【英语时差8,16】培育葡萄（在线收听）

Grapes are one of man’s oldest cultivated crops. Ancient hieroglyphics show Egyptians harvesting grapes. Greeks, Phoenicians, and Romans used grapes for food as well as wine. Today, about seventy-percent of harvested grapes are used to make wine. Wine makers grow special cultivars to obtain specific color, clarity, sweetness, acidity, balance, and body. But obtaining these qualities is a slow arduous process of breeding and creating hybrids from various members of the Vitis genus. Grapes, it seems, do not give up their secrets easily. This was particularly evident in the mid-1800s, when two North American pests, an aphid and a fungus, invaded Europe. They destroyed grapes and decimated the wine industry. European growers were at a loss. They ended up using North American grapes to develop new European strains. But the wine just wasn’t the same. Along with pest resistance came a musty aroma. What they needed at the time were geneticists. Today, geneticists are looking at the very heart of the grape. They have found that a plant’s history can be read on the molecular level, much like DNA fingerprinting can be used to determine paternity. In one study, pigments that give grapes their red, purple, and blue color were found to be produced not by one, but by two gene mutations. It explained why growers were having such problems breeding plants with the preferred pigment. With tools to isolate and clone genes and rewrite parts of the genetic code, geneticists are already developing better grapes. They expect to create new breeding methods to develop new pest resistant varieties with desirable flavors and aromas. Grapes will have to give up their secrets at last.