how is papaya ringspot virus spread

Gonsalves et al. This resistance was still evident up to termination of the trials in early 1998. PRSV isolates and sequence for PRSV CP genes. The impact of the transgenic papaya in increasing papaya production in Puna is also seen by analyzing the relative bearing acres of Rainbow and the nontransgenic Kapoho (Table 2). Fig. The industry was full of hope then, but it remained to be seen whether the transgenic papaya would translate this hope to a reality. Although present in Hawaii since the 1940s, PRSV was a nuisance but not a major economic factor to Hawaii’s papaya industry since the 1960s (3). There are many countries with markets that are dependent on the political and consumer demands of importing countries. Plant Health Progress doi:10.1094/PHP-2003-1113-03-RV, Gonsalves, D., Ferreira, S., Manshardt, R., Fitch, M., and Slightom, J. Mol. 3. CP expressed by the transgene within a transgenic plant may enter another invading virus infecting the plant via a process of heteroencapsidation. (A) Healthy Puna papaya fields in 1992; APS Education Center Online Teaching Portal, Internship, REU, REEU & Work Experience Opportunities, Gonsalves, D., and S. Ferreira. After extensive experimental testing (Fig. The development of transgenic papaya to prevent infection by PRSV has been employed after the successful development of transgenic tobacco, expressing the CP gene of the tobacco mosaic virus, which showed disease resistance. Due to its success, the transgenic papaya has often been referred to as the model for the use of biotechnology to help agriculture without investments by large companies. These efforts, along with the effectiveness of the transgenic papaya in helping in the economic production of nontransgenic papaya, have allowed Hawaii to maintain significant shipments of the latter to Japan. The GMO papaya, called the Rainbow papaya, is an example of a GMO crop developed to be resistant to a virus. Picture taken in 1999. PRSV has limited number of hosts belonging to the families Caricaceae, Chenopodiaceae, and Cucurbitaceae. Transgenic papaya: A case for managing risks of papaya ringspot virus in Hawaii. A section of the trial included small replicated blocks of Rainbow, SunUp, nontransgenic Sunset, and a transgenic Sunset line 63-1. PRSV isolates and the sequence for PRSV CP genes have been presented in Table 1. PRSV-resistant gene is available in some wild varieties related to the Carica species. Furthermore, production of similar amounts of papaya can be obtained with less acreage. The reasoning is that viruliferous aphids will feed on transgenic plants and thus be purged of virus before traveling to the nontransgenic plantings within the buffer. [26] summarized the development of transgenic papaya technology and research activities by different countries but did not cover all areas of PRSV management. Fermín et al. The BITC value of transgenic papaya and nontransgenic papaya is similar and consequently transgenic papaya does not pose any increased threat to human health. This F1 hybrid should have the horticultural characteristics of current Rainbow but would likely have much wider resistance then the current Rainbow due to increase in coat protein gene dosage. However, the effectiveness of CP mediated PRSV resistance depends upon the origin of PRSV isolates. 4). On the other hand, Hsieh and Pan [83] reported that PRSV-resistant transgenic plants had a limited effect on the microbial community of the soil. PRSV infected papaya that were cut down in the foreground and healthy transgenic Rainbow papaya in the background. This could be used as a stand-alone cultivar, or it could serve as a transgenic parent for creating a new type of Rainbow by crossing the transgenic Kapoho with SunUp. Symptoms of PRSV manifest as a prominent mosaic pattern on the leaf lamina, wet-oily streaks on the petioles and upper part of the trunk, and the distortion of young leaves. Transgenic virus resistant papaya: New hope for control of papaya ringspot virus in Hawaii. 