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First published online December 23, 2004; 10.1104/pp.104.053165 Plant Physiology 137:297-307 (2005) © 2005 American Society of Plant Biologists Male Germ Line Development in Arabidopsis. duo pollen Mutants Reveal Gametophytic Regulators of Generative Cell Cycle Progression1,[w]Department of Biology, University of Leicester, Leicester LE1 7RH, United Kingdom
Male germ line development in flowering plants is initiated with the formation of the generative cell that is the progenitor of the two sperm cells. While structural features of the generative cell are well documented, genetic programs required for generative cell cycle progression are unknown. We describe two novel Arabidopsis (Arabidopsis thaliana) mutants, duo pollen1 (duo1) and duo pollen2 (duo2), in which generative cell division is blocked, resulting in the formation of bicellular pollen grains at anthesis. duo1 and duo2 map to different chromosomes and act gametophytically in a male-specific manner. Both duo mutants progress normally through the first haploid division at pollen mitosis I (PMI) but fail at distinct stages of the generative cell cycle. Mutant generative cells in duo1 pollen fail to enter mitosis at G2-M transition, whereas mutant generative cells in duo2 enter PMII but arrest at prometaphase. In wild-type plants, generative and sperm nuclei enter S phase soon after inception, implying that male gametic cells follow a simple S to M cycle. Mutant generative nuclei in duo1 complete DNA synthesis but bypass PMII and enter an endocycle during pollen maturation. However, mutant generative nuclei in duo2 arrest in prometaphase of PMII with a 2C DNA content. Our results identify two essential gametophytic loci required for progression through different phases of the generative cell cycle, providing the first evidence to our knowledge for genetic regulators of male germ line development in flowering plants.
1 This work was supported by the Biotechnology and Biological Sciences Research Council and by the Department of Biology, University of Leicester, UK. [w] The online version of this article contains Web-only data. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.104.053165. * Corresponding author; e-mail twe{at}le.ac.uk; fax 44(0)1162522791. Received September 9, 2004; returned for revision November 13, 2004; accepted November 15, 2004. This article has been cited by other articles:
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