Papaya lethal yellowing virus (PLYV) infects Vasconcellea cauliflora

Abstract

Autor para correspondência: Manoel Teixeira Souza Júnior RESUMO Papaya Lethal Yellowing Virus (PLYV) infecta Vasconcellea cauliflora (Jacq.) A. DC Papaya lethal yellowing virus (PLYV) é um dos três vírus descritos infectando mamoeiros (Carica papaya L.) no Brasil. Vasconcellea cauliflora (Jacq.) A. DC., antes denominada de Carica cauliflora (Jacq.), é uma reconhecida fonte de resistência natural ao Papaya ringspot virus (PRSV), causador da "Mancha Anelar" ou "Mosaico" do mamoeiro. Neste estudo é demonstrado que V. cauliflora pode ser infectada por PLYV mediante inoculação mecânica. Esta é a segunda hospedeira de PLYV descrita até o momento. Por ser infectado por PLYV, mas não PRSV, esta espécie da família das Caricaceas pode ser utilizada para separação destes vírus quando em infecção mista numa planta de C. papaya. Greenhouse host range studies with more than 26 plant species from several different botanic families have shown that the PLYV host spectrum was restricted to C. papaya (Lima et al., Fitopatol. Bras. 19:437. 1994.), however these authors did not test any other member of the Caricaeae Dumort family. This family has six genera: Carica, Cylicomorpha, Jacaratia, Horovitzia, Jarilla and Vasconcellea. Vasconcellea cauliflora (Jacq.) A. DC., is one of the 21 species and five subspecies of the genus Vasconcellea present in South America. V. cauliflora, known as "tapaculo", "papayo de montaña" or "zonzapote", is found from the South of Mexico to the North of South America, as well as in Trinidad (Badillo, Ernstia 10: 74. 2000 and 11:75. 2001.), and is a well-known source of natural resistance to PRSV (Hammerschlag & Litz, Eds. Biotechnology of Perennial Fruit Crops. CAB International, Wallingford, U�. 1992). The present work aimed to evaluate the response of V. cauliflora to mechanical inoculation of PLYV. Seeds were kindly supplied by Dr. D. Foltran from IAC, and the PLYV isolate used was kindly provided by Dr. José A. Lima, from UFC. A PRSV isolate collected in Brasília was used to assess the response to mechanical inoculation. Twenty V. cauliflora plants were inoculated with PLYV in two batches. Eight plants were inoculated with PRSV at once. Plants were submitted to two mechanical inoculations, one week apart, when they were about 30 cm height, and showing from six to ten leaves. All plants were then maintained in greenhouse for at least six weeks to evaluate symptoms development. None of the plants inoculated with PRSV developed any symptoms after six weeks of the second inoculation. All control C. papaya plants were symptomatic two weeks after the second inoculation with PRSV. Plants of V. cauliflora inoculated with PLYV showed leaf distortion, as well as leaf cup and shoestring (Figure 1), which started at least two weeks after the second inoculation. Leaves from the symptomatic V. cauliflora were then used as inoculum source in mechanical inoculation of C. papaya, and all plants developed symptoms two weeks after inoculation. A RT-PCR test using PLYV-specific primers (5'-ctgaagcggatatttctgg-3' & 5'-...

Sorologia e sobrevivência do vírus do amarelo letal do mamoeiro

“…Nas folhas, a detecção do vírus por ELISA mantevese elevada (90%) até os 80 dias, enquanto que nas raízes caiu para 60% no mesmo período. No final do período de 120 dias a detecção por ELISA nas folhas ainda se manteve acima de 70% e nas raízes a detecção Por não apresentar hospedeira de lesão local, o PLYV foi avaliado quanto a sua capacidade infectiva em mudas de mamoeiro que apresentam sintomas sistêmicos, constituindo o único hospedeiro disponível (LIMA et al, 2001), embora o vírus possa infetar experimentalmente outra espécie do gênero Carica (AMARAL et al, 2006). Os resultados discrepantes entre o LIV do PLYV e sua sobrevivência em tecidos secos podem ser esclarecidos em função dos meios aos quais as partículas virais foram submetidas.…”

Genetic variability of papaya lethal yellowing virus isolates from Ceará and Rio Grande do Norte States, Brazil

“…5 μg) using a PLYV-specific reverse primer (5'-GTG TAT GGC ATA CAG TTA TC-3') which anneals at the 3'-end of the CP ORF based on the sequence of the Marco2 isolate (GU066876) (Amaral et al, 2006). Initially, the RNA, the primer (20 pmol) and nuclease-free water (to complete the volume to 12 μl) were incubated for 5 min at 65°C, and quickly transferred to ice.…”

“…The reaction was then completed with 4 μl of 5× reaction buffer, 1 μl of 10 mM dNTP mix, 2 μl of 0.1 M dithiothreitol (DTT) and 1 μl (200 units) of SuperScript III reverse transcriptase (Invitrogen) and incubated at 37 o C for 1 h followed by 95 o C for 5 min. PCR was performed in a total volume of 50 μl, using 2.5 μl of the cDNA, 5 μl 10× PCR buffer (200 mM Tris-HCl, pH 8.4, 500 mM KCl), 3 μl of 25 mM MgCl 2 , 1 μl of dNTPs (2.5 mM each), 20 pmol of each primer [the same reverse primer used in the reverse transcription reaction plus a forward primer, 5' TGA AGC GGA TAT TTC TGG 3', which anneals at the 3'-end of the RdRp ORF (Amaral et al, 2006)] and 1 unit of Taq DNA polymerase. The thermocycler (PTC-100, MJ Research Inc.) was programmed for 35 cycles of denaturing at 94°C for 1 minute, primer annealing at 55°C for 2 minutes and extension at 72°C for 1 minute, with a final extension at 72°C for 10 minutes.…”

Screening of papaya accessions resistant to Papaya lethal yellowing virus and capacity of Tetranychus urticae to transmit the virus

“…PLYV is easily mechanically transmitted to plants of the Caricaceae family and it can also be transmitted by contaminated hands, which shows the high stability of the virus (Amaral et al, 2006;Saraiva et al, 2006). PLYV is found in contaminated soils, irrigation water, dry leaves, leaf and root debris, and on seed surface of infected fruit, but there are no reports of transmission through the seed embryo (Camarço et al, 1998;Saraiva et al, 2006;Nascimento et al, 2010).…”