title: Rice ORMDL controls sphingolipid homeostasis affecting fertility resulting from abnormal pollen development.
abstract: The orosomucoids (ORM) are ER-resisdent polypeptides encoded by ORM and ORMDL (ORM-like) genes. In humans, ORMDL3 was reported as genetic risk factor associated to asthma. In yeast, ORM proteins act as negative regulators of sphingolipid synthesis. Sphingolipids are important molecules regulating several processes including stress responses and apoptosis. However, the function of ORM/ORMDL genes in plants has not yet been reported. Previously, we found that temperature sensitive genetic male sterility (TGMS) rice lines controlled by tms2 contain a deletion of about 70 kb in chromosome 7. We identified four genes expressed in panicles, including an ORMDL ortholog, as candidates for tms2. In this report, we quantified expression of the only two candidate genes normally expressed in anthers of wild type plants grown in controlled growth rooms for fertile and sterile conditions. We found that only the ORMDL gene (LOC_Os07g26940) showed differential expression under these conditions. To better understand the function of rice ORMDL genes, we generated RNAi transgenic rice plants suppressing either LOC_Os07g26940, or all three ORMDL genes present in rice. We found that the RNAi transgenic plants with low expression of either LOC_Os07g26940 alone or all three ORMDL genes were sterile, having abnormal pollen morphology and staining. In addition, we found that both sphingolipid metabolism and expression of genes involved in sphingolipid synthesis were perturbed in the tms2 mutant, analogous to the role of ORMs in yeast. Our results indicated that plant ORMDL proteins influence sphingolipid homeostasis, and deletion of this gene affected fertility resulting from abnormal pollen development.
authors.affiliation: National Center for Genetic Engineering and Biotechnology, Thailand Science Park, Klong Luang, Pathumthani, Thailand.
authors.forename: Chutharat
authors.initials: C
authors.lastname: Chueasiri
authors.affiliation: National Center for Genetic Engineering and Biotechnology, Thailand Science Park, Klong Luang, Pathumthani, Thailand.
authors.forename: Ketsuwan
authors.initials: K
authors.lastname: Chunthong
authors.affiliation: National Center for Genetic Engineering and Biotechnology, Thailand Science Park, Klong Luang, Pathumthani, Thailand.
authors.forename: Keasinee
authors.initials: K
authors.lastname: Pitnjam
authors.affiliation: National Center for Genetic Engineering and Biotechnology, Thailand Science Park, Klong Luang, Pathumthani, Thailand.
authors.forename: Sriprapai
authors.initials: S
authors.lastname: Chakhonkaen
authors.affiliation: National Center for Genetic Engineering and Biotechnology, Thailand Science Park, Klong Luang, Pathumthani, Thailand.
authors.forename: Numphet
authors.initials: N
authors.lastname: Sangarwut
authors.affiliation: National Center for Genetic Engineering and Biotechnology, Thailand Science Park, Klong Luang, Pathumthani, Thailand.
authors.forename: Kanidta
authors.initials: K
authors.lastname: Sangsawang
authors.affiliation: National Center for Genetic Engineering and Biotechnology, Thailand Science Park, Klong Luang, Pathumthani, Thailand.
authors.forename: Malinee
authors.initials: M
authors.lastname: Suksangpanomrung
authors.affiliation: Biological Chemistry Department, Rothamsted Research, Harpenden, Hertfordshire, United Kingdom.
authors.forename: Louise V
authors.initials: LV
authors.lastname: Michaelson
authors.affiliation: Biological Chemistry Department, Rothamsted Research, Harpenden, Hertfordshire, United Kingdom.
authors.forename: Johnathan A
authors.initials: JA
authors.lastname: Napier
authors.affiliation: National Center for Genetic Engineering and Biotechnology, Thailand Science Park, Klong Luang, Pathumthani, Thailand.
authors.forename: Amorntip
authors.initials: A
authors.lastname: Muangprom
mesh_terms: D053898:Biosynthetic Pathways; D002518:Ceramides / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D006706:Homeostasis; D009154:Mutation; D009961:Orosomucoid / Q000235:genetics* / Q000378:metabolism*; D012275:Oryza / Q000145:classification / Q000502:physiology*; D010802:Phylogeny; D030821:Plants, Genetically Modified; D011058:Pollen / Q000235:genetics*; D034622:RNA Interference; D012098:Reproduction / Q000235:genetics*; D013107:Sphingolipids / Q000378:metabolism*
chemical_list: D002518:Ceramides; D009961:Orosomucoid; D013107:Sphingolipids