Two greenhouse experiments were conducted in 2008-2010 at College of Agriculture, Shiraz University, Iran to evaluate the effectiveness of changes in protein content, peroxidase activity, phenolic compounds, free amino acids content and proline in response to wheat streak mosaic virus (WSMV) infection, in screening resistant bread wheat (Triticum aestivum L.) genotypes. Fifteen wheat genotypes consisting of WSMV tolerant, intermediate and susceptible genotypes were grown in two randomized complete designs with three replications. The experiments only differed with respect to their inoculation (either infected or non-infected). The results indicated that viral infection increased the total protein and peroxidase activity of leaves in tolerant genotypes but viral infection decreased them in susceptible genotypes. Phenolic compounds increased in all infected genotypes but these increases are the highest in tolerant genotypes as compared to intermediate and susceptible ones. Viral infection reduced free amino acids in genotypes in general. The changes in proline content did not show a typical trend in tolerant, intermediate or susceptible genotypes. The analysis of variance indicated that the linear regression of leaf damage rating on the changes in total protein, peroxidase activity and phenols in the leaf was significant but the linear regression of leaf damage rating on the changes in free amino acids and proline in the leaf was not significant. Our results demonstrate the changes in total protein, peroxidase activity and phenolic compounds in a genotype could be used as suitable biochemical markers for assessing the WSMV tolerant wheat plants when grown under infected condition.

The complete nucleotide sequence of the coat protein (CP) gene of Bermuda grass etched-line virus (BELV), including 376 nucleotides (nt) of the region to its 5' side, was determined and compared with sequences of the other viruses associated with the genus Marafivirus, substantiating the assignment of BELV to this group. The CP gene coding sequence was 585 nt in length. Inferred amino acid sequences showed homologies among marafiviral CP gene products ranging from 41% to 59%. A non-coding sequence motif characteristic of the marafiviruses lies in the region adjacent to the CP gene to the 5' side. In contrast to various homology levels in the coding regions of the CP genes, the interspecific sequence homology in this 18 nt motif was almost perfect.

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The complete nucleotide sequence of the genome of wheat Eqlid mosaic virus (WEqMV) (excluding the poly A tail) comprised 9636 nucleotides including 5' and 3' noncoding regions of 137 and 172 nt, respectively. It contained a single ORF coding for a polyprotein of 3,109 amino acid residues and had a deduced genome organization typical of members of the family Potyviridae and with proteinase cleavage sites very similar to those of the members of the genus Tritimovirus. Pairwise and multiple alignments and phylogenetic analysis showed that WEqMV is a distinct species in the genus Tritimovirus. WEqMV and Wheat streak mosaic virus (WSMV) shared the greatest nucleotide sequence identity in the NIb and HC-Pro cistrons (63.2% and 60.8%, respectively) and the lowest sequence identity in the P1 and CP cistrons (51.2% and 51.1%, respectively). Sequence identity for the complete genome of WEqMV and WSMV was 56.8% at the nucleotide level and 50.7% at the amino acid level. WEqMV had 57.2% nucleotide identity and 50.6% amino acid identity with Oat necrotic mottle virus and 52.5% nucleotide identity and 45.5% amino acid identity with Brome streak mosaic virus. The relationship of WEqMV with other members of the family Potyviridae was more distant. Structural analysis of WEqMV protein showed presence of potential transmembrane helices in 6k1, 6k2, and P3 proteins.