Starch is the major component of wheat flour and serves as a multifunctional ingredient in food industry. The objective of the present study was to investigate starch granule size distribution of Chinese wheat cultiva...Starch is the major component of wheat flour and serves as a multifunctional ingredient in food industry. The objective of the present study was to investigate starch granule size distribution of Chinese wheat cultivars, and to compare structure and functionality of starches in four leading cultivars Zhongmai 175, CA12092, Lunxuan 987, and Zhongyou 206. A wide variation in volume percentages of A- and B-type starch granules among genotypes was observed. Volume percentages of A- and B-type granules had ranges of 68.4–88.9% and 9.7–27.9% in the first cropping seasons, 74.1–90.1% and 7.2–25.3% in the second. Wheat cultivars with higher volume percentages of A- and B-type granules could serve as parents in breeding program for selecting high and low amylose wheat cultivars, respectively. In comparison with the B-type starch granules, the A-type granules starch showed difference in three aspects：（1） higher amount of ordered short-range structure and a lower relative crystallinity,（2） higher gelatinization onset（To） temperatures and enthalpies（ΔH）, and lower gelatinization conclusion temperatures（Tc）,（3） greater peak, though, and final viscosity, and lower breakdown viscosity and pasting temperature. It provides important information for breeders to develop potentially useful cultivars with particular functional properties of their starches suited to specific applications.展开更多
Rice grain chalkiness is an important characteristic,but the difference between chalky and translucent parts in grains is still unclear.Here,we investigated the differences of flour made from the chalky or translucent...Rice grain chalkiness is an important characteristic,but the difference between chalky and translucent parts in grains is still unclear.Here,we investigated the differences of flour made from the chalky or translucent part of rice grains in three indica and three japonica rice varieties.The chalky flour had significantly lower amylose and protein contents and looser starch granule morphology,and starches in the chalky flour had higher relative crystallinity,higher short chain content but lower long chain content than those in the translucent flour.The water states,determined with nuclear magnetic resonance,differed between the chalky and translucent flour after soaking,cooking and retrograding,and the chalky flour had more bound and free water but less constructural water than the translucent flour.Mostly,the chalky flour had lower viscosity and shorter gel consistency,but higher onset temperature and gelatinization enthalpy than the translucent flour.The results indicated that starch granule morphology would be more indicative than other attributions on pasting and gelatinization properties of chalky and translucent parts of rice grains.展开更多
A plastidic adenosine triphosphate（ATP）/adenosine diphosphate（ADP） transporter（AATP） is responsible for importing ATP from the cytosol into plastids. In dicotyledonous plants, increasing ATP supply is a potentia...A plastidic adenosine triphosphate（ATP）/adenosine diphosphate（ADP） transporter（AATP） is responsible for importing ATP from the cytosol into plastids. In dicotyledonous plants, increasing ATP supply is a potential way to facilitate anabolic synthesis in heterotrophic plastids. In this study, a gene encoding the AATP protein, named Ib AATP, was isolated from sweetpotato（Ipomoea batatas（L.） Lam.）. Transcripts of Ib AATP were predominantly detected in the storage roots and leaves and were induced by exogenous sucrose and subjected to circadian rhythm. Transient expression of Ib AATP in tobacco and onion epidermal cells revealed the plastidic localization of Ib AATP. The overexpression of Ib AATP in sweetpotato significantly increased the starch and amylose contents and led to enlarged starch granules. The IbA ATP-overexpressing plants showed altered fine structure of amylopectin, which contained an increased proportion of chains with a degree of polymerization（DP） of 10–23 and a reduced number of chains with a DP of 5–9 and 24–40. In addition, starch from the transgenic plants exhibited different pasting properties. The transcript levels of starch biosynthetic genes, including Ib AGP, Ib GBSSI, Ib SSIIV, and Ib SBE, were differentially regulated in the transgenic plants. These results revealed the explicit role of Ib AATP in the starch biosynthesis of sweetpotato and indicated that this gene has the potential to be used to improve starch content and quality in sweetpotato and other plants.展开更多
