A Century of Corn Selection

摘要

Using conventional selection methods, plant and animal breeders have made many beneficial changes to the yields and composition of crops and livestock (7). Yet we know little about the numbers, effects, and mode of action of the genes that account forthese long-term changes. A recent paper about maize selection in the journal Genetics demonstrates that such information is slowly becoming available (2). Since 1896, in one of the longest experiments ever, biologists at the University of Illinois havecontinuously selected maize (corn) to change the oil composition of its kernels (7, 3). Separate maize lines have been selected for more than 100 generations according to whether the kernels contain high or low amounts of oil, a trait of agronomic importance (3). Typically, mean oil concentration was estimated in 60 or so ears (cobs) of maize, and seeds from only 12 were selected to propagate the next generation. The change in oil concentration was almost continuous (3) and substantial: From a base of about 5%, the high oil-producing line now has about 20% oil in the kernel, and the low oil-producing line has almost none (see fig. SI). The two maize lines differ by about 32 standard deviations (SD, 0.42% in the base population).