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First published online January 24, 2008; 10.1104/pp.107.113506 Plant Physiology 146:1322-1332 (2008) © 2008 American Society of Plant Biologists OPEN ACCESS ARTICLE
Serine Palmitoyltransferase, a Key Enzyme for de Novo Synthesis of Sphingolipids, Is Essential for Male Gametophyte Development in Arabidopsis1,[W],[OA]State Key Laboratory of Plant Genomics and National Plant Gene Research Center (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China (C.T., H.D., L.S., Y.D., J.M., J.Z., X.Y., J.Z.); and Graduate School, Chinese Academy of Sciences, Beijing 100049, China (C.T., H.D., L.S., Y.D., J.M.)
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 B1 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.
1 This work was supported by the National Natural Science Foundation of China (grant nos. 30330360 and 30221002; Outstanding Young Investigator Award [30125025] to J.Z.) and the Chinese Academy of Sciences (grant to J.Z.). 2 These authors contributed equally to the article. The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Jianru Zuo (jrzuo{at}genetics.ac.cn). [W] The online version of this article contains Web-only data. [OA] Open Access articles can be viewed online without a subscription. www.plantphysiol.org/cgi/doi/10.1104/pp.107.113506 * Corresponding author; e-mail jrzuo{at}genetics.ac.cn. Received November 19, 2007; accepted January 17, 2008; published January 24, 2008. This article has been cited by other articles:
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