Isolation and expression analysis of three different flowering genes (TtLFY, TtAP1, and TtAP2) from an unusual legume species, Thermopsis turcica

LEAFY (LFY), APETALA1 (AP1), and APETALA2 (AP2) genes encode three different transcription factors that control and regulate flower initiation and development in Arabidopsis. By using 3'- and 5'-RACE analysis, we isolated and sequentially characterized TtLFY (a LEAFY-like gene), TtAP1 (a MADS-box-like gene), and TtAP2 (an AP2/ERBF-like gene) in Thermopsis turcica, an unusual endemic legume species with three free carpellated flower structure. Semiquantitative RT-PCR analysis for 18 different vegetative and reproductive tissues of T. turcica indicated TtLFY transcripts mainly in the shoot tips and young floral buds and TtAP1 transcripts in the sepals and petals; however, TtAP2 transcripts were detected in all tissues. This is the first record for a LFY-like gene, TtLFY, expressed in the shoot tips of an underground plant section and for an AP2-like gene transcript found in all tissues, similar to a housekeeping gene.