Japonica Rice Plants Research Articles

Stringently and developmentally regulated levels of a cytoplasmic double-stranded RNA and its high-efficiency transmission via egg and pollen in rice.

A very restricted amount of high-molecular-weight double-stranded RNA (dsRNA) has been found in healthy japonica rice plants. We discriminated dsRNA-carrying rice plants from noncarriers. The endogenous dsRNA was localized in the cytoplasm (about 100 copies per cell) and was transmissible to progeny plants by mating. In crosses between carriers and noncarriers, the RNA was transmitted efficiently to F1 plants via both egg and pollen. The rice dsRNA was maintained at an almost constant level by host plant cells from generation to generation. The high-efficiency transmission of the endogenous dsRNA to progeny plants appears to depend on the autonomously controlled replication of the dsRNA localized in cytoplasmic vesicles. However, an increase in copy number (about 10-fold) of the dsRNA was observed during the suspension culture of host cells. The number of copies of dsRNA returned to the original low value in regenerated plants, suggesting that the copy number is stringently and developmentally regulated in rice cells.

Fertile indica and japonica rice plants regenerated from protoplasts isolated from embryogenic haploid suspension cultures

A system to regenerate fertile rice (Oryza sativa L.) plants (both indica and japonica varieties) from protoplasts isolated from anther-derived embryogenic haploid suspension cultures has been established. Green plants were regenerated from protoplast-derived cell clusters five months after suspension culture initiation. Protoplast yields and subsequent growth of the protoplast-derived microcalli were enhanced by transferring suspension cells into AA medium (Muller et al. 1978) three to four days prior to protoplast isolation. Protoplasts were cultured initially in Kao medium (Kao et al. 1977) and in association with nurse cells for four weeks. Protoplast-derived microcalli were transferred onto N6 (Chu et al. 1975) or MS (Murashige and Skoog 1962) media for callus proliferation. Callus growth was more rapid and the calli were more enbryogenic when grown on N6 medium. The 2,4-D concentration used to develop the suspension culture was important. Cell cultures grown in medium containing 0.5 mg/l 2,4-D released protoplasts whose plating efficiency was higher than for protoplasts obtained from suspension cultures grown in 2.0 mg/l 2,4-D. However, suspension cells grown in 2.0 mg/l 2,4-D were superior with regard to the ability of protoplast-derived calli to regenerate green plants. Amongst several hormone treatments evaluated, a combination of 0.5 mg/l NAA + 5.0 mg/l BAP resulted in the largest number of green plants regenerated. There were no significant differences between BAP or kinetin regarding total number of plants regenerated. More than 200 green plants have been produced form six independently initiated suspension cell lines. The number of regenerated plants per 10(6) protoplats plated anged from 0.4 to 20.0, and the average seed fertility of single panicles of these RO plants was about 40%.

Development of endosperm and synthesis of starch in rice grain. III. Starch property as affected by the temperature during grain development.

Japonica rice plants (cultivar, Koshihikari) were treated at high and low temperatures in the early and late ripening stages. Starches prepared from the outer layer and inner portions of these rice grains were tested for their physicochemical properties. Generally, starch in the inner portion of rice grains was affected by temperature in the early ripening stage; whereas in the outer layer it was more affected in the late ripening stage. Amylose content was determined by iodine colorimetry and iodine binding capacity method. The amylose content of the outer layer and inner portion starches increased at low temperatures during grain development. Miniviscographic parameters of both starches were affected mainly by temperature in the early ripening stage and modified by that in the late ripening stage. The differential scanning calorimetric (DSC) transition temperature and gelatinization heat increased under high temperatures for the inner portion starch in the early ripening stage and for the outer layer starch in the late ripening stage. While the lipid content of inner portion starch increased at high temperatures in the early ripening stage, the lipid content of the outer layer starch decreased under high temperature in the late ripening stage. The fatty acid composition of lipids of the outer layer starch responded to temperature in a manner different from that of the inner portion starch.

Optical Configuration of Alanylalanine Detected in the Leaf Blades of Japonica Rice Plants FED withD-Alanine

Optical Configuration of Alanylalanine Detected in the Leaf Blades of Japonica Rice Plants FED with<scp>D</scp>-Alanine

Studies on the trisomics in rice plants (Oryza sativa L.). VI. An accomplishment of a trisomic series in japonica rice plants.

