Qingbo Ke, Zhi Wang, Ho Soo Kim, Seyeon Park, Jae Cheol Jeong, Haeng-Soon Lee and Sang- Soo Kwak
Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Daejeon 305-806, Korea
The timing of floral transition determines successful reproduction in higher plants and is precisely monitored by multiple environmental cues. The GIGANTEA (GI) gene participates in the network connecting environmental stress and developmental stage transition in Arabidopsis. We first identified GI gene orthologous from the perennial growth poplar (Populus alba × P. glandulosa) as PagGIa, PagGIb and PagGIc. PagGIs are predominantly localized at nuclear and its transcripts are diurnally regulated with a peak around zeitgeber time 12 under long-day conditions. Ectopic over-expression of the PagGIs in wild-type Arabidopsis plants resulted in early flowering and enhanced salt sensitivity; while gi-2 mutant Arabidopsis plants expressing PagGIs are rescued from delayed flowering and enhanced salt tolerance. Furthermore, PagGIs negatively regulate the salinity stress tolerance by interacting with PagSOS2 in poplar. In addition, transgenic poplars with downregulation of PagGIs by RNAi display enhanced salt tolerance. Taken together, our results reveal new insights on the link between flowering time regulator and adaptation to salt stress in poplar.
Keywords: Poplar, GIGANTEA, flowering, salt stress, RNAi.