title: Serine palmitoyltransferase, a key enzyme for de novo synthesis of sphingolipids, is essential for male gametophyte development in Arabidopsis.
abstract: Sphingolipids are important signaling molecules involved in various cellular activities. De novo sphingolipid synthesis is initiated by a rate-limiting enzyme, serine palmitoyltransferase (SPT), a heterodimer consisting of LONG-CHAIN BASE1 (LCB1) and LCB2 subunits. A mutation in the Arabidopsis thaliana LCB1 gene, lcb1-1, was found to cause embryo lethality. However, the underpinning molecular and cellular mechanisms remain largely unclear. Here, we report the identification of the fumonisin B(1) resistant11-2 (fbr11-2) mutant, an allele of lcb1-1. The fbr11-2 mutation, most likely an allele stronger than lcb1-1, was transmitted only through female gametophytes and caused the formation of abortive microspores. During the second pollen mitosis, fbr11-2 initiated apoptotic cell death in binucleated microspores characteristic of nuclear DNA fragmentation, followed by cytoplasm shrinkage and organelle degeneration at the trinucleated stage. In addition, a double mutant with T-DNA insertions in two homologous LCB2 genes showed a phenotype similar to fbr11-2. Consistent with these observations, the FBR11/LCB1 expression was confined in microspores during microgametogenesis. These results suggest that SPT-modulated programmed cell death plays an important role in the regulation of male gametophyte development.
authors.affiliation: State Key Laboratory of Plant Genomics and National Plant Gene Research Center, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Chong
authors.initials: C
authors.lastname: Teng
authors.forename: Haili
authors.initials: H
authors.lastname: Dong
authors.forename: Lihua
authors.initials: L
authors.lastname: Shi
authors.forename: Yan
authors.initials: Y
authors.lastname: Deng
authors.forename: Jinye
authors.initials: J
authors.lastname: Mu
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Yang
authors.forename: Jianru
authors.initials: J
authors.lastname: Zuo
mesh_terms: D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D016923:Cell Death / Q000502:physiology*; D015870:Gene Expression; D005816:Genetic Complementation Test; D008938:Mitosis / Q000502:physiology; D016254:Mutagenesis, Insertional; D010641:Phenotype; D011058:Pollen / Q000254:growth & development* / Q000648:ultrastructure; D051102:Serine C-Palmitoyltransferase / Q000235:genetics / Q000378:metabolism*; D013107:Sphingolipids / Q000096:biosynthesis; D019076:Transgenes
chemical_list: D029681:Arabidopsis Proteins; D013107:Sphingolipids; C518504:LCB1 protein, Arabidopsis; C530166:Lcb2 protein, Arabidopsis; D051102:Serine C-Palmitoyltransferase