A glutathione S-transferase IbGSTL2 interacts with IbcPGM to increase starch content and improve starch quality in sweetpotato

A glutathione S-transferase(GST)gene IbGSTL2 was cloned and characterized from sweetpotato.It harbored a variation associated with starch content in storage roots.Overexpression of IbGSTL2 increased starch content and amylopectin proportion,decreased gelatinization temperature,and improved degree of crystallinity in sweetpotato storage roots,while its RNA interference resulted in the opposite trends.IbGSTL2 physically interacted with IbcPGM,an enzyme of sucrose metabolism,and improve starch content and quality by regulating genes involved in starch biosynthesis.

Effects of Curing Techniques on Starch Contents of Leaves in Different Tobacco Parts with Varying Maturity Degrees

[Objective] The aim was to explore effects of different curing techniques on starch contents of tobaccos from different growth parts and with varying maturity degrees in order to reduce starch content of Yunnan tobacco. [Method] Compar- isons were conducted on tobaccos from upper, middle and down parts （immature, premature, mature and excessive mature） by low temperature and low humidity cur- ing technique, moderate temperature and moderate humidity curing technique, mod- erate temperature and high humidity curing technique to measure starch contents before and after curing. [Result] The results showed starch content of tobacco was increasing upon growth part. Low temperature and low humidity curing technique has poor effects on reduction of starch content; moderate temperature and moderate humidity curing technique improves starch content; moderate temperature and high humidity curing technique dramatically reduces starch content of tobaccos. [Conclu- sion] With consideration of tobacco appearance, inner quality and characters, moder- ate temperature and moderate humidity curing technique is recommended for tobac- co production.

Identification of QTLs for Starch Content in Sweetpotato(Ipomoea batatas(L.) Lam.)

Sweetpotato （Ipomoea batatas （L.） Lam.） breeding is challenging due to its genetic complexity. In the present study, interval mapping （IM） and multiple quantitative trait locus （QTL） model （MQM） analysis were used to identify QTLs for starch content with a mapping population consisting of 202 F1 individuals of a cross between Xushu 18, a cultivar susceptible to stem nematodes, with high yield and moderate starch, and Xu 781, which is resistant to stem nematodes, has low yield and high starch content. Six QTLs for starch content were mapped on six linkage groups of the Xu 781 map, explaining 9.1-38.8% of the variation. Especially, one of them, DMFN 4, accounted for 38.8% of starch content variation, which is the QTL that explains the highest phenotypic variation detected to date in sweetpotato. All of the six QTLs had a positive effect on the variation of the starch content, which indicated the inheritance derived from the parent Xu 781. Two QTLs for starch content were detected on two linkage groups of the Xushu 18 map, explaining 14.3 and 16.1% of the variation, respectively. They had a negative effect on the variation, indicating the inheritance derived from Xu 781. Seven of eight QTLs were co-localized with a single marker. This is the first report on the development of QTLs co-localized with a single marker in sweetpotato. These QTLs and their co-localized markers may be used in marker-assisted breeding for the starch content of sweetpotato.

Molecular Markers Associated with Starch Content and Implications for Sugarcane Introgression Breeding Using Saccharum spontaneum

Introgression with Saceharum spontaneum intended to broaden the genetic base of sugarcane resulted in an increase in desirable genes for broader adapt ability as well as undesirable genes for high starch content. Markers could provide a quick and efficient method of screening parental genotypes for low starch. The objectives of this study were to identify potential markers associated with starch in S. spontaneum population and evaluate their potential for screening for starch content. Data for starch content and （simple sequence repeats） SSR markers were collected from 51 S. spontaneum clones grown in replicated pots. The mixed procedure of statistical analysis system （SAS） was used to determine markers significantly associated with starch. Thirty-nine out of 357 polymorphic markers were significantly （P 〈 0.05） associated with starch content. Eighteen were positively associated and 21 were negatively associated. The presence of a positive marker produced 39% more starch than absence while the absence of a negative marker produced 57% more starch than presence. Selecting parents using negative markers may be more efficient than selecting using positive markers.

