Proline accumulation

Tymms, M.J. Gaff, D.F. (1979). Proline accumulation during water stress in resurrection plants. Journal of Experimental Botany, 30, 165-8. 

A frequently observed response of plant cells exposed to saline stress is the accumulation of proline. Two cell lines of tobacco, one resistant and the other sensitive to growth inhibition by NaCl, accumulated proline when exposed to 1.5% w/v NaCl in the growth media (Dix Pearce, 1981). The NaCl sensitive line accumulated proline more rapidly than did the resistant line, though the levels accumulated were not adequate to provide osmotic protection against salt stress. The authors suggested that proline accumulation may have a protective role other than osmoregulation and may be symptomatic of stress injury, the nature of which was not discussed. 

Brassica napus cells have been selected for tolerance to Na2S04 (Chandler Thorpe, 1987). When selected cells were compared with non-selected cells in response to Na2S04 salinity the selected cells grew better and showed less negative cell water potential than the non-selected cells. Both cell lines showed osmotic adjustment and proline accumulation. However, proline accumulation was related to inhibition of growth and did not play a significant role in osmotic adjustment. 

Chandler, S.F. Thorpe, T.A. (1987). Characterization of growth, water relations, and proline accumulation in sodium sulfate tolerant callus of Brassica napus L. cv. Westar (Canola). Plant Physiology, 84, 106-11. 

Dix, P.J. Pearce, R.S. (1981). Proline accumulation in NaCI-resistant and sensitive cell lines of Nicotiana sylvestris. Zeitschrift fur Pflanzenphysiologie, 102, 243-8. 

Duncan, D.R. Widholm, J.M. (1987). Proline accumulation and its implication in cold tolerance of regenerable maize callus. Plant Physiology, 83, 703-8. 

Handa, S., Handa, A.T., Hasegawa, P.M. Bressan, R.A. (1986). Proline accumulation and the adaptation of cultured plant cells to stress. Plant Physiology, 80, 938-45. 

Moftah, A.E. Michel, B.E. (1987). The effect of sodium chloride on solute potential and proline accumulation in soybean leaves. Plant Physiology, 83, 238-43. 

Hanson, A.D., Nelson, C.E., Pedersen, A.R. Everson, E.M. (1979). Capacity for proline accumulation during water stress in barley and its implications for breeding for drought resistance. Crop Science, 19, 489-93. 

Miller, G. et al.. Responsive modes of Medicago sativa proline dehydrogenase genes during salt stress and recovery dictate free proline accumulation, Planta, 222, 70, 2005. 

Morita, Y. Nakamori, S, Takagi, H. L-proline accumulation and freeze tolerance of Saccharomyces cerevisiae are caused by a mutation in the PROl gene encoding y-glutamyl kinase. Appl. Environ. Microbiol., 69, 212-219 (2003)... 

Aspinall, D. Paleg, L.G. (1981). Proline accumulation physiological aspects. In The Physiology and Biochemistry of Drought Resistance in Plants, ed. L.G. Paleg D. Aspinell, pp. 205-41. Sydney Academic Press. 

Figure 4. Effect of vitamin Be -deficiency in L. arabinosus on alanine and proline accumulation...

Figure 7. Comparative stimulation of glutamic acid, alanine, and proline accumulation in vitamin B6-deficient cells of L. arabinosus at various extracellular sucrose concentrations...

Kravic N., Markovic K., Andelkovic V., Hadzi-Taskovic Sukalovic V., Babic V., Vu-lehc M. Growth, proline accumulation and peroxidase activity in maize seedlings under osmotic stress. Acta Physiologie Plantarum 2013 35 233-239. 

Barthakur, S., Babu, V., and Bansal, K.C., Over-expression of osmotin induces proline accumulation and confers osmotic stress tolerance in transgenic tobacco, J. Plant Biochem. BiotechnoL, 10, 31, 2000. 

A number of other nitrogenous compounds accumulate in response to certain mineral deficiencies, including the imino acid pipecolic acid which has been reported to accumulate in Mg- (Frieberg and Steward, 1%0) and Cl-deficient plants (Freney et al., 1959). Another imino acid, proline is also reported to accumulate in Cl-deficient plants, in cabbage a 50-fold increase occurred while in cauliflower there was a sevenfold increase (Freney et al., 1959). It is curious that proline accumulates in Cl-deficient plants and those grown at high NaCl levels (see Section II,C). 

In addition to these differences in capacity to accumulate specific nitrogenous compounds, halophytes also exhibit differences in the behavior of these compounds under saline conditions. In general proline accumulating species contain low levels of proline when grown without NaCl, these increase markedly with an increase in external salinity (Stewart and Lee, 1974 Triechel, 1975 Stewart et al., 1978). Proline accumulation is not restricted to... 

Proline accumulates in salt-stressed gram-positive bacteria, some of which also accumulate y-aminobutyric acid while in the gram-negatives glutamate is accumulated (Measures, 1975). Proline together with alanine and glycine increase in response to an increase in external salinity in cells of the marine ciliate, Miamiensis avidus (Kaneshiro et al., 1969) and in another protozoan. 

Proline accumulation in salt-stressed cells may result from an increased rate of synthesis and a decreased rate of utilization, a relaxation of feedback inhibition over proline biosynthesis was suggested to contribute to this increased rate of synthesis (Liu and Hellebust, 1976c). 

In the majority of crop plants that have been studied proline accumulation in leaf tissue occurs only in response to severe water stress and is usually accompanied by visible wilting. A reduction in leaf water potentials to —10... 

Proline accumulated in water-stressed leaves decreases when normal water relations are restored (Singheta/., 1973a,c Stewart, 1972 McMichael and Elmore, 1977). It has been found, in water-stressed barley, that free proline only declines after relief of water stress in tissue remaining viable and not in tissue killed by drought (Hanson et al., 1977). 

Total proline increases in many plants subject to water stress. The level of free proline increases more than the decrease of proline in protein (Barnett and Naylor, 1966 Stewart al., 1966 Thompsons ai, 1966), suggesting that the major part of the proline accumulated in stressed leaves is not directly derived from the proteolytic release of protein-bound proline. Such observations do not, however, rule out the possibility that proteolysis is a source of precursors, glutamate, and arginine for this proline. In most mesophytic species proline accumulation in water-stressed tissue is accompanied by inhibition of protein synthesis and an increase in proteolysis (see Hsiao, 1973). It is of interest that Barnett and Naylor (1966) reported a significant loss of protein-bound arginine accompanied proline accumulation in water-stressed Bermuda grass. 

Hare PD, Cress WA (1997) Metabolic implications of stress-induced proline accumulation in... 

Mehta SK, Gaur JP (1999) Heavy-metal-induced proline accumulation and its role in ameliorating metal toxicity in Chlorella vulgaris. New Phytol 143 253-259... 

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