therefore gmo papaya preparation and techniques pdf

Therefore gmo papaya preparation and techniques pdf

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Introduction

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EXAMPLES OF GM TECHNOLOGY THAT WOULD BENEFIT WORLD AGRICULTURE

Genetically modified foods GM foods , also known as genetically engineered foods GE foods , or bioengineered foods are foods produced from organisms that have had changes introduced into their DNA using the methods of genetic engineering.

Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. Developments resulting in commercially produced varieties in countries such as the United States and Canada have centered on increasing shelf life of fruits and vegetables, conferring resistance to insect pests or viruses, and producing tolerance to specific herbicides. While these traits have had benefits for farmers, it has been difficult for the consumers to see any benefit other than, in limited cases, a decreased price owing to reduced cost and increased ease of production Nelson et al. A possible exception is the development of GM technology that delays ripening of fruit and vegetables, thus allowing an increased length of storage.

Introduction

This review focuses on the development of PRSV resistant transgenic papaya through gene technology. The concept of pathogen-derived resistance has been employed for the development of transgenic papaya, using a coat protein-mediated, RNA-silencing mechanism and replicase gene-mediated transformation for effective PRSV disease management.

PRSV-resistant transgenic papaya is environmentally safe and has no harmful effects on human health. Recent studies have revealed that the success of adoption of transgenic papaya depends upon the application, it being a commercially viable product, bio-safety regulatory issues, trade regulations, and the wider social acceptance of the technology.

This review discusses the genome and the genetic diversity of PRSV, host range determinants, molecular diagnosis, disease management strategies, the development of transgenic papaya, environmental issues, issues in the adoption of transgenic papaya, and future directions for research.

Papaya Carica papaya L belongs to the family Caricaceaeand is one of the most economically important fruit crops in many tropical and subtropical countries. Papaya is a dicotyledonous, polygamous, and diploid species. The geographical origin of papaya is Southern Mexico and Costa Rica [ 1 ].

Papaya fruit is known for its high nutritive and medicinal value [ 3 ]. Papaya is rich source of vitamin A, B, and C, as well as proteolytic enzymes like papain and chymopapain. It is an excellent source of beta carotene which may prevent cancer, diabetes, and heart disease [ 4 ]. Ripe fruits are usually eaten fresh and can be processed into jam, jelly, marmalade, and candy.

Papaya is also utilized in the pharmaceutical and cosmetics industries [ 5 ]. Papaya crops are currently beset by disease problems especially those caused by the papaya ringspot virus PRSV [ 6 , 7 ]. 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.

PRSV is the most serious threat to papaya production in the world [ 8 ]. PRSV is transmitted in a nonpersistent way by several species of aphids in a process involving coat protein CP and the helper component proteinase HC-Pro [ 17 — 19 ].

Papaya and the aphid transmitted virus are cosmopolitan in distribution [ 16 ]. PRSV is controlled by different methods such as rouging of infected plants, use of barrier crops, cross protection, and transgenic resistance [ 20 ]. PRSV disease management, via vector controlling, is very difficult to conduct whilst cross protection for controlling PRSV disease is not effective worldwide. On the other hand, several wild Carica species such as C.

The most effective method of controlling plant viruses is through enhancing population resistance [ 23 ]. Genetic transformation of plants has made it possible to introduce selected genes into plants for controlling plant diseases and pests. The concept of pathogen derived resistance has stimulated research into obtaining virus resistance in papaya through gene technology. Pathogen-derived resistance is mediated either by proteins encoded by transgenes protein-mediated or by the transcripts produced from the transgene RNA-mediated.

Recently, research has indicated that pathogen-derived resistance is mediated by an RNA-based posttranscriptional gene-silencing mechanism. Protein-mediated resistance provides moderate protection against a broad range of related viruses whilst RNA-mediated resistance offers high levels of protection to closely related strains of the virus [ 24 ].

This technology has been at the forefront of the new era in the development of eco-friendly molecular tools, which can be suppressed by specific genes which are responsible for disease management. Tecson Mendoza et al. Therefore, this review paper aims to review recent development of PRSV, genomic, diversity of PRSV, molecular identification, host-range determinants and vector transmission, biosafety, major challenges, and future research directions.

The virion contains The PRSV genome encodes a single large protein 3, amino acids which is subsequently cleaved into smaller proteins with various functions. The P1 protein is encoded by the Potyvirus genome and autocatalytically cleaves. The P1 protein is the least conserved protein and can move systemically in infected plants [ 28 ]. The helper component HC-Pro is a multifunctional protein which mediates aphid transmission, symptom expression, long distance movement, genome amplification, and suppression of posttranscriptional gene silencing PTGS.

