I checked our yeast database for this strain but unfortunately we do not have it. However, i had very good experiences with just asking other researchers which have used it, either they will provide it directly or the they might be able to hint to you where to get it. Here is one publication which describes the use of this strain:

http://www.plantcell.org/content/21/9/2928.long#sec-17

Obviously it might very well be that you already tried that, in this case, disregard my suggestion.

Best Regards and good luck finding the strain.

Thank you for your kind reply Michaela.

I will contact the corresponding author of the article you linked.

Best regards

Dear Dr. Sabina Berne,

 I am working at student of max planck institute for molecular plant physiology of Alisdair Fernie.  I read your question ask for the YTK12 strain in the Research gate.

I want to ask for the  invertase-deficient S. cerevisiae YTK12 strain with sucrose transporter and pSUC2 vector.

Does you still have this train and vector?

Cheers

Youjun 

Unfortunately not.