Molecular Investigation of Tomato Yellow Leaf Curl Virus (TYLCV) and Identification its Isolates Disseminated in some Tomato Protected Culture in Al-Qadisiyah Province.

This study aimed at conducting a molecular investigation of some virus isolates associated with tomato yellow leaf curl disease (TYLCD). Ten tomato samples exhibiting TYLCD are collected from fields and tunnel at certain tomato growing area in Al-Qadisiyah Province (El-HamzaEl-Sharqi district, Al-Sadeer and Al-Sunnia).. Begomoviruses are investigated by Polymerase chain reaction (PCR) using Deng a genus specific primer set in symptomatic samples. The amplified DNA fragments of expected size are sequenced, analyzed and compared to equivalent Gene Bank sequences using MEGA6 software. PCR technique using Deng primers could detect begomoviruses when amplified the 540 bp DNA fragments from 6 out of 10 symptomatic tomato samples. Sequence analysis shows that sequences obtained shared 96 - 99.5% nucleotide (nt) sequence identities with Tomato yellow leaf curl virus (TYLCV) equivalent Gene bank coat protein CP sequences from Cuba (AJ223505), USA (AY530931) and Israel (AB110217). Neighbor-Joining phylogenetic tree constructed from partial coat protein region confirmed the relatedness when grouped all sequences obtained to equivalent sequences belong to TYLCV from Gen Bank but not to other begomovirus species. Sequence comparison shows that TYLCV isolates are variable when share nt sequence 91-100% (approximated)to each other’s, which indicates that sequences isolated may belong to different TYLCV strains. The high nucleotide sequence identities suggests that TYLCV may have been introduced to Al-Qadisiyah Provence through infected plant materials, however full length sequence comparisons and biological assays are required to confirm this relatedness and resolve the possible origin of TYLCV isolates in Al-Qadisiyah Province.