May 30 (Reuters) - Shareroot Ltd SRO.AX :
* US online car sales giant signs up to sro's advanced tier SRO.AX
* Autotrader has signed up to the Shareroot ugc platform in shareroot's largest
deal to date
* Under the 12-month contract, autotrader will pay a monthly subscription fee
* Source text for Eikon ID:nASX52G18Z