Proline Accumulation and Varietal Adaptability to Drought in Barley: a Potential Metabolic Measure of Drought Resistance

Singh, T. N.; Aspinall, D.; Paleg, L. G.

doi:10.1038/newbio236188a0

Cited by 210 publications

(126 citation statements)

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“…This interpretation seems the only one justified so far by the data published for mesophytes (e.g. 6,11,17,21,23,27).…”

Section: I14ciformate Metabolism After 18-to 21-hr Incubation Inmentioning

confidence: 79%

“…17) and to salination (6,22). The genetically determined potentials for accumulating betaine and proline have been interpreted as adaptive traits associated with salt tolerance in the case of betaine (23), and with both drought resistance and salt tolerance in the case of proline (17,22). The survival value of proline accumulation during severe water stress has, however, been questioned by Hanson et al (11), who suggested that high proline levels in drought-stressed leaves are essentially a symptom of injury.…”

mentioning

confidence: 99%

“…Proline is known to accumulate in attached leaves of barley and many other plants subjected to water stress (e.g. 17) and to salination (6,22). The genetically determined potentials for accumulating betaine and proline have been interpreted as adaptive traits associated with salt tolerance in the case of betaine (23), and with both drought resistance and salt tolerance in the case of proline (17,22).…”

mentioning

confidence: 99%

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Betaine Accumulation and [¹⁴C]Formate Metabolism in Water-stressed Barley Leaves

Hanson¹,

Nelsen²

1978

Plant Physiol.

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Barley (Hordeum vulgare L.) plants at the three-leaf stage were waterstressed by flooding the rooting medium with polyethylene glycol 6000 with an osmotic potential of -19 bars, or by withholding water. While leaf water potential feli and leaf kill progressed, the betaine (trimethylgycine) content of the second leaf blade rose from about 0.4 micromole to about 1.5 micromoles in 4 days. The time course of betaine accumulation resembled that of proUne accumulation. Choline levels in unstressed second leaf blades were low (<0.1 micromole per blade) and remained low during water stress. Upon relef of stress, betaine-like proline-remained at a high concentration in drought-killed leaf zones, but betaine did not disappear as rapidly as proline from viable leaf tissue during recovery.When Imethyl-14Clcboline was applied to second leaf blades of intact plants in the growth chamber, water-stressed plants metabolized 5 to 10 times more 'C label to betaine than control plants during 22 hours. When infiltrated with tracer quantities of 114Clformate and incubated for various times in darkness or light, segments cut from water-stressed leaf blades incorporated about 2-to 10-fold more 14C into betaine than did segments from unstressed leaves. In segments from stressed leaves incubated with I14CIformate for about 18 hours in darkness, betaine was always the principal 14C-labeled soluble metabolite. This 14C label was located exclusively in the N-methyl groups of betaine, demonstrating that reducing equivalents were available in stressed leaves for the reductive steps of methyl group biosynthesis from formate. Incorporation of "C from formate into choline was also increased in stressed leaf tissue, but choline was not a major product formed from 114Clformate.These results are consistent with a net de novo synthesis of betaine from 1-and 2-carbon precursors during water stress, and indicate that the betaine so accumulated may be a metabolically inert end product. contribute to continued growth or survival during stress) and those which are deleterious or merely incidental consequences of the stress. These distinctions must be drawn before metabolic criteria can be used in plant-breeding programs targeted at improving stress resistance. As part of a program to investigate potential metabolic criteria for breeding plants adapted to water stress (11), we here present data on betaine and proline accumulation in water-stressed barley leaves. Betaine accumulation appears promising as a metabolic index of cumulative water stress experience.Betaine accumulation has been reported in leaves of several salt-tolerant species exposed to high NaCl concentrations (23), and preliminary experiments with barley in our laboratory showed that betaine levels in leaves rose also during water stress. Proline is known to accumulate in attached leaves of barley and many other plants subjected to water stress (e.g. 17) and to salination (6, 22). The genetically determined potentials for accumulating betaine and proline have been interpreted as ada...

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“…This interpretation seems the only one justified so far by the data published for mesophytes (e.g. 6,11,17,21,23,27).…”

Section: I14ciformate Metabolism After 18-to 21-hr Incubation Inmentioning

confidence: 79%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Betaine Accumulation and [¹⁴C]Formate Metabolism in Water-stressed Barley Leaves

Hanson¹,

Nelsen²

1978

Plant Physiol.

