Citrus Virus Diseases. Bill Dawson

Transcription

1 Citrus Virus Diseases Bill Dawson

2 All graft-transmissible diseases initially were considered to be caused by viruses Examples of changes Viroids citrus exocortis cachexia xyloporosis Phytoplasmas, Spiroplasmas stubborn new phytoplasma in Brazil that causes greening symptoms Bacteria greening citrus varigated chlorosis

3 VIRAL DISEASES Citrus mosaic Satsuma dwarf-related virus Bud union crease Virus for some combinations, otherwise genetic or unknown Citrus leaf rugose genus Ilarvirus, Citrus leaf rugose virus (CLRV) Citrus yellow mosaic genus Badnavirus Crinkly leaf Crinkly leaf ilarvirus (strain of citrus variegation virus) Infectious variegation genus Ilarvirus, Citrus variegation virus (CVV) Navel infectious mottling Satsuma dwarf-related virus Psorosis Spirovirus (ophiovirus) proposed new group Satsuma dwarf Satsuma dwarf virus (SDV) Tatter leaf = citrange stunt genus Capillovirus, Citrus tatter leaf virus (probably a closely related strain of apple stem grooving capillovirus rather than a distinct virus Tristeza = decline and stem pitting, seedling yellows genus Closterovirus, Citrus tristeza virus (CTV)

4 VIROIDS AND GRAFT-TRANSMISSIBLE PATHOGENS (GTP) Algerian navel orange virus GTP Impietratura Blight = young tree decline, rough lemon decline GTP GTP Indian citrus ringspot Blind pocket GTP GTP Leaf curl Cachexia GTP Citrus cachexia viroid (Hostuviroid) Leathery leaf Chlorotic dwarf GTP White-fly transmitted GTP Leprosis Citrus dwarfing GTP associated with Brevipalpus spp. mites Varios viroids Measles Citrus yellow mottle GTP GTP Milam stem-pitting Citrus yellow ringspot GTP GTP Multiple sprouting disease Concave gum GTP GTP Nagami kumquat disease Cristacortis GTP GTP Ringspot diseases Exocortis Various GTPs Citrus exocortis viroid (CEVd) (Pospiviroid) Vein enation = woody gall Fatal yellows GTP (possible luteovirus) GTP Xyloporosis = cachexia Gummy bark Citrus cachexia viroid (Hostuviroid) GTP, possible viroid Yellow vein Gum pocket and gummy pittings GTP GTP, possible viroid Yellow vein clearing of lemon GTP

5 Edited by J.O. Whiteside, S.M. Garnsey, and L.W. Timmer APS Press The American Phytopathological Society 1988

6 Endemic Viruses of Concern Tatterleaf / Citrange Stunt Infectious Variegation Citrus Leaf Rugose Psorosis complex Citrus leaf blotch Citrus tristeza decline

7 Department of Plant Industry Budwood certification Dr. Peggy Sieburth Winter Haven Budwood trees tested: Citrus tristeza virus decline isolate (MCA-13 positive) tested yearly OK to have budwood with the mild isolate of CTV Psorosis and Concave gum tested once by biological indexing now starting to test every 6 years Citrus leaf blotch virus (Dweet mottle virus) once every 6 years in budwood source trees and also in seed source trees since it is seed transmitted Citrus tatter leaf virus Infectious variegation virus is not tested for because it is mainly a problem for lemons which are limited in Florida Also test for viroids I, II, III, IV, V, and CEV every 6 years

8 Tatter Leaf and Citrange Stunt virus complex latent infections in Meyer lemons apparently wide spread in China Host Range and Symptoms when infected cultivars are propagated on trifoliate or hybrids (Swingle citrumelo, Carrizo, Troyer, and Kuharske citrange), trees are stunted and chlorotic, virus-induced incompability can infect a wide range of citrus cultivars causes mild symptoms if not on trifoliate rootstock can infect a wild range of herbaceous hosts

9 Tatter Leaf and Citrange Stunt virus complex continued Causal Agent one positive-sense RNA two subgenomic RNAs ORF 1 ORF 2 CP A(n) A(n) A(n) Transmission and Epidemiology graft transmitted by infected budwood mechanically transmitted to a range of hosts thought to be aphid transmitted? Identification characteristic bud union creasing symptoms on herbaceous hosts Control virus-free budwood, difficult to remove decontaminate tools, knives use rootstocks other than Poncirus hybrids Infectious cdna clone in our freezer

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11 Wild type virus infected (8 dpi) Wild type virus infected (15 dpi) Healthy

