Promotion of Seedling Growth of Seeds of Rice (Oryza sativa L. cv. Hitomebore) by Treatment with H2O2 before Sowing

High germinability of seeds and establishment of young seedlings in rice (Oryza sativa L.) are necessary for direct seeding in paddy fields. We investigated whether germinability and seedling growth were promoted by treatment of rice seeds (cv. Hitomebore) with hydrogen peroxide solution (H2O2) during the imbibition for 24 h. H2O2 treatment with 50 mM H2O2 promoted seed germination, and seedling growth (shoot length, root length and shoot fresh weight) in agar culture under a low temperature condition (18°C day/14°C night). Seedling growth was promoted by H2O2 treatment not only under the low-temperature condition but also under a normal (23°C day/18°C night) temperature condition. Furthermore, H2O2 treatment promoted seedling growth under a flooding condition in a greenhouse. These results suggest that H2O2 treatment of rice seeds during the imbibition is advantageous for direct seeding. We discussed the relation between the promotion of the seed germinability and the seedling growth under a low-temperature condition, and the expression of some genes encoding ROS scavenger enzymes induced by H2O2 treatment

Accumulation of Glycinebetaine in Rice Plants that Overexpress Choline Monooxygenase from Spinach and Evaluation of their Tolerance to Abiotic Stress

• Background and Aims Glycinebetaine (GB), a quaternary ammonium compound, is a very effective compatible solute. In higher plants, GB is synthesized from choline (Cho) via betaine aldehyde (BA). The first and second steps in the biosynthesis of GB are catalysed by choline monooxygenase (CMO) and by betaine aldehyde dehydrogenase (BADH), respectively. Rice (Oryza sativa), which has two genes for BADH, does not accumulate GB because it lacks a functional gene for CMO. Rice plants accumulate GB in the presence of exogenously applied BA, which leads to the development of a significant tolerance to salt, cold and heat stress. The goal in this study was to evaluate and to discuss the effects of endogenously accumulated GB in rice

An increase in unsaturation of fatty acids in posphatidylglycerol from leaves improves the rates of photosynthesis and growth at low temperatures in transgenic rice seedlings

The level of cis-unsaturated fatty acids in phosphatidylglycerol (PG) from rice leaves was genetically altered from 19.3% in the wild-type to 29.4 and 32.0% in T1 plants segregated with cDNAs for glycerol-3-phosphate acyltransferase of chloroplasts (GPAT; EC 2.3.1.15) from Arabidopsis (+AGPAT plant) and spinach (+SGPAT plant), respectively; and to 21.4% in a non-transformant segregated from +SGPAT plants (-SGPAT plant). In all these plants, O2 evolution from leaves was similar at 25 degrees C and was impaired to a similar extent at 5 and 11 degrees C. However, in parallel with the levels of cis-unsaturated fatty acids in PG, +AGPAT and +SGPAT plants showed less impaired rates of O(2) evolution from leaves than the wild-type and -SGPAT plants at 14 and 17 degrees C. In agreement with this, the fresh weight of 14-day-old seedlings increased to 571 + or - 18, 591 + or - 23, 687 + or - 32 and 705 + or - 31 mg in the wild-type, -SGPAT, +AGPAT and +SGPAT plants, respectively, after 6 weeks at 17/14 degrees C (day/night). These results demonstrate the practical importance of the present technology with GPAT in improvement of the chilling sensitivity of crops