Abstract:DELLA proteins works as a repressor and GID1 is the soluble receptor in GA signaling pathways, but currently little is known about interactive sites of GID1DELLA in conifers. we cloned two DELLA proteins (PtDPL; PtRGA) from Pinus tabuliformis named PtDPL and PtRGA. Sequence analysis showed these two DELLA proteins have DELLA and GRAS specific domains and their evolution distance both are between the rice and lycophyte, and they also have GID1DELLA interactive sites Δ17 domain as angiosperm; BiFC proved that Δ17 domain was key sites of interactions between the PtGID1PtDELLA; Without Δ17 domain, PtdplΔ17 and PtrgaΔ17 mutants showed a strong GAinsensitive phenotype compared to wildtype, suggesting that Δ17 domain is the key interactive sites in conifers GID1DELLA interaction. This research provides the basis for GID1DELLA interaction and GA signaling pathways mechanism.