The circadian clock controls physiological traits such as flowering time, photosynthesis, and growth in plants under laboratory conditions. Under natural field conditions, however, little is known about the significance of the circadian clock in plants. By time-course transcriptome analyses of rice (Oryza sativa) leaves, using a newly isolated rice circadian clockrelated mutant carrying a null mutation in Os-GIGANTEA (Os-GI), we show here that Os-GI controlled 75% (false discovery rate = 0.05) of genes among 27,201 genes tested and was required for strong amplitudes and fine-tuning of the diurnal rhythm phases of global gene expression in the field. However, transcripts involved in primary metabolism were not greatly affected by osgi. Time-course metabolome analyses of leaves revealed no trends of change in primary metabolites in osgi plants, and net photosynthetic rates and grain yields were not affected. By contrast, some transcripts and metabolites in the phenylpropanoid metabolite pathway were consistently affected. Thus, net primary assimilation of rice was still robust in the face of such osgi mutation-related circadian clock defects in the field, unlike the case with defects caused by Arabidopsis thaliana toc1 and ztl mutations in the laboratory.

SUMMARYThe role of NAD(P)H dehydrogenase (NDH)-dependent cyclic electron flow around photosystem I in photosynthetic regulation and plant growth at several temperatures was examined in rice (Oryza sativa) that is defective in CHLORORESPIRATORY REDUCTION 6 (CRR6), which is required for accumulation of subcomplex A of the chloroplast NDH complex (crr6). NdhK was not detected by Western blot analysis in crr6 mutants, resulting in lack of a transient post-illumination increase in chlorophyll fluorescence, and confirming that crr6 mutants lack NDH activity. When plants were grown at 28 or 35°C, all examined photosynthetic parameters, including the CO 2 assimilation rate and the electron transport rate around photosystems I and II, at each growth temperature at light intensities above growth light (i.e. 800 lmol photons m )2 sec )1 ), were similar between crr6 mutants and control plants. However, when plants were grown at 20°C, all the examined photosynthetic parameters were significantly lower in crr6 mutants than control plants, and this effect on photosynthesis caused a corresponding reduction in plant biomass. The F v /F m ratio was only slightly lower in crr6 mutants than in control plants after short-term strong light treatment at 20°C. However, after long-term acclimation to the low temperature, impairment of cyclic electron flow suppressed non-photochemical quenching and promoted reduction of the plastoquinone pool in crr6 mutants. Taken together, our experiments show that NDH-dependent cyclic electron flow plays a significant physiological role in rice during photosynthesis and plant growth at low temperature.

Although FDG-PET was not sensitive enough to detect prostate cancer in clinical use, it is suggested that glucose metabolism in prostate cancer tended to be higher in patients with tumors of advanced stages.

Rice (Oryza sativa L.) plants with substantially increased Rubisco content were obtained by Agrobacteriummediated transformation with the rice rbcS sense gene under the control of the rice rbcS promoter. The primary transformants were screened for the ratio of Rubisco to leaf-N content, and the transformants with 4120% wild-type levels of Rubisco were selected. In the progeny of the selected lines of the transformants, the mRNA levels of one member of the rbcS gene family were increased from 3.9-to 6.2-fold, whereas those of other members of the rbcS gene family were unchanged. The total levels of rbcS mRNA were increased from 2.1-to 2.8-fold. The levels of rbcL mRNA were increased from 1.2-to 1.9-fold. Rubisco protein content was significantly increased by 30% on a leaf area basis. The ratio of Rubisco-N to leaf-N was also increased by 10-20%, irrespective of N treatment. The specific activity of Rubisco per unit of enzyme protein was not different. However, light-saturated photosynthesis was not enhanced even when the rate was measured at low [CO 2 ] where Rubisco becomes limiting for photosynthesis. Some lines showed lower photosynthesis at high [CO 2 ] (460 Pa). We conclude that introduction of additional sense rbcS leads to overexpression of rbcS and that this overexpression slightly up-regulates the gene expression of rbcL at the transcript level and enhances the amount of Rubisco holoenzyme. However, overproduction of Rubisco protein does not improve photosynthesis.

