Suppression of the High Affinity Phosphate Uptake System: A Mechanism of Arsenate Tolerance in Holcus lanatus L.

A A Meharg, M R Macnair

Research output: Contribution to journalArticle

381 Citations (Scopus)

Abstract

In Holcus lanatus L. phosphate and arsenate are taken up by the same transport system. Short-term uptake kinetics of the high affinity arsenate transport system were determined in excised roots of arsenate-tolerant and non-tolerant genotypes. In tolerant plants the V(max) of ion uptake in plants grown in phosphate-free media was decreased compared to non-tolerant plants, and the affinity of the uptake system was lower than in the non-tolerant plants. Both the reduction in V(max) and the increase in K(m) led to reduced arsenate influx into tolerant roots. When the two genotypes were grown in nutrient solution containing high levels of phosphate, there was little change in the uptake kinetics in tolerant plants. In non-tolerant plants, however, there was a marked decrease in the V(max) to the level of the tolerant plants but with little change in the K(m). This suggests that the low rate of arsenate uptake over a wide range of differing root phosphate status is due to loss of induction of the synthesis of the arsenate (phosphate) carrier.

Original languageEnglish
Pages (from-to)519-524
Number of pages6
JournalJournal of Experimental Botany
Volume43
Issue number4
DOIs
Publication statusPublished - Apr 1992

Keywords

  • arsenate
  • Holcus-Lanatus L
  • phosphate uptake
  • tolerance mechanisms
  • uptake mechanisms
  • mineral-nutrition
  • barley roots
  • phosphorus
  • plants
  • transport
  • influx
  • deficiency
  • kinetics
  • growth
  • recovery

Cite this

Suppression of the High Affinity Phosphate Uptake System : A Mechanism of Arsenate Tolerance in Holcus lanatus L. / Meharg, A A ; Macnair, M R .

In: Journal of Experimental Botany, Vol. 43, No. 4, 04.1992, p. 519-524.

Research output: Contribution to journalArticle

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title = "Suppression of the High Affinity Phosphate Uptake System: A Mechanism of Arsenate Tolerance in Holcus lanatus L.",
abstract = "In Holcus lanatus L. phosphate and arsenate are taken up by the same transport system. Short-term uptake kinetics of the high affinity arsenate transport system were determined in excised roots of arsenate-tolerant and non-tolerant genotypes. In tolerant plants the V(max) of ion uptake in plants grown in phosphate-free media was decreased compared to non-tolerant plants, and the affinity of the uptake system was lower than in the non-tolerant plants. Both the reduction in V(max) and the increase in K(m) led to reduced arsenate influx into tolerant roots. When the two genotypes were grown in nutrient solution containing high levels of phosphate, there was little change in the uptake kinetics in tolerant plants. In non-tolerant plants, however, there was a marked decrease in the V(max) to the level of the tolerant plants but with little change in the K(m). This suggests that the low rate of arsenate uptake over a wide range of differing root phosphate status is due to loss of induction of the synthesis of the arsenate (phosphate) carrier.",
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AU - Macnair, M R

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N2 - In Holcus lanatus L. phosphate and arsenate are taken up by the same transport system. Short-term uptake kinetics of the high affinity arsenate transport system were determined in excised roots of arsenate-tolerant and non-tolerant genotypes. In tolerant plants the V(max) of ion uptake in plants grown in phosphate-free media was decreased compared to non-tolerant plants, and the affinity of the uptake system was lower than in the non-tolerant plants. Both the reduction in V(max) and the increase in K(m) led to reduced arsenate influx into tolerant roots. When the two genotypes were grown in nutrient solution containing high levels of phosphate, there was little change in the uptake kinetics in tolerant plants. In non-tolerant plants, however, there was a marked decrease in the V(max) to the level of the tolerant plants but with little change in the K(m). This suggests that the low rate of arsenate uptake over a wide range of differing root phosphate status is due to loss of induction of the synthesis of the arsenate (phosphate) carrier.

AB - In Holcus lanatus L. phosphate and arsenate are taken up by the same transport system. Short-term uptake kinetics of the high affinity arsenate transport system were determined in excised roots of arsenate-tolerant and non-tolerant genotypes. In tolerant plants the V(max) of ion uptake in plants grown in phosphate-free media was decreased compared to non-tolerant plants, and the affinity of the uptake system was lower than in the non-tolerant plants. Both the reduction in V(max) and the increase in K(m) led to reduced arsenate influx into tolerant roots. When the two genotypes were grown in nutrient solution containing high levels of phosphate, there was little change in the uptake kinetics in tolerant plants. In non-tolerant plants, however, there was a marked decrease in the V(max) to the level of the tolerant plants but with little change in the K(m). This suggests that the low rate of arsenate uptake over a wide range of differing root phosphate status is due to loss of induction of the synthesis of the arsenate (phosphate) carrier.

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KW - tolerance mechanisms

KW - uptake mechanisms

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KW - barley roots

KW - phosphorus

KW - plants

KW - transport

KW - influx

KW - deficiency

KW - kinetics

KW - growth

KW - recovery

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