Influx and Efflux of Phosphorus in Roots of Wheat Plants in Non-Growth-Limiting Concentrations of Phosphorus

Cogliatti, D. H.; Maria, Guillermo Esteban Santa

doi:10.1093/jxb/41.5.601

Cited by 45 publications

(19 citation statements)

References 7 publications

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“…The results in this study suggest that efflux out of the root to the external solution was an important component controlling net uptake in loblolly pine seedlings -at least under high-P growth conditions. In herbaceous plants, efflux becomes a progressively larger component of net uptake when the supply of P exceeds growth demands (Cogliatti and Santa Maria, 1990;Lee, 1993;Lee et al, 1990;SchjCrring and Jensdn, 1984), whereas under low-P soil conditions, the ratio of efflux to influx is low (Elliott et al, 1984). We have found comparable results with seedlings of Pinus serotina grown in 100 and 5 #M P (Topa and Sisak, 1996, unpublished data).…”

Section: Discussionsupporting

confidence: 67%

Seed source variation in 32P uptake in inus taeda L. seedlings: A possible regulation by efflux

Topa

1996

Plant Soil

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Short-term 32p uptake experiments were conducted with intact seedlings of loblolly pine (Pinus taeda L.) to examine possible seed source variation in net accumulation of 32p in roots and shoots, and in rates of unidirectional influx. Seed source had a highly significant effect on biomass and P concentrations of shoots and roots. Seedlings from two seed sources representing fast-growing populations (a broadly-adapted and wet-site seed source) accumulated over 60% more total seedling P than smaller seedlings from a drought-hardy seed source, reflecting higher biomass and root P concentrations. Rates of unidirectional 32p influx in seedlings from the drought-hardy seed source were more than twice the rates of the seedlings from the broadly-adapted seed source. However, after 24 h in labeled uptake solution, net accumulation of 32p was similar, suggesting that rates of unidirectional efflux from roots of the drought-hardy seed source were also high. Although there were no significant differences in biomass and tissue P concentrations between the two fast-growing seed sources, rates of unidirectional influx in seedlings from the broadly-adapted seed source were 42% lower than rates in seedlings from the wet-site source. Yet, after 24 h in labeled uptake solution, net accumulation of 32p in seedlings from the broadly-adapted seed source was 50% higher. Unidirectional efflux out of the root may regulate net uptake of P as much, if not more, than influx in loblolly pine seedlings -at least under high-P growth conditions. The results in this study do not support previous studies with herbaceous plants suggesting that fast-growing species typically exhibit higher rates of nutrient uptake than slow-growing species.

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Section: Discussionsupporting

confidence: 67%

Seed source variation in 32P uptake in inus taeda L. seedlings: A possible regulation by efflux

Topa

1996

Plant Soil

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“…Phosphate transport across the plasmalemma is mediated by a specific carrier molecule. This carrier protein is inducible under low phosphate status (McPharlin & Bieleski, 1987;Cogliatti & Santa Maria, 1990) and we have shown that in arsenate tolerant plants this inducibility is lost (Meharg & Macnair, 1992b). It is possible that the mutation studied here is a mutation of the gene control system resulting in the carrier being unconditionally suppressed.…”

Section: Generationmentioning

confidence: 78%

The genetics of arsenate tolerance in Yorkshire fog, Holcus lanatus L.

1992

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The genetics of arsenate tolerance in Holcus lanatus is investigated. Three tolerant plants from an abandoned arsenic mine, and three non-tolerant plants and one less tolerant plant (C9) from an uncontaminated site were crossed. Five polycrosses between plants from F1 crosses between mine and non-tolerants were set up. Four polycrosses between tolerant F2 progeny, and four polycrosses between non-tolerant F2 progeny, were established. A polycross involving the progeny of a single tolerant plant allowed to cross at random with a normal population was also established. The results are broadly compatible with a single-gene model for tolerance, with tolerance being dominant. The majority of F2 crosses segregated in to 3:1 ratios, and backcrosses gave 1:1 ratios. The crosses between C9 and non-tolerants gave 1:1 ratios, which suggests that the less tolerant C9 was heterozygous for tolerance. All crosses between non-tolerants gave all non-tolerant offspring. In one cross a major gene for albinism also segregated, and linkage of the tolerance gene to this gene (r.f. =35%) was demonstrated. A number of families produced progeny ratios incompatible with the simple major gene model. Possible causes of these anomalous crosses are discussed and it is suggested that the tolerance gene may show variable penetrance depending on the genetic background.

