title: High temperature attenuates the gravitropism of inflorescence stems by inducing SHOOT GRAVITROPISM 5 alternative splicing in Arabidopsis.
abstract: In higher plants, gravitropism proceeds through three sequential steps in the responding organs: perception of gravity signals, signal transduction and asymmetric cell elongation. Light and temperature also influence the gravitropic orientation of plant organs. A series of Arabidopsis shoot gravitropism (sgr) mutants has been shown to exhibit disturbed shoot gravitropism. SGR5 is functionally distinct from other SGR members in that it mediates the early events of gravitropic responses in inflorescence stems. Here, we demonstrated that SGR5 alternative splicing produces two protein variants (SGR5α and SGR5β) in modulating the gravitropic response of inflorescence stems at high temperatures. SGR5β inhibits SGR5α function by forming non-DNA-binding heterodimers. Transgenic plants overexpressing SGR5β (35S:SGR5β) exhibit reduced gravitropic growth of inflorescence stems, as observed in the SGR5-deficient sgr5-5 mutant. Interestingly, SGR5 alternative splicing is accelerated at high temperatures, resulting in the high-level accumulation of SGR5β transcripts. When plants were exposed to high temperatures, whereas gravitropic curvature was reduced in Col-0 inflorescence stems, it was uninfluenced in the inflorescence stems of 35S:SGR5β transgenic plants and sgr5-5 mutant. We propose that the thermoresponsive alternative splicing of SGR5 provides an adaptation strategy by which plants protect the shoots from hot air under high temperature stress in natural habitats.
authors.affiliation: Department of Chemistry, Seoul National University, Seoul, 151-742, Korea.
authors.forename: Joo-Young
authors.initials: JY
authors.lastname: Kim
authors.affiliation: Department of Chemistry, Seoul National University, Seoul, 151-742, Korea.
authors.forename: Jae Yong
authors.initials: JY
authors.lastname: Ryu
authors.affiliation: Department of Chemistry, Seoul National University, Seoul, 151-742, Korea.
authors.forename: Kon
authors.initials: K
authors.lastname: Baek
authors.affiliation: Department of Chemistry, Seoul National University, Seoul, 151-742, Korea.|Plant Genomics and Breeding Institute, Seoul National University, Seoul, 151-742, Korea.
authors.forename: Chung-Mo
authors.initials: CM
authors.lastname: Park
mesh_terms: D017398:Alternative Splicing; D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D018522:Gravitropism; D006358:Hot Temperature; D056626:Inflorescence / Q000235:genetics / Q000502:physiology; D008027:Light; D009154:Mutation; D010641:Phenotype; D018520:Plant Shoots / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D018547:Plant Stems / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D030821:Plants, Genetically Modified; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D002352:Carrier Proteins; C517428:SGR5 protein, Arabidopsis
keywords: Arabidopsis thaliana; SHOOT GRAVITROPISM 5 (SGR5); alternative splicing; high temperature; shoot gravitropism; thermotolerance