COAT PROTEIN-MEDIATED PROTECTION AND CLASSICAL CROSS PROTECTION TO CONTROL PAPAYA RINGSPOT VIRUS IN PAPAYA.

Papaya ringspot virus (PRSV) HA5-1, a mild mutant of type P Hawaii severe strain (PRSV P-HA), has been widely used for the control of PRSV type P strains in papaya, but did not provide practical protection against PRSV type W strains in cucurbits. In order to widen the protection effectiveness against W strains, chimeric mild strains were constructed from HA5-1 to carry the heterologous 3′ genomic region of a type W strain W-CI. Virus accumulation of recombinants and their crossprotection effectiveness against W-CI and P-HA were investigated. In horn melon and squash plants, the recombinant carrying both the heterologous coat protein (CP) coding region and the 3′ untranslated region (3′UTR), but not the heterologous CP coding region alone, significantly enhanced the protection against W-CI. The heterologous 3′UTR alone is critical for the enhancement of the protection against W-CI in horn melon, but not in zucchini squash. In papaya, the heterologous CP coding region or 3′UTR alone, but not both together, significantly reduced the effectiveness of cross protection against P-HA. Our recombinants provide broader protection against both type W and P strains in cucurbits; however, the protective effectiveness is also affected by virus accumulation, the organization of the 3′ genomic region, and host factors.

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Generation of mild recombinants of papaya ringspot virus to minimize the problem of strain-specific cross protection

Phytopathology ◽

10.1094/phyto-06-21-0272-r ◽

2021 ◽

Author(s):

Thi-Thu-Yen Tran ◽

Tzu-Tung Lin ◽

Chung-Ping Chang ◽

Chun-Hung Chen ◽

Van-Hoa Nguyen ◽

...

Keyword(s):

Nitrous Acid ◽

Carica Papaya ◽

Genomic Sequence ◽

Cross Protection ◽

Ringspot Virus ◽

Limiting Factor ◽

Papaya Ringspot Virus ◽

Severe Damage ◽

Mild Strain ◽

Geographic Regions

Papaya ringspot virus (PRSV) causes severe damage to papaya (Carica papaya L.) and is the primary limiting factor for papaya production worldwide. A nitrous acid-induced mild strain PRSV HA 5-1, derived from Hawaii strain HA, has been applied to control PRSV by cross protection for decades. However, the problem of strain-specific protection hampers its application in Taiwan and other geographic regions outside Hawaii. Here, sequence comparison of the genomic sequence of HA 5-1 with that of HA revealed 69 nucleotide changes, resulting in 31 aa changes in which 16 aa are structurally different. The multiple mutations of HA 5-1 are considered resulting from nitrous-acid induction since 86% of nucleotide changes are transition mutations. The stable HA 5-1 was used as a backbone to generate recombinants carrying individual 3’ fragments of Vietnam severe strain TG5, including NIa, NIb, and CP3’ regions, individually or in combination. Our results indicated that the best heterologous fragment for the recombinant is the region of CP3’, with which symptom attenuation of the recombinant is like that of HA 5-1. This mild recombinant HA51/TG5-CP3’ retained high levels of protection against the homologous HA in papaya plants and significantly increased the protection against the heterologous TG-5. Similarly, HA 5-1 recombinants carrying individual CP3’ fragments from Thailand SMK, Taiwan YK, and Vietnam ST2 severe strains also significantly increase the protection against the corresponding heterologous strains in papaya plants. Thus, our recombinant approach for mild strain generation is a fast and effective way to minimize the problem of strain-specific protection.

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Genetic analysis of an attenuated Papaya ringspot virus strain applied for cross-protection

European Journal of Plant Pathology ◽

10.1007/s10658-007-9130-z ◽

2007 ◽

Vol 118 (4) ◽

pp. 333-348 ◽

Cited By ~ 19

Author(s):

Chu-Hui Chiang ◽

Chun-Yee Lee ◽

Ching-Hsien Wang ◽

Fuh-Jyh Jan ◽

Shih-Shun Lin ◽

...

Keyword(s):

Genetic Analysis ◽

Virus Strain ◽

Cross Protection ◽

Ringspot Virus ◽

Papaya Ringspot Virus

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Engineered Resistance Against Papaya ringspot virus in Venezuelan Transgenic Papayas

Plant Disease ◽

10.1094/pdis.2004.88.5.516 ◽

2004 ◽

Vol 88 (5) ◽

pp. 516-522 ◽

Cited By ~ 28

Author(s):

Gustavo Fermin ◽

Valentina Inglessis ◽

Cesar Garboza ◽

Sairo Rangel ◽

Manuel Dagert ◽

...

Keyword(s):

Amino Acid ◽

Agrobacterium Tumefaciens ◽

Coat Protein ◽

Amino Acid Sequence ◽

Sequence Similarity ◽

Ringspot Virus ◽

Amino Acid Sequence Similarity ◽

Papaya Ringspot Virus ◽

Local Varieties ◽

Cp Gene

Local varieties of papaya grown in the Andean foothills of Mérida, Venezuela, were transformed independently with the coat protein (CP) gene from two different geographical Papaya ringspot virus (PRSV) isolates, designated VE and LA, via Agrobacterium tumefaciens. The CP genes of both PRSV isolates show 92 and 96% nucleotide and amino acid sequence similarity, respectively. Four PRSV-resistant R0 plants were intercrossed or selfed, and the progenies were tested for resistance against the homologous isolates VE and LA, and the heterologous isolates HA (Hawaii) and TH (Thailand) in greenhouse conditions. Resistance was affected by sequence similarity between the transgenes and the challenge viruses: resistance values were higher for plants challenged with the homologous isolates (92 to 100% similarity) than with the Hawaiian (94% similarity) and, lastly, Thailand isolates (88 to 89% similarity). Our results show that PRSV CP gene effectively protects local varieties of papaya against homologous and heterologous isolates of PRSV.

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