX251399 KX251400 KX251401 KX251402
P. sp. kelmania 24A7 KX251986 KX251987 KX251988 KX251989 KX251990 KX251991 KX251992
P. sp. lagoariana 60B4=P8220 EU080358 KX252502 EU080359 EU080360 EU080361 EU080362 EU080363
P. sp. personii P11555 EU080312 EU080313 EU080314 EU080315 EU080316 EU080317 EU080318
P. sp. sulawesiensis P6306 EU080345 N/A EU080346 EU080347 EU080348 EU080349 EU080350
P. stricta 58A2 KX252217 KX252218 KX252219 KX252220 KX252221 KX252222 KX252223
P. syringae# 23A6 KX252203 KX252204 KX252205 KX252206 KX252207 KX252208 KX252209
P. taxon parsley 61G1=BPIC 2584 KX252105 KX252106 KX252107 KX252108 KX252109 KX252110 KX252111
P. taxon walnut 40A7 KX251452 KX251453 KX251454 KX251455 KX251456 KX251457 KX251458
P. taxonaquatilis 38J5 KX250929 KX250930 KX250931 KX250932 KX250933 KX250934 KX250935
P. taxoncastitis 61E7=CBS 131246 KX252098 KX252099 KX252100 KX252101 KX252102 KX252103 KX252104
P. taxonemzansi 61F2 KX250859 KX250860 KX250861 KX250862 KX250863 KX250864 KX250865
P. tentaculata# 29F2=CBS 552.96 EU079955 EU079956 EU079957 EU079958 EU079959 EU079960 EU079961
P. terminalis 65B8=CBS 133865 KX250607 KX250608 KX250609 KX250610 KX250611 KX250612 KX250613
P. thermophila 55C1=CBS 127954 KX251354 KX251355 KX251356 KX251357 KX251358 KX251359 KX251360
P. trifolii 29B2 KX251951 KX251952 KX251953 KX251954 KX251955 KX251956 KX251957
P. tropicalis# 35C8=CBS 434.91 KX250698 KX250699 KX250700 KX250701 KX250702 KX250703 KX250704
P. uliginosa 62A3=CBS 109054 EU080011 EU080012 EU080013 KX251571 KX251572 EU080015 KX251573
P. vignae# 45G9=ATCC 64832 KX251783 KX251784 KX251785 KX251786 KX251787 KX251788 KX251789
P. virginiana 44G6 KX252371 KX252372 KX252373 KX252374 KX252375 KX252376 KX252377

Fig. 2 Maximum likelihood of Phytophthora based on the concatenated seven nuclear genetic markers (60S Ribosomal protein L10 (60S), beta-tubulin (tub), elongation factor 1 alpha (tef1), enolase (Enl), heat shock protein 90 (hsp90), 28S ribosomal DNA (28S), and tigA gene fusion protein (TigA)). ML bootstrap support values over 60% are indicated and BYPP≥0.90 are shown respectively near the nodes. The type species are in bold. Scale bar indicates number of substitutions per site. The tree was rooted with Phytopythiumvexansand Pythium undulatumas as the ourgroup. Likelihood of the best scoring ML tree was -114471.902046. Estimated base frequencies were as follows: A = 0.216570, C = 0.275568, G = 0.312230, T = 0.195632; substitution rates AC = 0.414835, AG = 1.176570, AT = 0.600142, CG = 0.970565, CT = 5.227735, GT = 1.000000.

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