Genetic Variability of Some Tomato Yellow Leaf Curl Virus Isolates and the Effect of the Virus on the Tomato (Solanum lycopersicom L.) Plant Content of Some Mineral Elements

Abstract

This study was conducted to isolate and identify three isolates of Tomato yellow leaf curl virus (TYLCV), infecting tomato, using polymerase chain reaction technology (PCR) and determining the nucleotide sequences produced by PCR- amplified products to determine the genetic similarity and differences amongst the virus isolates. It also aimed to analyze the plant content of mineral elements: magnesium, calcium, sodium, and potassium to determine the effect of the virus on the plant content of these elements. The laboratory experiments mentioned in this study were carried out in the Plant Virology Laboratory of the Plant Protection Department at the College of Agriculture/ Karbala University. Analysis of the mineral elements was carried out in the Soil Laboratory, College of Agriculture/ University of Kufa. A greenhouse experiment was also carried out to investigate the response of some tomato genotypes against TYLCV during the agricultural season 2018-2019. Results of PCR amplification by the CP-F and CP-R primer pair revealed the possibility of amplifying a 789bp product from each TYLCV isolate isolated from some farms located in some desert areas in Najaf and Karbala governorates. Analysis of the sequences resulting from the PCR-amplified products obtained from the viral isolates (5, 8, and 10) by BLAST Basic Local Alignment Search Tool (BLAST) indicated that all these viral isolates diagnosed in this study belong to TYLCV. TYLCV isolates 5 and 8 obtained from Najaf province had a 100% similarity in the sequences of PCR-amplified products amplified from the TYLCV coat protein. These isolates gave a difference (96%) in the coat protein nucleotide sequence of the virus isolate 10. Furthermore, analysis of some mineral elements in plants infected with TYLCV showed a decrease in the concentrations of magnesium and calcium and an increase in the concentrations of elements sodium and potassium with a significant difference from their normal concentrations in the non-infected plants.