An isolated polypeptide containing an amino acid sequence at least 70% identical to SEQ ID NO: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11, and an isolated nucleic acid encoding the polypeptide are disclosed. Disclosed is an isolated nucleic acid that, under stringent conditions, hybridizes to a probe containing SEQ ID NO:20; or its complementary sequence. Also disclosed are (1) a transformed cell or a transgenic plant containing such a nucleic acid and (2) a transformed cell or a transgenic plant lacking the polypeptide encoded by the nucleic acid. Also within the scope of the invention are methods for making the transformed cells or transgenic plants.