水稻胚乳突变体的诱发及其微卫星分子标记鉴定

用 3 50Gy6 0 Coγ射线辐照高表观直链淀粉含量 (apparentamylosecontent,AAC)早籼稻新品种金早 97 47,筛选鉴定出 4个暗胚乳突变体和 2个云雾状胚乳突变体。AAC测定表明 ,暗胚乳和云雾状胚乳突变的AAC明显比原亲本低。以Wxup2 485为引物 ,发现两类胚乳突变的Wx基因微卫星分子标记相同 ,与原亲本显著不同 ,前者为 (CT) 1 8 (CT) 1 8,后者为 (CT) 1 1 (CT) 1 1。     

胚乳突变体在水稻淀粉合成调控研究中的作用

淀粉作为稻米最主要的储藏物质,其含量、结构及其特性影响水稻的产量和品质。随着分子生物学的不断发展,通过筛选胚乳突变体,克隆了大量调控水稻淀粉合成相关的基因,使淀粉生物合成的机理也逐渐清晰。本文综述了水稻淀粉结构、淀粉生物合成,以及淀粉突变体,包括糯性、高直链淀粉、垩白、粉质、暗色、糖质、皱缩等突变体的突变基因克隆及功能研究最新进展,以期为进一步阐明水稻淀粉生物合成的途径,以及优质水稻新品种的培育提供参考。     

空间技术诱发的水稻早熟突变系的品质性状变异

对空间技术诱发产生的 9个水稻早熟突变系分析表明 :与原亲本相比 ,突变系的外观品质变化明显 ;表观直链淀粉含量 (AAC)出现高、中、低 3种变异 ;多数突变系的淀粉粘滞特性和碱消值比原亲本差 ,少数相似 ;胶稠度与原亲本相仿或明显改良 ;除突变系SP5 0 1外 ,农艺性状变差 ,但千粒重增加明显。     

空间诱变引起水稻9311的品质变异

水稻品种 931 1种子经返回式卫星搭载诱变后研究表明 ,空间诱变引起的SP1生理损伤轻 ,SP2 的叶绿素缺失突变和早熟突变频率较低 ,但品质突变丰富 ,筛选鉴定了不同表观直链淀粉含量、富含抗性淀粉以及高无机磷低植酸等突变体。     

实践八号育种卫星搭载籼稻的诱变效应研究

利用卫星搭载4个籼稻品种(系)的干种子,对SP1代种子活力和农艺性状、SP2代农艺性状、稻米直链淀粉含量和白叶枯病抗性进行诱变效应分析,结果表明:空间环境对籼稻种子损伤较小,SP1代的发芽率、芽长、株高以及结实率的生理损伤变幅为0～26.9%;对空间环境的敏感性由强到弱依次为桂99、航恢7号、R998、金航138。SP1代表型不发生分离;SP2代在株高、分蘖、谷粒重、稻米直链淀粉含量和白叶枯病抗性等性状出现分离,突变性状在SP3代能够遗传。空间诱变不仅能使水稻农艺性状发生变异,而且能使稻米品质和抗病性产生变异。     

小麦淀粉品质性状配合力效应及遗传分析

选用9个冬小麦品种,按NCⅡ不完全双列杂交设计,对淀粉主要品质性状进行了配合力及相关分析。结果表明：淀粉品质性状一般配合力和特殊配合力方差均达显著或者极显著水平,综合考虑亲本各性状一般配合力相对效应,中优9507、济麦20、偃展4110适合做面条和馒头小麦品质育种优良亲本;藁麦6/偃展4110和扬麦16/偃展4110,一般配合力效应和特殊配合力效应表现优秀,总的配合力效应表现也最好,利用价值大,为优良组合。直链淀粉的遗传主要是基因的累加效应,粘度性状、总淀粉、蛋白质品质性状的遗传以加性效应为主,非加性效应为辅;峰值粘度、低谷粘度、最终粘度狭义遗传力达74.47%以上,宜在早代进行选择;直链淀粉、膨胀势在50%以下,高世代选择效果较好。峰值粘度、低谷粘度、最终粘度与支链淀粉、总淀粉、膨胀势呈极显著的遗传负相关,而与直链淀粉、降落数值均呈显著或极显著遗传正相关,可以完全同向选择。     

通过养分管理调控水稻胚乳成分提高稻米食味品质

[目的]研究磷钾镁施肥配比对不同类型水稻胚乳成分及食味的影响,为通过施肥改善稻米食味品质提供依据.[方法]选取低直链淀粉含量的软米品种、优良食味的普通粳稻品种和高产的粳稻新品系为试验材料,通过4因素3水平正交设计,设置磷肥、钾肥和镁肥处理,并通过对糙米的逐层碾磨,分析不同层次米粉的直链淀粉含量、蛋白质含量差异,及其与食...     

