Exogenous Glycinebetaine Accumulation and Increased Salt-tolerance in Rice Seedlings

Abstract

Exposure of 28-day-old rice seedlings for 6 days to 150 mm NaCl was found to induce drastic decreases in relative water contents, chlorophyll, and proteins in the leaves. This effect was largely prevened when before the exposure to NaCl the seedlings were treated for 4 days with 15 mm glycinebetaine. Although rice plants do not accumulate glycinebetaine endogenously, added glycinebetaine was found to be taken up by the roots and to accumulate in the leaves to reach a concentration of up to 5.0 μmol per gram fresh weight. The level is comparable with those of barley and wheat, which are well known glycinebetaine accumulators, under salt stress. The quantum yield of PSII was decreased by 27% under salt stress. This decrease was also largely prevented by glycinebetaine application.

Improvement of Salinity Stress Tolerance in Rice: Challenges and Opportunities

“…Glycine betaine, a quaternary ammonium compound that occurs naturally in a wide range of plants, animals and microorganisms [33] is also a very effective compatible solute [34,35]. Although rice plants do not accumulate glycine betaine endogenously, Harinasut and co-workers [36] found that rice plants can uptake exogenous glycine betaine and accumulate it in leaves to help the plants to maintain quantum yield of PSII during salinity stress.…”

Inactivation of an aminoaldehyde dehydrogenase is responsible for fragrance in rice

“…BAD expression has previously been linked to salt tolerance in numerous plants (Ishitani et al 1995;Harinasut et al 1996;Wood et al 1996) and the gene expression of BAD2 (Fitzgerald et al Plant Mol Biol (2008) 68:439-449 445 2008) and the concentration of GABA (Kim et al 2007) has been found to increase in rice under salt stress. BAD2 has been shown to play a role in salt tolerance in rice, yet does not accumulate glycine betaine (Ishitani et al 1993;Rathinasabapathi et al 1993) and we have shown that GABald is the preferred substrate of BAD2.…”

Effect of NaCl on the Photosynthesis, Water Relations and Free Proline Accumulation in the WildOryzaSpecies

“…For example, 1) selective absorption of ions in roots (Badger and Ungar, 1990), 2) positive elimination of the absorbed salt (Matsushita and Matoh, 1991), and 3) storage of adaptation solutes in cytoplasm to maintain osmotic pressure (Munns and Termaat, 1986;Kalaji and Pietkiewicz, 1993). It has been proposed that rice acquires salt tolerance by excluding sodium ion from the roots (Akita and Cabuslay, 1990;Gregorio and Senadhira, 1993;Tsuchiya et al, 1994), and accumulation of proline and glycine betaine in leaves (Harinasut et al, 1996) for osmotic adjustment. However, these studies were made using cultivated rice species.…”