Engineering high amylose and resistant starch in maize by CRISPR/Cas9-mediated editing of starch branching enzymes

To improve the amylose content(AC)and resistant starch content(RSC)of maize kernel starch,we employed the CRISPR/Cas9 system to create mutants of starch branching enzyme I(SBEI)and starch branching enzyme IIb(SBEIIb).A frameshift mutation in SBEI(E1,a nucleotide insertion in exon 6)led to plants with higher RSC(1.07%),lower hundred-kernel weight(HKW,24.71±0.14 g),and lower plant height(PH,218.50±9.42 cm)compared to the wild type(WT).Like the WT,E1 kernel starch had irregular,polygonal shapes with sharp edges.A frameshift mutation in SBEIIb(E2,a four-nucleotide deletion in exon 8)led to higher AC(53.48%)and higher RSC(26.93%)than that for the WT.E2 kernel starch was significantly different from the WT regarding granule morphology,chain length distribution pattern,X-ray diffraction pattern,and thermal characteristics;the starch granules were more irregular in shape and comprised typical B-type crystals.Mutating SBEI and SBEIIb(E12)had a synergistic effect on RSC,HKW,PH,starch properties,and starch biosynthesis-associated gene expression.SBEIIa,SS1,SSIIa,SSIIIa,and SSIIIb were upregulated in E12 endosperm compared to WT endosperm.This study lays the foundation for rapidly improving the starch properties of elite maize lines.

Changes of Granule Structure and Enzyme Hydrolysability of Starch in Upper Flue-cured Tobacco Leaves During Bulk Flue-curing

[Objective] This study aimed to investigate the changes of granule struc- ture, characteristic and related enzymatic activity of starch in upper flue-cured tobac- co leaves during bulk flue-curing process, to provide theoretical basis for reasonably regulating the starch content in upper flue-cured tobacco leaves and improving the quality of upper flue-cured tobacco leaves. [Method] Changes of amylase activity, enzyme hydrolysability and granule structure of starch in upper flue-cured tobacco leaves were studied during flue-curing process using conventional physical and chemical analysis and SEM. [Result] During the flue-curing process, the starch con- tent of tobacco leaves changed greatly at yellowing stage, and the activity of amy- lase presented the double-peak curve. The SEM observation results showed that most of the starch granules in fresh tobacco leaves were spheroidal and long cylin- drical, while some individuals were in irregular shape, with obvious groove-like in- vagination and layered structure on granule surface; during the flue-curing process, a large amount of starch granules showed layered structure on the surface at yellow- ing stage, and the long cylindrical starch granules were reduced greatly; at the end of flue-curing, there were barely any long cylindrical starch granule in flue-cured to- bacco leaves. Average long-axis-diameter of starch granules in fresh tobacco leaves was 3.21 μm, showing an overall gradually increasing trend during the flue-curing process, which was significantly enhanced at 38 and 42 ℃. The diameter of starch granules increased by more than 60% at the end of 42 ℃ and there was no re- markable difference after 47 ℃. During the flue-curing process, enzyme hydrolysabil- ity of starch in flue-cured tobacco leaves first increased, reached a peak at 38 ~C, and then decreased. [Conclusion] During the bulk flue-curing, the yellowing stage is the critical period for starch content, granule structure and characteristic changes of flue-cured tobacco leaves, it is of positive effects to improve the quality of upper flue-cured tobacco leaves by regulating the flue-curing conditions at yellowing stage.

Effects of Weak Light on Starch Accumulation and Starch Synthesis Enzyme Activities in Rice at the Grain Filling Stage

Dynamic changes of starch, amylose, sucrose contents and the activities of starch synthesis enzymes under shading treatments alter flowering were studied using two rice varieties IR72 （indica） and Nipponbare （japonica） as materials. Under shading treatments, the starch, amylose and sucrose contents decreased, while ADP-glucose pyrophosphorylase （ADPGPPase） activity only changed a little, soluble starch synthase activity and granule bound starch synthase activity decreased, soluble starch branching enzyme （SSBE, Q-enzyme） activity and granule bound starch branching enzyme （GBSBE, Q-enzyme） activity increased, and starch debranching enzyme （DBE, R-enzyme） activity varied with varieties. Correlation analyses showed that the changes of starch content were positively and significantly correlated with the changes of sucrose content in the weak light. Both ADPGPPase activity and SSBE activity were positively and significantly correlated with starch accumulation rate. It was implied that the decline of starch synthase activities was related to the decrease of starch content and the increase of the activity of starch branching enzyme played an important role in the decrease of the ratio of amylose to the total starch under the weak light.

