Next is an easy step, because I just use the previous gradient again. Here are the steps:
1. Select gradient
2. Duplicate
3. Go to DRAW >> ROTATE OR FLIP >> ROTATE RIGHT 90′
4. Position at bottom of slide
5. Stretch left/right to width of slide

With another layer a nice effect has been achieved leaving a lighter area in the top left, which creates a subtle visual motion with the darker streak (from the first autoshape)on the opposite axis:

– Troy @ TLC