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1.
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2.
The effects of endosperm vitreousness, cooking time and temperature on sorghum and maize starch digestion in vitro were studied using floury and vitreous endosperm flours. Starch digestion was significantly higher in floury sorghum endosperm than vitreous endosperm, but similar floury and vitreous endosperm of maize. Cooking with 2-mercaptoethanol increased starch digestion in both sorghum and maize, but more with sorghum, and more with vitreous endosperm flours. Increasing cooking time progressively reduced starch digestion in vitreous sorghum endosperm but improved digestibility in the other flours. Pressure-cooking increased starch digestion in all flours, but markedly more in vitreous sorghum flour; probably through physical disruption of the protein matrix enveloping the starch. Irrespective of vitreousness or cooking condition, the alpha-amylase kinetic constant (k) for both sorghum and maize flours remained similar, indicating that differences in their starch digestion were due to factors extrinsic to the starches. SDS-PAGE indicated that the higher proportion of disulphide bond-cross-linked prolamin proteins and more extensive polymerisation of the prolamins on cooking, resulting in polymers of Mr>100k, were responsible for the lower starch digestibility of the vitreous sorghum endosperm flour.  相似文献   

3.
为深入研究磷素在小麦淀粉产量和品质形成过程中的作用,以新疆冬小麦主栽品种新冬20号为试验材料,研究0 kg·hm-2（CK）、105 kg·hm-2（LP）和210 kg·hm-2（HP）3种施磷（P2O5）量对小麦籽粒灌浆特性、淀粉合成关键酶(AGPase和GBSS)活性和基因表达、胚乳可溶性蛋白和淀粉粒结合蛋白含量及谱带特征、胚乳微观特性等的影响。结果表明,籽粒灌浆后期磷肥对粒重的促进作用逐渐增强;低磷（LP）条件下, agp1、 agp2、 gbss1、 gbss2基因表达量显著提高;3个处理下AGPase活性的变化趋势基本一致;籽粒灌浆中期（14～21 d）,低磷处理的GBSS活性显著高于CK;不同磷处理对淀粉粒结合蛋白和胚乳可溶性蛋白含量的影响显著,但对蛋白谱带特征的影响较弱。扫描电镜结果显示,不同磷处理的胚乳淀粉粒形态未发生明显变化;与CK和高磷（HP）处理相比,低磷处理下籽粒胚乳横断面蛋白基质较少,淀粉粒与蛋白质结合较疏松。说明常规施磷（低磷）条件下,淀粉合成关键酶基因（agp和gbss）相对表达量提高或酶活性变化可影响籽粒淀粉合成及胚乳中蛋白与淀粉粒的嵌合度,并最终造成粒重的增加和淀粉特性的变化。  相似文献   

4.
High-temperature stress during the grain-filling stage reduces grain quality of rice, and this is a serious problem in Japan, especially in the Kyushu region. To solve this problem, various heat-tolerant cultivars have been bred, such as ‘Nikomaru’, ‘Kumasannochikara’, ‘Genkitsukushi’, ‘Sagabiyori’, and ‘Otentosodachi’. When cultivated under high temperature after flowering, these heat-tolerant cultivars had lower percentages of chalky grains than in the heat-sensitive cultivar ‘Hinohikari’. All the heat-tolerant cultivars markedly decreased the nonstructural carbohydrate content in the stem under the high temperature compared to control condition during early grain-filling stage, which is considered to be a common trait of heat tolerance. Notably, ‘Sagabiyori’, ‘Genkitsukushi’, and ‘Nikomaru’ maintained a nucellar epidermis at 17 days after flowering (DAF) under high temperature, whereas the nucellar epidermis disappeared in ‘Hinohikari’. In addition, the expression of AGPS2b, thought to be a rate-limiting enzyme in starch synthesis, in ‘Kumasannochikara’, ‘Otentosodachi’, and ‘Nikomaru’ did not decrease under high temperature, whereas ‘Hinohikari’, ‘Sagabiyori’, and ‘Genkitsukushi’ could not maintain expression of the gene at 17 DAF. Moreover, the expression of Amy3E, a starch-degradation-related gene considered to induce grain chalkiness, in ‘Kumasannochikara’ at 17 DAF was not increased by high temperature. These results suggest that the heat-stress-tolerant cultivars have various mechanisms for dealing with high-temperature stress.  相似文献   