Cloning and Expression of the Promoter of Maize Starch-Branching Enzyme sbeⅡb Gene

[Objective] The aim was to construct promoter of maize starch-branching enzyme sbe Ⅱb gene specifically expressed in seed.[Method] The promoter sequence of maize starch-branching enzyme sbe Ⅱb gene was amplified by LA-PCR and then cloned into pMD18-T vector.Subsequently,the promoter was cloned into pBI121 vector to construct plant expression vector pBI121-sbe Ⅱb.Recombinant plasmid pSBE-GUS was constructed by connecting GUS gene into pBI121-sbe Ⅱb and transformed into tobacco mediated by Agrobacterium tumefaciens,before detection by PCR and Southern blot.The biochemical analysis and fluorescence detection of GUS activity were performed in different parts of the tobacco by Gene Gun Method and Agrobacterium tumefaciens transformation respectively.[Result] The homology between promoter sequence cloned in this experiment and the corresponding sequence announced in the GenBank reached 98.52%.Four transformed tobaccos were obtained by PCR and Southern blot after co-culture and selective culture.A small number of blue spots appeared in leaves,and the spots could barely been seen in the stems and roots,while a large number of blue spots were found in seeds.So,it could be concluded that the promoter of sbeⅡb gene was specifically expressed in seeds.[Conclusion] Promoter of maize starch branching enzyme sbe Ⅱb specifically expressed in seeds was successfully cloned.

Changes in Starch Accumulation and Activity of Enzymes Associated with Starch Synthesis of Rice at Different N Supplying Dates

The changes in grain-filling, starch accumulation and activity of enzymes associated with starch synthesis in two different hybrid rice varieties were analyzed at different N supplying dates (earlier-date-emphasized, mean-date-emphasized and later-date- emphasized). The results showed that the N application of later-date-emphasized could promote grain-filling rate, increase grain weight and amylopectin content. The peak of activity in three enzymes of ADPglusoce pyriphosphorylase (ADPG), starch synthesis enzyme (SSS) and starch branching enzyme (SBE) in grains of two different rice varieties was not changed obviously, but the mean and maximum activity of these three enzymes changed, and the changes of SSS and ADPG were bigger than that of SBE as N supplying date changed. The N application of earlier-date-emphasized increased SSS activity and the N application of later-date-emphasized increased ADPG and SBE activities. The mean SSS activity during whole grain-filling period, and ADPG and SBE activities at middle and late period of grain-filling were significantly or very significantly correlated with grain-filling rate and accumulating rate of amylose and amylopectin. Both of ADPG and SBE played an equal important role in the changes of amylose and amylopectin content. The N application of later-date-emphasized increased amylose and amylopectin accumulating rate.

Characterization and Expression Analysis of Starch Branching Enzymes in Sweet Potato

Spatial and temporal expression patterns of Sbel and Sbe2 that encode starch branching enzyme （SBE） Ⅰ and Ⅱ, respectively, in sweet potato （Ipomoea batatas L.） were analyzed. Expression of both genes in Escherichia coli indicate that both genes encoded active SBE. Analysis with real-time quantitative polymerase chain reaction technique indicates that IbSbel mRNA was expressed at very low levels in leaves but was the predominant isoform in tuberous root while the reverse case was found for lbSbe2. The expression pattern of IbSbel, closely resembles that of AGPase S, a gene coding for one of the subunits ofADP-glucose pyrophosphorylase, which is the key regulatory enzyme in the starch biosynthetic pathway. Western analysis detected at least two isoforms of SBE I in tuberous roots, those two isoforms showed adverse expression patterns with the development of the tuberous roots. Expression of the two IbSbe genes exhibited a diurnal rhythm during a 12-h cycle when fed a continuous solution of sucrose. Abscisic acid （ABA） was aother potent inducer of IbSbe expression, but bypassed the semidian oscillator.

Effect of Temperature at Grain Filling Stage on Activities of Key Enzymes Related to Starch Synthesis and Grain Quality of Rice

Three japonica rice varieties with different cooking and eating quality were grown at high temperature in the greenhouse and natural field. Effects of temperature at the grain filling stage on these varieties were investigated in terms of the activities of key enzymes related to starch synthesis and cooking and eating quality of rice grain. The high temperature at the grain filling stage increased protein content, and decreased amylose content and taste meter value of rice; inferior grain quality varieties showed a greater magnitude of the increase or decrease than the superior ones. Reaction of rapid visco analyser profiles to the temperature varied with rice varieties. The activities of adenosine diphosphoglucose pyrophosphoryiase （AGPP）, soluble starch synthase （SSS） and starch branching enzyme （SBE） gradually increased to a peak value, and thereafter declined as grain filling progressed. Enzyme activities in different varieties differed in a same filling stage, and also in the time when the enzyme activity reached a maximum. AGPP and SSS were insensitive to the environmental temperature, but SBE was comparatively sensitive to the temperature, and its activity declined when temperature was too high or too low.