1998. Production dropped from 40 million pounds in 2001 to 36 million pounds in 2002. Cross protection needs extra agricultural practice and care. Prior to the release of transgenic papaya, Oahu growers farmed only small plots of papaya due to the effect of PRSV on production. In this review, we find that PRSV-resistant papaya varieties have been developed using CP genes or RNA interference. While it would seem prudent that SunUp should be the cultivar of choice for ensuring the resistance to PRSV in Hawaii, the demand for Rainbow has grown because the industry and market prefer that cultivar. Papaya (Carica papaya) is severely damaged by the papaya ringspot virus (PRSV). Fortunately, our research had resulted in the development of a transgenic papaya that was resistant to PRSV; in fact, an initial field trial of the transgenic papaya was established on Oahu island at about the time PRSV was discovered in Puna (2,6). Papaya fruit is known for its high nutritive and medicinal value [3]. Hsieh and Pan [83] reported that PRSV-resistant transgenic papaya had only limited effects on the microbial life within soil. 2010. Differential protection against papaya ringspot virus isolates in coat protein gene transgenic papaya and classically cross-protected papaya. We had not succeeded in obtaining a suitable transgenic papaya of the yellow fleshed Kapoho, which was by far the dominant cultivar growing in Hawaii. Transgenic flow is a major concern amongst growers, exporters, and consumers. Currently, transgenic Papaya is being grown in Hawaii and accounts for more than 70% of Hawaii’s Papaya acreage. Common scenarios were to grow transgenic plants next to mature papaya plants, which were subsequently cut after the transgenic plants were established (Fig. Although, cross protection is not clearly understood at the molecular level, posttranscriptional gene silencing (PTGS) is effective for PRSV management when cultivating Papaya. 4. Technically, the project has progressed as planned. Ruiz-Castro and Silva-Rosales [47] reported that reverse transcription and polymerase chain reaction (RT-PCR) showed reliable results for the detection of PRSV in papaya samples. [66] used gene gun technology when transferring an untranslatable CP gene for the development of a PRSV-resistant papaya variety. Help in production of nontransgenic Kapoho in Puna. Transgenic papaya via gene technology has been used for PRSV disease management. The adoption rate of transgenic papaya is still slow due to lack of engagement from farmers, who are frequently persuaded against the technology by antigenetic engineering NGO networks. Pathogen derived genes interfere with the replication process of viruses in their host plants in different ways. APSnet Feature, American Pythopathological Society. PRSV diagnosis is very important as it exists in different strains [44]. But heteroencapsidation in transgenic papaya expressing virus CP gene has limited significance in practice and environmental effects would be negligible. Generally crops with resistance to viral disease may be developed through genes derived from viral sequences providing pathogen derived resistance (PDR), genes from various other sources that can interfere with target virus, and natural resistance genes. The work on transgenic papaya up to 1998 has been presented in the APSnet Feature and other articles. Research on transgenic papaya was started in 1985. Table 2. The most effective method of controlling plant viruses is through enhancing population resistance [23]. Scientific Name. Jyoti Sharma; Jain RK; Ramiah M; Varma A, 2005. [42] reported that the CP gene is not a determinant for the infection of papaya. 2 and 3). J. 5), or to simply grow transgenic papaya among abandoned fields (Fig. 2). For example, 97–100% of the sequence homology to transgene CP was found in PRSV isolates from Hawaii whilst 89–93% sequence homology of transgene CP was found in PRSV isolates from elsewhere [8]. Efforts to deregulate the transgenic papaya were carried out by the investigators and funding for deregulation and licensing was provided by the Papaya Administrative Committee (PAC), a grower organization regulated under a USDA marketing order. Lius, S., Manshardt, R. M., Fitch, M. M. M., Slightom, J. L., Sanford, J. C., and Gonsalves, D. 1997. Researchers have preferred CP genes as the agents utilized to develop PRSV-resistant papaya [65]. The PRSV-resistant (Hawaiian) transgenic papaya variety SunUp was developed through transformation of somatic embryos with the CP gene of the Hawaiian PRSV strain [59]. A. Olarte Castillo, G. Fermin, J. Tabima et al., “Phylogeography and molecular epidemiology of Papaya ringspot virus,”, D. Gonsalves and M. Ishii, “Purification and serology of papaya ringspot virus,”, G. Chen, C. M. Ye, J. C. Huang, M. Yu, and B. J. Li, “Cloning of the papaya ringspot virus (PRSV) replicase gene and generation of PRSV-resistant papayas through the introduction of the PRSV replicase gene,”, C.