Effects of chilling on male gametophyte development in rice

Authors

  • E.A. Mamun,

    Corresponding author
    1. Cooperative Research Centre for Sustainable Rice Production, The University of Sydney, NSW 2006, Australia
    2. Faculty of Agriculture, Food and Natural Resources, The University of Sydney, NSW 2006, Australia
      Corresponding author. The University of Sydney, Faculty of Agriculture, Food and Natural Resources, John Wooley Building A20, Sydney, NSW 2006, Australia. Tel.: +61 2 93512939; fax: +61 2 93514172. emamun@bio.mq.edu.au
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  • S. Alfred,

    1. Cooperative Research Centre for Sustainable Rice Production, The University of Sydney, NSW 2006, Australia
    2. Faculty of Agriculture, Food and Natural Resources, The University of Sydney, NSW 2006, Australia
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  • L.C. Cantrill,

    1. School of Biological Sciences, The University of Sydney, NSW 2006, Australia
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  • R.L. Overall,

    1. School of Biological Sciences, The University of Sydney, NSW 2006, Australia
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  • B.G. Sutton

    1. Cooperative Research Centre for Sustainable Rice Production, The University of Sydney, NSW 2006, Australia
    2. Faculty of Agriculture, Food and Natural Resources, The University of Sydney, NSW 2006, Australia
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Corresponding author. The University of Sydney, Faculty of Agriculture, Food and Natural Resources, John Wooley Building A20, Sydney, NSW 2006, Australia. Tel.: +61 2 93512939; fax: +61 2 93514172. emamun@bio.mq.edu.au

Abstract

Chilling during male gametophyte development in rice inhibits development of microspores, causing male sterility. Changes in cellular ultrastructure that have been exposed to mild chilling include microspores with poor pollen wall formation, abnormal vacuolation and hypertrophy of the tapetum and unusual starch accumulation in the plastids of the endothecium in post-meiotic anthers. Anthers observed during tetrad release also have callose (1,3-β-glucan) wall abnormalities as shown by immunocytochemical labelling. Expression of rice anther specific monosaccharide transporter (OsMST8) is greatly affected by chilling treatment. Perturbed carbohydrate metabolism, which is particularly triggered by repressed genes OsINV4 and OsMST8 during chilling, causes unusual starch storage in the endothecium and this also contributes to other symptoms such as vacuolation and poor microspore wall formation. Premature callose breakdown apparently restricts the basic framework of the future pollen wall. Vacuolation and hypertrophy are also symptoms of osmotic imbalance triggered by the reabsorption of callose breakdown products due to absence of OsMST8 activity.

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