Hi Candra,

I know that Prof. Anders Kvarnheden (Swedish University of Agricultural Sciences,

Department of Plant Biology and Forest Genetics) is working on geminiviruses. Maybe you can ask him for more information.

Cheers, Nadine

there are hundreds of geminiviruses, and hundreds of crops or non-crops that can be hosts. I think you should provide more details on your personal interests in order to receive proper answers.

I am guessing that you are working with begomoviruses? pls be more specific. If you are interested in mastreviruses I might be able to help but still as Gian said for one virus can have tens of hosts.

Hi. You could contact the Brazilian scientists Alice Nagata (Embrapa), Murilo Zerbini (Universidade Federal de Vicosa).

I am from India. I am facing same problem in Sunflower we screened all the available germplasm lines in field as well as controlled conditions. Out of 2140 accessions non of the line found resistant to Sunflower Necrosis Disease. We have lots of susceptible checks for Geminivirus but we don't have resistant checks. Now we are screening 48 wild species against this virus. Some of the wild species found tolerant to SND. Please discuss with crop specialist or good virologist for the same.

Thank You,

Dear Mam,

if u hv tissue culture lab facilities go through embryo rescue...

before it u should knw the inheritance pattern of resistant gene

but it is difficult to breed for single virus because so many secondary infection of the same group so i would like say think

some othr way like breeding against nuclear material DNA or RNA or both.....

Please contact Dr. Stephan Winter of DSMZ , Germany by email at stephan.winter@@jki.bund.de

He is an authority on Geminivirus.

Good luck

Abolade S Afolabi

Hi, my wife has done some research on gemini viruses affecting cassava cultivars during her masters course. her contact [email protected].

Dr.Maruthi Gowda, my friend and faculty working with Natural Resources Institute, University of Greenwich, UK has done some good work in this area. www.nri.org

For any clarifications, don't hesitate to contact me

good luck

siddick

Thank you for the contributions. Let me specify my interest. I have tens of tomato, hot pepper, eggplant, long bean, cucumber, loofah, and melon accession lines which will be screened for whitefly transmitted - virus (geminiviruses) resistance. I wish anyone could provide me any information about resistant check of those crops (differential varieties name/code/number).

Hi, your list includes several different plant families you are interested in. Unfortunately, there will be different species of Begomovirus (whitefly-transmitted Geminivirus) attacking these different families and different sets of species in different locations/countries. Thus there is no definitive list of resistant check varieties you can use as the few known resistances may only be effective against the Begomovirus species in certain locations. Of the plant species you mention, tomato is probably the most advanced in terms of known resistance genes - they are known as Ty-genes (from Tomato yellow leaf curl resistance), and come from the wild relatives of tomato such as Solanum habrochaetes. Ty-1/Ty-3 and Ty-2 are widely used in commercial hybrid tomato so you could look out for these to include in your screening. Otherwise, Peter Hanson here at AVRDC is pyramiding different combinations of Ty-genes in his advanced breeding lines - different combinations of Ty-genes may be more effective in different locations. See http://www.avrdc.org/ or send me a message for more detail. Lawrence

Hi Candra, I wish to add my advice to that of Lawrence! I work with cassava mosaic disease, a geminivirus that has devastated smallholder cassava crops in Africa. I also do transmission studies using the whitefly, Bemisia tabaci. First you will have to set up the trials in insect proof screen/greenhouses to ensure that the plants do not get infected with other viruses that might distort your study. Then, carry out seperate screening studies for each crop, using known susceptible and resistant checks and geminivirus inoculum sources. But, note that whiteflies preferentially infest or colonise different varieties and this will affect the transmission of the geminiviruses to these varieties. What then might arise is screening for whitefly resistance and not necessarily virus resistance. Lastly, we see in Africa different whitefly (B. tabaci) infesting different crops and so take care to use whitefly that are known to infest/colonise the specific crops. I hope this helps. Peter Sseruwagi

For developing differentials, why don't you take advantage of one of my article dealing with the subject. You can adopt the strategy i develop for you study.

the article is in the European Journal of Plant Pathology

Hi,

I have been working in Dr. Anders Kvarnheden's group for 6 years with Geminiviruses. Please explain me what help do you want. I shall try to help if I can.

Best Regards,

I hope I can help with some information regarding begomoviruses in tomatoes. First of all, it is known that there is no resistance gene for tomatoes that confers immunity to infection to any of the begomos. Lawrence and Peter comments are important and should be taken into consideration. So, if there is no resistant material, it is always difficult to do a screening test. If you inoculate in a too high pressure, all the plants will become infected and possibly with severe symptoms. Therefore, it is essential to set experiments with some controls. I believe resistant hybrids will be available in your country as commercial materials. Contact the seed company distributors, Try them, and always include a susceptible material. Try also to test two different whitefly populations, maybe 5 and 20 insects per plant. In Brazil, it is difficult to do a screening for begomos by whiteflies, as crinis may be present. This comment can be applicable to other hosts. As a first step, I would advise you to go to the field and talk with growers and extension service. They know a lot.

Good luck, Alice

I worked on tomato breeding for TYLCV resistance. Resistance to TYLCV has been discovered in numerous wild tomato species, including S. pimpinellifolium, S. peruvianum, S. chilense, S. habrochaites, and S. cheesmaniae. In contrast, cultivated tomato (Solanum lycopersicum L.) is highly susceptible to TYLCV.

Hi, I also a plant virologist on begomovirus. We found that many geminivirus (we work on begomoviruses) resistant crops is not due to the incapable replication of the viruses but due to the endurance to the replication of the viruses. Although no obvious symptoms can be observed on the plants, the viruses do replicate on it. In fact, the viral replication quantities are similar between resistant and susceptible varieties. I hope this information will help you in your research.