Viruses Genomes - BEAN GOLDEN YELLOW MOSAIC VIRUS

Bean golden yellow mosaic virus (BGYMV), is a whitefly ( Bemisia tabaci) transmitted virus that is is a serious bean disease in Central America, the Caribbean and southern Florida. Most frequently the common bean (Phaseolus vulgaris L.) is affected which in these regions constitutes a major component of dietary protein.

The most striking foliage symptom is a bright yellow or golden mosaic. Leaf wrinkling and rolling is also apparent, along with plant distortion and stunting. Infected pods may be malformed, stunted and show mosaic spots, while the seeds therein are discoloured, malformed and reduced in size. Individual diseased plants bordered by healthy ones are commonly seen. Yield losses can reach 100% if plants are infected early in development however, disease incidence and the extent of losses vary depending on populations of the whitefly vector (Bemisia tabaci Genn.), environmental conditions, and cultural practices.

Spread of the BGYMV virus relies on the insect vector, the whitefly ( Bemisia tabaci). The adult is a snow white, moth like insect about 1/32" long with piercing-sucking mouthparts. Whiteflies have a wide host range involving several hundred species in more than 70 plant families. They congregate, feed, mate and lay eggs on the underside of the leaves of the host plant. The whitefly has a minimum acquisition time of 15 to 30 Minutes. This is the least amount of time it takes for the insect to acquire the virus from the plant tissue. After acquisition, a latent period, estimated to be at least four to six hours, is necessary before the whitefly becomes infective. The virus must be absorbed from the insect's digestive tract and travel to the accessory salivary glands and into the saliva before plant infection can occur. There is no evidence of virus replication in the vector. Once acquired, the virus may be retained several days (perhaps 20 days or more), but does not pass through the egg to the offspring. Reservoirs of the virus are ornamental plants or other vegetables from which the whitefly can acquire the virus.

Measures that might help control the disease include isolation of bean fields from virus reservoir plants and whitefly susceptible crops, remove crop residue after harvest and maintain fields free of volunteer plants that could serve as sources of virus inoculum during the crop free period, plant at a time that will expose the young bean plants to the lowest whitefly activity and controlling the vector with pesticides.

References:

http://www.apsnet.org/phyto/pdfs/2000/0905-01R.pdf.
http://www.css.msu.edu/bic/PDF/BGYMV.pdf
http://gemini.biosci.arizona.edu/viruses/bgymv/
http://www.imok.ufl.edu/LIV/groups/IPM/path/bgmosaic.htm