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Research Article
ScienceAsia 30 (2004): 247-253 |doi: 10.2306/scienceasia1513-1874.2004.30.247
Biochemical and Physiological Responses of Thai
Jasmine Rice (Oryza sativa L. ssp. indica cv. KDML105)
to Salt Stress
Suriyan Cha-um,a,b* Chalermpol Kirdmaneea and Kanyaratt Supaibulwatanab
ABSTRACT: The aim of this research was to investigate glycinebetaine (Glybet) accumulation in rice seedlings
via the activity of betaine aldehyde dehydrogenase (BADH) and to characterize the physiological responses
of Glybet-accumulated seedlings to salt stress. The BADH activity of Thai jasmine rice seedlings cultured
photoautotrophically showed a progressive elevation during the first four days after growth under salt-stress
condition (342 mM NaCl), but gradually decreased thereafter (days 6-8). This increase in BADH activity was
accompanied by an accumulation of Glybet. In contrast, the BADH activity and Glybet content of control
seedlings (0 mM NaCl) remained at a low and constant level during the same 8-day interval. Significant
reductions in the concentrations of chlorophyll a, chlorophyll b, total chlorophyll and total carotenoid of
salt-stressed seedling were observed with increasing exposure time to salt-stressed conditions. The decrease
in total chlorophyll concentrations of salt-stressed seedlings was positively related to reductions in the net
photosynthetic rate (r = 0.89), and dry weight (r = 0.89). The dry weight of in-vitro salt-stressed seedling was
positively related to their survival percentage (r = 0.94). The survival percentage of salt-stressed seedlings
was significantly decreased with increasing exposure time to the salt-stressed conditions. The Glybet
accumulation in salt-stressed rice seedlings is consistent with a defense response to salt-stressed conditions.
These results suggest that assaying BADH activity and/or Glybet accumulation may be further used in
screening for salt-tolerant varieties of indica rice.
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a National Center for Genetic Engineering and Biotechnology, National Science and Technology
Development Agency, 113 Thailand Science Park, Paholyothin Road, Klong 1, Klong Luang,
Pathumthani 12120, Thailand.
b Department of Biotechnology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok 10400,
Thailand.
* Corresponding author, E-mail: suriyanc@biotec.or.th
Received 1 Mar 2004,
Accepted 13 Jul 2004
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