The present invention relates to transgenic plants that have increased nitrogen use efficiency, stress tolerance, or both and that have been transformed using a novel vector construct including nucleic acid sequences that modulate nitrogen use in plants. In various embodiments, the vector construct includes one or more nucleic acid sequences selected from the group consisting of SEQ ID NO: 2, 4, 7, 9, 11, 13, 15, 17, 22, 24, 26, 28, 30, 32, 34, 36, or 38. The invention also relates to isolated vectors for transforming plants and to antibodies used for detecting transformed plants. The invention also relates to methods of expressing in plants the nucleic acid molecules corresponding to the nucleic acid sequences that modulate nitrogen use in plants or are modulated by nitrogen conditions.