The Guangxi Key Laboratory of Theory and Technology for Environmental Pollution Control, College of Environmental Science & Engineering, Guilin University of Technology, Guilin 541004, P.R. China


Hydroponic experiments were performed to exam the dynamic change of endogenous proline in rice seedlings exposed to potassium chromate chromium (VI) or chromium nitrate chromium (III). Although accumulation of both chromium species in rice seedlings was obvious, more chromium was detected in plant tissues of rice seedlings exposed to chromium (III) than those in chromium (VI), majority being in roots rather than shoots. Results also showed that the accumulation capacity of chromium by rice seedlings was positively correlated to chromium concentrations supplied in both chromium variants and the accumulation curve depicted an exponential trend in both chromium treatments over the entire period of exposure. Proline assays showed that both chromium variants induced the change of endogenous proline in shoots and roots of rice seedlings. Chromium (VI) of 12.8 mg/L increased proline content significantly (p<0.05) compared to control, while the effect of chromium (III) on proline content was more evident at 30.0 mg/L (p<0.05). The results collected here suggest that both chromium variants are able to cause the change of endogenous proline in rice seedlings, but the response was found to be different between the two chromium treatments.

Graphical Abstract

Responses of endogenous proline in rice seedlings under chromium exposure


  • Phyto-accumulation of Cr(III) by rice seedlings was more evident than Cr(VI)
  • Translocation was more efficient in Cr(VI) treatments than Cr(III) treatments
  • Both Cr variants induced change of endogenous proline in rice seedlings
  • High doses of both Cr species caused increase of proline content significantly
  • Proline accumulation was found to be different between the two Cr variants