Genome-wide association study for starch content and constitution in sorghum(Sorghum bicolor(L.) Moench)

Starch is the most important component in endosperm of sorghum grain.Usually,two types of starch are present:amylose(AM)and amylopectin(AP).The levels of AM and AP contents play a significant role in the appearance,structure,and quality of sorghum grains and in marketing applications.In the present study,a panel of 634 sorghum(Sorghum bicolor(L.)Moench)accessions were evaluated for starch,AM,and AP contents of grain,which included a mini core collection of 242 accessions from the International Crops Research Institute for the Semi-Arid Tropics(ICRISAT)in India,and 252 landraces and 140 cultivars from China.The average starch content was 67.64%and the average AM and AP contents were 20.19 and 79.81%,respectively.We developed a total of 260000 high-confidence single nucleotide polymorphism(SNP)markers in the panel of 634 accessions of S.bicolor using specific locus amplified fragment sequencing(SLAF-seq).We performed genome-wide association studies(GWAS)of starch,AM,and AM/AP of grain and SNP markers based on a mixed linear model(MLM).In total,70 significant association signals were detected for starch,AM,and AM/AP ratio of grain with P<4.452×10^-7,of which 10 SNPs were identified with significant starch,51 SNPs were associated with AM,and nine SNPs were associated with the AM/AP ratio.The Gene Ontology(GO)analysis identified 12 candidate genes at five QTLs associated with starch metabolism within the 200-kb intervals,located on chromosomes 1,5,6,and 9.Of these genes,Sobic.006G036500.1 encodes peptidyl-prolyl cis-trans-isomerase CYP38 responsible for hexose monophosphate shunt(HMS)and Sobic.009G071800 encodes 6-phospho-fructokinase(PFK),which is involved in the embden-meyerhof pathway(EMP).Kompetitive allele specific PCR(KASP)markers were developed to validate the GWAS results.The C allele is correlated with a high starch content,while the T allele is linked with a low level of starch content,and provides reliable haplotypes for MAS in sorghum quality improvement.

Mapping QTL underlying tuber starch content and plant maturity in tetraploid potato

Tuber starch content and plant maturity are two important agronomic traits of potato. To investigate the complex genetic basis of these traits in the cultivated potato, as well as the relationship between them, we developed a linkage map in a tetraploid population of 192 clones derived from the cross Longshu 8 × Zaodabai and mapped quantitative trait loci(QTL) for tuber starch content and plant maturity using data collected in three diverse environments over two years. We detected eleven QTL for tuber starch content distributed on seven chromosomes, of which four, on chromosomes I, II, and VIII, were expressed in at least three environments. For plant maturity, we identified six QTL on chromosomes II, IV,V, VII, and XI, one of which, on chromosome V, showed LOD peaks ranging from 45.2 to 62.5 cM and explained 21.6%–26.6% of phenotypic variation was expressed in five of the six environments. Because the reproducible QTL for plant maturity and tuber starch content mapped to different chromosomes and neither overlapping QTL, nor any genetic interaction between QTL were detected, we infer that tuber starch content and plant maturity are controlled by independent genetic loci. This inference supports the prospect of breeding potato for both early maturity and high starch content.

Effects of Bacterial Manure from Cassava Alcohol Fermentation Mash on Yield and Starch Content of Cassava

In order to provide a scientific basis for the utilization of cassava alcohol fermentation mash and the high-yield and high-efficiency cultivation of cassava,compound microbial inoculum was inoculated into the cassava alcohol fermentation mash to prepare bacterial manure,which was then applied to two cassava varieties,Nanzhi 199 and SC 205 to explore the optimum application amount,application method and application concentration. The results showed that when the inoculation amount of the compound microbial inoculum was 2‰ of the mass of the mash,the requirements of industrial production of liquid bacterial manure and agricultural application can be met,saving costs. After the emergence of cassava seedlings,if they were drenched with the bacterial manure of cassava alcohol fermentation mash through roots once according to the amount of 67. 5 t/ha and irrigated with the bacterial manure once every 15 d under drought conditions,both the yield and quality of cassava can be improved significantly. The yield and starch content of Nanzhi 199 reached 26 196. 23 kg/ha and 30. 32%,36. 57% and4. 75 percentage points higher than those of CK. The yield and starch content of SC 205 reached 41 126. 06 kg/ha and 23. 74%,99. 25% and3. 19 percentage points higher than those of CK. Under the application modes of foliar spray,root irrigation and foliar spray + root irrigation,the fertilization effect was more obvious. When undiluted bacterial manure of cassava alcohol fermentation mash was applied according to the amount of 52. 5 t/( ha·time),the fertilization effect of the application mode of foliar spray + root irrigation was the best. The bacterial manure from cassava alcohol fermentation mash can be directly applied without dilution,and the fertilizer efficiency will be reduced significantly after dilution.

