Wheat (Triticum aestivum L.) as the most abundant ceraeal, plays an important role in providing energy, carbohydrates and plant protein for humans. The wheat streak mosaic virus (WSMV; Genus Tritimovirus; Family Potyviridae) causes significant annual damage to cereal production, especially wheat, in many regions of the world including Iran. This virus has a single-stranded RNA genome with positive polarity (+ssRNA) and is transmitted in nature by the wheat cur mite, WCM (Aceria tosichella) (Eriophyidae). This research was conducted in two separate studies. In the first study, to determine the genetic diversity of WSMV, a total of 196 leaf samples showing streak mosaic symptoms were collected from wheat and barley fields in Isfahan and Chaharmahal and Bakhtiari provinces, during the years 2022 to 2024. Total RNA extraction was performed using the CTAB method, and RT-PCR was carried out using the specific primer pair WSMVF/WSMVR to detect WSMV. The results indicated the presence of WSMV in hosts such as Bermuda grass, foxtail, Johnson grass, Aegilops sp., oats, rye, millet, and crabgrass, in addition to wheat and barley. Among the samples in which a 948 bp fragment was amplified, six isolates from different region related to hosts Aegilops sp., Bermuda grass, wheat, millet, and barley were sequenced using the Sanger method. The quality of sequences was assessed using Chromas software version 2. 6. 6 and compared to other sequences available in GenBank using BLASTn. The BLASTn analysis showed a high nucleotide similarity to the WSMV sequences. Multiple sequence alignment of the sequences in this study along with other sequences available in GenBank and the construction of a phylogenetic tree using the Neighbor-joining method with bootstrap validation of 1000 were performed using the DNAMAN X software version 10. 02 The results of the alignment indicated a nucleotide identity of these isolates with the WSMV sequences available in GenBank ranging from 96.56% to 97.92%. These findings demostrate the high similarity of these isolates at the nucleotide level despite host differences. Based on the phylogenetic tree, the isolates of this study grouped within the Iranian Plateau isolates and were closely clustered with the Saadatshahr isolate. In the second study, the transmission efficiency of two WSMV isolates (Kouhrang and Dehaghan) was eva‎luated by two WCM populations from genotype type 2 (Kouhrang and Dehaghan) in two developmental stages (immature and mature) in a factorial arrangement within a completely randomized design with six treatment combinations. The treatments for each developmental stage included a total of 360 pots, arranged in 20 biological replicates (each pot being one biological replicate) and three statistical replicates. After the transfer of individuale viruliferous mites to the wheat plants at the two-leaf stage, plants showing symptoms were counted 30 days post-inoculation. To confirm the infection of plants, RNA extraction and RT-PCR were conducted using the specific primer pair WSMVF/WSMVR. The results from the analysis of variance and mean comparison of transmission efficiency indicated that the type of virus isolate plays a key role in determining transmission efficiency and that there are significant differences between the transmission efficiencies of the viral isolates. It was also observed that immature mites had higher efficiency than mature mites in transmitting WSMV. The interaction effect of the developmental stage and the viral isolate was also significant. Regarding the mite populations, the results showed no significant difference in transmission rates between the two populations Kuhareng and Dehaghan.

امير مساح

لادن طلايي

نفيسه پورجواد , حسن كريم مجني