Ashraf, M.; Foolad, M.R., (2007) Roles of glycine betaine and proline in improving plant abiotic stress resistance. Environ. Exp. Bot., (59): 206–216 (11 pages).
Carrier, P.; Baryla , A.; Havaus, M., (2003) Cadmium distribution and microlocalization in oilseed rape (Brassica napus) after long-term growth on cadmium-contaminated soil. Planta., (216): 939-950 (12 pages).
Claussen, W., (2005) Proline as a measure of stress in tomato plants. Plant Sci., (168): 241–248 (8 pages).
Delauney, A.J.; Verna, D.P.S., (1993) Proline biosynthesis and osmo regulation in plants. Plant J., (4) 215–223 (9 pages).
Ebbs, S.D.; Piccinin, R.C.; Goodger, J.Q.D.; Kolev, S.D.; Woodrow, I.E.; Baker, A.J.M., (2008) Transport of ferrocyanide by two eucalypt species and sorghum. Int. J. Phytorem., (10): 343–357 (15 pages).
Hare, P.D.; Cress, W.A.; van Staden, J., (1999) Proline synthesis and degradation: a model system for elucidating stress-related signal transduction. J. Exp. Bot., (50): 413–434 (22 pages).
Hasegawa, P.M.; Bressan, R.A.; Zhu, J.K.; Bohnert, H.J., (2000) Plant cellular and molecular responses to high salinity. Annu. Rev. Plant Physiol. Plant Mol. Biol., (51):463–499 (37 pages).
Khan, M.I.R.; Iqbal, N.; Masood, A.; Khan, N.A., (2012) Variation in salt tolerance of wheat cultivars: role of glycinebetaine and ethylene. Pedosphere., (22):746–754 (9 pages).
Kumar, A.K.; Prasad, M.N.V.; Achary, V.M.M.; Panda, B.B., (2013) Elucidation of lead-induced oxidative stress in Talinum triangulare roots by analysis of antioxidant responses and DNA damage at cellular level. Environ. Sci. Pollut. Res., (20): 4551–4561 (11 pages).
Islam, M.M.; Hoque, M.A.; Okuma, E.; Banu, M. N. A.; Shimoishi, Y.; Nakamura, Y.; Murata, Y., (2009) Exogenous proline and glycine betaine increase antioxidant enzyme activities and confer tolerance to cadmium stress in cultured tobacco cells. J. Plant Physiol., (166):1587–1597 (11 pages).
Li, H.S., (2006) Principles and Techniques of Plant Physiology and Biochemistry, Higher Education Press: Beijing, China (In Chinese).
Mansour, M.M.F., (2000) Nitrogen containing compounds and adaptation of plants to salinity stress, Biol. Plant., (43): 491–500 (10 pages).
Mei, B.J.; Puryear, J.D.; Newton, R.J., (2002) Assessment of Cr tolerance and accumulation in selected plant species. Plant Soil., (247):223–231 (9 pages).
Misra, N.; Gupta, A.K., (2005) Effect of salt stress on proline metabolism in two high yielding genotypes of green gram. Plant Sci., (169) 331–339 (9 pages).
Ren, J.H.; Ma, L.Q.; Sun, H.J.; Cai, F.; Luo, J., (2014) Antimony uptake, translocation and speciation in rice plants exposed to antimonite and antimonate. Sci. Total Environ., (475):83–89 (7 pages).
Scoccianti, V.; Crinelli, R.; Tirillini, B.; Mancinelli, V.; Speranza, A., (2006) Uptake and toxicity of Cr in celery seedlings. Chemosphere., (64): 1695–1703 (9 pages).
Sharma, S.S.; Dietz, K.J., (2006) The significance of amino acids and amino acid-derived molecules in plant responses and adaptation to heavy metal stress., J. Exp. Bot., (57):711–726 (16 pages).
Sharma, S.; Villamor, J.G.; Verslues, P.E., (2011) Essential role of tissue- specific proline synthesis and catabolism in growth and redox balance at low water potential. Plant Physiol., (157): 292–304 (163pages).
Vajpayee, P.; Tripathi, R.D.; Rai, U.N.; Ali, M.B.; Singh, S.N., (2000) Chromium(VI) accumulation reduces chlorophyll biosynthesis, nitrate reductase activity and protein content in Nymphaea alba L. Chemosphere., (41): 1075–1082 (8 pages).
Verbruggen, N.; Hermans, C., (2008) Proline accumulation in plants: a review. Amino Acids., (35): 753–759 (7 pages).
Wang, F.J.; Zeng, B.; Sun, Z.X.; Zhu, C., (2009) Relationship between proline and Hg2+-induced oxidative stress in a tolerant rice mutant. Arch. Environ. Contam. Toxicol., 56:723–731 (9 pages).
Wang, H.; Tang, X.; Wang, H.; Shao, H.B., (2015) Proline accumulation and metabolism-related genes expression profiles in Kosteletzkya virginica seedlings under salt stress. Front. Plant Sci., (6):792 (9 pages).
Yu, X.Z.; Peng, X, Y.; Xing, L.Q., (2010) Effect of temperature on phytoextraction of hexavalent and trivalent chromium by hybrid willows. Ecotoxicology., (19): 61–68 (8 pages).
Yu, X.Z.; Zhang, F.Z., (2013) Effects of exogenous thiocyanate on mineral nutrients, antioxidative responses and free amino acids in rice seedlings. Ecotoxicology., (22): 752–760 (9 pages).
Yu, X.Z.; Feng, Y.X.; Yue, D.M., (2015) Phytotoxicity of methylene blue to rice seedlings. Global J. Environ. Sci. Manage., (1):199-204 (6 pages).
Zar, J.H., (1999) Biostatistical analysis (4rd edition) Prentice Hall: New Jersey, USA.
Zhang, X.H.; Yu, X.Z.; Liang, Y.P., (2014) Parameter determination involved in phytotoxicity and transport of cadmium in rice seedlings. Int. Biodeter. Biodegra., (96): 121–126 (6 pages).

Letters to Editor

GJESM Journal welcomes letters to the editor for the post-publication discussions and corrections which allows debate post publication on its site, through the Letters to Editor. Letters pertaining to manuscript published in GJESM should be sent to the editorial office of GJESM within three months of either online publication or before printed publication, except for critiques of original research. Following points are to be considering before sending the letters (comments) to the editor.

[1] Letters that include statements of statistics, facts, research, or theories should include appropriate references, although more than three are discouraged.
[2] Letters that are personal attacks on an author rather than thoughtful criticism of the author’s ideas will not be considered for publication.
[3] Letters can be no more than 300 words in length.
[4] Letter writers should include a statement at the beginning of the letter stating that it is being submitted either for publication or not.
[5] Anonymous letters will not be considered.
[6] Letter writers must include their city and state of residence or work.
[7] Letters will be edited for clarity and length.