Photosynthesis with Single-Rooted Amaranthus Leaves. I. Changes in the Activities of RuBP-1,5-bisphosphate Carboxylase and Phosphoenolpyruvate Carboxylase and the Amounts of Intermediates in Photosynthetic Metabolism in Response to Changes in the Source-Sink Balance

Photosynthesis with Single-Rooted Amaranthus Leaves. II. Regulation of Ribuelose-1,5-Bisphosphate Carboxylase, Phosphoenolpyruvate Carboxylase, NAD-Malic Enzyme and NAD-Malate Dehydrogenase and Coordination between PCR and C4 Photosynthetic Metabolism in Response to Changes in the Source-Sink Balance

“…Sawada et al (1999) suggested that, in the sink-limited leaves exposed to CL, the inhibition of sucrose synthesis by the accumulation of sucrose would result in a decrease in the level of free P i in the cytoplasm of both mesophyll and bundle-sheath cells. Thus, the low P i level in chloroplasts in the bundle-sheath cells may directly result in inactivation of RuBPcase, as mentioned above.…”

“…However, studies on the fine coordinated control of mesophyll and bundle sheath reactions via a change in the source-sink balance in C4 plants are rare. Sawada et al (1999) studied the coordinated control of photosynthetic metabolism in mesophyll and bundle-sheath cells of source-sink C4 model plants. The model consisted of single-rooted leaves without petioles, prepared from the leaves of NAD malic enzyme type Amaranthus cruentus.…”

Regulation of Leaf Photosynthesis Through Photosynthetic Source-Sink Balance in Soybean Plants

“…Therefore, the correspondence of data from original intact soybean plants and those from single-rooted soybean leaves highlights that properties of single-rooted soybean leaves and those of original intact soybean plants are very similar, thus suggesting that properties of single-rooted soybean leaves and those of original intact soybean plants can reflect each other. As described in the Introduction, studies using single-rooted soybean leaves have implicated that there is a regulatory mechanism of leaf photosynthetic rate through deactivation of Rubisco, which is associated with accumulation of photosynthetic carbohydrates in leaf under excessive photosynthetic source capacity (Sawada et al, 1986(Sawada et al, , 1989(Sawada et al, , 1990(Sawada et al, , 1992(Sawada et al, , 1999(Sawada et al, , 2003. Data from the present study using the original intact soybean plants have also suggested the same regulatory mechanism of leaf photosynthetic rate.…”

“…Leaf chlorophyll content was determined according to the method of Mackinney (1941). Leaf sucrose and starch contents were determined as described by Sawada et al (1999). Leaf water content was analyzed by measuring fresh weight and dry weight of leaf disks.…”

Effect of Sink-Limitation on Leaf Photosynthetic Rate and Related Characteristics in Soybean Plants

“…Rubisco was quantified as described by Makino et al (1986) using purified spinach Rubisco as the standard. Sucrose and starch were quantified as described by Sawada et al (1999). The activity of Rubisco was determined enzymatically essentially as described by Cheng and Fuchigami (2000).…”