Extra chromosomes of 3 trisomic types, M, N and O, discovered recently in rice were clarified. Adding these 3 types to 9 types previously found, a complete set of 12 primary trisomics, having the homogeneous background of the cultivar Nipponbare, was established in japonica rice. The relationships among trisomics, chromosomes and linkage groups made clear up to the present time are shown.

Effecfs of temperature and light intensity on the uptake and assimilation of15N-labeled ammonium and nitrate in Indica and Japonica rice plants

Absrtact The effects of various environmental conditions such as temperature and light intensity on the uptake and assimilation of ammonium and nitrate in 4-week-old Indica and Japonica rice plants were studied using the 15N tracer technique. Both temperature and light intensity profoundly affected the uptake and assimilation of ammonium and nitrate, and the effects were more apparent in the utilization of nitrate by both Indica and Japonica rice plants. The uptake as well as assimilation of the two forms of nitrogen were greatly inhibited at low temperature and low lidlt intensity. On the other hand, although no significant difference in the effects of environmental conditions on the utilization of ammonium was observed between the Indica and Japonica rice plants, the former were more sensitive than the latter in the utilization of nitrate. At high temperature and high light intensity, the Indica rice plants absorbed, reduced, and assimilated nitrate more effectively than the Japonica, and this effect di...

Comparison of the uptake and assimilation of ammonium and nitrate in indica and japonica rice plants using the tracer15N method

Abstract The uptake of 15N-labeled ammonium and nitrate and their assimilation in 4-week-old Indica and Japonica rice plants were studied during 24 hr exposure to 2 mM solutions of (15NH4)SO4 and/or Na13NO3. Although there was no clear difference in the uptake and assimilation or 15NH4 +, significant differences in the uptake and assimilation or 15NH4 +. by both varieties were observed. When NH4 + or NO3 - was supplied exclusively, the Indica rice plants absorbed the latter more effectively than the Japonica. In addition, despite a preference for uptake of NO4 + rather than NO3 - as shown by both varieties when both forms were supplied together, the relative amounts or NO3 - uptake by the Indica were higher than those of Japonica. On the other hand, the Indica rice plants reduced the absorbed 15NO3 - more rapidly than the Japonica. The incorporation or 15NO2 - into the ethanol insoluble nitrogen fraction of the Indica rice also exceeded that of the Japonica. These results suggest that the Indica has the a...

Effects of various environmental and medium conditions on the response of Indica and Japonica rice plants to ammonium and nitrate nitrogen

Abstract The responses of two subspecies of rice, Oryza sativa subsp. Indica and Oryza sativa subsp. Japonica, to NH4 + and NO3 - under various environmental and medium conditions were studied by the water culture method. The results obtained indicated different effects of seasonal variations, particular of temperature and light intensity, on the responses of both rice subspecies to NH4 + and NO3 -. In summer, when the temperature and light intensity were high, the Indica rice plant fed with NO3 - was definitely superior to that fed with NH4 + or NHN++NO3 -, while the Japonica showed a better response to NH4 ++NO3 - than to NH4 + or NO3 -. However, as the season progressed to autumn, the response of the Indica rice plant to NH4 + and NO3 - followed the same trend as that of the Japonica. In contrast, the growth of both rice subspecies fed with NH4 + relative to that of plants grown in NH4 ++NO3 - was better in autumn than in summer. On the other hand, although the responses of both rice subspecies to NH4 ...

Comparative study on the response of Indica and Japonica rice plants to ammonium and nitrate nitrogen

Abstract The effects of NH4 + and NO3 - as nitrogen sources on the growth of two subspecies of rice, Oriza saliva subsp. Indica and Oriza saliva subsp. Japonica, during the first 6 weeks of growth were studied by the water culture method. The results obtained indicated that Indica and Japonica rice plants respond differently to NO3 -. Although both Indica and Japonica grew fairly well in solutions containing the two forms of nitrogen, the growth of the former was superior in NO3 - than in NH4 ++NO3 - or NH4 + solutions, especially at relatively low nitrogen concentrations, whereas the growth of the latter was inferior in NO3 - than in NH4 ++NO3 -solutions. In addition, plants of both subspecies fed with NH4 + showed growth retardation wtih tip-burning of the lower leaves and poorly branched roots. On the other hand, under moderately warmed glass house conditions with natural sunlight in winter, the growth of Indica in NO3 - solution was appreciably reduced compared to that in NH4 ++NO3 -. Thus, the effect...

Studies on Transpiration and Water Requirement of Indica and Japonica Rice Plants

Studies on Transpiration and Water Requirement of Indica and Japonica Rice Plants