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“…Under conditions of growth-limiting P supply, Pi efflux diminishes in absolute terms but increases relative to Pi influx and becomes a significant component of net uptake (Elliott et al, 1984). O n the other hand, plants well supplied with P exhibit increased Pi efflux compared with P-stressed plants (Pettersson and Strid, 1989;Cogliatti and Santa Maria, 1990;Adalsteinsson et al, 1994, and refs. therein).…”

Section: Root Apical Pi Exudationmentioning

confidence: 99%

“…Pi efflux from roots (Elliot et al, 1984;Cogliatti and Santa Maria, 1990) is another potential Al-resistance mechanism in plants. In the presente of Al, Pi efflux could lower the rhizosphere A13+ activity via the formation of AI-Pi complexes either in the apoplasm, on the root surface, or in the rhizosphere (Taylor, 1991;Liittge and Clarkson, 1992, and refs.…”

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confidence: 99%

Multiple Aluminum-Resistance Mechanisms in Wheat (Roles of Root Apical Phosphate and Malate Exudation)

1996

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Although it is well known that aluminum (AI) resistance in wheat (Trificum aestivum) is multigenic, physiological evidence for multiple mechanisms of AI resistance has not yet been documented. l h e role of root apical phosphate and malate exudation in AI resistance was investigated i n two wheat cultivars (AI-resistant Atlas and AI-sensitive Scout) and two near-isogenic lines (AI-resistant E13 and AI-sensitive ES3). I n Atlas AI resistance is multigenic, whereas in E13 resistance is conditioned by the single Alfl locus. Based on rootgrowth experiments, Atlas was found to be 3-fold more resistant in 20 PM AI than ET3. Root-exudation experiments were conducted under sterile conditions; a large malate efflux localized to the root apex was observed only in Atlas and in ET3 and only i n the presence of AI (5 and 20 p~) .Furthermore, the more AI-resistant Atlas exhibited a constitutive phosphate release localized to the root apex. As predicted from the formation constants for the AI-malate and AI-phosphate complexes, the addition of either ligand to the root bathing solution alleviated AI inhibition of root growth in AI-sensitive Scout. These results provide physiological evidence that AI resistance in Atlas is conditioned by at least two genes. I n addition to the alf locus that controls AI-induced malate release from the root apex, other genetic loci appear to control constitutive phosphate release from the apex. We suggest that both exudation processes act in concert to enhance AI exclusion and AI resistance i n Atlas.A1 toxicity is one of the major factors that limits the productivity of crop plants in acid soils. A number of crop species and cultivars exhibit significant genetically based variability in their response to the toxic levels of soil A1 (Kochian, 1995). This variability has served as the basis for a considerable amount of recent research on the underlying mechanisms that result in crop A1 resistance. We are beginning to understand the cellular processes that confer A1 resistance in plants. Most of the recent work has focused on A1 exclusion from the root apex as a primary mechanism of A1 resistance (Kochian, 1995).Root exudation of organic acids that can chelate A13+ in the rhzosphere and, thus, detoxify A1 was first reported in an

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Influx and Efflux of Phosphorus in Roots of Wheat Plants in Non-Growth-Limiting Concentrations of Phosphorus

Cited by 45 publications

References 7 publications

Seed source variation in 32P uptake in inus taeda L. seedlings: A possible regulation by efflux

Seed source variation in 32P uptake in inus taeda L. seedlings: A possible regulation by efflux

The genetics of arsenate tolerance in Yorkshire fog, Holcus lanatus L.

Multiple Aluminum-Resistance Mechanisms in Wheat (Roles of Root Apical Phosphate and Malate Exudation)

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