<it>GmGBP1</it>, a homolog of human <it>ski</it> interacting protein in soybean, regulates flowering and stress tolerance in Arabidopsis

<p>Abstract</p> <p>Background</p> <p><it>SKIP</it> is a transcription cofactor in many eukaryotes. It can regulate plant stress tolerance in rice and Arabidopsis. But the homolog of SKIP protein in soybean has been not reported up to now.</p> <p>Results</p> <p>In this study, the expression patterns of <it>soybean GAMYB</it> binding protein gene (<it>GmGBP1</it>) encoding a homolog of <it>SKIP</it> protein were analyzed in soybean under abiotic stresses and different day lengths. The expression of <it>GmGBP1</it> was induced by polyethyleneglycol 6000, NaCl, gibberellin, abscisic acid and heat stress. <it>GmGBP1</it> had transcriptional activity in C-terminal. <it>GmGBP1</it> could interact with R2R3 domain of <it>GmGAMYB1</it> in SKIP domain to take part in gibberellin flowering pathway. In long-day (16 h-light) condition, transgenic Arabidopsis with the ectopic overexpression of <it>GmGBP1</it> exhibited earlier flowering and less number of rosette leaves; Suppression of <it>AtSKIP</it> in Arabidopsis resulted in growth arrest, flowering delay and down-regulation of many flowering-related genes (<it>CONSTANS</it>, <it>FLOWERING LOCUS T</it>, <it>LEAFY</it>); Arabidopsis <it>myb33</it> mutant plants with ectopic overexpression of <it>GmGBP1</it> showed the same flowering phenotype with wild type. In short-day (8 h-light) condition, transgenic Arabidopsis plants with <it>GmGBP1</it> flowered later and showed a higher level of <it>FLOWERING LOCUS C</it> compared with wild type. When treated with abiotic stresses, transgenic Arabidopsis with the ectopic overexpression of <it>GmGBP1</it> enhanced the tolerances to heat and drought stresses but reduced the tolerance to high salinity, and affected the expressions of several stress-related genes.</p> <p>Conclusions</p> <p>In Arabidopsis, <it>GmGBP1</it> might positively regulate the flowering time by affecting <it>CONSTANS</it>, <it>FLOWERING LOCUS T</it>, <it>LEAFY</it> and <it>GAMYB</it> directly or indirectly in photoperiodic and gibberellin pathways in LDs, but <it>GmGBP1</it> might represse flowering by affecting <it>FLOWERING LOCUS C</it> and <it>SHORT VEGETATIVE PHASE</it> in autonomous pathway in SDs. <it>GmGBP1</it> might regulate the activity of ROS-eliminating to improve the resistance to heat and drought but reduce the high-salinity tolerance.</p>