JOHANNESBURG, May 29 (Reuters) - South Africa's rand weakened on Tuesday morning against a stronger dollar and amid ebbing investor enthusiasm for emerging market assets.
* At 0638 the rand was 0.64 percent down at 12.5425 against the dollar after closing at 12.4250 on Monday.
* Bonds fell, with the yield on the benchmark government bond due in 2026 up 4.5 basis point to 8.485.
* The Johannesburg Stock Exchange opened lower with the Top-40 index down 0.5 percent shortly after the opening bell. (Reporting by Patricia Aruo Editing by Ed Cropley)