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“…Other solutes not accounted for include organic acids. Proline, which is reported as being the best indicator of drought tolerance in plants (Singh et al, 1972 ;Pearson & Stewart, 1987), accounted for only a small portion of the solute that did accumulate in cells (Table 4). Nevertheless, proline was closely related to changes in sap osmolality (Fig.…”

Section: mentioning

confidence: 99%

Role of proline and leaf expansion rate in the recovery of stressed white clover leaves with increased phosphorus concentration

et al. 2000

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Osmotic adjustment (OA) and increased cell-wall extensibility required for expansive leaf growth are well defined components of adaptation to water stress in dry soil, which might interact with soil phosphorus (P) concentration and defoliation frequency for intensively grazed white clover in legume-based pastures. Experiments were conducted with frequently and infrequently defoliated mini-swards of white clover growing in dry soil with low and high P concentrations. The higher yielding high-P plants were able to dry the soil to greater soil water suctions ; their leaves had lower water potential values, yet they showed fewer water stress symptoms and underwent a more complete recovery from the water stress symptoms on rewatering, than the low-P plants. High-P plants had greater OA, proline concentration and leaf expansion rate. On the other hand, low-P plants showed an increased osmotic concentration when there was no change in the total solute content per unit of leaf d. wt, indicating more loss of water from the leaf tissue. The key measures that appeared to be directly associated with plant recovery over a short period following water stress were increased proline concentration and leaf expansion rate, probably resulting from increased cell-wall extensibility rather than increased production of cells for the high-P plants.Key words : osmotic adjustment, leaf expansion rate, leaf water potential, phosphorus, white clover, proline, drought tolerance, plant recovery. The susceptibility to drought of the shallow-rooted white clover plant (Trifolium repens) is widely accepted (Hart, 1987). The decrease in osmotic potential of white clover leaves with developing water stress is reported to be insufficient to maintain pressure potential and associated metabolic activities and growth, and therefore leaves wilt and die early in the development of water stress (Turner, 1990). However, in recent studies it has been observed that an increased P supply to white clover plants growing in dry soil results in increased drought tolerance (Singh et al., 1997). Plants growing in low-P soil showed severe wilting symptoms with desiccation and drying of the leaves and stolons, and some *Author for correspondence (tel j61 8 9166 4000 ; fax j61 8 9166 4066 ; e-mail dsingh!agric.wa.gov.au). eventual mortality. These effects on low-P plants were exacerbated by frequent defoliation. However, frequently defoliated plants with adequate P supply showed minimum wilting symptoms ; they maintained higher leaf water potential (Ψ leaf ) and continued to grow in very dry soil, extracting considerably more water than the P-deficient plants. Importantly, rewatering resulted in an immediate, overnight recovery of stressed leaves for the high-P plants, but not for the low-P plants.It is not known why and how these high-P plants showed greater drought tolerance and recovery compared with low-P plants. It appears that an increased P concentration in high-P plants induced some osmotic adjustments (OA) that would improve their drought...

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“…Proline accumulation affects osmotic potential (Bussis & Heineke, 1998) and is therefore regarded as an important criterion for selecting drought tolerant crops (Singh, Aspinall & Paleg, 1972). For instance, Van Heerden & De Villiers (1996) showed that proline accumulation is positively correlated with drought tolerance in wheat.…”

Section: Introductionmentioning

confidence: 99%

Plant water relations and proline accumulation on two cowpea (Vigna unguiculata (L.) Walp.) cultivars as a response to water stress

Chiulele

Agenbag

2004

South African Journal of Plant and Soil

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Proline Accumulation and Varietal Adaptability to Drought in Barley: a Potential Metabolic Measure of Drought Resistance

Cited by 210 publications

References 10 publications

Betaine Accumulation and [¹⁴C]Formate Metabolism in Water-stressed Barley Leaves

Betaine Accumulation and [¹⁴C]Formate Metabolism in Water-stressed Barley Leaves

Role of proline and leaf expansion rate in the recovery of stressed white clover leaves with increased phosphorus concentration

Plant water relations and proline accumulation on two cowpea (Vigna unguiculata (L.) Walp.) cultivars as a response to water stress

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Proline Accumulation and Varietal Adaptability to Drought in Barley: a Potential Metabolic Measure of Drought Resistance

Cited by 210 publications

References 10 publications

Betaine Accumulation and [14C]Formate Metabolism in Water-stressed Barley Leaves

Betaine Accumulation and [14C]Formate Metabolism in Water-stressed Barley Leaves

Role of proline and leaf expansion rate in the recovery of stressed white clover leaves with increased phosphorus concentration

Plant water relations and proline accumulation on two cowpea (Vigna unguiculata (L.) Walp.) cultivars as a response to water stress

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Betaine Accumulation and [¹⁴C]Formate Metabolism in Water-stressed Barley Leaves

Betaine Accumulation and [¹⁴C]Formate Metabolism in Water-stressed Barley Leaves