Gyeongsang National University Jinju-si, Kyongsang-namdo, Republic of Korea
Body of Abstract: Plants can sense gravity and reorient their organs in response to the direction of gravity. Upon perception of gravity, statolith (a substance that responds to gravity) is accumulated in the direction of gravity in the shoot-endodermal cells. The factor controlling the gravity response downstream of the statolith gravity sensing is SGR5 (SHOOT GRAVITROPISM 5) / IDD15 (INDETERMINATE DOMAIN15). SGR5 is a C2H2 type zinc finger protein with four zinc finger domains at the C-terminus and one coiled-coil domain at the N-terminus. The mechanism of the regulation of gravitropism of SGR5 is not known yet. Recently, we found a GRZHD-1, a transcription factor with Zinc-finger homeodomain protein, which is a novel target for SGR5 through yeast-two hybrid screening of Arabidopsis transcription factor prey library. We further confirmed the interaction between SGR5 and GRZHD-1 through co-immunoprecipitation and in planta BiFC. Phenotypic analysis of mutant plants shows that grzhd-1 showed hyper gravitropism response with faster angle change than wild and sgr5-1 mutant plants. This suggests that GRZHD-1 may play a negative role in plant gravitropism, which is opposite to SGR5, a positive regulator. Then, we proceed with RNA-seq by using plant-type non-gravity and 60 min gravity response in Col-0, sgr5 k/o, and SGR5 overexpression plants for downstream identification gene of SGR5.