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DIFFERENTIAL ACCUMULATIONS OF PROLINE AND FLAVONOIDS IN INDICA RICE VARIETIES AGAINST SALINITY

SUTEE CHUTIPAIJIT¹, SURIYAN CHA-UM² AND KANOKPORN SOMPORNPAILIN^{1, 3*}

Abstract: Four varieties of indica rice differing in salt sensitivity were used for comparative study of defense systems in response to salinity.  Rice seedlings were transferred into the photoautotrophic system containing NB medium with 100 mM NaCl as a salt stress treatment for 4 days. The physiological responses of jasmine rice (KDML105) and Sangyod (SY) varieties showed the better tolerance to salinity than those of Pathumthani 1 (PT1) and Black Sticky (BS) varieties.  In salt stress treatment, the relative water content (RWC) of rice seedlings was decreased when compared to untreated seedlings. The RWC of salt-tolerant seedlings (KDML105 and SY) were decreased (0.33-0.53%) less than those of salt-sensitive seedlings (PT1 and BS), which exhibited 1.18-2.63% reductions. The salt-tolerant KDML105 and SY showed the lesser extent of membrane damage (lipid peroxidation; 7.94-19.26%) while enhanced the proline level (56.56-78.56%) and the flavonoid level (1.72-3.48%) more than those of the sensitive PT1 and BS varieties. Moreover, the positive correlation between proline or flavonoid accumulations and RWC was observed whereas the correlation between proline or flavonoid accumulations and MDA content was negative. These results suggest that high proline and flavonoids levels accumulated in each varieties of rice might be closely related to tolerant abilities indicating by physiological performances.

¹Department of Applied Biology, Faculty of Science, King Mongkut’s Institute of Technology Ladkrabang, Bangkok, 10520, Thailand

²National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Thailand Science Park, Klong Luang, Pathumthani, 12120, Thailand

³College of KMITL Nanotechnology, King Mongkut’s Institute of Technology Ladkrabang, Bangkok, 10520, Thailand.