A method for early diagnosis of plant productivity using a luciferase bioluminescence assay at the early stage of cultivation was developed for transgenic Arabidopsis thaliana carrying the CCA1::LUC construct, in which the promoter of the CCA1 clock gene had been fused to a modified firefly luciferase (LUC) gene. Because the intensity of luciferase bioluminescence is proportional to the CCA1 promoter activity and the expression level of LUC, the dynamics of both can be investigated by measuring the bioluminescence. In this paper, plant biomass was considered a measure of plant production andLUC protein a measure of foreign protein production. The leaf area and bioluminescence of seedlings at the early stage of cultivation were investigated as indexes for early diagnosis of productivity; leaf area was a reflection of morphological information, and bioluminescence, molecular information. Bioluminescence showed higher correlation to productivity based on biomass andLUC protein than the leaf area under various growth conditions, indicating that bioluminescence is a better index for early diagnosis. In addition, we developed a general statistical method for selecting superior seedlings based on this early diagnosis and a general theory for determining an optimal parameter set for maximizing profit. This early diagnostic methodology appears suited to enhance the quality of the products in plant factories.
The role of three tip fabrication methods and of tip size in cell pressure probe measurements was investigated. The stability over time of turgor pressure (P) in mesocarp cells of intact grape berries was determined for microcapillary tips of contrasting sizes and methods of production (micro-beveler, micro-grinder, and breaking) at contrasting depths below the berry epidermis. SEM images showed that breaking, and in some cases micro-grinding methods produced tips with irregular, fractured surfaces, compared to relatively smooth surfaces produced with micro-beveling. Finely pointed glass microcapillaries were made with reproducibly small tip dimensions (i.d.<5 μm) by using a jet-stream micro-beveler and a mass flow meter to continuously monitor pressurized (pneumatic) air flow from the tip during the beveling process. Optically determined tip i.d. was highly correlated (r2=0.99) to pneumatic tip conductance. Overall cell dimensions ranged from about 10 μm near the epidermis to over 100 μm at a depth of 2 mm. At shallow depths (<250 μm), P was relatively instable (declined at −0.035 MPa/min) when measured using large tips (i.d.>5 μm) and significantly more stable (−0.009 MPa/min) using small tips (i.d.<5 μm). At deeper depths (>250 μm), both tip sizes gave relatively stable P values (−0.007 and −0.004 MPa/min for large and small tips, respectively). For tips of comparable size, micro-beveling gave improved P stability compared to breaking, and an improved ability to measure cells closer to the epidermis compared to micro-grinding. Literature values for acceptability of P values as stable in higher plant cells range from −0.001 to −0.05 MPa/min. These data suggest that P stability might be influenced by both tip size/shape and cell dimensions, and that improved tip fabrication techniques should improve the stability and reproducibility of P measurements, particularly for small cells.
To elucidate the interaction between tropospheric O3 and CO2 in paddy rice, combined applications of O3 (0–0.3 cm3 m−3) and CO2 (380, 800 cm3 m−3) were performed at the vegetative stage or flowering to early maturing stage of rice plants using environmentally controlled chambers: O3 decreases growth and yield, although CO2 exhibits the opposite action. At the vegetative stage, elevated O3 decreased the relative growth rate (RGR) and net assimilation rate (NAR) but elevated CO2 ameliorated those effects. At the flowering to early ripening stage, elevated O3 decreased dry matter production and yield with lowering of the percent maturity of grains, but the elevated CO2 tended to offset these declines. The results indicate that elevated O3 primarily inhibits photosynthesis-related process of paddy rice. Elevated CO2, which is predicted for the future, interactively ameliorates that inhibition.
We investigated the relationship between the water status of watermelon fruits and sugar accumulation during fruit growth and ripening. In 2007 and 2009 the water status of various part of the fruit's flesh from 0 to 44 days after pollination was measured with an isopiestic psychrometer. We also determined the sugar (glucose, fructose and sucrose) contents by means of high-performance liquid chromatography. When the osmotic pressure created by the sugar content of tissue at the center of the fruit were calculated by using Van't Hoff's equation, the osmotic potential (the negative of the osmotic pressure) accounted for 47% to 66% of the total osmotic potential measured by the psychrometer, indicating that the sugar content decreases the water potential of watermelon flesh during fruits development.
To evaluate the interaction between O3 and CO2 on photosynthesis and nitrogen metabolism in rice, combined exposures of O3 [0, 0.1, 0.3 cm3 m−3 (abbreviated as O0, O0.1, O0.3)] and CO2 [400, 800 cm3 m−3 (abbreviated as C400, C800)] were applied for 5 h using environment-controlled chambers with natural-light. Subsequently, the plants were raised for 3 d under clean air (O0+C400) conditions. Immediately before (BE), immediately after (AE-0), and 1 and 3 d after (AE-1, AE-3) gas exposure, the chlorophyll fluorescence of photosystem II (PSII) and activities of nitrate (NR) and nitrite (NiR) reductase were determined. Results show that maximum (Fv/Fm) and operating (Fq'/Fm') quantum efficiencies and NiR activity were inhibited by O3, but they were ameliorated by elevated CO2, suggesting that the O3-inhibition of photosynthesis accompanied the reduced electron transport toward the downstream of photosystem and suggesting that the reduction power became deficient. Because NiR locates in the chloroplast and uses reducing power from PSII, it must receive a greater O3-inhibition than cytoplasmic NR does.
The hydraulic characteristics of plant organs and the absorption functions of roots of corn and tomato plants were analyzed by using a specialized high-pressure flowmeter (HPFM), which was equipped with a root chamber as well as a coupling to connect to the plant organs. The HPFM can detect changes in the hydraulic properties of the respective parts of the plant body. The hydraulic resistances of the leaf and root decreased with an increase in the water flow rate; this dependence was remarkable at low water flow rates. On the other hand, the hydraulic resistance of the stem was only slightly affected by the water flow. However, a positive linear relationship between hydraulic conductance (reciprocal of resistance) and water flow rate was found for the shoot, stem, and root, respectively. Further, the rate of nutrient (NO3−) absorption by the root was evaluated from the water flow (root water absorption) and NO3− concentration in the xylem sap exuded from the root stump. The high-pressure flowmeter with the root chamber can be used for studying water and nutrient transport in plants and their responses to environmental elements.