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Aiming to controvert whether the photosynthetic capacity of transgenic rice expressing C4 genes is enhanced, with the C3-type untransformed rice (WT) and maize (a C4 plant) as controls, the activity of C4 photosynthetic enzymes, gas exchange parameters and water use efficiency (WUE) under different light intensities and temperatures, the stable carbon isotope ratio (δ13C) value and the metabolic index of active oxygen as well as plant yield parameters were determined in transgenic rice carrying the PEPC and PPDK genes (CK) in this study. The results showed that the light-saturated photosynthetic rate of CK was intermediate between that of WT and maize, with a slight bias towards that of maize. Under a high light intensity (1 200 μmol m−2 s−1) and high temperature (35°C), CK still exhibited higher photosynthetic capacity, while the Gs decreased. The WUE of CK was only slightly increased, and was similar to that of WT. The δ13C value indicated that CK functioned as a C3 plant. In addition, the tolerance to photo-oxidation and grain yield of CK was enhanced by sprayed with NaHSO3. In conclusion, CK possesses higher photosynthetic productivity under the conditions of high photon flux density (PFD), high temperature and spraying with NaHSO3 solution, thereby providing a new technical approach and physiological basis for constructing C4-like rice.

In an attempt to explore the relationships between phosphatidylglycerol (PG) molecular species of thylakoid membrane lipids and sensitivities to chilling-induced photoinhibition, PG molecular species, D1 protein, electron transport activities of thylakoid membrane and the potential quantum yield (F(v)/F(m)) in rice treated under middle and low photon flux density (PFD) at 11 degrees C were analyzed by high performance liquid chromatography, enzyme hydrolysis, gas phase chromatography (GC) and so on. Results showed that the major molecular species of PGs in rice thylakoid membrane were 18:3/16:0, 18:3/16:1(3t), 18:2/16:0, 18:2/16:1(3t), 18:1/16:0, 18:1/16:1(3t), 16:0/16:0, 16:0/16:1(3t). There were large differences in the contents of unsaturated PG molecular species such as 18:1 approximately 3/16:0 approximately 16:1(3t) and saturated PG molecular species like 16:0/16:0 approximately 16:1(3t) among japonica cv 9516 (j-9516), japonica-indica hybrid F1 j-9516/i-SY63 (ji-95SY) and indica cv Shanyou 63 (i-SY63). J-9516 containing higher contents of unsaturated PG molecular species was manifest in stable D1 protein contents under chill and tolerant to chill-induced photoinhibition. In contrast to j-9516, i-SY63 with lower contents of unsaturated PG molecular species, exhibited unstable D1 protein contents under chill and was sensitive to chill-induced photoinhibition. ji-95SY containing middle contents of unsaturated PG molecular species between those of j-9516 and i-SY63, exhibited mid extent of sensitivity to chill-induced photoinhibition. The losses in D1 protein also account for the inhibition in electron transport activity of thylakoid membrane and the observed decline in F(v)/F(m). The PG molecular species that is efficient in raising chilling-resistant capacity were those containing unsaturated fatty acids, namely, unsaturated PG molecular species. These results implied that the substrate selectivity of the glycerol-3-phosphate acyltransferase in chloroplasts towards 16:0 or 18:1 displayed greatly the difference between japonica and indica rice. It was possible to enhance the capacity of resistance to chilling-induced photoinhibition by improving or modifying the GPAT gene.

