plot in the x-axis a rotate labels in R

plot in the x-axis a rotate labels in R

I've to plot these data:
day temperature
02/01/2012 13:30:00 10
10/01/2012 20:30:00 8
15/01/2012 13:30:00 12
25/01/2012 20:30:00 6
02/02/2012 13:30:00 5
10/02/2012 20:30:00 3
15/02/2012 13:30:00 6
25/02/2012 20:30:00 -1
02/03/2012 13:30:00 4
10/03/2012 20:30:00 -2
15/03/2012 13:30:00 7
25/03/2012 20:30:00 1
in the x-axis I want to label only the month and the day (e.g. Jan 02 )
rotating of 45 degree. How can I do this using the command plot()?