Canna yellow streak virus

Keith Hayward of Hart Canna, the UK National Canna Collection, has reported to the International Canna Group that the formal report on this new canna virus has now been published: "Archives of Virology" (2007) 152: 1527-1530. "Canna yellow streak virus: a new potyvirus associated with severe streaking symptoms in canna" WA Monger, V Harju, SE Seal, RA Mumford. You can read a summary on the website http://www.springerlink.com/content/0304-8608, though to download the full article you need to be a subscriber.

Keith provided the Central Science Laboratory with most of the diseased and healthy stock, and so the author has kindly sent him a reprint, which Keith is kindly sending a copy on to us as well.

They say that there are now 5 viruses which are known to infect cannas:

1. Canna yellow streak virus CaYSV (the new virus)
2. Canna yellow mottle virus CaYMV
3. Bean yellow mosaic virus BYMV
4. Cucumber mosaic virus CMV
5. Tomato aspermy virus TAV
   

Test results

They screened 14 samples for each of the 5 viruses.

• 7 samples were showing severe symptoms of virus disease and 7 looked healthy.
• CaYSV was detected in all the 7 diseased-looking samples.
• Of these 7 diseased-looking samples, 3 were also infected with CaYMV and 2 were also infected with BYMV.
• 2 of the 7 diseased-looking samples were infected only with CaYSV.
• 2 samples that looked healthy were infected with CaYMV.
• No sample that looked healthy was infected with CaYSV.
• None of the samples tested positive for CMV or TAV (by ELISA).

It therefore seems that, in these tests, the predominant cause of severe visible symptoms of disease was the new virus CaYSV.

They say that the closest relation in the virus world to CaYSV is the Johnsongrass mosaic virus JGMV which infects grass and cereal crops in Australia and the USA.

Keith said that he is hoping that the CSL will continue to do research on canna virus.

A revelation

An interesting new angle is that, this year, Keith was sent 5 rhizomes of C. tuerckheimii collected in the wild in a distant part of Belize, with no other cannas for miles. When he grew them, guess what? They all had rampant virus disease! So, virus is not just a disease of cultivated canna, it also exists in the wild.

Now we are starting to understand the problems...