relations between antioxidant enzymes and chlorophyll fluorescence parameters in common bean cultivars differing in sensitivity to drought stress

• Published in: Russian journal of plant physiology 2011, Vol.58 (1), p.60-68
• Main Authors: Saglam, A, Saruhan, N, Terzi, R, Kadioglu, A
• Format: Article
• Language: English
• Subjects: antioxidants; Biomedical and Life Sciences; chlorophyll fluorescence; drought; Life Sciences; Phaseolus vulgaris; Plant Physiology; Plant Sciences; Research Papers
• ISSN: 1021-4437; 1608-3407
• DOI: 10.1134/S102144371101016X

Effects of the antioxidant system and chlorophyll fluorescence on drought tolerance of four common bean (Phaseolus vulgaris L.) cultivars were studied. The cultivars were positioned in the order of a decrease in their drought tolerance: Yakutiye, Pinto Villa, Ozayse, and Zulbiye on the basis of changes in the water potential, stomatal conductance, photosynthetic pigment content, and lipid peroxidation. Under drought conditions, the level of H₂O₂ was not changed in cv. Pinto Villa but decreased in other cultivars. Antioxidant enzymes (superothide dismutase (SOD), guaiacol peroxidase (GPX), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR)) were generally activated in all cultivars. Interestingly, CAT, APX, and GR activities were not changed in cv. Pinto Villa, APX activity decreased in cv. Yakutiye, and CAT activity was not changed in cv. Zulbiye. The increases in SOD and GPX activities in cv. Ozayse were higher than in other cultivars. Drought stress reduced the effective quantum yield of PS2 (ΦPS₂) and the photochemical quenching (qp), while it increased nonphotochemical quenching (NPQ) in all cultivars. The reduction or increase was more pronounced in cv. Zulbiye. There were generally significant correlations between qp, NPQ, and ROS scavenging by SOD and APX. Also, there were significant correlations between SOD and qp in tolerant cultivars and APX and qp in sensitive ones. The results indicate that activation of SOD and APX was closely related to the efficiency of PS2 in common bean cultivars. This interaction was essential for protection of photosystems and plant survival under drought.