Temperature is one of the abiotic factors limiting growth and productivity of plants. In the present work, the effect of low non-freezing temperature, as an inducer of “chilling resistance”, was studied in three cultivars of rice (Oryza sativa L.), japonica cv. 9516 (j-9516), the two parental lines of superhigh-yield hybrid rice between subspecies, Peiai/E32 (ji-PE), and the traditional indica hybrid rice Shanyou 63 (i-SY63). Leaves of chill-treated rice showed chilling-induced resistance, as an increase of their low-temperature tolerance was measured using chlorophyll fluorescence measurements, revealing a change in photosystem II (PSII) efficiency. After 5 d of exposure to 11°C under low light (100 μmol m-2 s-1), levels of unsaturated fatty acids in PSII thylakoid membrane lipids decreased during the initial 1-2 d, then increased slowly and reached 99.2%, 95.3% and 90.1% of the initial value (0 d) in j-9516, ji-PE and i-SY63, respectively, on the fifth day. However, under medium light (600 μmol m-2 s-1), all cultivars experienced similar substantial photoinhibition, which approached steady state levels after a decline in levels of unsaturated fatty acids in PSII thylakoid membrane lipids to about 57.1%, 53.8% and 44.5% of the initial values (0 d) in j-9516, ji-PE and I-SY63 on the fifth day. Under either chilling-induced resistance (the former) or low temperature photoinhibition (the latter) conditions, the changes of other physiological parameters such as D1 protein contents, electron transport activities of PSII (ETA), Fv/Fm, xanthophyl cycle activities expressed by DES (deepoxide state) were consistent with that of levels of unsaturated fatty acids in PSII thylakoid membrane lipids. So there were negative correlations between saturated levels of fatty acids (16:1(3t), 16:0, 18:0), especially the 16:1(3t) fatty acid on thylakoid membrane and other physiological parameters, such as D1 protein contents, ETA and (A+Z)/(A+V+Z). A specific role of desaturation of fatty acids and the photoprotective pigments of the xanthophyl cycle, leading to an acclimation response in thylakoid membrane lipids may be involved. We conclude that chilling-induced resistance is accelerated by the unsaturation of thylakoid membranes, and the ability of rice plants to cold-harden can be enhanced by genetic engineering.

To elucidate the photosynthetic physiological characteristics and the physiological inherited traits of rice (Oryza sativa L.) hybrids and their parents, physiological indices of photosynthetic CO2 exchange and chlorophyll fluorescence parameters were measured in leaves of the maize phosphoenolpyruvate carboxylase (PEPC) transgenic rice as the male parent, sp. japonica rice cv. 9516 as the female parent, and the stable JAAS45 pollen line. The results revealed that the PEPC gene could be stably inherited and transferred from the male parent to the JAAS45 pollen line. Moreover, the JAAS45 pollen line exhibited high levels of PEPC activity, manifesting higher saturated photosynthetic rates, photosynthetic apparent quantum yield (AQY), photochemical efficiency of photosystem II and photochemical and non-photochemical quenching, which indicated that the JAAS45 pollen line has a high tolerance to photo-inhibition/photo-oxidation under strong light and high temperature. Furthermore, JAAS45 was confirmed to still be a C3 plant by δ13C carbon isotope determination and was demonstrated to have a limited photosynthetic C4 microcycle by feeding with exogenous C4 primary products, such as oxaloacetate or malate, or phosphoenolpyruvate. The present study explains the physiological inherited properties of PEPC transgenic rice and provides an expectation for the integration of traditional breeding and biological technology. (Managing editor: Ping He)

Spraying a 1–2 mmol/L solution of NaHSO3 on the leaves of wild-type rice (Oryza sativa L.) Kitaake (WT), phosphoenolpyruvate carboxylase (PEPC) transgenic (PC) rice and PEPC+phosphate dikinase (PPDK) transgenic rice (PC+PK), in which the germplasm was transformed with wild-type Kitaake as the gene receptor, resulted in an enhancement of the net photosynthetic rate by 23.0%, 28.8%, and 34.4%, respectively, for more than 3 d. It was also observed that NaHSO3 application caused an increase in the ATP content in leaves. Spraying PMS (a cofactor catalysing the photophosphorylation cycle) and NaHSO3 separately or together on leaves resulted in an increase in photosynthesis with all treatments. There was no additional effect on photosynthetic rate when the mixture was applied, suggesting that the mechanism by which NaHSO3 promotes photosynthesis is similar to the mechanism by which PMS acts and that both of compounds enhanced the supply of ATP. After spraying a solution of NaHSO3 on leaves, compared with the WT Kitaake rice, a greater enhancement of net photosynthetic rate was observed in PEPC transgenic (PC) and PEPC+PPDK transgenic (PC+PK) rice, with the greatest increase being observed in the latter group. Therefore ATP supply may become the limiting factor that concentrates CO2 in rice leaves transformed with an exogenous PEPC gene and exogenous PEPC+PPDK genes. (Managing editor: Ping HE)

