The majority of genes cloned via positional cloning explain large portions of the phenotypic variation, e.g., “fruit weight2.2” in tomato, “teosinte branched1 (tb1)” in maize, “heading date1” in rice, and FRIGIDA and CRYPTO- CHROME2 in Arabidopsis (6, 8, 13, 25, 59). The productin of NILs is also time consuming, especially for long-generation species. However, when nothing is known about the genes in a particular pathway, positional cloning may be the best option.