Effects of Elevated Ozone Concentration on Starch and Starch Synthesis Enzymes of Yangmai 16 Under Fully Open-Air Field Conditions

O3 is not only greenhouse gas but also a primary gaseous contaminant in the atmosphere.It has long-lasting effects on crop growth,yield and quality,and brings a series of ecological and environmental problems.A free-air controlled enrichment（FACE） system was applied to study the effect of elevated ozone concentration on activities of key enzymes of starch synthesis of Yangmai 16 in 2009-2010.The main-plot treatment had two levels of O 3 ：ambient level（A-O 3） and 50% higher than ambient level（E-O 3）.The main results were that accumulation rate of amylose,amylopectin and starch were represented in a single peak curve,and their content and accumulation amount rose gradually.The O 3 elevation decreased the accumulation rate of amylose,amylopectin and starch amylase,reduced the accumulation amount of amylopectin and starch,and decreased the content of amylopectin and starch,but increased the content of amylose.With the increase of O 3 concentration,the enzyme activity of grain granule-bound starch synthase（GBSS）,soluble starch synthase（SSS） and starch branching enzyme（SBE） decreased after anthesis.The activities of GBSS and SSS had highly significant correlations with amylose,amylopectin and starch accumulation rate,and the activity of SBE had significant correlations with these items.So the O 3 elevation decreased the activity of key enzymes of starch synthesis,which led to the variation of starch synthesis.

Effect of Drought Stress During Flowering Stage on Starch Accumulation and Starch Synthesis Enzymes in Sorghum Grains

Starch content is a key factor affecting sorghum grain quality. The research of sorghum grain starch accumulation and the related synthesis enzyme activities has great signiifcance for understanding the mechanisms of starch metabolisms. The differences between a high and a low starch content sorghum hybrids （Tieza 17 and Liaoza 11, respectively） in grain starch accumulation and the related synthesis enzyme activities were assessed following imposition of water stress during lfowering stage. The total starch, amylase and amylopectin accumulation all decreased at the mid-late stage of grain iflling under drought stress during lfowering stage. The maximum and mean accumulation rates also decreased. During grain iflling, soluble starch synthase （SSS）, granule-bound starch synthase （GBSS）, starch branching enzyme （SBE）, and starch debranching enzymes （DBE） activities were all affected, though differently. Drought stress reduced starch accumulation in a larger extent for Tieza 17 than Liaoza 11. Drought stress during lfowing stage reduced starch synthesis enzyme activities, thus reducing starch accumulation in grains, and the differences between starch components were also demonstrated under drought stress.

Effects of Early- and Late-Sowing on Starch Accumulation and Associated Enzyme Activities During Grain Filling Stage in Rice

The environmental temperature occurring during the grain filling stage is an important factoraffecting starch synthesis and accumulation in rice. We investigated starch accumulation, amylaseactivity and starch granule size distribution in two low-amylose japonica rice varieties, Nanjing 9108 andFujing 1606, grown in the field at different filling temperatures by manipulating sowing date. The two ricevarieties exhibited similar performances between two sowing dates. Total starch, amylose andamylopectin contents were lower at the early-filling stage of T1 treatment (Early-sowing) compared withthose at the same stage in T2 treatment (Late-sowing). In contrast, at the late-filling stage, when fieldtemperatures were generally decreasing, total starch and amylopectin contents in T1 were highercompared to those in T2. The ideal temperature for strong activity of ADP-glucose pyrophosphorylaseand soluble starch synthase was about 22℃. A higher temperature from the heading to maturity stagesin T1 increased the activities of starch branching enzyme and suppressed the activities of granule boundstarch synthetase and starch debranching enzyme. We found that rice produced larger-sized starchgranules under the T1 treatment. These results suggested that due to the early-sowing date, the hightemperature (30℃) occurring at the early-filling stage hindered starch synthesis and accumulation,however, the lower temperatures (22 ℃) at the late-filling stage allowed starch synthesis and accumulationto return to normal levels.