5.
结实期高温胁迫对糯玉米子粒发育和内源激素含量的影响   总被引：2，自引：1，他引：1  
杨欢  沈鑫  丁梦秋  陆大雷  陆卫平 《玉米科学》2017,25(2):55-60,67
利用人工智能温室研究结实期高温胁迫(35℃)对糯玉米子粒发育和内源激素含量的影响。结果表明,结实期高温胁迫降低子粒鲜重和干重,高温胁迫下较低的含水率表明子粒灌浆进程加快。高温胁迫加快果皮中淀粉体的降解速度,胚乳细胞中淀粉体充实提前,淀粉积累加速,但持续积累时间缩短,成熟期淀粉含量低于常温处理。与常温相比,高温胁迫增加子粒中ABA和GA_3含量,IAA、CTK和Z含量前期增加,后期降低。内源激素含量的变化可部分解释高温胁迫下淀粉积累提前但持续时间缩短的原因。  相似文献   

6.
Storage product synthesis and accumulation in developing grains of wheat   总被引：1，自引：0，他引：1  
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7.
Gelatinized waxy and normal corn starches at various concentrations (20–50%) in water were stored under temperature cycles of 4°C and 30°C (each for 1 day) up to 7 cycles or at a constant temperature of 4°C for 14 days to investigate the effects of temperature cycling on the retrogradation of both starches. Compared to starches stored only at 4°C, both starches stored under the 4/30°C temperature cycles exhibited smaller melting enthalpy for retrogradation (ΔHr), higher onset temperature (To), and lower melting temperature range (Tr) regardless of the starch concentration tested. Fewer crystallites might be formed under the temperature cycles compared to the isothermal storage, but the crystallites formed under temperature cycling appeared more homogeneous than those under the isothermal storage. The effect of starch content on the retrogradation was greater when the starch gels were stored under cycled temperatures. The reduction in ΔHr and the increase in conclusion temperature (Tc) by retrogradation under 4/30°C temperature cycles became more apparent when the starch concentration was lower (20 or 30%). Degree of retrogradation based on melting enthalpy was greater in normal corn starch than in waxy corn starch when starch content was low.  相似文献   

8.
《Plant Production Science》2013,16(2):160-168
Abstract

The resistance to high-temperature stress and the structural appearance of the imperfect grains caused by a high temperature at the ripening stage were studied using 13 selected cultivars of rice. High temperature treatment (daily maximum temperature range, 32-40°C) given from the 4th day after heading caused the decrease in panicle weight in all of the cultivars examined. The number of empty grains in the upper and lower parts of a panicle was increased by the high temperature in 10 cultivars. Cultivars KRN, Citanduy, Belle patna and BPB were tolerant to the high-temperature treatment at the ripening stage, and cvs. Koshihikari, Sanlicun, Tainung 67, Yamada-nishiki and Lady Wright were sensitive. Light microscopic observation showed that, the whole endosperm was covered with a nucellar epidermis (NE) under both high and natural temperature (26-31°C) conditions at the first week after heading (WAH). Under high-temperature conditions the NE degenerated earlier than under natural temperature conditions. Scanning electron microscopic observation showed that, the endosperm cells of the seeds with a specific gravity (s.g.) of higher than 1.06 had large amyloplasts filled with starch granules. However, the endosperm cells of seeds with a s.g. of 1.00-1.06 had many small amyloplasts containing small single starch granules and had numerous spaces among the amyloplasts. In the endosperm cells at the dorsal side of imperfect grain, layered structures showing progressive decomposition of starch granules were observed.  相似文献   

9.
《Plant Production Science》2013,16(4):285-290
Abstract:

