This post is part of the Science Tuesday feature series on the USDA blog. Check back each week as we showcase stories and news from the USDA's rich science and research portfolio.By Jennifer Sowerwine, University of California – BerkeleyMy mouth begins to water just thinking about all the delicious fruits and vegetables I will enjoy this coming weekend celebrating the Fourth of July. And we’re lucky here in Northern California to have a wealth of fresh produce grown locally.