-H. Chiang, C.-Y. The failure of PRSV resistance has frequently involved the silencing by suppressor proteins of viral origin [73]. PRSV is controlled by different methods such as rouging of infected plants, use of barrier crops, cross protection, and transgenic resistance [20]. Fig. The diversity at amino acid and nucleic acid levels was highest among the Asian population of PRSV isolates [37]. It is an excellent source of beta carotene which may prevent cancer, diabetes, and heart disease [4]. Manshardt [89] showed that transgenic seeds were found in 7% of nontransgenic hermaphrodite. [8] reported that the CP expression of transgenic papaya plants was lower in homozygous SunUp than hemizygous Rainbow. This review focuses on the development of PRSV resistant transgenic papaya through gene technology. On the other hand, the silencing suppressor was the main factor for the suppression of PRSV transgenic resistance [78]. This was the first result that demonstrated that CP mediated resistance can be used to control PRSV. 3. The mechanism of RNA-mediated virus resistance is also referred to as homology dependency resistance to reflect the specific mechanism of posttranscriptional gene silencing (PTGS) [75, 76]. Transgenic papaya developed by various research groups through gene technology. Red imported fire ant. The authors would like to thank the Universiti Kebangsaan Malaysia for providing financial support for the publication of this paper under the UKM-AP-CMNB-2009/1 and DPP-2013-201 grant. Fig. The disease causes severe mottling, leaf malformation, reduction of laminae, streaks and ringspot symptoms especially in fruits. RNA-mediated protection would be effective only when the transgene is highly similar to the attacking virus. The availability of PRSV resistant papaya provided options for papaya growers on Oahu island. Bau, L.-F. Chen, and S.-D. Yeh, “The ability of Papaya ringspot virus strains overcoming the transgenic resistance of papaya conferred by the coat protein gene is not correlated with higher degrees of sequence divergence from the transgene,”, D. B. Golemboski, G. P. Lomonossoff, and M. Zaitlin, “Plants transformed with a tobacco mosaic virus nonstructural gene sequence are resistant to the virus,”, T. Nunome, F. Fukumoto, F. Terami, K. Hanada, and M. Hirai, “Development of breeding materials of transgenic tomato plants with a truncated replicase gene of cucumber mosaic virus for resistance to the virus,”, X. Wei, C. Lan, Z. Lu, and C. Ye, “Analysis on virus resistance and fruit quality for T4 generation of transgenic papaya,”, S. Sakuanrungsirikul, N. Sarindu, V. Prasartsee et al., “Update on the development of virus-resistant papaya: virus-resistant transgenic papaya for people in rural communities of Thailand,”, Y.-T. Hsieh and T.-M. Pan, “Influence of planting papaya ringspot virus resistant transgenic papaya on soil microbial biodiversity,”, M. Roberts, D. A. Minott, P. F. Tennant, and J. C. Jackson, “Assessment of compositional changes during ripening of transgenic papaya modified for protection against papaya ringspot virus,”, R. Stone, “China plans $3.5 billion GM crops initiative,”, C. Gonsalves, D. R. Lee, and D. Gonsalves, “The adoption of genetically modified papaya in Hawaii and its implications for developing countries,”, G. Fermin, V. Inglessis, C. Garboza, S. Rangel, M. Dagert, and D. Gonsalves, “Engineered resistance against Papaya ringspot virus in Venezuelan transgenic papayas,”, N. Phironrit, B. Phuangrat, P. Burns, and W. Kositratana, “Determination of possible impact on the cultivation of PRSV resistant transgenic papaya to rhizosphere bacteria using the community-level physiological profiles (CLPP),” in, R. Manshardt, “Is organic papaya production in Hawaii threatened by crosspollination with genetically engineered