Temperature Stress at Grain Filling Stage Mediates Expression of Three Isoform Genes Encoding Starch Branching Enzymes in Rice Endosperm

An early-maturity indica rice variety Zhefu 49, whose grain quality and starch structure are sensitive to environmental temperature, was subjected to different temperatures （32℃ for high temperature and 22℃ for optimum temperature） at the grain filling stage in plant growth chambers, and the different expressions of three isoform genes （SBEI, SBEIII and SBE/V） encoding starch branching enzyme （SBE） in the endosperms were studied by the real-time fluorescence quantitative PCR （FQ-PCR） method. Effects of high temperature on the SBE expression in developing rice endosperrns were isoform-dependent. High temperature significantly down-regulated the expressions of SBEI and SBEIII, while up-regulated the expression of SBEIV. Compared with SBEIV and SBEIII, the expression of SBEI gene in Zhefu 49 rice endosperms was more sensitive to temperature variation at the grain filling stage. This study indicates that changes in weather/climate conditions especially temperature stress influence rice grain formation and its quality as evidenced by isoform expression.

Relationship Between Variation in Activities of Key Enzymes Related to Starch Synthesis During Grain Filling Period and Quality of Eating and Cooking in Rice

Four japonica rice varieties with significant differences in quality of eating and cooking were used in the experiment. The varieties showed differences in amylose and amylopectin contents at different grain filling stages, which were attributed to the accumulative speed of starch at different grain filling stages. During grain filling period, the varieties had no difference in the time when the activities of ADPglocose pyrophosphorylase （AGPP） and soluble starch synthesis （SSS） reached a maximum, but had difference in the time when the activity of starch branching enzyme （SBE） reached a maximum, in which the inferior quality varieties were earlier than the high quality ones, and high quality varieties still kept high enzyme activities at the late stage of grain filling. The correlation and correlative degree between AGPP, SSS, SBE and amylose content, amylopectin content, taste meter value, and RVA properties varied with the different stages of grain filling. The correlation between SSS activity and taste meter value was not significant during the whole period of grain filling, but the activities of AGPP and SBE had significant or highly significant correlation with taste meter value. It was helpful for improving quality of eating and cooking of japonica rice to use the materials with low enzyme activity at the early stage of grain filling or high enzyme activity at the late stage as parents.

Activities of the Enzymes Involved in Starch Synthesis and Starch Accumulation in the Grains of Wheat Cultivars, GC8901 and SN1391

Two wheat cultivars, GC8901 (hard winter wheat) and SN1391 (soft winter wheat), were used for investigating the changes of enzyme activities for sucrose metabolism and starch biosynthesis and the accumulation character of starch composition. The result showed that activities of sucrose (SS), sucrose-phosphate synthase (SPS), adenosine diphosphorate glucose pyrophrylase (AGPase) and soluble starch syntheses (SSS) of 1391, which have more starch, were significant higher than those of 8901, that with low starch content. But the changing of granule-bound starch synthase (GBSS) activity was consistent with the amylose content, which indicated that amylose contents in grain were determined by GBSS activity, especially the activity at later grain filling stages. Simulating with Richards equation showed that it was initiating time and accumulation rate, but not accumulation duration that determined the content of starch composition. Furthermore, changing of sucrose transport capacity was consistent with SSS and GBSS activities, starch accumulation rate was accordant to AGPase and SS/SPS ration, not SS, SPS, SSS or GBSS activities. The results suggested that there was no inevitable relation of starch accumulating rate and starch composition contents with the activity of single enzyme such as SS, SPS, SSS or GBSS, but closely related to AGPase activity and SS/SPS ratio, and it was SPS and AGPase that play a vital role in the biosynthetic pathway. Later polymerization reactions catalyzed by SSS and GBSS don’t seem to control the rate of starch accumulation, but do affect starch structure.

Changes in the Activities of Enzymes Involved in Starch Synthesis in the Kernel During Grain Filling in Winter Wheat Cultivars of Different Spike Types

Two winter wheat(Triticum aestivum L.)cultivars, large-spike type Yumai66 and small-spike type Yumai49, were used to study the activities of enzymes involved in starch synthesis in the kernel during grain filling. Starch accumulated faster in the kernel of Yumai49 than Yumai66 up to 25 d after anthesis, thereafter starch accumulated faster in the kernel of Yumai66. Starch accumulation in Yumai66 peaked at 20 -25 d after anthesis, while in Yumai49 starch accumulation peaked at 15 -20 d after anthesis and 25 -30 d after anthesis. The first peak was much higher than that of the second. Sucrose content and sucrose synthase activity peaked at 20 and 15 d after anthesis in Yumai66 and Yumai49, respectively. The sucrose content and sucrose synthase activity in Yumai66 were higher than that in Yumai49 during grain filling. ADP-glucose pyro-phosphorylase and starch branching enzyme activity in the kernel of Yumai66 peaked at 20 d after anthesis. while soluble starch synthase activity peaked at 10 and 20 d after anthesis. The second peak was much higher than that of the first.

