J Integr Plant Biol. ›› 2009, Vol. 51 ›› Issue (9): 840-849.DOI: 10.1111/j.1744-7909.2009.00863.x

• Cell and Developmental Biology • Previous Articles     Next Articles

A Comparative Study on the Role of Cytokinins in Caryopsis Development in the Maize miniature1 Seed Mutant and its Wild Type

Tomaž Rijavec1, Maja Kovač1, Aleš Kladnik2, Prem S. Chourey3 and Marina Dermastia1,2*   

  1. 1 National Institute of Biology, Department of Biotechnology and Systems Biology, Ljubljana 1000, Slovenia
    2 Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana 1000, Slovenia
    3 US Department of Agriculture, Agricultural Research Service, Chemistry Research Unit, CMAVE, Gainesville FL 32608, USA
  • Received:2009-03-25 Accepted:2009-07-01 Published:2009-08-31
  • About author: * Author for correspondence. Tel: +38 61 423 3388; Fax: +38 61 241 2980; E-mail: marina.dermastia@nib.si


We report here on a comparative developmental profile of plant hormone cytokinins in relation to cell size, cell number and endoreduplication in developing maize caryopsis of a cell wall invertase-deficient miniature1 (mn1) seed mutant and its wild type, Mn1, genotype. Both genotypes showed extremely high levels of total cytokinins during the very early stages of development, followed by a marked and genotype specific reduction. While the decrease of cytokinins in Mn1 was associated with their deactivation by 9-glucosylation, the absolute and the relative part of active cytokinin forms was higher in the mutant. During the exponential growth phase of endosperm between 6 d after pollination and 9 d after pollination, the mean cell doubling time, the absolute growth rate and the level of endoreduplication were similar in the two genotypes. However, the entire duration of growth was longer in Mn1 compared with mn1, resulting in a significantly higher cell number in the Mn1 endosperm. These data correlate with the previously reported peak levels of the Mn1-encoded cell wall invertase-2 (INCW2) at 12 d after pollination in the Mn1 endosperm. A model showing possible crosstalk among cytokinins, cell cycle and cell wall invertase as causal to increased cell number and sink strength of the Mn1 developing endosperm is discussed.

Rijavec T, Kova?M, Kladnik A, Chourey PS, Dermastia M (2009). A comparative study on the role of cytokinins in caryopsis development in the maize miniature1 seed mutant and its wild type. J. Integr. Plant Biol. 51(9), 840–849.

Key words: 9-glucosylation, cell wall invertase, cytokinins, maize caryopsis, miniature1.

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