varieties,”, S. D. Yeh and D. Gonsalves, “Practices and perspective of control of papaya ringspot virus by cross protection,” in, G. Fermín, R. C. Keith, J. Y. Suzuki et al., “Allergenicity assessment of the papaya ringspot virus coat protein expressed in transgenic rainbow papaya,”, H. T. Lin, G. C. Yen, T. T. Huang, L. F. Chan, and et. So far, we have not observed breakdown of resistance of Rainbow in Puna or on Oahu. Resistance created by the introduction of replicase gene was first demonstrated for the tobacco mosaic virus (TMV) in Nicotiana tabacum [79]. Papaya ringspot. The approach has been to utilize the coat protein gene from the country of origin and to transform papaya that are grown in that country. The long distance movement and genome replication of HC-Pro depends on PTGS suppression [30]. Fuchs and Gonsalves [23] reported that gene flow is quite low among papaya as most of the papaya was hermaphrodite in Hawaii. 2003. Thus, research efforts to develop control measures for PRSV were initiated in 1978 starting with purification and characterization of PRSV, the development of a mild mutant, and the testing of cross protection. Online. In Thailand, the transgenic papaya has been field trialed extensively (Vilai Prasartsee, personal communication), two lines were selected for their horticultural characteristics and resistance, and the processes for deregulating the transgenic papaya are well under way and moving along. The results were dramatic, all nontransgenic plants became infected within 11 months of starting the field trail while none of the transgenic test plants became infected (Fig. The cultivars were commercially released in May 1998, six years to the month after PRSV was discovered in Puna. Therefore, country-specific varieties of PRSV-resistant transgenic papaya should be developed through PTGS technology using geographically distinct PRSV isolates. Recently, research has indicated that pathogen-derived resistance is mediated by an RNA-based posttranscriptional gene-silencing mechanism. The C1 protein of PRSV has NTP binding, NTPase, RNA binding, and RNA helicase activity [32, 33]. [68] developed genetically engineered papaya using the CP gene of Philippine PRSV and regenerated putative transgenic R0 plantlets, which were moderately susceptible whilst R1 plantlets were completely resistant. Papaya has been cultivated in the USA, India, Brazil, Mexico, Nigeria, Jamaica, Indonesia, China, Taiwan, Peru, Thailand, and the Philippines [2]. Transmission occurs when aphids feed upon infected papaya plants and subsequently feed upon healthy papaya plants. Bateson et al. There is little sequence variation among the CP genes of PRSV isolates from the USA and Australia [35, 36]. However, as noted above, the red-fleshed SunUp is not the preferred cultivar in Hawaii. ‘Lioness’ is resistant to zucchini yellow mosaic virus, watermelon mosaic virus, papaya ringspot virus, and cucumber mosaic virus. The CP gene can carry determinants for pathogenicity and the properties of the virus in transgenic plants might be changed. Transgenic papaya fruit can be recognised as an equivalent substitution for traditional papaya in food safety [92]. Alternatively, we backcrossed Rainbow F2 plants with Kapoho four times to obtain backcrossed lines that were subsequently self-pollinated. Phironrit et al. Pathogen-derived resistance is mediated either by proteins encoded by transgenes (protein-mediated) or by the transcripts produced from the transgene (RNA-mediated). Major challenges face the adoption of transgenic papaya which include the application of the biotechnological protocols for the development of transgenic papaya, its viability as a commercial product, biosafety regulatory issues, and trade regulations. Picture taken in 1999. The reduction in virus inoculum allowed for strategic planting of nontransgenic papaya in areas that were free of infected plants and were not surrounded by areas of infected plants, such as had been present in 1992. Md. The petition to the MAFF was approved in December of 2000. The PRSV is divided into two major biotypes or strains based on their host range. Picture taken in 1999. Transgenic Virus-Resistant Papaya: From Hope to Reality in Controlling Papaya Ringspot Virus in Hawaii. On the other hand, posttranscriptional gene silencing (PTGS) technology is possibly a more powerful and effective method for the development of PRSV-resistant transgenic papaya. A subsequent APSnet Feature will provide details on research done to document the adoption of the transgenic papaya by farmers soon after it was released. 