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Crop Science Abstract -

Nutritionally Induced Changes in Endosperm of shrunken-1 and brittle-2 Maize Kernels Grown In Vitro


This article in CS

  1. Vol. 36 No. 4, p. 947-954
    Received: Aug 1, 1995

    * Corresponding author(s): f-below@uiuc.edu
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  1. R. R. S. Faleiros,
  2. J. R. Seebauer and
  3. F. E. Below 
  1. Depto. Tecnologia, FCAV/UNESP, Campus de Jabotical, Rodovia Carlos Tonani, Km 5, Jaboticabal-San Paulo, CEP 14870-000, Brazil



Although mineral nutrition affects maize (Zea mays L.) yield by controlling starch deposition in kernels, the mechanisms involved are largely unknown. Our objectives were to examine this relationship by nutritionally and genetically altering starch production in the endosperm. Kernels of W64A and two starch-deficient mutants, shrunken-1 and brittle-2, were grown in vitro with varying supplies of N (0–50 raM) or P (0–6 raM) to produce different degrees of endosperm starch production, and the levels of enzyme activities and metabolites associated with carbohydrate and N metabolism were examined. In vitro grown kernels exhibited the expected starch phenotypes, and a minimum level of media N (25 mM) and P (2 mM) was required optimal growth. However, increasing the availability of N or P could not overcome the genetically induced decrease in starch deposition of the mutants. Nitrogen deficiency enhanced sugar accumulation, but decreased amino acid levels, soluble protein, enzyme activity, starch synthesis, and endosperm dry weight. Phosphorous deficiency also decreased starch production and endosperm dry weight, but with only a minimal effect on the activities of ADP-glucose pyrophosphorylase and alanine transaminase. Genotypic differences in endosperm starch, and the increases induced by N and P supply, were closely associated with the level of endosperm N, but not endosperm P. Thus, while both N and P are crucial for optimal yield of maize grain, they appear to act by different means, and with different importance in governing starch deposition in the endosperm.

This study was part of project no. 15-0390 of the Agric. Exp. Stn., College of Agricultural, Consumer and Environmental Sciences, Univ. of Illinois at Urbana-Champaign. It was supported in part by a sabbatical award to R.R.S. Faleiros from the Depto. Tecnologia, FCAV/UNESP, Campus de Jabotical and Fundacao de Amparo a Pesquisa de Estado de Sao Paulo.

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