If you dont want the columns to be autogenerated, you should define like below,
<sdk:DataGrid AutoGenerateColumns="False" ItemsSource="{Binding Data.FruitName, ElementName=AccountsDDS} Name="AccountsDG" >
<data:DataGrid.Columns>
<data:DataGridTextColumn Header="YourColumName1" Binding="{Binding ColumName1}" />
<data:DataGridTextColumn Header="YourColumName2" Binding="{Binding ColumName2}" />
</data:DataGrid.Columns>
</sdk:DataGrid>