Analysis of gemini pollen 3 mutant suggests a broad function of AUGMIN in microtubule organization during sexual reproduction in Arabidopsis.
In flowering plants, male gametes arise via meiosis of diploid pollen mother cells followed by two rounds of mitotic division. Haploid microspores undergo polar nuclear migration and asymmetric division at pollen mitosis I to segregate the male germline, followed by division of the germ cell to generate a pair of sperm cells. We previously reported two gemini pollen (gem) mutants that produced twin-celled pollen arising from polarity and cytokinesis defects at pollen mitosis I in Arabidopsis. Here, we report an independent mutant, gem3, with a similar division phenotype and severe genetic transmission defects through pollen. Cytological analyses revealed that gem3 disrupts cell division during male meiosis, at pollen mitosis I and during female gametophyte development. We show that gem3 is a hypomorphic allele (aug6-1) of AUGMIN subunit 6, encoding a conserved component in the augmin complex, which mediates microtubule (MT)-dependent MT nucleation in acentrosomal cells. We show that MT arrays are disturbed in gem3/aug6-1 during male meiosis and pollen mitosis I using fluorescent MT-markers. Our results demonstrate a broad role for the augmin complex in MT organization during sexual reproduction, and highlight gem3/aug6-1 mutants as a valuable tool for the investigation of augmin-dependent MT nucleation and dynamics in plant cells.
School of Applied Biosciences, Kyungpook National University, Daegu, 41566, Korea.
Sung-Aeong
SA
Oh
School of Applied Biosciences, Kyungpook National University, Daegu, 41566, Korea.
Jien
J
Jeon
School of Applied Biosciences, Kyungpook National University, Daegu, 41566, Korea.
Hyo-Jin
HJ
Park
Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, 0316, Oslo, Norway.
Paul Eivind
PE
Grini
Department of Genetics, University of Leicester, University Road, Leicester, LE1 7RH, UK.
David
D
Twell
School of Applied Biosciences, Kyungpook National University, Daegu, 41566, Korea.
Soon Ki
SK
Park
D017360:Arabidopsis / Q000235:genetics / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D008540:Meiosis / Q000502:physiology; D008870:Microtubules / Q000378:metabolism*; D008938:Mitosis / Q000502:physiology; D056771:Ovule / Q000254:growth & development*; D011058:Pollen / Q000235:genetics* / Q000502:physiology; D012098:Reproduction / Q000235:genetics / Q000502:physiology
D029681:Arabidopsis Proteins
Arabidopsis thaliana; augmin complex; gemini pollen 3; microtubule organization; sexual reproduction