It can affect the microRNA-mediated development pathway in plants and help in the establishment of the heterologous virus. HC-Pro is responsible for synergism between polyviruses and unrelated viruses that can cause severe symptoms and an accumulation of virus in infected leaves [ 31 ]. Nib is a codependent RNA polymerase that has been shown to have replicase activity. CP is involved in aphid transmission systemic movement and the encapsidation of the viral RNA [ 28 ].

The PRSV is divided into two major biotypes or strains based on their host range. Knowledge of the genetic diversity of PRSV is important for effective evidence-based disease management.

The genetic diversity of PRSV was observed in different regions of the world [ 34 ]. Sequence diversity among isolates of the virus and their distribution are important for establishing virus origin, development, dispersion, and disease etiology, in the pursuit of effective virus disease management. The diversity at amino acid and nucleic acid levels was highest among the Asian population of PRSV isolates [ 37 ].

Bateson et al. PRSV might have been transported from India to America in the early 18th century and spread in 19th and 20th centuries [ 40 ]. The genetic diversity of PRSV depends on geographical location.

Plant viruses spread from cell to cell with the interaction of virus and host factors. The plant viruses enter the host cell through wound sites, mechanically or via vector mechanisms. Viruses infect the plants by two further ways: short distance cell to cell movement and long distance.

Virus movements within the plant are dependent on host specific reactions. There are two strains of PRSV which can be differentiated on the basis of their host range [ 41 ]. Both strains are closely related. Chen et al. The interaction between host and PRSV is fundamental for biological interest and for developing disease management strategies.

Although, cross protection is not clearly understood at the molecular level, posttranscriptional gene silencing PTGS is effective for PRSV management when cultivating Papaya. The virus is transmitted by several species of aphids in a nonpersistent manner. Transmission occurs when aphids feed upon infected papaya plants and subsequently feed upon healthy papaya plants.

The most important step is identification of virus for effective PRSV control. PRSV diagnosis is very important as it exists in different strains [ 44 ]. The virus particle is very unstable and tends to aggregate with plant debris. PRSV is primarily diagnosed by assessment of symptoms; visual diagnosis is quick but it is also unreliable. The symptoms similar to PRSV can be due to the effects of micronutrient deficiency in soil and a variety of weather conditions.

ELISA is widely used for rapid detection in the different parts of the world as a quick and reliable technique for PRSV detection in papaya [ 34 , 45 ]. Dot immune binding assay DIBA is useful for virus indexing, as it is a simple and cheap method for large scale virus detection [ 48 ]. PRSV is the most destructive viral disease of papaya. Control of PRSV includes rouging infected plants and spraying them with aphicides. However, rouging cannot stop the spread of the disease once it is established.

Similarly, spraying with aphicides is often ineffective since the virus is transmitted to the plants before the aphids are killed [ 49 ]. The PRSV disease management has been focused on developing tolerant or resistant varieties of papaya, but these varieties are rarely planted due to poor fruit quality and vigour [ 50 ]. PRSV-resistant gene is available in some wild varieties related to the Carica species. But the development of PRSV-resistant varieties through conventional breeding methods has been complicated due to the sexual incompatibility of wild species and cultivated papaya [ 51 , 52 ].

Disease tolerance in back crosses with commercial papaya also limits this approach for PRSV disease management. Cross protection was used to control PRSV which involved the use of a mild virus strain against economic damage caused by severe strains of the same virus [ 6 , 53 ].

Cross protection depends on the availability of mild strains that can be used for effective protection against the target virus. Cross protection needs extra agricultural practice and care. However, strain specificity and the technical difficulties associated with propagating pure strains of mild forms of the virus and the unavailability of such mild strains limit the benefits of this approach [ 55 ]. Field evaluations revealed that cross protection was marginally effective for PRSV management evaluation in the field [ 8 ].

The concept of pathogen derived resistance was proposed by Sanford and Johnston [ 56 ] for developing resistance against pathogens. This research group has applied the concept of pathogen derived resistance which has stimulated research into obtaining virus resistance through gene technology.

Pathogen derived resistance is governed either by protein-mediated or RNA-mediated methods. An alternative strategy using RNA-mediated gene silencing with transgenic plants expressing viral genes has been developed [ 57 ].

Resistance levels of PRSV differ with environmental factors and plant development stages despite of the success with this approach. Broad spectrum resistance against different PRSV isolates depends on the homology of transgenes with viral target genes and the genetic divergence of different PRSV strains which are correlated with their geographical distribution [ 58 ].