A plastidic ATP/ADP transporter gene, IbAATP, increases starch and amylose contents and alters starch structure in transgenic sweetpotato

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.

Effects of RNAi Silencing of SSIII Gene on Phosphorus Content and Characteristics of Starch in Potato Tubers

The sense and antisense fragments of the soluble starch synthase （SSII1） gene and the intron fragment of somatic embryogenesis receptor-like kinase （SERK1） gene were cloned from potato using PCR techniques. The RNAi plant expression vectors pBI-SSIII-RNAi and pBIC-SSIII-RNAi were constructed which containing fusion fragment of ＂sense fragment-intron-antisense fragment＂ driven by the constitutive expression promoter CaMV 35S and the tuber-specific expression promoter CIPP, respectively. The putative transgenic plants of potato cultivars Kexin-1 and Kexin-4 were obtained using Agrobacterium-mediated transformation method. PCR assay showed that the interference fragment of SSlll gene was integrated into potato genome. The RT-PCR analysis showed that the expression of SSlll gene was repressed apparently on the transcription level. Starch granules of the transgenic potato plants were different in morphology and became cracked in starch granule centre compared with the non-transgenic control plants. The amylose content of starch was increased by 2.68-29.05%, amylopectin to amylose ratio of starch had declined significantly, and the phosphorus content of the starch of the transgenic plants was reduced 9.94-58.36% compared with control plants. The results could provide certain foundation for improvement of potato starch quality.

Effect of Different Moisture Contents on Crystallized State of Microwave Modified Tapioca Starch

Effect of microwave modification on tapioca starch at different moisture contents was studied with polarized light microscope. It was observed that loss of birefringence was initiated at hilum of granule. The polarization cross of most granules had become somewhat unclear, and reduction in clarity of the polarization cross was proportioned with the moisture contents of native starch as modification by microwave. When the moisture contents reached to 35.0%, the polarization cross of most granules was lost, and the critical point of native starch was 30% in microwave modification.

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.

The Source of Genes Related to Rice Grain Starch Synthesis Among Cultivated Varieties and Its Contribution to Quality

The property of starch in rice grain endosperm is a very important determinant for rice quality, and it is essential to understand the genetic effect of the genes related to starch synthesis in high-yielding rice varieties for rice quality improvement. The physicochemical properties （e.g., amylose content, gel consistency, and RVA profile） were assessed on 53 rice varieties, including certain typical indica/japonica landraces and certain high-yielding modern varieties. And molecular markers for Sbel, Sbe3 developed on the basis of sequence diversities between the rice subspecies indica and japonica, together with PCR-Acc I marker for Wx gene were used to investigate the genotypes of 53 rice cultivars. The result showed that the developed molecular markers for Wx, Sbel, Sbe3 could distinguish indica or japonica alleles at three loci. Among all the 53 rice cultivars, six genotypes were observed when Sbel, Sbe3, and Wx loci were considered together, while the genotypes of WxiSbelJSbe3i and WxiSbelJSbe3J were absent. In order to explore the genetic effects of the three genes, especially for starch branching enzyme genes, ANOVA and multiple comparison analysis were conducted. The results showed that rice cultivars with different genotypes exhibited different phenotypes, including amylose content, gel consistency and certain RVA characteristics, and the significant differences among the six genotypes were observed. It was concluded that these three genes had randomly recombined during the process of the rice variety development. And the genetic effects of indica and japonica alleles at three gene loci were different, of which, Wx gene plays a major role in determining the starch properties, followed by Sbel and Sbe3, and the genetic effects of Sbel and Sbe3 in different backgrounds （Wx~, WxJ） are different. The results have provided a clue for rice good quality variety development, and the molecular markers will benefit to the improvement in quality of rice.

