University of South Carolina West Columbia, South Carolina
Body of Abstract: Correct development timing is essential for fitness and reproductive success of a plant. In Arabidopsis, vegetative development consists of a juvenile phase (V1) and an adult phase (V2). After floral induction, several cauline leaves are produced before flowers are produced. The development of cauline leaves is then an intermediate phase (V3) between vegetative development and reproductive development. Previous studies showed that the miR156-SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) model regulates the V1 to V2 phase transition and V2 to V3 phase transition. In our study, we found that cauline leaves from spl9, spl9/13 and spl9/15 are rounder than that of wild type, though the number of cauline leaves in them are not different from that of wild type. The V2 to V3 transition is regulated by flowering times genes, such as AGAMOUS-LIKE 24 (AGL24), SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1/AGL20) and FRUITFUL (FUL/AGL8), FD, and CONSTANS (CO). We found that mutations in these flowering time genes does not affect V1 to V2 phase transition but affect V2 to V3 phase transition. The number of cauline leaves are increased in these mutants, but the length/width ratio is decreased (becomes rounder) in these mutants. Our results suggest new mechanism for vegetative to reproductive phase transition.