Article

Effect of salinity stress on growth and carbohydrate metabolism in three rice (Oryza sativa L.) cultivars differing in salinity tolerance.

Applied Taxonomic Research Center, Department of Biology Faculty of Science, Khon Kaen University, Khon Kaen, 40002 Thailand.
Indian journal of experimental biology (Impact Factor: 1.2). 11/2008; 46(10):736-42.
Source: PubMed

ABSTRACT Rice seedlings cv. Khao Dawk Mali 105 (salt-sensitive), Luang Anan (moderately salt-tolerant) and Pokkali (salt-tolerant) were exposed to 0, 50, 100 and 150 mM NaCI for 9 d. Salinity stress caused reduction in leaf relative water contents in all cultivars. Shoot length of cv. Pokkali was least affected by salinity stress whereas increased root length in response to salinity stress was apparent in cvs. Khao Dawk Mali 105 and Luang Anan. Increased salinity level also caused reduction in fresh and dry weights in cvs. Khao Dawk Mali 105 and Luang Anan, but had no effect in cv. Pokkali except at 150 mM. Accumulation of total soluble sugars and sucrose in mature leaves were observed in cv. Khao Dawk Mali 105 exposed to high level of salinity whereas their concentrations in cvs. Luang Anan and Pokkali remained the same as control plants. Accumulation of sucrose in cv. Khao Dawk Mali 105 was suggested to be resulted from the alteration of photosynthate partitioning since the activities of sucrose phosphate synthase were not affected by salinity in this cultivar. On the contrary, salinity stress induced an accumulation of starch in cv. Pokkali. It is suggested that partitioning sugars into starch may involve in salinity tolerance by avoiding metabolic alterations.

1 Bookmark
 · 
222 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Finger millet (Eleusine coracana L.) is a hardy cereal known for its superior level of tolerance against drought, salinity, diseases and its nutritional properties. In this study, attempts were made to unravel the physiological and molecular basis of salinity tolerance in two contrasting finger millet genotypes viz., CO 12 and Trichy 1. Physiological studies revealed that the tolerant genotype Trichy 1 had lower Na+ to K+ ratio in leaves and shoots, higher growth rate (osmotic tolerance) and ability to accumulate higher amount of total soluble sugar in leaves under salinity stress. We sequenced the salinity responsive leaf transcriptome of contrasting finger millet genotypes using IonProton platform and generated 27.91 million reads. Mapping and annotation of finger millet transcripts against rice gene models led to the identification of salinity responsive genes and genotype specific responses. Several functional groups of genes like transporters, transcription factors, genes involved in cell signaling, osmotic homeostasis and biosynthesis of compatible solutes were found to be highly up-regulated in the tolerant Trichy 1. Salinity stress inhibited photosynthetic capacity and photosynthesis related genes in the susceptible genotype CO 12. Several genes involved in cell growth and differentiation were found to be up-regulated in both the genotypes but more specifically in tolerant genotype. Genes involved in flavonoid biosynthesis were found to be down-regulated specifically in the salinity tolerant Trichy 1. This study provides a genome-wide transcriptional analysis of two finger millet genotypes differing in their level of salinity tolerance during a gradually progressing salinity stress under greenhouse conditions.
    Plant Molecular Biology 05/2014; · 3.52 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Soluble carbohydrates play a key role as osmolytes and significantly contribute in salt defence mechanism, especially in halophyte species. The objective of this study is to investigate the transcriptional expression of starch-related genes, sugar profile and physiological performances of two contrasting rice genotypes, Pokkali (salt tolerant) and IR29 (salt sensitive), in response to salt stress. Total soluble sugars, glucose and fructose levels in the flag leaf of salt-stressed Pokkali rice were enhanced relative to soluble starch accumulation in plants exposed to EC = 13.25 dS m(-1) (salt stress) for 3 days. In Pokkali, the net photosynthetic rate and starch metabolism may play a key role as energy resources under salt stress. In contrast, photosynthetic performance, indicated by photosynthetic pigment levels and chlorophyll fluorescence parameters, in salt-stressed IR29 was significantly reduced, leading to delayed starch biosynthesis. The reduction in photosynthetic ability and lack of defence mechanisms in IR29 caused growth inhibition and yield loss. Soluble starch and soluble sugar enrichment in Pokkali rice may function alternatively as osmotic adjustment in salt defence mechanism and strengthen carbon energy reserves, greater survival prospects under salt stress and enhanced productivity.
    Protoplasma 04/2013; · 2.86 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Three-week old seedlings of 3 rice varieties: KDML105, RD6 (both moderately salt-susceptible) and Pokkali (salt-tolerant) were treated with 100 mM NaCl for 6 days. Fluorescence (Fv/Fm, ∆F/Fm', ETR and NPQ) and growth (FW and DW of root and shoot, root/shoot and height) parameters were investigated. The results showed that Fv/Fm in all rice varieties was unaffected by salt stress. In contrast, ∆F/Fm' and ETR in KDML105 and RD6 showed significant reduction in the salt-treated group compared to the control. Salt treatment resulted in a dramatic increase in NPQ in KDML105 and RD6. However, ∆F/Fm', ETR and NPQ in Pokkali were unaffected by salt stress. Strong negative correlation was found between NPQ and ETR in all 3 rice varieties. Root and shoot FW in KDML105 treated with salt decreased significantly (P<0.05) but its root/shoot was unaffected by salt stress. In contrast, root and shoot growth in RD6 and Pokkali were not affected by salt stress. This result suggested that only the salt sensitive species showed high sensitivity to salt stress. Additionally, PSII photosynthetic performance (∆F/Fm', ETR and NPQ) was more responsive than growth parameter. Therefore, PSII photosynthetic efficiency can potentially be used as an indicator to evaluate salt tolerance in rice seedlings.
    08/2013;

Full-text (2 Sources)

View
36 Downloads
Available from
Jun 6, 2014