12 Infectious Variegation Citrus Variegation Virus (CVV) Host Range and Symptoms can infect most citrus species lemons, sour orange, citron, and grapefruit develop chlorotic leaf symptoms and distortion mild strains exist that cause only mild mottle or chlorotic flecking trees can be stunted, some fruit may be distorted symptoms are less in warm weather can be mechanically transmitted to some cowpeas (chlorotic or necrotic lesions and beans (chlorotic mottle or veinbanding)

13 Infectious Variegation Citrus Variegation Virus (CVV) continued Causal Agent ilarvirus 4 positive-sense RNAs, sperical particles Citrus crinkly leaf virus is a mild variant Transmission and Epidemiology grafting budwood mechanically inoculate seed transmitted apparently rare pollen transmission? Identification indexing by graft inoculation to lemon or citron mechanical inoculation to cowpea or bean Control infected budwood can be freed by thermotherapy or shoot tip grafting then use virus-free budwood

14 Leaf Rugose Citrus leaf rugose virus (CLRV) Host Range and Symptoms infects a broad range of citrus hosts Mexican lime, Eureka lemon, and Duncan grapefruit develop leaf puckering, pinpoint chlorotic spotting, and stunting can be mechanically transmitted to a range of noncitrus hosts

15 Leaf Rugose Citrus leaf rugose virus (CLRV) continued Causal agent ilarvirus 4 positive-sense RNAs, isometric particles Transmission and Epidemiology grafting and mechanical transmission no vector known, but get some local spread pollen? Identification indexing by grafting Eureka lemon or bush bean serology Control use virus-free budwood decontamination of pruning tools

16 Psorosis (psorosis A, mild; psorosis B, severe; concave gum; ) probably a complex of several diseases, which share common symptoms usually found present in old-line trees often bark scaling Host Range and Symptoms symptoms stronger on young leaves ranging from chlorotic flecks, to leaf mottling and chlorotic patterns scaling and flaking of bark on the trunk and limbs of sweet orange and grapefruit and occasionally mandarins -- usually not on other citrus wood becomes impregnated with gum concave gum thought to be related, mandarins and sweet oranges are affected, deep concavities in the trunk and main branches

17 Concave Gum Psorosis

18 Psorosis (psorosis A, mild; psorosis B, severe) continued Causal Agent Transmission and Epidemiology graft transmitted seed transmission rare apparently some unknown vector Identification field symptoms of bark scaling indexing by grafting to sweet orange or mandarin seedlings for leaf-flecking Control use virus-free budwood, use seed only from virus-free trees can use shoot-tip grafting or thermotherapy decontaminate tools

19 Citrus ringspot virus (CRSV) Psorosis B Host Range and Symptoms irregular spots or large, irregular chlorotic patterns on mature leaves frequently gum impregnated and are slightly raised on the lower surface fruit may have ringspots some isolates are mechanically transmitted to Chenopodium spp

20 Citrus ringspot virus (CRSV) Psorosis B continued Causal Agent ophiovirus, 3 negative-sense RNAs very thin thread-like particles next slide has genome description Transmission and Epidemiology graft transmissible mechanical transmissible vector suspected but unknown Control virus-free budwood decontamination of tools

21 The complete nucleotide sequence of a Spanish isolate of Citrus psorosis virus: comparative analysis with other ophioviruses Brief Report S. Mart ın1, C. L opez2, M. L. Garc ıa3, G. Naum- Ongan ıa3, O. Grau3, R. Flores2, P. Moreno1, and J. Guerri1 Arch Virol (2005) 150:

22 Association of citrus psorosis B symptoms with a sequence variant of the Citrus psorosis virus RNA 2 Velazquez, K (Velazquez, K.)1; Pina, JA (Pina, J. A.)1; Navarro, L (Navarro, L.)1; Moreno, P (Moreno, P.)1; Guerri, J (Guerri, J.) PLANT PATHOLOGY 61: The virus induces two different syndromes: psorosis A (PsA), characterized by limited bark scaling lesions in the trunk and main limbs, and a more aggressive form of the disease called psorosis B (PsB) with rampant bark lesions affecting even thin branches and chlorotic blotches in old leaves. In the greenhouse, the PsA and PsB syndromes can be induced by graft inoculating healthy citrus seedlings with non-lesion or with lesion bark inoculum from PsA-affected field trees. PsA- and PsB-inducing CPsV sub-isolates obtained by this procedure from the same tree showed segments of the RNA 2 enabled discrimination between PsA- and PsB-associated sequence variants. (i) PsA-inducing isolates contain PsB-associated sequence variants at low frequency, (ii) the PsB-associated sequence variant is predominant in blistered twigs and gummy pustules affecting old leaves, characteristic of PsB isolates, and (iii) the PsB-associated sequence variant accumulates preferentially in bark lesions of the trunk and limbs.

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24 P Moreno, J Guerri, and ML García The psorosis disease of citrus: a pale light at the end of the tunnel. Journal of Citrus Pathology 2: 1-18.

