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Keywords:

  • roots;
  • expressed sequence tags (ESTs);
  • nutrient acquisition;
  • white lupin (Lupinus albus);
  • genetics;
  • plant stress

Contents

  • I.
    Introduction  424
  • II.
    The phosphorus conundrum 424
  • III.
    Adaptations to low P 424
  • IV.
    Uptake of P  424
  • V.
    P deficiency alters root development and function 426
  • VI.
    P deficiency modifies carbon metabolism 431
  • VII.
    Acid phosphatase 436
  • VIII.
    Genetic regulation of P responsive genes 437
  • IX.
    Improving P acquisition 439
  • X.
    Synopsis  440

Summary

Phosphorus (P) is limiting for crop yield on > 30% of the world's arable land and, by some estimates, world resources of inexpensive P may be depleted by 2050. Improvement of P acquisition and use by plants is critical for economic, humanitarian and environmental reasons. Plants have evolved a diverse array of strategies to obtain adequate P under limiting conditions, including modifications to root architecture, carbon metabolism and membrane structure, exudation of low molecular weight organic acids, protons and enzymes, and enhanced expression of the numerous genes involved in low-P adaptation. These adaptations may be less pronounced in mycorrhizal-associated plants. The formation of cluster roots under P-stress by the nonmycorrhizal species white lupin (Lupinus albus), and the accompanying biochemical changes exemplify many of the plant adaptations that enhance P acquisition and use. Physiological, biochemical, and molecular studies of white lupin and other species response to P-deficiency have identified targets that may be useful for plant improvement. Genomic approaches involving identification of expressed sequence tags (ESTs) found under low-P stress may also yield target sites for plant improvement. Interdisciplinary studies uniting plant breeding, biochemistry, soil science, and genetics under the large umbrella of genomics are prerequisite for rapid progress in improving nutrient acquisition and use in plants.