title: Exogenous proline application ameliorates toxic effects of arsenate in Solanum melongena L. seedlings.
abstract: Hydroponic experiments were conducted to investigate an effect of exogenous application of proline (Pro; 25 µM) in alleviating arsenate (As(V); 5 and 25 µM) toxicity in Solanum melongena L. (eggplant) seedlings. Exposure of As(V) declined growth of eggplant, which was coincided with an enhanced accumulation of As. However, exogenous Pro application alleviated As(V) toxicity in eggplant seedlings by reducing the accumulation of As. The fluorescence characteristics (JIP-test): φP0, Ψ0, φE0, PIABS, ABS/RC, TR0/RC, ET0/RC, DI0/RC, NPQ and qP were also affected by As(V). However, the effects of As(V) were more prominent on PIABS DI0/RC and NPQ. In Pro treated seedlings, following parameters viz. φP0, Ψ0, φE0 and PIABS were stimulated, while, energy flux parameters (ABS/RC, TR0/RC, ET0/RC and DI0/RC) were inhibited. Toxic effects of As(V) on photochemistry of photosystem II (PS II) were ameliorated by an exogenous application of Pro. Oxidative stress markers: superoxide radical, hydrogen peroxide and malondialdehyde (lipid peroxidation) were enhanced by As(V) exposure, however, their levels were significantly diminished by an exogenous application of Pro. Treatment of As(V) stimulated the activities of superoxide dismutase, peroxidase and catalase except that of glutathione-S-transferase. Exogenous Pro application improved the activities of enzymatic antioxidants. The level of endogenous Pro was higher in As(V) treated as well as in Pro fed seedlings. The activity of a key enzyme of Pro biosynthesis: Δ(1)-pyrroline-5-carboxylate synthetase was higher in Pro fed seedlings. The activity of Pro dehydrogenase was inhibited under As(V) stress, and its activity was minimum in case of Pro+As(V) combination. These results indicate that Pro metabolism could play a key role in regulating the accumulation of As and levels of antioxidants, which concomitantly result into a better growth of eggplant seedlings when compared to the As(V) treatments alone.
authors.affiliation: Ranjan Plant Physiology and Biochemistry Laboratory, Department of Botany, University of Allahabad, Allahabad 211 002, India.
authors.forename: Madhulika
authors.initials: M
authors.lastname: Singh
authors.affiliation: Govt. Ramanuj Pratap Singhdev Post Graduate College, Baikunthpur, Koriya 497 335, Chhattisgarh, India. Electronic address: vijaypratap.au@gmail.com.
authors.forename: Vijay
authors.initials: V
authors.lastname: Pratap Singh
authors.affiliation: Department of Botany, University of Rajasthan, Jaipur 302004, India.
authors.forename: Gunjan
authors.initials: G
authors.lastname: Dubey
authors.affiliation: Ranjan Plant Physiology and Biochemistry Laboratory, Department of Botany, University of Allahabad, Allahabad 211 002, India. Electronic address: profsmprasad@gmail.com.
authors.forename: Sheo
authors.initials: S
authors.lastname: Mohan Prasad
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D001149:Arsenates / Q000378:metabolism / Q000633:toxicity*; D002374:Catalase / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D008315:Malondialdehyde / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects*; D010788:Photosynthesis / Q000187:drug effects*; D045332:Photosystem II Protein Complex / Q000378:metabolism; D011392:Proline / Q000378:metabolism / Q000494:pharmacology*; D011758:Pyrroles; D017382:Reactive Oxygen Species / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development; D032323:Solanum melongena / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D000975:Antioxidants; D001149:Arsenates; D045332:Photosystem II Protein Complex; D011758:Pyrroles; D017382:Reactive Oxygen Species; D002734:Chlorophyll; C015485:delta-1-pyrroline-5-carboxylate; D008315:Malondialdehyde; D011392:Proline; D006861:Hydrogen Peroxide; D002374:Catalase; D013482:Superoxide Dismutase; C025657:arsenic acid
keywords: Antioxidant system; Arsenate stress; Chlorophyll fluorescence; Growth; Oxidative stress; Proline metabolism