Occurrence and Spread of Sugar Beet Rhizomania Disease Caused by Beet Necrotic Yellow Vein Benyvirus in Some Governorates of Egypt
Occurrence and Spread of Sugar Beet Rhizomania Disease Caused by Beet Necrotic Yellow Vein Benyvirus in Some Governorates of Egypt
S.Y.M. Mahmoud1 and M. Hashem2
ABSTRACT
Beet necrotic yellow vein Benyvirus (BNYVV) is the important soilborne virus disease in the production areas of sugar beet. In this study. field survey was carried out in sugar beet growing areas belonging to Kafr-ElSheikh, El-Beheira, El-Dakahlia, El-Gharbia. and Minia Governorates. The results of this survey revealed the presence of characteristic symptoms of rhizomania syndrome. i.e., stunted, and constricted roots which developed proliferation of rootlets. The foliar symptoms appeared as yellowing rounded patches in the field, including general chlorosis, wilting and necrotic vein yellowing. Samples Of rhizomania-like symptom roots and its adjacent soil were taken from these areas and tested for the presence of BNYVV using indirect DAS-ELISA with specific polyclonal antibodies to C-terminal 60 amino acids of BNYVV coat protein and bait plants test, respectively. The results confirmed the presence of BNYVV in 46 out of 184 and 24 out of 50 root and soil samples, respectively. The virus was found with percentage of 65% in root samples collected from Kafr EI-Sheikh. The transmission experiments indicated that BNYVV was mechanically transmitted to Chenopodium amaranticolor, C. quinoa, Beta Vulgaris cvs. Pleno. Tripl and Gloria. D. macrocarpa and B. maritema inducing chlorotic local lesions spreads into the veins. The virus was also transmitted by a soilborne parasitic fungus, Polymyxa betae Keskin as a vector and by seed coating with viruliferous cystosori. the thick-walled resting spores of P. betae. as well as by root vortexing in virus inoculum containing carborundum. The virus is not adsorbed to the exterior of the fungal vector but is internalized. Our results indicated that BNYVV is a widespread in sugar beet in Kafr EI-Sheikh Governorate. thus, precaution methods must be taken for reducing virus transmitting to other free-virus regions.
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