Arabidopsis RNA Isolation Plants often present a challenge to researchers wanting to isolate nucleic acids for subsequent analyses as a result of the high amounts of polysaccharides and other contaminating metabolites present in plant tissues. Suzuki et al. (p. 542) describe an isolation method that produces RNA free of contamination by protein or polysaccharides or degradation, suitable for reverse transcription PCR (RT-PCR). The authors extracted RNA from Arabidopsis siliques, seeds, flower buds, leaves, roots, and stems with no decrease in the quality or quantity of RNA. Their method was both time- and cost-effective over more conventional methods and is simple enough to be routinely applied to other species.

As ribulose 1·5-bisphosphate carboxylase/oxygenase (Rubisco) activity limits light-saturated photosynthesis under present atmospheric condition, the effects of an overexpression of RBCS on Rubisco content and photosynthesis were examined in the leaves at different positions in rice (Oryza sativa L.). Rubisco content in the transformant was significantly greater in the uppermost, fully expanded leaves but decreased to levels similar to those in wild-type plants in the lower leaves. The mRNA levels of total RBCS and rbcL in these leaves were much less than those in the expanding leaves, where Rubisco synthesis is active, suggesting commensurately low level of synthesis. Although the activation state of Rubisco was lower in the uppermost, fully expanded leaves of the transformant, it recovered to its full level in the lower leaves. As a result, the photosynthetic rate did not differ in leaves at the same position between the transformant and the wild type. Similarly, whole plant biomass did not differ between these genotypes. Thus, we conclude that although the overexpression of RBCS led to an enhancement of Rubisco protein content in the uppermost, fully expanded leaves, it does not result in increased photosynthetic rates or plant biomass, because of an apparent down-regulation in its activation state.

Results and discussionBiomass production, yield and NUE. In the experimental conditions tested when more than 10.0 g N m −2 N fertilizer was supplied, the dry matter production and brown rice yield in RBCS-sense plants were increased by up to 23% (Fisher's test, P = 0.000-0.006) and up to 28% (Fisher's test, P = 0.000-0.016), respectively, compared to wild-type plants (Tables 1 and 2). The greatest dry matter production and brown rice yield from the RBCS-sense plants were observed in the 15.0 g N m −2 plot in 2019, at 1,657 g m −2 and 706 g m −2 , respectively, and the highest ratios of increase for both parameters were found in the 14.1 g N m −2 plot in 2018. In the plot with no N application from 2017 to 2019, no difference in dry matter production (Fisher's test, P = 0.506 in 2017; P = 0.208 in 2018; P = 0.208 in 2019) or brown rice yield (Fisher's test, P = 0.842 in 2017; P = 0.335 in 2018; P = 0.911 in 2019) was observed between RBCS-sense and wild-type plants, and brown rice yield of RBCSsense plants in the 7.1 g N m −2 plot in 2018 was lower than that of wild-type plants (Fisher's test, P = 0.000) (Tables 1 and 2). In RBCSantisense plants, the brown rice yield was 14-34% lower than in wild-type plants (Fisher's test, P = 0.000-0.030)-this was regardless of N application except in the plot with no N application in 2019 (Fisher's test, P = 0.934) (Tables 1 and 2). The lack of difference in 2019 might have been the effect of 2 yr without N fertilization. In the 17.0 g N m −2 plot in 2017, all plants were blown down by two typhoons and then almost lodged during their ripening stagestheir dry matter production and brown rice yield were, therefore, The green revolution's breeding of semi-dwarf rice cultivars in the 1960s improved crop yields, with large increases in the use of nitrogen (N) fertilizer. However, excess N application has caused serious environmental problems, including acid rain and the eutrophication of rivers and oceans. To use N to improve crop yields, while minimizing the associated environmental costs, there is a need to produce crops with higher N-use efficiency and higher yield components. Here we show that transgenic rice overproducing ribulose 1,5-bisphosphate carboxylase-oxygenase (Rubisco)-the key enzyme of photosynthesis-exhibits increased yields with improved N-use efficiency for increasing biomass production when receiving sufficient N fertilization in an experimental paddy field. This field experiment demonstrates an improvement in photosynthesis linked to yield increase due to a higher N-use efficiency in a major crop.

Background: Rhizotoxic ions in problem soils inhibit nutrient and water acquisition by roots, which in turn leads to reduced crop yields. Previous studies on the effects of rhizotoxic ions on root growth and physiological functions suggested that some mechanisms were common to all rhizotoxins, while others were more specific. To understand this complex system, we performed comparative transcriptomic analysis with various rhizotoxic ions, followed by bioinformatics analysis, in the model plant Arabidopsis thaliana.