White-belly and white-core are the major two types of grain chalkiness in japonica rice. This study aims to compare the morphological features of white-belly and white-core using a scanning electron microcope (SEM). A japonica rice cultivar Wuyujing3 and its mutants were used as materials. Nearly 1000 SEM images were observed, and 12 representative photos were selected. SEM images showed contrasting differences between white-belly and white-core in endosperm microstructure including the shape of endosperm cell, the size distribution of starch granules, and the amount of protein bodies. White-belly and white-core also varied markedly in morphological features of the cracked compound starch granules. Our findings should help to advance our understanding of the multi-faceted nature of grain chalkiness from the perspective of starch and protein accumulation, and should be of value for future work on rice grain chalkiness.  相似文献   

10.
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11.
As each of the classes of wheat-grain protein has been implicated in some aspect of man's interest in wheat utilization, we are motivated to learn more about the genetic control of their synthesis so that breeders may better tailor wheats to specific requirements. The gliadins have particularly merited study because they appear to be responsible for coeliac condition and for depressed lysine content, and as they are proving valuable for varietal identification and grain-quality prediction. Genetic aspects of gliadin synthesis have been studied using aneuploids, by examining F1 and F2 segregation after crossing, and by computer comparison of the gliadin composition of many genotypes in conjunction with systematic pedigree comparisons. These studies indicate gliadin synthesis to be controlled by blocks of tightly linked genes on the short arms of the chromosomes of groups 1 and 6. The high molecular weight subunits of glutenin are genetically distinct from the gliadins, being coded by genes on the long arms of chromosomes 1A, 1B and 1D. A better understanding of the relationship between grain quality and specific endosperm proteins is now developing. It is likely to provide simpler means of selecting for quality type in both breeding and harvest segregation.  相似文献   

12.
Micro-beam X-ray diffraction analyses were carried out on slices from wild-type rice and mutants. The method permitted the crystalline structure to be analyzed with less destruction of cells and fewer artificial effects that occur during the purification of starch from tissue and provided information concerning the localization and crystalline structure of starches distributed in the endosperm. The starch on kernel slices from the wild-type and waxy mutant, carrying a defect for the Granule-bound starch synthase I (GBSSI) gene, displayed an A-type of diffraction pattern; no difference in the crystalline patterns between starches located in the inner and outer region in a kernel were observed. A double mutant of the waxy and amylose extender (ae) mutant carrying a defect for the Starch branching enzyme IIb gene accumulated amylose-free B-type starches. The kernel slice from the double mutant of waxy and sugary1, mutated on the Isoamylase I locus, displayed an A-type diffraction pattern in the outer region and was amorphous in the inner region. A chain-length distribution analysis of polyglucans in kernels from wild-type and mutants showed that ae amylopectin had more long chains and less short chains than the wild-type and waxy amylopectin. On the other hand, the water-soluble polysaccharide in the inner region of the sugary1 endosperm had more short chains than the amylopectin in the outer region counterparts. These results indicate that branch chain length in amylopectin is crucial in determining the formation of A- and B-type starches.  相似文献   

13.
为探明干旱胁迫下小麦颖果内源激素与胚乳发育的关系,以小麦品种扬麦16为材料,在幼苗返青至颖果成熟阶段进行干旱处理,采用树脂切片及显微摄影等技术观察小麦颖果和胚乳细胞发育的形态结构特征,并通过酶联免疫吸附法测定颖果生长素(IAA)、脱落酸(ABA)、赤霉素(GA_3、GA_4)、玉米素核苷(ZR)、二氢玉米素核苷(DHZR)的含量。结果显示,干旱胁迫缩短了小麦颖果发育进程,促进颖果早衰,导致颖果发育不良;显著降低了籽粒千粒重、可溶性糖含量和总淀粉含量,提高了蛋白质含量;促进颖果发育早期胚乳细胞分裂和淀粉积累,抑制了发育后期胚乳细胞的分裂、体积扩大和淀粉体充实,并提高了颖果整个发育过程中胚乳蛋白体的积累;提高了颖果发育前期IAA、GA_3、GA_4、ZR和DHZR的含量,ABA含量在整个发育时期均较高。说明干旱胁迫能通过影响颖果内源激素的积累来调控胚乳发育。  相似文献   

