The isobaric tags for relative and absolute quantitation (iTRAQ)-based proteome analysis reveals that streptomycin treatment alters the protein accumulation profile in ‘Shine Muscat’ grape flower clusters

Seedless grapes occur naturally or through the treatment of flower clusters with streptomycin (Stm) and/or gibberellic acid (GA). Stm inhibits protein synthesis in plastids and is an antibiotic used as a pesticide. The molecular mechanisms underlying their effects remain unclear. Therefore, we analyzed protein abundance using Stm-treated flower clusters of the ‘Shine Muscat’ grape 6 h after the treatment; similarly, the effect of GA treatment was also investigated. The isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomic analyses detected 3,386 non-redundant protein groups in Stm- or GA-treated flower clusters and revealed that these treatments altered the protein profiles in grape flower clusters. The common differentially expressed proteins (DEPs) significantly upregulated by Stm- or GA-treatment were annotated as a sucrose transporter domain-containing protein and a Phi-class glutathione S-transferase (GST), whereas the common significantly downregulated DEPs were annotated as a dehydroascorbate reductase-class GST and a fatty acyl-CoA reductase. These DEPs are potentially involved in the seedless effect of Stm or GA through the inhibition of pollen and ovule development. A few DEPs are encoded by the chloroplast/mitochondrial genome; the nuclear genome encodes most of the DEPs. Stm also demonstrated its inhibitory effect on seed development in rice and Arabidopsis. Overall, these findings reveal that Stm induced seedlessness in crops other than grapes and citrus, indicating that the Stm-mediated seedlessness is conserved in other plants.