Acetoglycans, proteoglycans, fructose, galactose, Gactoside pearmease, and actylase are good markers for fruit starch and sugars. 

Try genes for enzymes of starch metabolism, such as invertases, fructokinase, glucokinase, sucrose synthase (SuSy).

I'm attaching you a bunch of papers about starch metabolism in a variety of species, mostly potato and Arabidopsis, but there are also a few papers about fruit. I think Patrick et al. 2013 will be interesting for you, but take a look at all of them.

I hope this helps you to get some starting ideas.

thank you very much for your answers and information,