What does PRSV do to papaya?
Papaya exhibits yellowing, leaf distortion, and severe mosaic. Oily or water-soaked spots and streaks appear on the trunk and petioles. The fruit will exhibit bumps and the classic “ringspot”. A severe isolate of PRSV has also been shown to cause tissue necrosis.
How is PRSV transmitted?
Papaya ringspot disease is spread from plant-to-plant by aphids, which are small sap-sucking insects. There are many species of aphids that are capable of transmitting the virus.
What did the papaya ringspot virus do?
Papaya ringspot virus infects papaya and cucurbits systemically. Symptoms on papaya are somewhat similar to those on cucurbits. In papaya, leaves develop prominent mosaic and chlorosis on the leaf lamina, and water soaked oily streaks on the petioles and upper part of the trunk.
What process was used to very successfully combat ringspot virus infection of the Hawaiian papaya crop in the 1980s?
To counter the infection, scientists utilized a phenomenon known as parasite-derived resistance, in which the expression of a gene from a parasite confers resistance to that same parasite. In this case, transgenic papaya was created that expressed the coat protein from PRSV.
What gene is added to papaya?
The first commercialized transgenic papaya carrying the PRSV CP gene was introduced to Hawaii in 1998 and saved the remains of the papaya industry10. However, CP-transgenic resistance of papaya is expressed in a nucleotide-sequence-homology-dependent manner11.
How do Potyviruses enter cells?
Potyviruses replicate in the cytoplasm of infected cells, as schematically shown in Figure 4. After entering the cell, the viral genomic RNA must first be translated in the cytoplasm.
Which gene was used for development of transgenic papaya against Prsv?
Is it safe to eat papaya with ringspot virus?
PRSV-resistant transgenic papaya is environmentally safe and has no harmful effects on human health.
How can papaya Ringpot virus be prevented?
Preventive sprays Barrier crops like Jowar / Maize should be sown densely along the perimeter one month before papaya transplanting. Plastic silver coloured mulch should be laid on the field. One year crop schedule to maximise production can be attempted in areas with severe PRSV infection.
What is the PRSV CP gene?
The cp gene from PRSV encodes the coat protein (CP) gene from Papaya ringspot virus. Through a process related to viral cross-protection, transgenic lines with this gene exhibit resistance to infection and subsequent disease caused by PRSV.
How much were papaya crop yields reduced by PRSV?
The production remained high for two years following the discovery of PRSV in Puna due to massive efforts to control the spread of the virus. However, by 1995 papaya production in Puna had dropped to 39 million pounds and was down to 26 million pounds in 1998 when transgenic seeds of cultivars were released to farmers.
How many amino acids are in the PRSV genome?
Typical of potyviruses, the PRSV genome encodes a single large protein, (in the case of PRSV, 3,344 amino acids) which is subsequently cleaved into smaller proteins with various functions. The cleaved proteins are: P1, HC-Pro, P3, CI, 6K, NIa-Pro, NIb and CP ( Figure 4 ).
What kind of crops are susceptible to PRSV?
As mentioned above, the economically relevant host range of PRSV includes papaya and cucurbits, two crops that are very different in growth characteristics. Papaya is a large perennial tropical herbaceous tree while cucurbits are vegetable crops that are grown over a period of only several months.
How is PRSV transmitted from person to person?
Virions of PRSV are filamentous and flexuous measuring 760-800 x 12 nm with a monopartite single-stranded positive sense RNA as its genome. Like other potyviruses, PRSV is transmitted in a nonpersistent manner by several species of aphids. Genetically engineered (GE) papaya has been used to successfully control the disease caused by PRSV in Hawaii.
What is the thermal inactivation point of PRSV?
The thermal inactivation point (TIP) of PRSV is 54-60°C and the longevity in vitro (LIV) is about 0.3 days. The first complete PRSV genome sequence was obtained from a PRSV isolate from Hawaii (PRSV HA).