The cross-field diffusion coefficient (D⊥) at the edge in the HT-7 tokamak is close to the Bohm value when the line average electron density ranges from 1.5×1019 to 3.0×1019m−3. The energy profile of the particles is derived directly from the Hα(Dα) line shape; the dissociative excitation of molecules is dominating when the local electron temperature is above 10eV. By means of the Monte Carlo method the Dα line shape is also simulated. We find that the molecular dissociation contributes to 57% of neutral atoms and 53% of emission intensity in front of the limiter and 85% of neutral atoms and 82% of emission intensity in front of the wall. The influence of atomic and molecular processes on the energy balance is discussed for the scrape-off layer (SOL) and the power loss from molecular dissociation is found to be 6×104kW at the SOL. The ion Bernstein wave (IBW) can effectively suppress the magnetohydrodynamic behaviour, the fluctuation levels and the turbulence; the D⊥ in front of the limiter declines from 0.84 to 0.2m2.s−1 and the particle confinement time rises from 9 to 12ms.

The photosynthetic characteristics of four transgenic rice lines over-expressing rice NADP-malic enzyme (ME), and maize phosphoenolpyruvate carboxylase (PC), pyruvate,orthophosphate dikinase (PK), and PC+PK (CK) were investigated using outdoor-grown plants. Relative to untransformed wild-type (WT) rice, PC transgenic rice exhibited high PC activity (25-fold increase) and enhanced activity of carbonic anhydrase (more than two-fold increase), while the activity of ribulose-bisphosphate carboxylase/oxygenase (Rubisco) and its kinetic property were not significantly altered. The PC transgenic plants also showed a higher light intensity for saturation of photosynthesis, higher photosynthetic CO(2) uptake rate and carboxylation efficiency, and slightly reduced CO(2) compensation point. In addition, chlorophyll a fluorescence analysis indicates that PC transgenic plants are more tolerant to photo-oxidative stress, due to a higher capacity to quench excess light energy via photochemical and non-photochemical means. Furthermore, PC and CK transgenic rice produced 22-24% more grains than WT plants. Taken together, these results suggest that expression of maize C(4) photosynthesis enzymes in rice, a C(3) plant, can improve its photosynthetic capacity with enhanced tolerance to photo-oxidation.

Transgenic rice plants expressing the maize phosphoeno/pyruvate carboxylase (PEPC) and pyruvate, orthophosphate dikinase (PPDK) exhibit a higher photosynthetic capacity (up to 35%) than untransformed plants. The increased photosynthetic capacity in these plants is mainly associated with an enhanced stomatal conductance and a higher internal CO2 concentration. Plants simultaneously expressing high levels of both enzymes also have a higher photosynthetic capacity. The results suggest that both PEPC and PPDK play a key role in organic acid metabolism in the guard cells to regulate stomatal opening. Under photoinhibitory and photooxidative conditions, PEPC transgenic rice plants are capable of maintaining a higher photosynthetic rate, a higher photosynthetic quantum yield by PSII and a higher capacity to dissipate excess energy photochemically and non-photochemically than untransformed plants. Preliminary data from field trials show that relative to untransformed plants, the grain yield is about 10-20% higher in selected PEPC and 30-35% higher in PPDK transgenic rice plants, due to increased tiller number. Taken together, these results suggest that introduction of C4 photosynthesis enzymes into rice has a good potential to enhance its tolerance to stress, photosynthetic capacity and yield.

Based on the random field theory and reliability theory, the statistical methods used in the research on the probabilistic features of parameters,P s ,f i ,P sb had been studied. In addition, the problems with the correlation distance, pile cross section dimensions and the range of pile tip resistance, which would be used in the reliability analysis, were discussed in this paper. The reliability analyses were made on seventeen (17) construction sites based on forty-six (46) CPT test curves in Shanghai area, China. The reliability indices were obtained and the probabilistic characteristics of reliability indices were derived accordingly.The study shows that: (1) generally, the reliability index of large pile in diameter is greater than that of small pile for either prefabricated pile or cast-in-place pile, and the coefficient of variation of reliability index of prefabricated pile is less than that of cast-in-place pile; and (2) For bored piles, the variation coefficient of reliability index is less for big pile in diameter (or dimensions) than that for small pile in diameter (or dimensions). ...

