Abstract
BackgroundSKIP 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.ResultsIn this study, the expression patterns of soybean GAMYB binding protein gene (GmGBP1) encoding a homolog of SKIP protein were analyzed in soybean under abiotic stresses and different day lengths. The expression of GmGBP1 was induced by polyethyleneglycol 6000, NaCl, gibberellin, abscisic acid and heat stress. GmGBP1 had transcriptional activity in C-terminal. GmGBP1 could interact with R2R3 domain of GmGAMYB1 in SKIP domain to take part in gibberellin flowering pathway. In long-day (16 h-light) condition, transgenic Arabidopsis with the ectopic overexpression of GmGBP1 exhibited earlier flowering and less number of rosette leaves; Suppression of AtSKIP in Arabidopsis resulted in growth arrest, flowering delay and down-regulation of many flowering-related genes (CONSTANS, FLOWERING LOCUS T, LEAFY); Arabidopsis myb33 mutant plants with ectopic overexpression of GmGBP1 showed the same flowering phenotype with wild type. In short-day (8 h-light) condition, transgenic Arabidopsis plants with GmGBP1 flowered later and showed a higher level of FLOWERING LOCUS C compared with wild type. When treated with abiotic stresses, transgenic Arabidopsis with the ectopic overexpression of GmGBP1 enhanced the tolerances to heat and drought stresses but reduced the tolerance to high salinity, and affected the expressions of several stress-related genes.ConclusionsIn Arabidopsis, GmGBP1 might positively regulate the flowering time by affecting CONSTANS, FLOWERING LOCUS T, LEAFY and GAMYB directly or indirectly in photoperiodic and gibberellin pathways in LDs, but GmGBP1 might represse flowering by affecting FLOWERING LOCUS C and SHORT VEGETATIVE PHASE in autonomous pathway in SDs. GmGBP1 might regulate the activity of ROS-eliminating to improve the resistance to heat and drought but reduce the high-salinity tolerance.
Highlights
SKIP is a transcription cofactor in many eukaryotes
GmGBP1 encodes a homolog of the human SKIP transcriptional coregulator The SKIP homolog gene in soybean was obtained from subtracting long-day from short-day treated mRNA
The SKIP protein domain of GmGBP1 was located between amino acids 190 and 360 (Figure 1A) with an S-N-W-K-N peptide signature (Figure 1B)
Summary
SKIP is a transcription cofactor in many eukaryotes. It can regulate plant stress tolerance in rice and Arabidopsis. Flowering time plays key roles in plant development, plant adaptation to growing regions [1], crop yield [2,3] and disease resistance [4] Abiotic stress such as drought, high salinity and heat, is another major limiting factor for crop yield [2]. AtSKIP functions as a positive regulator and putative potential transcription factor in the abiotic stress signaling pathway in Arabidopsis [23], and a component of the spliceosome linking alternative splicing and the circadian clock in Arabidopsis [24]. There has been no report on the identification of SKIP homologs in soybean and on their functions in the regulation of flowering time in any species so far
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