8. Therefore, PRSV-resistant papaya is environmentally safe and suitable for human consumption. CP is involved in aphid transmission systemic movement and the encapsidation of the viral RNA [28]. By 1999 healthy fields of transgenic papaya were commonly seen as opposed to the period of 1994-1998 where it was very difficult to find healthy papaya fields in Puna (see Fig. Papaya crops are currently beset by disease problems especially those caused by the papaya ringspot virus (PRSV) [6, 7]. Since the resistance of transgenic papaya can be narrow, the transgenic papaya was targeted for resistance to viral strains in their countries. The virus is transmitted by several species of aphids in a nonpersistent manner. (A) Healthy Puna papaya fields in 1992; (B) Severely PRSV-infected papaya fields in 1994 that were abandoned. Thus, technology has moved along, and the major challenge will be to see how political processes proceed toward decisions on whether this technology will actually be used to fight this very severe problem in Thailand, Jamaica, and other countries. So, vector nontransmissible virus in transgenic plants would be transformed into a transmissible virus through heteroencapsidation resulting in new viral epidemics. The genus is named after the type virus (potato virus Y).Potyviruses account for ~30% of the currently known plant viruses. The micropropagation of the papaya also has the added benefits of ensuring the production of only hermaphrodite plants demanded by the market, earlier and lower bearing trees with initially higher yields, and providing selected, superior clones that could result in improved quality and yield. PRSV has been recognized as a destructive disease in many tropical and subtropical areas including the USA, South America, Africa [9], India [10], Thailand, Taiwan, China and the Philippines [11], Mexico [12], Australia [13], Japan [14], French Polynesia, and the Cook islands [15] resulting in the decline in fruit production. The virus is transmitted in a non-persistent manner, meaning that the virus does not multiply within the aphid but is instead carried on its Gonsalves, D., and S. Ferreira. Fire ant biosecurity zones map (PDF, 5.2MB) Sugarcane plant pests. Papaya ringspot virus is transmitted from infected papaya trees to healthy trees by the feeding action of various species of aphids, especially the green peach aphid and melon aphid. This section provides only a brief summary. In 1992, Puna produced 53 million of the state’s 55 million pounds of fresh papaya. Growers on Oahu enjoy a niche market, growing Rainbow papaya for residents in Honolulu and other urban areas of the island. [74] suggested that HcPro is an important component which needs to be taken into consideration for the development of PRSV-resistant papaya on the Indian subcontinent. This latter observation is attributed to the higher level of production of Rainbow compared to nontransgenic Kapoho. Lee, C.-H. Wang et al., “Genetic analysis of an attenuated Papaya ringspot virus strain applied for cross-protection,”, C. H. Wang, H. J. Bau, and S. D. Yeh, “Comparison of the nuclear inclusion b protein and coat protein genes of five papaya ringspot virus strains distinct in geographic origin and pathogenicity,”, S. D. Yeh, H. J. Bau, Y. H. Cheng, T. A. Yu, J. S. Yang, and R. A. [42] reported that replicase gene (RP) conferred resistance to PRSV in transgenic papaya. A practical consequence is that increasing the transgene dosage can lead to increased resistance. Resistance levels of PRSV differ with environmental factors and plant development stages despite of the success with this approach. Ripe fruits are usually eaten fresh and can be processed into jam, jelly, marmalade, and candy. There have been some studies upon the development of PRSV-resistant varieties of C. papaya through gene technology but no review article on PRSV disease management is available.

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