25 Citrus leaf blotch virus (CLBV) Host Range and Symptoms first found in kumquat on Troyer citrange rootstock with bud union crease Spain, France, Japan, Australia, Florida associated with abnormal bud unions on poncirus hybrid rootstocks Causal Agent filamentous particles one positive-stranded RNA with 2 subgenomics p41 p227 p40 Transmission and Epidemiology no known vector seed transmitted Poly-A Poly-A Poly-A Control virus-free budwood alternative rootstocks if necessary

26 Citrus tristeza virus Causes four disease syndromes: decline only on sour orange rootstocks can be quick decline can be slow seedling yellows -- usually seen in greenhouse on sour orange and grapefruit no disease mild strains stem pitting on all rootstocks

27 EXOTIC VIRUSES

28 Exotic Viruses of Concern Citrus chlorotic dwarf (CCD) Citrus yellow mosaic Leprosis Satsuma Dwarf Tristeza stem pitting Vein enation Sudden death

29 Vein Enation (Woody Gall) important commercially only when severe galling occurs on young trees budded to rough lemon rootstocks Host Range and Symptoms enations on the veins of Mexican lime, sour orange, and rough lemon swelling or galls on the stems of rough lemon and Mexican lime

30 Vein Enation (Woody Gall) continued Casual Agent spherical viruslike particles Transmission grafting aphid transmitted Myzus persicae, Toxoptera, citricida, and Aphis gossipii not mechanically transmitted Control clean budwood avoid use of rough lemon rootstocks

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32 Leprosis and Zonate Chlorosis Host Range and Symptoms observed primarily on sweet orange sour orange and mandarins are also show symptoms other citrus normally do not show symptoms symptoms are chlorotic lesions, sometimes with a necrotic center later lesions become flat or raised necrotic areas leaves and fruit abscise when lesions are abundant, can get twig dieback can mechanically transmit to Chenopodium spp

33 Leprosis

34 Leprosis and Zonate Chlorosis continued Causal Agent controversy may be two different viruses causing similar diseases rare nuclear form that is rod shaped and more prevalent cytoplasmic form of baciliform particles would be expected to be a rhabdovirus positive-sense RNA virus with 2 RNAs virus is a mite virus Brevipalpus spp. virus multiplies in mites Transmission and Epidemiology transmitted by mites -- millions of individual infections graft transmitted with difficulty virus does not move long distances, systemically Control eliminate sources of inoculum control mites, acaricides to reduce mite population

35 Satsuma dwarf virus (SDV) Host Range and Symptoms wide host range in citrus widely spread in Japan stunting and narrow, boat- or spoon-shaped leaves in satsuma mandarin Chenopodium, cowpea, bean, Physalis, Gomphrena

36 Complete nucleotide sequence, genomic organization and phylogenetic analysis of Citrus leprosis virus cytoplasmic type EC Locali-Fabris Freitas-Astúa - Journal of, jgv.microbiologyresearch.org The complete nucleotide sequence of the genomic RNA 1 (8745 nt) and RNA 2 (4986 nt) of Citrus leprosis virus cytoplasmic type (CiLV-C) was determined using cloned cdna. The complete nucleotide sequence and genomic organization of citrus leprosis associated virus, cytoplasmatic type (CiLV-C) RC Pascon, P Kitajima, MC Breton, L Assumpção - Virus Genes, 2006 A novel virus of the genus Cilevirus causing symptoms similar to citrus leprosis A Roy, N Choudhary, LM Guillermo, J Shao -

37 Satsuma dwarf virus (SDV) continued Causal Agent small isometric virus with 2 RNAs genome on next slide Transmission and Epidemiology graft transmitted by infected budwood mechanically transmitted to herbaceous hosts local spread, maybe a soilborne vector Control virus-free budwood

38 Nucleotide sequences and taxonomy of satsuma dwarf virus Toru Iwanami,1 Yoshiko Kondo1 and Alexander V. Karasev2 J Gen Virol Mar;80 ( Pt 3):793-7.

39 Citrus Sudden Death new disease reported in Brazil in 1999 Host Range and Symptoms decline disease limited to Rangpur lime and to limited extent on Volkamer lemon during periods of drought rapid death of trees during drought characteristic yellow stain at or below the bud union

40 Citrus Sudden Death -- continued Causal Agent some controversy, a sobemovirus-like, marafivirus but CTV association genome on next slide Transmission and Epidemiology spread looks similar to aphid transmission of CTV no vector identified can be grafted? Identification decline determine whether on Rangpur lime or Volkamer lemon yellow stain at graft union Control virus-free budwood irrigation inarching

