Rate of Imposition of Water Stress Alters the Accumulation of Nitrogen-Containing Solutes by Wheat Seedlings

Naidu, BP; Paleg, L. G.; Aspinall, D.; Jennings, AC; Jones, GP

doi:10.1071/pp9900653

Cited by 23 publications

(7 citation statements)

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“…When plants were exposed to varying levels of plant moisture stress the concentration of organic acids (but not amino acids) in xylem fluid during midday increased with Xt. The increase in organic N commonly reported in leaf tissue or whole plants with increasing plant moisture stress (Naidu et al 1990, Rabe 1990, Ranieri et al 1989) did not occur. However, increased concentrations of organic acids in conjunction with complexed cations in xylem fluid (Clark et al 1986) may also facilitate turgor maintenance in leaves.…”

Section: Discussionmentioning

confidence: 74%

Diurnal variations of amino acids and organic acids in xylem fluid from Lagerstroemia indica: an endogenous circadian rhythm

Andersen

Brodbeck

Mizell

1993

Physiologia Plantarum

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Diurnal variations in the concentrations of major organic compounds occurred in xylem fluid extracted from Lagerstroemia indica L. The concentration of amino acids and the N/C ratio was at a maximum and that of organic acids was at a minimum between 1230 and 2030 h. Since the concentrations of total organic nitrogen, total amino acids and most individual amino acids (but not organic acids or sugars) were also proportional to xylem tension two experiments were performed to discern whether variations in chemistry were a consequence of diurnal changes in moisture stress. In the first experiment, L. indica, exposed to variable levels of moisture stress during midday, manifested an increase in organic acids and a reduction in the N/C ratio. In the second experiment, chemical profiles of xylem fluid were collected and compared for plants exposed to a natural photoperiod, constant darkness or continuous light at noon and midnight. After 1 day amino acids increased in concentration during midday for all treatments; the variation was greatest (10‐fold) for plants in constant darkness where xylem tension varied from 0.20 to 0.25 MPa. Only plants exposed to continuous light lost a diurnal rhythm after 3 days. Thus, the circadian rhythm was endogenous, terminated in continuous light and was not mediated by changes in moisture stress. Glutamine accounted for most of the diurnal variation in total amino acids, organic nitrogen and the N/C ratio in xylem fluid.

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Section: Discussionmentioning

confidence: 74%

Diurnal variations of amino acids and organic acids in xylem fluid from Lagerstroemia indica: an endogenous circadian rhythm

Andersen

Brodbeck

Mizell

1993

Physiologia Plantarum

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“…Reynoso and Gamboa (1982) found a linear relation between the concentration of proline added to the medium and tolerance to salt in freshwater alga Chlamydomonas. In wheat seedlings (Naidu et al 1990) and in durum wheat (Bajji et al 2001) a positive correlation was observed between proline levels and osmotic potential, and it was concluded that proline is an osmoregulatory component. It was also reported that the net accumulation of proline as an organic compatible solute contributed to osmotic adjustment in saline conditions (Heuer 1995), and in water stress environments (Zhul et al 2005).…”

Section: Introductionmentioning

confidence: 93%

Proline accumulation as a response to salt stress in 30 wheat (Triticum aestivum L.) cultivars differing in salt tolerance

Poustini

Siosemardeh

Ranjbar

2006

Genet Resour Crop Evol

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The effects of NaCl salt (EC = 16 dS m -1 ) on water potential, and accumulation of proline, Na + and K + in leaves on the main stem of 30 wheat cultivars (Triticum aestivum L.) at awn appearance and 20 days after anthesis (20 DAA) were evaluated in a greenhouse experiment. Plants were arranged in a according to a randomized complete block design with factorial treatments in three replications. Proline accumulation at 20 DAA increased with increasing salt stress. This increase was 27.4-fold with the salt-sensitive cultivar ''Ghods,'' while the mean was 5.2-fold for 19 salt-resistant cultivars. Positive correlations between proline, and K + + Na + concentrations associated with higher sensitivity to salt stress indicated that proline may not have a protecting role against salt stress. No correlation was observed between leaf proline and water potential. Almost no contribution to the osmotic adjustment seems to be made by proline. The contribution made by proline to the osmotic adjustment of plants at 20 DAA was 0.69 bar, whereas that made by K + and Na + was 2.11 and 4.48 bar, respectively. The 30 wheat CV s used in this experiment showed different performances regarding the traits observed. Eleven of them showing the higher stress sensitivity indices had the highest level of proline and Na + concentrations. They were considered to be salt-sensitive cultivars. Among the others, nine cultivars showed salt tolerance with almost the same Na + and proline concentrations, but a higher K + /Na + selectivity of ions from leaf to grains. In 10 of the cultivars, Na + and proline concentrations were low, indicating the presence of a salt avoiding mechanism.

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“…Their approach was similar to ours in that they inhibited ABA synthesis using either FLU (in barley) or the flacca mutant of tomato, but they found that neither treatment altered the extent of Pro accumulation. Although it is possible that the different results in the two studies are due to species or organ differences, the nature and rate of low qW imposition might also be involved (Naidu et al, 1990). In the Stewart and Voetberg study, detached leaves were dehydrated rapidly by either floating on PEG (barley) or air-drying on the laboratory bench (tomato).…”

Section: Dlscusslonmentioning

confidence: 99%

Proline Accumulation in Maize (Zea mays L.) Primary Roots at Low Water Potentials (I. Requirement for Increased Levels of Abscisic Acid)

1994

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Previous work showed that the concentration of proline (Pro) increases greatly in the primary root tip of maize (Zea mays 1.) at low water potentials (qw). It was also shown that the maintenance of root elongation at low $ , depends on increased levels of abscisic acid (ABA). In this study we have assessed whether ABA is required for the increase in Pro concentration. Seedlings were grown in vermiculite of various $ , , and endogenous ABA levels were decreased using either fluridone (FLU) or the vp5 mutant to inhibit carotenoid (and ABA) synthesis. In both treatments, Pro concentrations at low qW were substantially decreased throughout the apical centimeter, which encompassed the elongation zone. Pio concentrations in FLU-treated roots were restored by addition of 7 BM ABA to the vermiculite, which raised the interna1 ABA content to the leve1 in untreated roots at the same qW. Pro and water content profiles were combined with published growth-velocity distributions to calculate the distribution of net Pro and water deposition rates using the continuity equation. At a $w of -1.6 MPa, the rate of Pro deposition in the root tip was decreased by 75% in FLUtreated compared to untreated roots. FLU treatment increased root diameter and, therefore, water content per unit length, but water deposition rates decreased due to the dominant influence of reduced longitudinal expansion. Thus, the decrease in Pro concentration was attributable entirely to the decrease in Pro deposition.The results demonstrate that increased ABA is required for high rates of Pro deposition and, thereby, high Pro concentrations in the growing region of maize primary roots at low qW.

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Rate of Imposition of Water Stress Alters the Accumulation of Nitrogen-Containing Solutes by Wheat Seedlings

Cited by 23 publications

References 0 publications

Diurnal variations of amino acids and organic acids in xylem fluid from Lagerstroemia indica: an endogenous circadian rhythm

Diurnal variations of amino acids and organic acids in xylem fluid from Lagerstroemia indica: an endogenous circadian rhythm

Proline accumulation as a response to salt stress in 30 wheat (Triticum aestivum L.) cultivars differing in salt tolerance

Proline Accumulation in Maize (Zea mays L.) Primary Roots at Low Water Potentials (I. Requirement for Increased Levels of Abscisic Acid)

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