A fusarium DNA test, otherwise known as a molecular diagnostic, is a test that detects the presence of Fusarium graminearum through DNA.
Why Do a DNA Test?
F. graminearum causes fusarium head blight (FHB) in cereal crops, reducing yields and producing a mycotoxin that prevents or limits grain sales into food and feed markets.
While fungicide treatments can limit the extent of infection, they cannot prevent FHB from happening, and there are no effective means of rehabilitating fields once infected.
Testing seed before you plant will protect your crop of today and your fields tomorrow.
How is a DNA Test Done?
In cereals, FHB can be caused by four different fusarium species. The DNA test specifically detects F. graminearum, which is of particular concern due to its aggressive nature.
A fifth species, F. pseudograminearum, sometimes occurs on seed but does not cause FHB. It can be easily confused with F. graminearum in routine plate tests, but is distinguishable in the molecular diagnostic test.
The test analyzes 400 to 600 seed. Compared to conventional culture plate testing, the DNA method offers:
- Larger sample analysis. Using two to three times the amount of seed than is used in other tests gives more accurate results.
- Greater sensitivity. The process recognizes and amplifies DNA sequences that are unique to F. graminearum and reliably detects as few as eight cells of the fungus.
- Faster diagnosis. The presence of the fungus can be detected in as little as 24 hours, a quarter of the time of conventional testing.
The increased sample size, test sensitivity and specificity provides for lower testing errors and greater confidence in results. To date, 97% of samples tested at 20/20 Seed Labs Inc. using this method have been free of F. graminearum.
How long does the DNA test take?
Routine testing of samples takes two business days to complete: DNA is extracted on the day samples are received, amplified overnight and analyzed the following day. Samples must be received by 11:00 a.m. to be extracted the same day.
What does a positive test mean?
A positive test means that your sample has been exposed to F. graminearum.
A follow-up plate test is recommended to estimate the level of contamination. If the plate test is negative, it indicates a low level of contamination, less than 0.5%, or non-viable fungus.
What are the Pros and Cons of a DNA Test?
- Greater sensitivity for better accuracy. A 0.125% infected wheat sample, consisting of one-half of a fusarium-damaged wheat kernel in 400 seeds, has been shown to test positive by the DNA method. We have not tested at lower levels of infection, but believe the actual detection limit is lower.
- All cereals are eligible. DNA testing for F. graminearum is offered on all cereal crops: wheat, rye, triticale, oat, corn, and barley.
- One species only. The DNA test looks for F. graminearum only. It does not detect other fusarium species that may be responsible for FHB or other diseases, such as fusarium wilt. A Fungal Screen™ is recommended for these other fungi.
Click here for complete information on how to submit a sample for this test.