41 Identification and Genomic Characterization of a New Virus (Tymoviridae Family) Associated with Citrus Sudden Death Disease Walter Maccheroni, 1 Marcos C. Alegria, 1 Christian C. Greggio, 1 João Paulo Piazza, 1 Rachel F. Kamla, 1 Paula R. A. Zacharias, 1 Moshe Bar-Joseph, 1, Elliot W. Kitajima, 2 Laura C. Assumpção, 1 Giovana Camarotte, 1 Jussara Cardozo, 1 Elaine C. Casagrande, 1 Fernanda Ferrari, 1 Sulamita F. Franco, 1 Poliana F. Giachetto, 1 Alessandra Girasol, 1 Hamilton Jordão Jr., 1 Vitor H. A. Silva, 1 Leonardo C. A. Souza, 1 Carlos I. Aguilar-Vildoso, 1 Almir S. Zanca, 1 Paulo Arruda, 1 João Paulo Kitajima, 1 Fernando C. Reinach, 1 Jesus A. Ferro, 1 and Ana C. R. da Silva 1* J Virol Mar;79(5):

42 Citrus Sudden Death inarching

43 Citrus yellow mosaic virus India, perhaps Japan Host Range and Symptoms mosaic of leaves does not reduce fruit production, but fruit have less juice and ascorbic acid wide citrus host range but apparently does not infect Mexican lime

44 Citrus yellow mosaic virus Causal Agent badnavirus double-stranded circular DNA virus Transmission and Epidemiology mechanically transmitted transmitted by aphids or mealybugs?

45 Citrus chlorotic dwarf virus (CCD) found in Turkey Host Range and Symptoms causes crinkled and puckered leaves in lemon, tangelo, and sweet orange Transmission and Epidemiology transmitted by the bayberry whitefly Parabemisia myricae grafting of infected budwood mechanically transmitted Identification can do greenhouse experiments, but no simple identification Control

46 CCD in lemon CCD in mandarin CCD in grapefruit

47 Identification of a single-stranded DNA virus associated with citrus chlorotic dwarf disease, a new member in the family Geminiviridae Giuliana Loconsole a, Pasquale Saldarelli b, Harshavardhan Doddapaneni c, Vito Savino a, b, Giovanni P. Martelli a, b, Maria Saponari b, Virology 432: (2012)

48 Citrus Tristeza Virus (CTV) Decline Host Range and Symptoms can infect most citrus varieties and relatives Poncirus spp are resistant to most isolates disease is limited to scions on sour orange rootstocks

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52 Roots of declining tree no feeder roots

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54 Gold-labeled CP antiserum Gold-labeled CPm antiserum CTV virions From: Tian et al. J. Gen. Virol.80:1111 (1999) p27 (minor capsid protein, CPm) p25 (major capsid protein, CP)

55 Citrus tristeza virus ORF 1a 1b probe PRO PRO MT IDR Polyprotein: Replicase HEL RdRp +1 Ribosomal frameshift: p33 p6 ( ) RdRp ( ) HSP70h ( ) p61 ( ) CPm ( ) ( ) CP p18 p20 ( ) p13 ( ) ( ) p23 ( ) p33 p6 HSP70h p61 CPm CP p18 p13 p20 p23 3 probe Proteins

56 Citrus tristeza virus (CTV) decline Transmission and Epidemiology aphid transmitted by a series of aphids, brown citrus aphid best also melon, cotton aphids transmitted in a semi-persistent manner ~ 1 hr to ~ 24 hr Identification in field, identify rootstock sour orange bud union staining, scion overgrowth, thickened bark at union serology can detect CTV; can differentiate FL mild from decline biological assay in greenhouse vein clearing and leaf cupping in Mexican lime Control use alternative rootstock use virus-free or decline-free budwood

57 Citrus tristeza virus (CTV) stem pitting no severe stem pitting isolates of CTV known to be in Florida every effort is being made to keep them out Host Range and Symptoms stem pitting does not kill trees reduces vigor, reduces growth, reduces yield and fruit size stem pitting is specific to virus isolate and host some isolates cause stem pitting in grapefruit some isolates cause stem pitting in sweet orange some isolates cause stem pitting in both mandarins are more tolerant Control keep stem pitting isolates out mild strain cross protection

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60 FS674 on DG

61 Risk evaluation of exotic pathogens for citrus Disease Impact Intro Estab Spread Estab m Estab F Detection Control factor 1 factor 2 4factRel % 6factRel% HLB % % Blackspot % 78.75% CTV-SP % 47.96% Canker % 23.54% CVC % 18.71% Phaeoram % 16.75% CCD % 9.48% Leprosis % 2.13% Swt. Scab % 0.41% Vein Enation % 0.23% SDV % 0.21% CYM % 0.15% ACD % 0.12% Stubborn % 0.11% Pow. Mil % 0.02% LWB % 0.01% Mal Secco % 0.00%