Sweet potato leaf curl virus facts for kids
Quick facts for kids Sweet potato leaf curl virus |
|
|---|---|
Virus classification  |
|
| (unranked): | Virus |
| Realm: | Monodnaviria |
| Kingdom: | Shotokuvirae |
| Phylum: | Cressdnaviricota |
| Class: | Repensiviricetes |
| Order: | Geplafuvirales |
| Family: | Geminiviridae |
| Genus: | Begomovirus |
| Species: |
Sweet potato leaf curl virus
|
The Sweet potato leaf curl virus, often called SPLCV, is a tiny germ that infects sweet potato plants. Sometimes, people add letters after SPLCV to show where it was found, like SPLCV-Br for Brazil.
This virus is one of more than 20 different viruses that can make sweet potatoes sick. It belongs to a group of viruses called "sweepoviruses." Viruses are very common in sweet potatoes because these plants are often grown from stored roots or stems. This means viruses can build up over time and cause problems later. When sweet potatoes get sick, they don't grow as well, and their roots might not store properly. This is a big deal because sweet potatoes are a super important food crop around the world!
SPLCV usually spreads from sick plants to healthy ones with the help of tiny insects called whiteflies (Bemisia tabaci). It can also spread if you plant parts of a sick plant, like stems or roots, or if you join parts of plants together (called grafting). Even seeds can sometimes carry the virus. Scientists think that controlling the number of whiteflies is key to stopping SPLCV from spreading. In some cases, the virus has spread very quickly through a field in just two years!
Contents
What Does the Virus Look Like?
The sweet potato leaf curl virus is very small and shaped like a short rod. It doesn't have an outer "envelope" like some other viruses. Each virus particle, called a nucleocapsid, is about 38 nanometers long and 15-22 nanometers wide. (A nanometer is super tiny, much smaller than a speck of dust!) Each particle is made of 22 small parts called capsomeres. Imagine two incomplete soccer balls joined together – that's kind of what these virus particles look like!
The Virus's DNA
The virus's genetic material is a single, circular strand of DNA, about 2.8 kilobases long. Most viruses in the Begomovirus family have their DNA split into two parts, but SPLCV has only one part. This single part is similar to one of the DNA pieces found in other viruses from older parts of the world. This DNA contains instructions for the virus to make six different proteins. These proteins help the virus make copies of itself and spread.
How the Virus Makes Copies
When the virus gets inside a plant cell, its DNA travels into the cell's control center, called the nucleus. Inside the nucleus, the virus DNA makes many copies of itself.
Getting Inside a Plant Cell
Scientists are still learning exactly how SPLCV gets into a plant cell. It's a bit of a mystery right now!
Making More Virus DNA
One important step in the virus's life cycle is changing its single-stranded DNA into a double-stranded form. This first step is helped by the plant's own cell parts. The virus then uses a process called "rolling-circle replication" to make many more copies of its DNA.
The virus also makes special proteins that help it copy its DNA. One key protein is called REP. It helps start and continue the copying process. Other proteins also play roles in making sure the virus can create new copies of its DNA and spread.
Building New Viruses
After making many copies of its DNA, the virus needs to put them into new virus particles. The REP protein also helps with this step. It cuts the newly made DNA strands and helps them get packed into new virus particles, ready to infect more cells.
What Are the Symptoms?
The main sign that a sweet potato plant has SPLCV is when its leaves start to curl upwards. This is usually seen on younger plants. As the plants get older, these signs might disappear. Other symptoms can include twisted seedlings, strangely shaped flowers, and fewer seeds. Scientists often use a special test called PCR to check if a plant has the virus.
The virus can also stop the plant's pollen from developing properly. A protein from the virus, called C4, messes with how the plant grows, especially affecting the parts that make pollen.
While SPLCV is most common in sweet potatoes, it has also been seen in a type of morning glory flower called Ipomoea indica.
How the Virus Interacts with Its Host
The sweet potato whitefly (Bemisia tabac) is a tiny insect that spreads over 100 different plant viruses, including SPLCV. Both male and female whiteflies can spread the virus. They don't carry the virus for their whole lives, but they can carry it for up to 35 days.
The virus spreads in a special way called "persistent-circulative." This means the virus travels through the whitefly's body, from its gut to its blood (called haemolymph), and then to its spit glands. The virus does not make copies of itself inside the whitefly. Instead, a special helper protein from tiny germs living inside the whitefly protects the virus.
How to Control and Prevent SPLCV
Scientists have tried using bug sprays (insecticides) to stop SPLCV. A study in 2014 found that these sprays didn't really reduce the number of whiteflies. However, they did help reduce the amount of SPLCV in about half of the sprayed areas.
To control the spread of viruses carried by insects, three things are needed: a source of the virus (sick plants), insects that can carry the virus, and insects that move around. Scientists often use PCR tests to see if SPLCV has spread.
Since whiteflies are the main way SPLCV spreads, reducing their numbers might help reduce the virus. If whiteflies eat less or fly around less, it could slow down the spread of SPLCV. This is one reason why some people think insecticides could help.
However, using insecticides to control whiteflies hasn't been very successful in stopping virus diseases. In one study, only 2 out of 36 plots showed fewer whiteflies after two years of using different insecticides. Because of these results, many experts believe that insecticides aren't the best way to manage viruses in sweet potatoes.
New types of insecticides, called neonicotinoids, were also tried. But plants and insects around the world became resistant to them because they were used so much. This also led to resistance against other types of insecticides. Often, when insecticides were used to stop SPLCV, the disease actually got worse instead of better.
Despite these challenges, some studies have shown that certain chemicals, like buprofezin and pyriproxyfen, when used with neonicotinoids, have helped control SPLCV spread by whiteflies.
Related Viruses
The Sweet potato leaf curl virus is one of 322 types of viruses in the Begomovirus family. It has many close relatives, often named after the place where they were found. Some examples include:
- Sweet potato leaf curl virus Brazil (SPLCV-Br)
- Sweet potato leaf curl virus Puerto Rico
- Sweet potato leaf curl Canary virus (SPLCCaV)
- Sweet potato leaf curl China virus (SPLCV-CN)
- Sweet potato leaf curl Georgia virus (SPLCGV)
- Sweet potato leaf curl Guangxi virus
- Sweet potato leaf curl Henan virus
- Sweet potato leaf curl Lanzarote virus (SPLCLaV)
- Sweet potato leaf curl Sao Paulo virus
- Sweet potato leaf curl Sichuan virus 1
- Sweet potato leaf curl Sichuan virus 2
- Sweet potato leaf curl South Carolina virus (SPLCSCV)
- Sweet potato leaf curl Spain virus (SPLCESV)
- Sweet potato leaf curl Uganda virus (SPLCUV)
SPLCV is also related to other "sweepoviruses," which are all Begomoviruses found in sweet potatoes and other similar plants. These include Sweet potato Golden vein associated virus (SPGVaV), Sweet potato mosaic virus, Ipomoea leaf curl virus (ILCV), and Sweet potato mild mottle virus (SPMMV).
|