A genetic diversity assessment of starch quality traits in rice landraces from the Taihu basin,China

There are nearly 1 000 rice landrace varieties in the Taihu basin, China. To assess the genetic diversity of the rice, 24 intragenic molecular markers（representing 17 starch synthesis-related genes） were investigated in 115 Taihu basin rice landraces and 87 improved cultivars simultaneously. The results show that the average genetic diversity and polymorphism information content values of the landraces were higher than those of improved cultivars. In total, 41 and 39 allele combinations（of the 17 genes） were derived from the landraces and improved cultivars, respectively; only two identical allele combinations were found bet ween the two rice variety sources. Cluster analysis, based on the molecular markers, revealed that the rice varieties could be subdivided into five groups and, within these, the japonica improved rice and japonica landrace rice varieties were in two separate groups. According to the quality reference criteria to classify the rice into grades, some of the landraces were found to perform we ll, in terms of starch quality. For example, according to NY /T595-2002 criteria from the Ministry of Agriculture of China, 25 and 33 landraces reached grade 1, in terms of their apparent amylose content and gel consistency. Th e varieties that had outstanding quality could be used as breeding materials for rice quality breeding programs in the future. Our study is useful for future applications, such as genetic diversity studies, the protection of rice variety and improvment of rice quality in breeding programs.

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.

Morphological and Rheological Properties of Starches Separated from Cultivars of Rice (<i>Oryza sativa</i>L.) from North East India

Starch granules isolated from different accessions of rice from North East India showed a typical polygonal morphology with size ranging from 3.4 ± 0.8 μm to 6.4 ± 1.2 μm. The apparent amylose content (AAC) of the granules varied from 1.9% to 28.33%. Our results identify starch from IC-583088 as “waxy” and IC-583085, IC-583038, DPRR-168 as “very low” amylo-. The coefficient of resistance to flow (n) for starch pastes from the varieties of rice studied in the present investigation recorded a value of <1.0. The observed “n” value deviates from the Newtonian flow indicating the pseudoplastic nature of starches isolated from these varieties. While starch pastes from the accession IC-583088 recorded the highest ‘‘n’’ value of 0.6, that from the accession IC-545197 showed the lowest value of 0.03. The variations in coefficient of resistance to flow clearly revealed a higher ‘‘n’’ value for starch pastes from the “waxy” and ‘‘low” amylo-cultivars than the “intermediate” or ‘‘high” amylo-cultivars. Our results clearly established characteristic rheological properties for starches from the accessions SKY-AK-1608, IC-583035, YS-RC-219, IC-564939 and IC-332963, which exhibited greater resistance to thinning and shearing than other varieties.

96份谷子种质资源淀粉多样性及优异资源鉴选利用

采用双波长微量法对国内有代表性的96份谷子种质资源的直链淀粉和支链淀粉含量进行了测定,分析其淀粉多样性与直/支比变异类型。结果表明,各品种直链淀粉含量介于0~24.91%,平均值为15.66%,支链淀粉含量介于4.77%~34.26%,平均值为14.67%;44份育成品种和52份地方品种直链淀粉含量变化幅度分别为8.66%~21.81%和0~24.91%;96份谷子的直/支比变化范围为0~3.60,平均为1.18,其中直/支比<0.05的地方品种仅2个,而直/支比>0.33的品种93个,占总数的96.87%。直链淀粉含量小于3.5%的糯性品种3个,其中完全糯性品种2个;高直链淀粉品种4个,直链淀粉含量介于12.0%~18.0%的种质有60份,占总数的62.50%。筛选出适合加工糍粑、汤圆类糯质食品的地方品种3个,为红毛谷、三爪谷和酒谷;可用于加工米粉等高膳食纤维的地方品种4个,分别为金皇谷、金棒子、茄谷和山西白米。96份谷子种质资源中地方品种直链淀粉变异类型较为丰富,育成品种直链淀粉遗传基础相对单一。

不同热处理条件下橡胶木淀粉含量与抗蠹虫性能关系研究

为克服橡胶木易发生蠹虫危害的缺陷,采用不同热处理温度(90、120、150℃和180℃)和不同热处理时间(2、4 h和6 h)对橡胶木进行热处理,利用分光光度计考察不同温度和时间条件下热处理橡胶木中的淀粉含量变化,并分析蠹虫对橡胶木的蛀蚀程度与淀粉含量之间的关系。结果表明:热处理温度和处理时间对橡胶木中的淀粉含量有显著影响,且随着热处理温度的升高和热处理时间的延长,淀粉含量逐渐下降,从12.79%降至1.25%。在橡胶木抗蠹虫试验中,热改性处理后橡胶木的抗蠹虫效果均优于对照材,且橡胶木淀粉含量越低,其抗蠹虫效果越好。在实际生产过程中,在120℃下处理6 h为生产热处理橡胶木的优化条件,既能刚好维持橡胶木抗蠹虫的最低要求,也能降低热处理过程中木材强度的损失。