广西早籼品种(组合)的稻米品质状况及改良目标

广西多数早籼品种(组合)的糙米率、精米率、粒长、粒形、糊化温度、胶稠度、蛋白质含量等指标。达到了农业部(NY122-86)二级优质食用稻米标准。但完整米率的达标率偏低,胚乳的垩白程度偏大,垩白粒率偏高,直链淀粉含量偏高,米粒的蒸煮延长性差。今后,早籼稻的品质育种应把提高完整米率,降低直链淀粉含量和提高胚乳的透明度作为品质改良的主攻目标。     

水稻低淀粉粘滞突变体的理化特性和淀粉结构

以水稻低淀粉粘滞突变体RSV-1及其野生型品种II-32B为材料,研究了低淀粉粘滞突变的理化特性和淀粉结构。结果表明,低淀粉粘滞突变体的最高粘度、热浆粘度和冷胶粘度明显小于野生型,但表观直链淀粉含量、胶稠度、碱消值均大于野生型,达最高粘度时间接近,糊化过程中所需能量较低,糊化过程较长;淀粉晶体表现为C型结构,淀粉颗粒与野生型的正六面体颗粒完全不同,呈大小不等的无规则形,淀粉晶体及颗粒结构的改变可能是导致淀粉粘滞性下降及其他理化指标改变的重要原因。     

用二组法和三组法预测稻米直链淀粉和蛋白质含量的研究

摘 要:直链淀粉和蛋白质含量是影响稻米品质的重要性状,对其进行有效预测具有重要意义。本研究用18个亲本及其所配制的81个水稻杂交组合（按NCⅡ设计）为材料,利用有多态性的SSR标记筛选与 F1直链淀粉和蛋白质性状相关的阳性位点和增效位点,分别用二组法和三组法对F1性状值进行预测,并建立相应的预测模型。结果表明：1)对稻米直链淀粉和蛋白质含量预测可以取得较好的效果,增效位点明显优于阳性位点;2）因性状和材料不同存在一定差异,固定恢复系预测优于固定不育系预测,对直链淀粉的预测优于蛋白质的预测;3)二组法对固定恢复系的预测效果明显优于三组法,直链淀粉和蛋白质的预测值在二组法中分别为0.8076和0.6722,三组法分别为0.6823和0.4174;在固定不育系的预测中两种方法差异不明显。     

Starch Characteristics Influencing Resistant Starch Content of Cooked Buckwheat Groats

Cooked buckwheat groats are suggested to contain a greater amount of resistant starch (RS) than cereal grains. High RS content, in addition to dietary fibers present in groats, contributes to the low‐calorie, high‐fiber food status of buckwheat. Six buckwheat genotypes exhibiting high, medium, and low RS content of cooked groats were selected, and starches were isolated to determine their functional properties to explore the possible cause of high RS content of cooked buckwheat groats. Apparent and actual amylose contents were 27.4 and 31.6–34.5% in high, 27.4–28.6 and 32.5–33.7% in medium, and 21.4–25.6 and 24.5–32.0% in low RS genotypes, respectively. Genotypes of high RS content exhibited greater amylose leaching based on total starch content during cooking than genotypes of low RS content, mainly because of higher amylose content in the former than latter. Genotypes of low RS content exhibited a relatively high content of amylose‐lipid complexes, as determined with a differential scanning calorimeter (DSC). Gelatinization enthalpy and degree of amylopectin retrogradation determined with a DSC were not related to RS content. An evident relationship was observed between RS content of cooked groats and amylose retrogradation determined by gel hardness (r = 0.91, P < 0.05), cohesiveness (r = 0.89, P < 0.05), and syneresis (r = 0.88, P < 0.05). Increases in starch amylose content, amylose leaching capacity, and amylose retrogradation, as well as a decrease in the amount of amylose‐lipid complexes all appear to be related to high RS content of cooked buckwheat groats.     

