Diospyros virginiana In respect to the power of making heartwood, the persimmon rarely develops any heartwood until it is nearly one hundred years old. This heartwood is extremely close-grained and almost black, resembling ebony (of which it is a true variety). It is a common misconception persimmon fruit needs frost to ripen and soften, called bletting. Some, such as the early-ripening varieties "pieper" and "NC21"(also known as "supersweet"), easily lose astringency and become completely free of it when slightly soft at the touch—these are then very sweet, even in the British climate. On the other hand, some varieties (like the very large
Genetically modified tomato function of genes naturally present in tomatoes. Wild tomatoes are small, green and largely unappetizing, but after centuries of breeding there are now thousands of varieties grown worldwide. Agrobacterium-mediated genetic engineering techniques were developed in the late 1980s that could successfully transfer genetic material into the nuclear genome of tomatoes. Genetic material can also be inserted into a tomato cell's chloroplast and chromoplast plastomes using biolistics. Tomatoes were the first food crop with an edible fruit where this was possible. Tomatoes have been used as a model organism to study the fruit ripening of climacteric fruit. To understand the mechanisms