NIAB News Archive - August 2007
NIAB warns: Microdochium seedling blight hits 9 year high – test your home-saved seed
[Posted August 2007]
Early results from NIAB’s seed testing laboratory in Cambridge are showing that Microdochium seedling blight is at its highest level in seed lots since 1998. Many samples are showing high levels of infection with some seed lots showing over 50% infection. This is due to the warm spring followed by prolonged periods of rain during anthesis and beyond experience across the UK that were ideal for the development of Microdochium seedling blight. However where growers have timed their ear wash sprays well they have kept the infection levels lower and 30% of seed lots have not required a seed treatment to control Microdochium infection.
On a more positive note levels of bunt are at a very low level with over 95% of seed lots not requiring treatment for this disease.
NIAB plant pathologist Dr David Kenyon said “ Where seed is to be home-saved then it is important that it is tested for both Mycodochium seedling blight and Bunt to ensure that it is suitable for use as seed.”
Dr Steve Jones, manager of the seed quality laboratory said: “This year we are seeing much higher levels of dormancy in wheat samples than previous years, some samples showing 10-15% fresh (dormant) seeds. The dormancy may well disappear on storage but in extreme cases may also contribute to uneven field emergence.”
Overall quality is still good with nearly 90% of seed lots having 85% or better normal germinating seedlings. But this is not as good as last year, where 96% of wheat samples tested achieved this level.
For further information contact Dr David Kenyon
Key barley genes under the microscope
[Posted August 2007]
NIAB scientists have recently published the results from a study of gene diversity in large set of popular modern and historic barley varieties collected from around Europe. A paper in the journal of Theoretical and Applied Genetics published online on 24th August investigates naturally occurring DNA sequence variation occurring in two genes known to be responsible for the determination of seasonal growth habit of barley varieties – the characteristic that makes a variety suitable for autumn or spring sowing. In the process of cataloguing variation in more than 400 UK & European varieties, three previously unknown variants of one of the genes were discovered. Once these variants were fully described, it was possible to establish a virtually perfect correlation between growth habit and DNA profile, a goal which has eluded researchers until now.
“Understanding how functionally distinct forms of genes are distributed in such a wide set of relevant materials has several practical uses”, says study leader Donal O'Sullivan. “First of all, when transferring desirable traits from spring to winter varieties and vice versa, breeders can use this information to select for growth habit based on the results of a rapid laboratory test rather than in the field over the course of an entire growing season. Another benefit for breeders and researchers is being able to tell if potentially useful variants are missing from current varieties and to identify a number of possible historic sources from which those ‘lost’ variants may be recovered and evaluated. Looking to the future, the picture we hope to build up by looking not at just one gene at a time, as we have done to date, but at thousands simultaneously, is to reveal unfavourable linkages of desired gene variants to ‘poor’ gene variants in the linear DNA sequence and to provide the data and tools to breeders to restore ‘good’ to ‘good’ linkages”.'
An example of such an unfavourable linkage was published by Dr. O’Sullivan’s team last year in the journal Molecular Breeding. A major finding of that paper was that the vast majority of winter barley varieties across Europe carry a single variant that encodes a medium thermostability form of the beta-amylase enzyme, crucial in determining malting potential and this is thought to be due to selection for a form of the nearby VRN-H2 gene conditioning winter growth habit. The malting quality of future winter varieties might benefit by being bred from the few known sources which contain the winter growth habit gene linked to alternative higher thermostability beta-amylase sources.
More information can be obtained from the NIAB Research Publications page or by contacting Donal OSullivan
Seed Health Warnings
[Posted August 2007]
The warm spring followed by prolonged periods of rain during anthesis and beyond experience across the UK have been ideal for the development of Fusarium ear blight and Microdochium seedling blight. Cereal ear samples submitted to NIAB have already shown that both diseases are regularly found this year with Fusarium species, including those known to potentially result in mycotoxins, being most commonly present this year. This is in contrast to the last couple of years where seed has been relatively free from disease. Unfortunately for growers there are no measures that they can now take to avoid mycotoxins developing but where seed is to be home-saved then it is important that it is tested for Mycodochium seedling blight to ensure that it is suitable for use as seed.
For further information contact Dr David Kenyon, Plant Pathologist.