The transgenic papaya varieties resistant to PRSV against different viral strains must be developed individually for various papaya growing regions. The development of PRSV-resistant lines is generally considered the best strategy for efficient PRSV disease control in papaya for long-term protection [ 20 ]. 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.

Pathogen derived genes interfere with the replication process of viruses in their host plants in different ways. 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. Fitch et al. Cheng et al. Many scientists have begun to develop PRSV-resistant transgenic papaya using different explants with plasmids containing the neomycin phosphotransferase II npt II gene [ 42 , 61 — 63 ].

Gonsalves et al. Tennant et al. Bau et al. Magdalita et al. RNA mediated gene control mechanism has provided a new platform for developing molecular tools for gene functions study and crop improvements [ 70 ]. RNA silencing pathways play a role in both biotic and abiotic stress responses in plants defence against pathogens and insects that will help humankind to face the challenges of productive agriculture in the increasingly unfavourable environmental conditions associated with climate change.

This technology can be used for generating disease resistance by suppressing a specific gene or genes [ 71 ].

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This review focuses on the development of PRSV resistant transgenic papaya through gene technology. The concept of pathogen-derived resistance has been employed for the development of transgenic papaya, using a coat protein-mediated, RNA-silencing mechanism and replicase gene-mediated transformation for effective PRSV disease management. PRSV-resistant transgenic papaya is environmentally safe and has no harmful effects on human health. Recent studies have revealed that the success of adoption of transgenic papaya depends upon the application, it being a commercially viable product, bio-safety regulatory issues, trade regulations, and the wider social acceptance of the technology. This review discusses the genome and the genetic diversity of PRSV, host range determinants, molecular diagnosis, disease management strategies, the development of transgenic papaya, environmental issues, issues in the adoption of transgenic papaya, and future directions for research. Papaya Carica papaya L belongs to the family Caricaceaeand is one of the most economically important fruit crops in many tropical and subtropical countries.


Efforts should therefore also be focused on the development of methods for the detection of non-approved GMOs like Papaya, Bt10 maize or LL rice which.


EXAMPLES OF GM TECHNOLOGY THAT WOULD BENEFIT WORLD AGRICULTURE

Contact your local county Extension office through our County Office List. Print this fact sheet. Since GM crops were introduced in the U. This fact sheet explains the technology for developing GM crops and describes GM crops currently on the market in the U.

This commentary is a face-to-face debate between two almost opposite positions regarding the application of genetic engineering in agriculture and food production. Seven questions on the potential benefits of the application of genetic engineering in agriculture and on the potentially adverse impacts on the environment and human health were posed to two scientists: one who is sceptical about the use of GMOs in Agriculture, and one who views GMOs as an important tool for quantitatively and qualitatively improving food production. Since the mids, the release of GMOs into the environment and the marketing of foods derived from GM crops has resulted in a scientific and public debate.

The emergence of high-throughput, massive or next-generation sequencing technologies has created a completely new foundation for molecular analyses. Various selective enrichment processes are commonly applied to facilitate detection of predefined known targets. Such approaches, however, inevitably introduce a bias and are prone to miss unknown targets. Here we review the application of high-throughput sequencing technologies and the preparation of fit-for-purpose whole genome shotgun sequencing libraries for the detection and characterization of genetically modified and derived products. The potential impact of these new sequencing technologies for the characterization, breeding selection, risk assessment, and traceability of genetically modified organisms and genetically modified products is yet to be fully acknowledged.

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Ты ничего не можешь с этим поделать, Дэвид. Не лезь не в свое. - Ну. Беккер кивнул. Уже в дверях он грустно улыбнулся: - Вы все же поосторожнее.

 Да, да, конечно… очень приятно. - Так вы гражданин Канады. - Разумеется. Как глупо с моей стороны. Прошу меня извинить. К человеку в моем положении часто приходят с… ну, вы понимаете.

В этом их слабость - вы можете путем скрещивания отправить их в небытие, если, конечно, знаете, что делаете. Увы, у этой программы такого тщеславия нет, у нее нет инстинкта продолжения рода. Она бесхитростна и целеустремленна, и когда достигнет своей цели, то скорее всего совершит цифровое самоубийство.  - Джабба театральным жестом указал на громадный экран.  - Дамы и господа, - он опять тяжело вздохнул, - перед вами компьютерный агрессор-камикадзе… червь.

Gene Technology for Papaya Ringspot Virus Disease Management

Звонок из Соединенных Штатов.

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