Expression Profiles and Protein Complexes of Starch Biosynthetic Enzymes from White-Core and Waxy Mutants Induced from High Amylose Indica Rice

Physicochemical properties of endosperm starches in milled rice determine its cooking and eating quality.Amylose is synthesized by granule-bound starch synthase I(GBSSI),whilst amylopectin is synthesized by the synergistic activities of starch synthases(SSs),branching enzymes(BEs)and debranching enzymes(DBEs).However,the complexes formed by starch biosynthetic enzymes are not well characterized.Gene expression profiles and protein complexes were determined in white-core(GM645)and waxy(GM077)mutants derived from a high amylose indica rice Guangluai 4(GLA4).In GM645,genes including AGPS1,GBSSI,SSIIa,BEI,BEIIa,BEIIb,PUL,ISA1 and SP were significantly downregulated during seed development.In GM077,the expression levels of AGPL2,AGPS1,AGPS2b,SSIIIa,BEI,PUL and ISA1 were significantly upregulated.Co-immunoprecipitation assays revealed interactions of SSs-BEs,SSs-PUL and BEs-PUL in developing seeds.However,weak SSI-SSIIa interaction was detected in GM077,whilst SSI-PUL interaction was absent.Weak interaction signals for SSI-SSIIa,SSIIa-BEI,SSIIa-BEIIb,BEI-BEIIb and SSI-BEI were also observed in GM645.These results suggest that the protein-protein interactions for starch biosynthesis are modified in mutants,which provides insight into the mechanisms of starch biosynthesis,particularly in indica rice.

Effect of Soil Texture on Starch Accumulation and Activities of Key Enzymes of Starch Synthesis in the Kernel of ZM 9023

Three kinds of soil texture （clay-loam, mid-loam, and sand-loam soil） were used to study the effects of soil texture on starch accumulating rate and the changes in activities of the key enzymes of starch synthesis in the kernel during grain filling in high gluten content wheat ZM 9023, under conditions of pond culture. The content of starch and its components were measured according to the method of double-wave length described by Bao （1996）. ADP-glucose pyrophosphorylase （AGPP） activity was tested according to the method described by Doehlert et al. （1988）. Soluble starch synthase （SSS） and starch branching enzyme （SBE） activities were tested according to the method described by Nakamura et al. （1989）. The amylose, amylopectin, and total starch accumulating rate in the kernel of ZM 9023 were found to be a single-peak curve in three different soil textures during grain filling, and peaked 20, 15, and 15 d after anthesis, respectively. The activities of the enzymes, AGPP, SSS, and SBE, in the kernel of ZM 9023 had a single-peaked curve, which peaked 20, 15, and 15 d after anthesis, respectively. The activities of the above three enzymes of ZM 9023 were higher in the sand-loam soil. The accumulating peak of amylose formed later compared to that of amylopectin. The sand-loam soil could help high gluten content cultivars to synthesize starch.

Changes in Activities of the Key Enzymes Related to Starch Synthesis in Rice Grains During Grain Filling and Their Relationships with the Filling Rate and Cooking Quality

With 10 rice cultivars (lines) as materials, the changes in activities of adenosine diphosphoglucose pyrophosphorylase(ADPGPase), starch synthase (SSase) and starch branching enzyme (Q-enzyme) in the grains during grain filling, and theirrelationships with the filling rate, gel consistency (GC), alkali spreading value (ASV) and amylose content (AC) werestudied. The results showed that changes in activities of ADPGPase, SSase and Q-enzyme exhibited a single peak duringgrain filling, and the time of the activity peaks for the former two enzymes was earlier than that of the maximum grain-fillingrate (Tmax), and the time reaching the peak for Q-enzyme was synchronous with Tmax. The activities at early grain fillingstage, and the mean and maximum activities of each enzyme during grain filling period were positively and significantly orvery significantly correlated with the mean and maximum grain filling rate and starch content (mg grain-1) in the grains.Activities of ADPGPase at all grain filling stages and those of Q-enzyme at the early and mid filling stages were notsignificantly correlated the cooking quality (GC, ASV and AC). SSase activities at the early filling stage were significantlyand negatively correlated with GC and ASV, and positively correlated with AC. Activities of SSase at mid and late grainfilling stages and Q-enzyme at the late filling stage were significantly and positively correlated with GC and ASV, andnegatively correlated with AC. Spraying zeatin or abscisic acid at early grain filling stage could obviously regulate theactivities of ADPGPase, SSase and Q-enzyme in the grains.

