The current study represents the first identification of Bean Yellow Mosaic Virus (BYMV) in bean plants (Phaseolus vulgaris) from Al-Makhwah Governorate, Saudi Arabia and nucleotide sequencing of capsid protein gene of BYMV. Thirty plant species and cultivars to twelve different families were mechanically inoculated by BYMV. Seventeen of them showed systemic symptoms mosaic, yellowing, vein clearing, stunting streaking mosaic, malformation and severe mosaic as a result of BYMV infection. Chenopodium amaranticolor and Chinopodium quinoa L. were found to be local lesion host after 4-6 days of inoculation. Two aphids, Myzus persicae Sluz. and Aphis faba were used to study the transmission of BYMV. Aphis faba was found to be the most effective vector with 60% of BYMV transmission. Immunological techniques namely Enzyme Linked Immuno Sorbent Assay (ELISA), Tissue Blot Immuno Binding Assay (TBIA) and Dot Blot Immune Binding Assay (DBIA) were amplified to study BYMV. Positive reaction was obtained and the prevalence of the virus in the flowers and seed parts was confirmed. The RT-PCR products were amplified from total RNA of bean plant tissues using specific primer BYMV1 and BYMV2 (designed on conserved sequences of BYMV NIb-CP). A cDNA fragment of 700 bp nuclear inclusion body and coat protein gene region primer (5'-NIb-CP 3') was amplified. Digoxigenin-labelled BYMV cDNA probe through Southern blot and Dot blot hybridization techniques were employed for the detection of BYMV infected bean plants. A strong positive reaction was observed with bean and faba bean infected with BYMV. A part of the 3' end of Nib-region and the 5' end of the CP region of BYMV Potyvirus Al-Makhwah KSA isolate (700 nt) was sequenced and analyzed (The DNA sequence submitted in GenBank acc.no. LC025531). Identity percentage of Al-Makhwah KSA isolate BYMV Potyvirus (NIb-CP) with a Japanese isolate was 99% and with USA gladiolus isolate and another Japanese isolate were 95% and 93%, respectively confirming that BYMV viral group is diversified mainly in some specific parts of genome, especially in the CP region, whereas NIb gene is very conservative.

Bean Yellow Mosaic Virus (BYMV) causing yellow mosaic and leaf malformation was detected and isolated from naturally infected bean plants collected from Southern region of Saudia Arabia BYMV was transmitted mechanically and identified by serologica1 tests. Light microscopy examinations revealed amorphous cytoplasmic and crystalline inclusions in bean plants infected with BYMV. Ultra structural changes in the deformed chloroplasts and grana were severe affected, chloroplasts were more affected, swollen, irregular, rupture lamella, crash grana and combination with each in the form of amoebic. The nucleus was elongated irregular with spindle like shape. The results suggest that the depressive effect in the mitotic process of Vicia faba L. was demonstrated when infected with Bean yellow mosaic virus. Remarkably, there was a progressive decrease in mitotic indices and increase in the total percentage of abnormalities due to bean yellow mosaic virus infection. Types of abnormalities revealed the induction of spindle disturbance, stickiness, laggards, fragments, bridges and micronuclei which lead to the loss of genetic material.