14.
【Objective】Aminoacyl-tRNA synthetases (aaRSs) are closely related to the transmission of genetic information. Besides translation, aaRSs in plants participate in gametogenesis and embryo development, early plastid development, immune signal perception and disease defense. In this study, we used a rice endosperm defective mutant to analyze the function of tryptophanyl-tRNA synthase (WRS1) during seed development, proving that WRS1 gene encodes a key factor affecting rice endosperm development. 【Method】In this study, a stably-inherited rice floury endosperm mutant (wrs1) was screened from the mutant library of indica cultivar N22 (Oryza sativa subsp. indica) induced by ethyl methane sulfonate (EMS). Map-based cloning and complementation test identified the target gene. Morphological observation and starch physicochemical properties of wrs1 mature seeds were analyzed. Semi-thin sections were prepared to observe the developing endosperm structure with a scanning electron microscope. qRT-PCR and GUS staining were performed to analyze the expression of WRS1. The expression of starch synthesis related genes in the endosperm at 12 days after flowering was determined by qRT-PCR, and these protein expression levels in mature seed were detected by immunoblotting. The free amino acid contents of mature seeds were measured with a fully automatic amino acid analyzer. 【Result】The seedlings of wrs1 were featured by obvious delay in development and finally withered and died. The floury grains isolated from the heterozygous mutant (WRS1wrs1) showed shrunken belly, decreased grain thickness and thousand-grain weight. Total starch contents, the peak viscosity and breakdown viscosity of pasting starch were lower in wrs1. The compound starch granules in developing endosperm of wrs1 were smaller and loosely arranged. WRS1 was restricted to the 183 kb region of the long arm of chromosome 12. Sequencing revealed a single base substitution in exon 6 of the tryptophanyl-tRNA synthetase gene (WRS1), resulting in a substitution of methionine. The expression of most starch synthesis-related genes in wrs1 was down-regulated, while these proteins showed different accumulation levels. The contents of proteins in wrs1 grains were decreased, while free amino acids contents were significantly increased. 【Conclusion】WRS1 encodes tryptophanyl-tRNA synthase. Mutation of this gene affects amino acid homeostasis and protein synthesis in rice endosperm, resulting in abnormal expression of the genes in starch synthesis pathway which affects starch synthesis and accumulation, and eventually lead to seed development defects.  相似文献   

15.
Starch is composed of two types of glucose polymers: amylose and amylopectin. The Waxy (Wx) locus controls amylose synthesis in the wheat kernel. Hexaploid wheat has three Wx loci located on chromosomes 7A (Wx-A1), 4A (Wx-B1), and 7D (Wx-D1). Eight near isogenic lines (NILs) of Triticum aestivum cv. Tremie with one, two or three Wx null alleles were used. The albumin–globulin fraction, and amphiphilic proteins were separated using 2-dimensional electrophoresis (2DE) allowing the changes in the waxy kernel to be identified. Albumin–globulin fraction showed overexpression of sucrose synthases in the waxy NILs compared to the normal form of Tremie and a decrease in many proteins related to stress and defence metabolism such as serpins. A subunit of ADP-glucose pyrophosphorylase (AGPase), which is known to play a major role in starch synthesis, was also shown to be down regulated in the waxy NILs. Amphiphilic proteins confirmed the observations made on the albumin–globulin fraction with a decrease in a stress-related protein. These different regulations linked to observations made on wheat kernel (thousand kernel weight (TKW), protein amount per grain, size and distribution of the starch granules) led to formulation of the hypothesis that waxy endosperm does not reach maturity of the wild-type endosperm.  相似文献   