紫外辐照及甲基磺酸乙酯诱变对马铃薯早熟品种淀粉含量和产量性状的影响

针对黑龙江省现有马铃薯早熟品种淀粉含量较低的问题,通过紫外辐照和甲基磺酸乙酯浸泡2种方式,对东农303和中龙薯1号的组培苗进行处理,经过3 a的种植、调查和数据采集,确定诱变方式对不同品种马铃薯变异程度和诱变方向的影响,以改良获得早熟且高淀粉含量的马铃薯品种。结果表明,诱变后,整体变化表现为无变化>抑制>促进,其中东农303更易发生变异,紫外辐照的诱变效果更佳。在组培苗阶段,多数处理显示为抑制作用;在原原种阶段,紫外辐照有利于东农303产量的提升和中龙薯1号淀粉含量的增加;在原种阶段,甲基磺酸乙酯浸泡对东农303的商品性有提升作用,而2种诱变方式对中龙薯1号的产量和结薯数量均有明显抑制作用,紫外辐照的影响更为显著。在紫外辐照处理中,2个品种均发现了1个淀粉含量明显提升的单株,2个单株的发现将有利于黑龙江省不同熟期品种的搭配种植,减少完全依赖晚熟品种所带来的种植风险,并可有效提升产业效益。

基于转录组分析的甘薯贮藏根淀粉含量相关SNPs开发

甘薯是重要的粮食和经济作物,贮藏根淀粉含量是甘薯的重要农艺性状,开发与淀粉含量相关的分子标记对于加快育种进程具有重要意义。但甘薯具有自交不亲和特性,基因组是高度杂合的六倍体,增加了开发分子标记的难度。本试验以高淀粉品种漯徐薯8号和低淀粉品种郑薯20及其杂交F1代中6个高淀粉株系和6个低淀粉株系为材料,基于转录组测序分析并结合表型分析,发现44个高淀粉特异的SNPs位点,从中选取9个进行PCR单克隆分析,筛选到3个与高淀粉含量显著相关的位点,分别为chr9.27120209、chr9.27120256和chr9.13675504,用上述12个株系和F_(1)群体中的另外16个株系进行验证,最终得到3个与贮藏根淀粉含量相关的单核苷酸多态性(SNPs)位点。本试验丰富了甘薯分子标记开发的途径,为甘薯贮藏根淀粉含量相关育种提供了可选择的标记。

9个不同使用类型木薯品系在合浦县的适应性研究

为筛选适宜在合浦县推广的木薯品系,本研究以主栽品种‘南植199’为对照,对9个木薯新品系的生物学特性进行了观察,并测定其农艺性状和经济性状,同时进行相关性分析。结果表明,9个品系分枝角度小、块根长度适中和主茎高度中等以上;‘RC4’的块根产量显著高于对照,其余8个品系与对照差异不显著;‘RC4’等8个品系的淀粉产量高于对照;9个品系的淀粉含量高于对照,其中‘RC3’等5个品系的淀粉含量显著或极显著高于对照;9个木薯品系的直链淀粉含量显著或极显著低于对照‘;RC6’等6个品系的氢氰酸含量低于50 mg/kg。相关性分析结果表明:块根产量与生长中期株高、成熟期株高、块根直径呈极显著正相关,与茎粗呈显著正相关;淀粉含量与生长中期株高、成熟期株高、茎粗呈显著正相关;淀粉产量与生长中期株高、成熟期株高、茎粗、块根直径、块根产量呈极显著正相关,与淀粉含量呈显著正相关。综合来看,这9个木薯新品系的综合表现良好,适合在合浦县进行推广。其中‘,RC3’、‘RC4’和‘RC7’可作为加工型品系;‘RC5’和‘RC10’可作为食用品系;‘RC2’、‘RC6’、‘RC11’和‘RC12’可作为鲜食加工兼用品系;‘RC2’和‘RC5’作为食用品系具有很好的推广前景。