The Arabidopsis Exine Formation Defect (EFD) gene is required for primexine patterning and is critical for pollen fertility. Issue 1 (3rd April 2014)

• Record Type: Journal Article
• Authors: Hu, Jun; Wang, Zhaodan; Zhang, Liyao; Sun, Meng‐xiang
• Is Part Of: New phytologist. Volume 203:Issue 1(2014)
• Page Start: 140
• Page End: 154
• Publication Date: 2014-04-03
• Subjects: Botany -- Periodicals; 580
• DOI: 10.1111/nph.12788
• Languages: English
• ISSNs: 0028-646X

Abstract

<abstract abstract-type="main" id="nph12788-abs-0001"> <title>Summary</title> <p> <list id="nph12788-list-0001" list-type="bullet"> <list-item> <p>Exine, the outermost layer of a pollen grain, has important roles in protecting microspore cytoplasm and determining species‐specific interactions between pollen and stigma. The molecular mechanism underlying pollen exine formation, however, remains largely unknown.</p> </list-item> <list-item> <p>Here, we report the characterization of an Arabidopsis male‐sterile mutant, <italic>efd</italic>, which exhibits male sterility in first‐forming flowers. The <italic>Exine Formation Defect</italic> (<italic>EFD</italic>) gene is strongly expressed in microsporocytes, tetrads and the tapetum, and encodes a nuclear‐localized <italic>de novo </italic>DNA methyltransferase.</p> </list-item> <list-item> <p>Detailed observations revealed that <italic>EFD</italic> is involved in both callose wall and primexine formation during microsporogenesis. Microspores in tetrads are not well separated in <italic>efd</italic> due to an abnormal callose wall. Its plasma membrane undulation appears normal, but primexine patterning is impaired. Primexine matrix establishment and sporopollenin accumulation at specific positions are disturbed, and thus exine formation is totally blocked in <italic>efd</italic>.</p> </list-item> <list-item> <p>We confirmed that <italic>EFD</italic> is required for pollen exine formation and male fertility <italic>via</italic> the regulation of callose wall and primexine formation. We also found that positional sporopollenin accumulation is not involved in regulating membrane undulation, but is related to the complete separation of tetrad microspores during primary exine patterning.</p> </list-item> </list> </p> </abstract>