Sodium Chloride Salt Stress Induced Changes in Thylakoid Pigment-Protein Complexes, Photosystem II Activity and Thermoluminescence Glow Peaks

Abstract

Salt stress, Thylakoid membrane, Pigment-protein complex, PS II, Thermoluminescence, Mung bean ( Vigna radiata L.), Indian mustard (Brassica juncea Coss.)In the present study, mung bean (Vigna radiata L.) -a salt susceptible and Indian mustard (.Brassica juncea L.) -a salt resistant crop was studied to find out the differences in stress responses of these crops. Seedlings were grown in water soaked cotton under continuous illumination of 35 (.imole m 2 s 1 at 26 ± 1 °C. Salinity treatment of 0, 0.5 and 1.0% (w/v) was given to the seedlings at 6 day Photosynthetic pigment content and PS II electron trans port activity was reduced under salinity in both mung bean and Indian mustard. The pigment protein pattern of both the crops were similar. Ratio analysis of B and Q thermolumines cence (T L ) glow peaks suggested that S2Q a-charge recombination was relatively more af fected than S2/?Qb-charge recombinations.

Increase in the intensity of thermoluminescence Q‐band during leaf ageing is due to a block in the electron transfer from QA to QB

“…Thermoluminescence glow curves are extensively used to decipher the changes in charge recombination in photosystem II (18,19,21). The TL bands at 10°C and 32°C are widely studied and well characterized (2-6).…”

“…These samples were excited by a sequence of two flashes (General Radio, Stroboslave) with a halfdecay time of 3 ms (0.5 J) white light and quickly frozen to 77K by dropping them into a Dewar containing liquid nitrogen. TL glow curves were recorded as described by Misra et al (18,19). To inhibit electron transfer between Q A and Q B in the reaction centre of photosystem II, 5 mL 10 mmol/L DCMU was added to the chloroplast thylakoid sample before illumination.…”

Effects of salt stress on basic processes of photosynthesis

“…In some studies salt stress had no effect on PS2 (Robinson et al 1983, Brugnoli and Björkman 1992, Morales et al 1992. The PS2 inhibition under salt stress was characterized by Misra et al (1999). In some reports, the PS2 activity was decreased in response to salt stress due to the dissociation of 23 kDa polypeptide extrinsically bound to PS2 (Kuwabara and Murata 1982, Miyao and Murata 1983, Murata et al 1992.…”

Structural and functional changes of PSI-LHCI supercomplexes of Chlamydomonas reinhardtii cells grown under high salt conditions

“…In the red alga Porphyra perforata, Satoh et al (1983) demonstrated that the salinity stress-induced decrease in PSII activity was due to a decrease in the excitation energy reaching PSII reaction centers, as well as damage to the oxidizing side of PSII. Salt stress also inhibits PSII activity in higher plants (Everard et al 1994;Tiwari et al 1997;Misra et al 1999), including salt-tolerant plants such as mangroves (Parida et al 2003). In some reports, the eVects of salt stress on PSII were due to the dissociation of the 23-kDa polypeptide extrinsically bound to PSII (Murata et al 1992).…”