Properties of Starches from Several Low‐Amylose Rice Cultivars

The starch properties of five low‐amylose rice cultivars, Yawarakomachi, Soft 158, Hanabusa, Aya, and Snow Pearl, were compared with those of two normal amylose rice cultivars, Nipponbare and Hinohikari. There were no large differences in the distributions of the amylopectin chain length determined by high‐performance anion‐exchange chromatography, and the starch gelatinization properties determined by differential scanning calorimetry, between normal and low‐amylose rice cultivars. Results obtained using rapid viscosity analysis indicated that low‐amylose rice starches had lower peak viscosity, breakdown, and setback values than normal amylose rice starches. Starch granules from low‐amylose rice cultivars had a higher susceptibility to glucoamylase than those from normal amylose rice cultivars. The results of this study showed some differences between normal and low‐amylose rice starches in pasting properties and enzymatic digestibility.     

Variation in total and soluble beta-glucan content in hulless barley: effects of thermal, physical, and enzymic treatments

Total and soluble beta-glucan content and effects of various treatments of barley grain on extractability and molecular characteristics of soluble beta-glucan were studied. Four types of hulless barley (normal, high amylose, waxy, and zero amylose waxy) from 29 registered and experimental genotypes were analyzed. For each, moisture, protein, amylose, 100 kernel weight, starch, beta-glucan (total and soluble), beta-glucanase activity, and slurry viscosity were determined. Significant differences in total beta-glucan were observed among the groups, with average values of 7. 49%, 6.86%, 6.30%, and 4.38% for high amylose, waxy, zero amylose waxy, and normal barley, respectively. The extractability of beta-glucan in high amylose barley was relatively low (20.6-29.7%) compared to that in normal (29.8-44.3%), zero amylose waxy (34.0-52. 5%), and waxy (36.7-52.7%) barley genotypes. Viscosity of barley flour slurries was affected by the content of soluble beta-glucans, beta-glucanase activity, and molecular weight of beta-glucans. Hydrothermal treatments (autoclaving and steaming) of barley had no effect on extractability of beta-glucans, but prevented enzymic hydrolysis of beta-glucans, and thereby substantially improved their molecular weight. The addition of enzymes (protease and esterase) during extraction and/or physical treatments (sonication) increased extractability of beta-glucans from barley.     

Physicochemical Properties of Zero Amylose Hull-less Barley Starch

Zero amylose starch isolated from hull-less barley (HB) showed a typical A-type diffraction pattern. The X-ray analysis suggested that granules of zero amylose (SB94794) and 5% amylose (CDC Candle) HB starches had lower crystallinity than did commercial waxy corn starch. Differential scanning calorimetry showed lower transition temperatures and endothermal enthalpies for the HB starches than for the waxy corn starch. The zero amylose HB starch showed a Brabender pasting curve similar to that of waxy corn starch, but with lower pasting and peak temperatures and a higher peak viscosity. Noteworthy characteristics of zero amylose HB starch were its low pasting temperature and high paste clarity and freezethaw stability, which make this starch useful for many food and industrial applications.     

Multiple Measurements of Physical Properties of Individual Cooked Rice Grains with a Single Apparatus

Multiple measurements of physical properties of cooked rice grains were applied to 55 rice samples with waxy to high amylose contents using a single apparatus (Tensipresser). The multiple measurements consisted of low, high, and continuous progressive compression tests (LC, HC, CPC). The overall hardness (H₂) determined by the HC test, and the surface hardness (H₁) determined by the LC test, were used as indices to classify the samples into the several groups corresponding to amylose content. The surface hardness was more suitable than the overall hardness for differentiating the effect of protein contents. The difference of stickiness among the cooked rice samples could be detected by the surface adhesion distance (L₃) using the LC test. The ratio of elastic limit length (RELL), estimated by the back pressure curve on the CPC test, increased with amylose content. These three tests were meaningful in characterizing the physical properties of cooked rice samples with waxy to high amylose contents.     

