Search

Background: The gametophyte s are essential for the productive process in angiosperms. During sexual reproduction in flowering plants, haploid spores are formed from meioses of spore mother cells. The spores then undergo mitosis and develop into female and male gametes and give rise to seeds after fertilization. Results: We identified a female sterile mutant from EMS mutagenesis, and a BC1F2 population was generated for map based cloning of the causal gene. Genome re-sequencing of mutant and non-mutant pools revealed a candidate gene, AP1G2 . Analyses of two insertions mutants, ap1g2-1 +/- in exon 7 and ap1g2-3 -/- in 3’ UTR, revealed partial female sterility. Complementation test using native promoter of AP1G2 restored the function in ap1g2-1 +/- and ap1g2-3 -/- . AP1G2 is a paralog of AP1G1 , encoding the large subunit (γ) of adaptor protein-1 (AP-1). ap1g2 mutation led to defective female and male gametophyte development was determined. In the ap1g2 mutants, the mitotic cycles and synchronic development of female gametophytes were impaired, which led to the arrest of female gametophytes at one nucleus stage FG1. Pollen development in ap1g2 was also arrested at one nucleus stage before PMI (pollen mitosis I). AP1G2 was expressed at high levels in different stages of ovule and pollens and actively dividing tissues, including shoot apical meristems, leaf primordial and root tips. Conclusions: AP1G2 was identified to have a role in the processes of female and male gametogenesis by regulating the first mitosis at one nucleus stage, and the expression pattern suggested AP1G2 is crucial for plant growth and development. Keywords: Arabidopsis, AP1G2 , megagametogenesis, microgametogenesis, development.