To study the nature and mechanisms of resistance of rice plants to chilling stress, the effects of low temperature treatment (8 degrees C) on the photosynthetic rate and some important compounds forming redox cycles were measured. The rice varieties used are two japonica rice varieties, i.e., Taipei 309 and Wuyujing; three indica rice varieties, i.e., IR64, Pusa and CA212; and one intermediate type, i.e., Shanyou 63. Three types of varieties were studied by comparing. The light intensity-photosynthesis curves, CO2-photosynthesis curves, primary photochemical efficiency (Fv/Fm), active oxygen species (AOS) (O2*- and H2O2), glutathione (both oxidized and reduced forms) and ascorbate contents in their six-week old seedlings were measured before and after chilling treatment. The results showed that relative to the rice varieties chilling tolerance such as Taipei 309 and Wuyujing, the sensitive ones indica IR64, Pusa and CA212 exhibited a stronger inhibition of maximum photosynthetic rate (Pmax) (Figs.1 and 2) and a decrease in Fv/Fm (Fig.3), which led to the accumulation of AOS (Fig.6). It was found that the glutathione disulphide (GSSG) content in glutathione pool and that of dehydroascorbate (DHA) in ascorbate pool of the leaves of these sensitive ones under chilling were induced to increase obviously (Table 3). The correlation coefficient between the increases in GSSG, DHA and the decrease of Chl content were -0.701**, -0.656** respectively (Table 4). This indicated that the regeneration of reduced glutathione (GSH) and ascorbate was inhibited, resulting in accumulations of AOS and the reduction of Chl content (Fig.4) and the inhibition of photosynthetic activity (Fig.1 and Fig.2). The changes in japonica Taibei 309 and Wuyujing were small. And the changes in indica hybrid were lying between the above-mentioned types. Particularly, the ratio of AsA/DHA and GSH/GSSG (Fig.7) showed similar changes as those in Chl content (Fig.4). The correlation coefficient among Chl content and AsA/DHA, GSH/GSSG were 0.811**, 0.728** respectively (Table 4), significant at 0.01 probability levels. The levels of AsA/DHA and GSH/GSSG ratio in rice leaves may be the physiological indexes associated with the sensitivity to chilling in rice varieties.

By cross breeding, the maize pepc gene in the pepc transgenic rice was successfully incorporated into the parents of two-, three-line hybrid rice, including sterile lines (Peiai64S, 2302S, 2304S, 2306S and Shuangjiu A) and restorer lines (5129, 02428 and Wanjing97) to breed the high-photosynthetic efficiency parents of hybrid rice and utilize heterosis between C4 and C4/C3 rice. Some lines of pepc transgenic rice (LPTR) have been developed. The study on the generations of LPTR suggests the following: (1) The segregation observed in F2 and BC1 progenies demonstrated that pepc transgene inherited as a single dominant gene in the progenies of LPTR. (2) The maize pepc gene is actively expressed at high level in LPTR, and changes of pepc gene expression in the progenies of LPTR may be related to position effect, difference of gene copy number and environmental factors. (3) Through the selection method of soaking seeds into hygromycin solution to germinate, tracing the pepc gene by PCR analysis, evaluating the performance of the rice plants in the field and examining PEPC activities, the segregation of the pepc transgene in LPTR was controlled effectively. Based on the above strategy three pepc transgene lines, H1596, H1597 and Y1470, have been selected. The result suggests that it is possible to breed practical, stable and high-expression pepc transgenic rice by conventional crossing.

Plants that experience additional stress shuch as physical, chemical and biotic factors that show regular and irregular diurnal and seasonal variations, often exhibit some photosynthetic responses and their adaptive regulation. Recently have such studies been developed, particularly in studies of the secondary stress caused by excessive excitations in photosynthetic apparatus under drought, high or low temperature[1]. Photoinhibition and photooxidation caused by vissible radiation have attached the attention of biologists in the last 2 decades. During photoinhibition, D1-protein was primarily damaged by high irradiation and high rate of turnover of the protein occured. The primary sites of photoinhibition had been suggested to be located within the DI-protein to which the PSII reaction center was bound[2]. In recent years, It was found that difference in response to photoinhibition did exist in rice (O. Sativa L) subspecies indica and japonica[3]. This work was made to study the photochemical efficiency of PSII and characteristic of photosynthetic CO2 exchange in indica and japonica subspecies and their reciprocal F1 hybrids so as to develop an effective approach for breeding program of indica-japonica hybrid rice with both photoinhibition-tolerance and higher photosynthetic efficiency.