16.
To increase the thermotolerance of improved White Ponni (IWP), two quantitative trait loci (QTLs), qHTSF1.1 and qHTSF4.1, controlling spikelet fertility under high-temperature stress, were introgressed from Nagina 22 into IWP through marker-assisted breeding. The progenies were subjected to foreground selection of target QTLs using simple sequence repent markers RM431 and RM5757 linked to qHTSF1.1 and qHTSF4.1, respectively. At each generation, foreground selection with single target QTL or both QTLs was done together. The QTL-positive plants were forwarded to next generation by selfing. The F2:3 progenies were subjected to phenotypic analyses under high-temperature stress at the flowering stage. Chlorophyll stability index, malondialdehyde content, grain yield, and yield-related components of the F2:3 progenies were measured. The progenies IWP-295, IWP-277 and IWP-246 harboring both qHTSF1.1 and qHTSF4.1 showed higher fertility percentages under high-temperature stress at the flowering stage. These QTLs were responsible for maintaining membrane integrity and yield under elevated temperature conditions.  相似文献   

17.
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18.
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19.
温度对早籼稻米垩白发生与胚乳物质形成的影响   总被引：44，自引：8，他引：44  
沈波  陈能 《中国水稻科学》1997,11(3):183-186
 以早籼品种中优早3号(少垩白)和泸红早1号(多垩白)为材料进行盆钵土培试验。在人工气候箱的设置两种温度处理（高温：昼/夜，33℃/29℃；适温：昼/夜，26℃/22℃）。结果表明温度对稻米垩白形成的显著影响，而且不同垩白的水稻品种在高温、适温条件下胚乳物质及酶类活性等的表现差异。少垩白的中优早3号通过高温和适温的同期比较处理，可以明显看到胚乳内部物质、相关酶活性及垩白度变化的温度处理效应，表明外部的高温条件影响了胚乳内部的生理生化状态及垩白的形成过程；而多垩白的泸红早1号的高温、适温处理差异相对较小。由此说明，少垩白的的品种更易受高温影响。  相似文献   

20.
【目的】氨酰-tRNA合成酶（aminoacyl-tRNA synthetases, aaRSs）与遗传信息传递密切相关,已发现植物中aaRSs家族蛋白在维持翻译功能之余,还参与配子发生与胚发育、质体的早期发育以及免疫信号的感知与病害防御等生物学过程。本研究利用水稻胚乳发育缺陷突变体,分析水稻色氨酰-tRNA合成酶（WRS1）在胚乳发育中的作用,证明WRS1基因编码一个影响水稻胚乳发育的关键因子。【方法】本研究通过甲烷磺酸乙酯（ethyl methane sulfonate, EMS）诱变籼稻（Oryza sativa subsp. indica）品种N22,筛选到一个稳定遗传的水稻粉质胚乳突变体（wrs1）,图位克隆获得目标基因。对wrs1成熟种子进行形态学观察以及淀粉相关理化性质测定,利用细胞学切片分析wrs1发育中胚乳的结构,利用实时荧光定量PCR（quantitative real-time PCR, qRT-PCR）和GUS活性染色分析基因表达模式,通过qRT-PCR比较野生型与突变体花后12 d胚乳中淀粉合成相关基因表达情况,免疫印迹检测野生型与突变体成熟种子中淀粉合成酶蛋白积累情况,使用全自动氨基酸分析仪测定游离氨基酸含量。【结果】 wrs1突变体幼苗表现出明显的发育滞后且逐渐蔫萎死亡,从杂合突变体（WRS1wrs1）中分离到的粉质籽粒呈现明显的腹部皱缩,粒厚、千粒重下降,同时总淀粉含量下降,糊化淀粉的峰值黏度和崩解值均低于野生型。wrs1突变体发育胚乳中复合淀粉颗粒变小,排列疏松。WRS1定位于第12染色体长臂约183 kb的区间内,测序发现编码色氨酰-tRNA合成酶（tryptophanyl-tRNA synthetase, WRS）基因的第6外显子上发生单碱基替换,导致一个保守位置上的甲硫氨酸被替换。wrs1突变体中大部分淀粉合成相关基因表达量下调,且野生型与突变体间基因表达的变化与相应蛋白积累的差异存在不一致的趋势。wrs1突变体籽粒中蛋白质积累降低,而游离氨基酸含量显著升高。【结论】 WRS1编码色氨酰-tRNA合成酶,该基因突变后通过影响氨基酸稳态和蛋白质合成,造成淀粉合成相关基因异常表达从而影响淀粉的合成与积累,导致种子发育缺陷。  相似文献   

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