基金financial support from the National Natural Science Foundation of China (31171547,31401651)
文摘Starch is the major component of wheat flour and serves as a multifunctional ingredient in food industry. The objective of the present study was to investigate starch granule size distribution of Chinese wheat cultivars, and to compare structure and functionality of starches in four leading cultivars Zhongmai 175, CA12092, Lunxuan 987, and Zhongyou 206. A wide variation in volume percentages of A- and B-type starch granules among genotypes was observed. Volume percentages of A- and B-type granules had ranges of 68.4–88.9% and 9.7–27.9% in the first cropping seasons, 74.1–90.1% and 7.2–25.3% in the second. Wheat cultivars with higher volume percentages of A- and B-type granules could serve as parents in breeding program for selecting high and low amylose wheat cultivars, respectively. In comparison with the B-type starch granules, the A-type granules starch showed difference in three aspects：（1） higher amount of ordered short-range structure and a lower relative crystallinity,（2） higher gelatinization onset（To） temperatures and enthalpies（ΔH）, and lower gelatinization conclusion temperatures（Tc）,（3） greater peak, though, and final viscosity, and lower breakdown viscosity and pasting temperature. It provides important information for breeders to develop potentially useful cultivars with particular functional properties of their starches suited to specific applications.
基金supported by the National Natural Science Foundation of China (Grant Nos. 32172080 and 31971925)China Agriculture Research System (Grant No. CARS-01-16)
文摘Rice grain chalkiness is an important characteristic,but the difference between chalky and translucent parts in grains is still unclear.Here,we investigated the differences of flour made from the chalky or translucent part of rice grains in three indica and three japonica rice varieties.The chalky flour had significantly lower amylose and protein contents and looser starch granule morphology,and starches in the chalky flour had higher relative crystallinity,higher short chain content but lower long chain content than those in the translucent flour.The water states,determined with nuclear magnetic resonance,differed between the chalky and translucent flour after soaking,cooking and retrograding,and the chalky flour had more bound and free water but less constructural water than the translucent flour.Mostly,the chalky flour had lower viscosity and shorter gel consistency,but higher onset temperature and gelatinization enthalpy than the translucent flour.The results indicated that starch granule morphology would be more indicative than other attributions on pasting and gelatinization properties of chalky and translucent parts of rice grains.
基金supported by the National Natural Science Foundation of China(31371680)the Beijing Food Crops Innovation Consortium Programthe China Agriculture Research System(CARS-11)
文摘A plastidic adenosine triphosphate（ATP）/adenosine diphosphate（ADP） transporter（AATP） is responsible for importing ATP from the cytosol into plastids. In dicotyledonous plants, increasing ATP supply is a potential way to facilitate anabolic synthesis in heterotrophic plastids. In this study, a gene encoding the AATP protein, named Ib AATP, was isolated from sweetpotato（Ipomoea batatas（L.） Lam.）. Transcripts of Ib AATP were predominantly detected in the storage roots and leaves and were induced by exogenous sucrose and subjected to circadian rhythm. Transient expression of Ib AATP in tobacco and onion epidermal cells revealed the plastidic localization of Ib AATP. The overexpression of Ib AATP in sweetpotato significantly increased the starch and amylose contents and led to enlarged starch granules. The IbA ATP-overexpressing plants showed altered fine structure of amylopectin, which contained an increased proportion of chains with a degree of polymerization（DP） of 10–23 and a reduced number of chains with a DP of 5–9 and 24–40. In addition, starch from the transgenic plants exhibited different pasting properties. The transcript levels of starch biosynthetic genes, including Ib AGP, Ib GBSSI, Ib SSIIV, and Ib SBE, were differentially regulated in the transgenic plants. These results revealed the explicit role of Ib AATP in the starch biosynthesis of sweetpotato and indicated that this gene has the potential to be used to improve starch content and quality in sweetpotato and other plants.
