to characterize at the level of their anatomic organization as well as at the level of their ability to store starch. The purpose of this study was to localize and to quantify starch reserves in the various plant organs. To do this, we adopted an
Wahiba Boutebtoub, Michel Chevalier, Jean-Claude Mauget, Monique Sigogne, Philippe Morel, and Gilles Galopin
Takashi Nishizawa and Yoshihiro Shishido
June-bearing strawberry plants (Fragaria ×ananassa Duch. `Morioka 16') were forced in a greenhouse and either allowed to fruit or deflowered continuously. Plants were harvested at the start of the experiment (day 0), at full bloom (day 35), during rapid growth of green fruit (day 53), at first fruit coloring (day 63), at full coloring of the primary and some secondary fruit in the primary and secondary inflorescences (day 68), and at overripe of many primary and secondary fruit in the primary and secondary inflorescences (day 81). Dry matter accumulation in the vegetative organs in fruiting plants was less than that in deflowered plants as the fruit matured, but the total plant dry mass did not differ significantly between treatments throughout the forcing period. Reducing sugar and sucrose concentrations in roots, crown, and old leaves decreased continuously until day 68, particularly in roots. The concentrations did not differ between treatments. Starch concentrations in roots declined rapidly in both treatments between day 0 and day 35, and then the decline slowed. Starch level was significantly lower in the roots of fruiting plants from day 35 through fruit harvest. These results suggest that carbohydrate reserves in roots of forced June-bearing strawberry plants are used primarily to support the growth of inflorescences and developing leaves. They are less available for fruit growth and maturation since the levels are already relatively low by this stage.
Silver Tumwegamire, Regina Kapinga, Patrick R. Rubaihayo, Don R. LaBonte, Wolfgang J. Grüneberg, Gabriela Burgos, Thomas zum Felde, Rosemary Carpio, Elke Pawelzik, and Robert O.M. Mwanga
preferences have been found in EA ( CIP, 2005 ; Tumwegamire et al., 2004 ). Approximately 80% to 90% of sweetpotato storage root DM is made up of carbohydrates, mainly starch (≈60% to 70% of DM) and sugars (≈15% to 20% of DM with a wide range from ≈5% to 40
Huicong Wang and Lailiang Cheng
coloration of apples has been well documented, much less attention has been paid to its effect on other aspects of fruit maturity. Because maturity at harvest greatly affects apple fruit quality and storage performance, starch hydrolysis indices (starch
Terence R. Bates, Richard M. Dunst, and Paula Joy
We thank Mike Vercant, Ted Taft, Christine Cummings, and Eileen Eacker for their viticulture assistance. We thank Alan Taylor and his laboratory staff for their help in tissue starch analysis. This research was supported by the New York Wine
Yuanyuan Miao, Qiaosheng Guo, Zaibiao Zhu, Xiaohua Yang, Changlin Wang, Yuan Sun, and Li Liu
). Similarly, Takahashi et al. (2003) previously showed that AR formation is stimulated by sucrose. Sucrose is translocated to the stem base to be cleaved into hexoses, which are used directly as a carbon source or converted into starch for storage ( Ahkami
Donald E. Irving, Glen J. Shingleton, and Paul L. Hurst
Extractable activities of α-amylase, β-amylase, and starch phosphorylase were investigated in order to understand the mechanism of starch degradation in buttercup squash (Cucurbita maxima Duchesne ex Lam. `Delica') with the ultimate goal of improving the conversion of starch into sweet sugars. During rapid starch synthesis (0 to 30 days after flowering), extractable activities of α-amylase and β-amylase were low, but those of starch phosphorylase increased. After harvest, during ripening at 12 °C, or in fruit left in the field, activities of α-amylase and β-amylase increased. Starch contained 20% to 25% amylose soon after starch synthesis was initiated and until 49 days after harvest irrespective of whether the crop remained in the field or in storage at 12 °C. Maltose concentrations were low prior to harvest, but levels increased during fruit ripening. Data suggest starch breakdown is hydrolytic in buttercup squash, with α-amylase being the primary enzyme responsible for initiating starch breakdown.
Douglas C. Whitaker, Mihai C. Giurcanu, Linda J. Young, Pedro Gonzalez, Ed Etxeberria, Pamela Roberts, Katherine Hendricks, and Felix Roman
). Another notable characteristic of HLB-affected citrus trees is the massive accumulation of starch in photosynthetic cells and other parenchymatous tissues of non-reproductive aerial parts ( Etxeberria et al., 2009 ; Folimonova and Achor, 2010 ; Schneider
Desmond G. Mortley, Conrad K. Bonsi, Walter A. Hill, Carlton E. Morris, Carol S. Williams, Ceyla F. Davis, John W. Williams, Lanfang H. Levine, Barbara V. Petersen, and Raymond M. Wheeler
from the absence of a strongly dominant gravity vector ( Smith and Luttges, 1994 ). In addition, decreases in plant tissue starch from space flight have been one of the most consistent responses to microgravity ( Brown et al., 1996 ). Musgrave et al
Dane K. Fisher, Charles D. Boyer, and Mark Guiltinan
During plant starch biosynthesis, starch branching enzymes (SBE) catalyze a-1,6 branch point formation in starch, and thus are responsible for many properties of the starch polymer. Recently we have cloned cDNAs encoding the two major branching enzymes in developing maize endosperm, SBEI and SBEII. These genes are being used to alter starch biosynthesis via genetic engineering strategies. Transgenic tobacco plants with sense and antisense constructs of SBEI and SBEII have been produced. No major difference in the phenotypes of control and transgenic plants have been observed. Initial experiments demonstrated the transcription of the introduced genes. Enzyme levels and the molecular properties of the starch in the transgenic plants will be determined. These experiments will provide us with information as to the role of starch branching enzymes in starch biosynthesis, the feasibility of creating novel starch, and the effect altered starch has on plastid development and photosynthesis.