Comprehensive utilization of corn starch processing by-products:A review

Corn is a high starchy cereal crop with the highest production and provides over 85%of the starch produced worldwide.Various by-products,differentiated by technological process features such as steep liquor,corn germ,corn bran,gluten,are created largely during corn starch processing.They are inexpensive,nutrient-rich,and vary widely in chemical composition such as proteins,oils,carbohydrates,and minerals.In an increasingly resource-constrained modern world,the utilization approach of these by-products for non-starch industrial processing is attractive widely considering both nutritive value and economic aspects.In fact,at present,applications of these by-products can often be found in feed,fermentation,nutrient extraction and other industries.For example,protein-rich corn gluten can be used as a good animal feed,and corn germ can be used as a raw material for the high-quality edible oil industry.Undoubtedly,increasing utilization means that these by-products will no longer be treated as waste but will be transformed into high value-added products.In this work,the separation process and chemical composition of several main by-products of the corn starch industry is briefly described,and the application in many industrial fields of these by-products over the last ten years are discussed in particular.This review attempts to summarize all aspects of the application and research of these by-products.For the by-products of the corn starch industry,the most promising way is to be utilized in high value and used to produce high value-added products.According to the characteristics of their chemical composition,they have a better application prospect and research significance in the industries directly related to human beings,such as medicine,green food and health care products.In fact,in recent years,some researchers have recognized this and carried out the research.It is clear fromthese studies that the main issues to be faced nowand in the future are how to produce efficiently while maintaining the quality of the product and using it effectively.The retrospective discussions also provide some ideas for other grain and oilseed crops to be fully utilized.

The difference of soluble sugar contents and starch synthetic key enzyme activities between high and low starch cultivar of cassava

The difference of soluble sugar contents and starch synthetic key enzyme activities between high starch cultivar and low starch cultivar were studied in this experiment, of which FuXuan01, GR891, SC124, and SC201 were used as materials. The results showed that the contents of reducing sugar in root tube of low starch cultivars were higher than those of high starch cultivars in all growth periods, the contents of sucrose in root tube of high starch cultivar were higher than those of low starch cultivars in the early growth period, but, lower in the late growth period, and there were almost no difference in the contents of soluble sugar in root tube between high starch cultivar and low starch cultivar in the early growth period, but notable difference in the late growth period and the soluble sugar contents of low starch cultivars were higher than those of high starch cultivars. It also-showed that the activities of ADPGPpase, SSS, and SBE （starch branching enzyme） of high starch cultivars were higher than those of low starch cultivars. It was evident that there were close correlations between the content of sucrose, reducing sugar and soluble sugar in root tube, and the activities of ADPGPpase, SSS, SBE, and the starch accumulation in the root tubers of cassava. It was quite evident in this experiment that the soluble sugar and starch synthetic key enzyme were main factors controlling starch accumulation in root tubers. These results provided important indication for physiological controlling in high starch cultivation and gene engineering breeding of high starch cultivar of cassava.

Effects of Non-starch Polysaccharide Enzyme Products on Meat Performance in Broilers

[ Objective] To investigate the effects of non-starch polysaccharide （NSP） enzyme products on meat performance of broilers and thus to provide a scientific basis for their rational use. [Method] Two hundred 21-day-old Ross broilers were assigned to five groups. The broilers in group Ⅰ and group Ⅱ were fed positive control diet and negative control diet, respectively, which were slightly different. The broilers in group Ⅲ, Ⅳ and V were fed the negative control diet respectively supplemented with different commercial NSP enzyme products. The broilers were slaughtered at 56 days old, and their meat yield was determined. [ Result] The percentage of carcass yield and percentage of abdominal fat were significantly higher in the group Ⅲ than in the group Ⅱ （P 〈 0.05）. The percentage of small intestine weight in slaughter weight was lower in the group Ⅱ than in other groups. [ Conclusion] Diets supplemented broad-rang and highly active NSP enzyme products can promote absorption of routine feed ingredients, increase meat yield, and improve meat performance.