Wheat Tortilla Quality: Impact of Amylose Content Adjustments Using Waxy Wheat Flour

Amylose content is closely related to wheat flour pasting or thermal properties, and thus affects final food qualities. Fourteen flour blends with amylose content ranges of <1 to 29% were used to study tortilla production and quality parameters. Reduced amylose contents decreased dough stickiness and pliability; low amylose doughs were also very smooth in appearance. Very low flour amylose content was associated with earlier tortilla puffing and poor machinability during baking, darker color, low opacity, larger diameters, and reduced flexibility after storage. Tortilla texture analysis indicated that lowering amylose content gave fresh tortillas higher extensibility; after three or more days storage, however, low amylose flours required more force to break the tortillas and the rupture distances became shorter. These results, as reflected in covariate analysis, were not significantly affected by the flour blend's protein content, swelling volume/power, SDS‐sedimentation volume, mixograph dough development time, or mixograph tolerance score. Based on our observation of an initial increase in extensibility with reduced‐amylose tortillas, adding 10–20% waxy flour into wild‐type flours should be ideal for restaurant (on‐site) tortilla production or circumstances where tortillas are consumed shortly (within a day) after production. The optimal flour amylose content for hot‐press wheat tortilla products is 24–26%.     

Distribution of β‐Glucan in the Grain of Hull‐less Barley

Nine hull‐less barley (HB) containing waxy (0–7% amylose), normal (≈25% amylose), or high amylose (≈42% amylose) starch with normal or fractured granule make‐up and 4–9% (1→3)(1→4)‐β‐d ‐glucans (β‐glucan) were pearled to remove 70% of the original grain weight in 10% intervals. The pearled fractions were analyzed for β‐glucan distribution within HB grain. Protein content of the pearled fractions indicated that the three outermost fractions contained pericarp and testa, aleurone, and subaleurone tissues, respectively. For all HB, β‐glucan and acid‐extract viscosity were very low in the outermost 20% of the kernel. For low β‐glucan HB, β‐glucan content was the greatest in the subaleurone region and declined slightly toward inner layers. For high β‐glucan HB, however, more than 80% of grain β‐glucan was distributed more evenly throughout the endosperm. Acid extract viscosity was significantly (P < 0.01) correlated with total (r = 0.75) and soluble (r = 0.87) β‐glucan content throughout the kernel of all HB. Growing conditions, location and year, had significant effects on the concentration of protein, starch and β‐glucan. However, protein, starch, and β‐glucan distribution patterns were not affected by growing conditions. The difference in β‐glucan distribution between low and high β‐glucan HB may explain the difference in milling performance of HB with low or high β‐glucan.     

Effects of Resistant Starch and Fiber from High‐Amylose Non‐Floury Corn on Tortilla Texture

A high‐amylose, non‐floury corn, a floury corn, and a 1:1 blend were made into masa and then tortillas. The masa flour made with the high‐amylose corn had a greater amount of resistant starch (RS 28.8%) and a greater amount of total dietary fiber (TDF 42.1%) than that with the floury corn (RS 2.9%, TDF 9.6%), producing a high‐fiber tortilla. The masa was evaluated for pasting properties using a Rapid ViscoAnalyser (RVA). The high‐amylose masa slurry gelatinized little at 95°C. The floury masa had the greatest peak viscosity, whereas the 1:1 blend was intermediate in value. Sensory evaluations of the tortillas for the textural attributes showed the floury tortillas to be chewier, more rollable, and grittier than the high‐amylose tortillas, whereas the blend tortillas were intermediate for most attributes. The cutting force of the high‐amylose tortillas, measured on a texture analyzer, was very low; the blend and floury tortillas required more force. Chewiness was correlated to rollability (r = 0.99, P = 0.05). The %RS and %TDF were correlated to rollability (r = –0.99), and cutting force (r = 0.99). The floury and blend tortillas had firm textures expected of desirable tortillas, whereas the high‐amylose tortillas broke under little force, and would not roll. The high‐amylose tortillas had high amounts of RS and TDF but poor texture. The blend tortillas retained most floury tortilla textural properties, making them suitable products for consumer use.     

Characteristics of taro (Colocasia esculenta) starches planted in different seasons and their relations to the molecular structure of starch

Physico-chemical properties and molecular structure of starches from three cultivars (Dog hoof, Mein, and KS01) of taro tubers planted in summer, winter, and spring were investigated. The effects of the planting season on the physico-chemical properties and the molecular structure of starch were determined, and the relations between the physico-chemical properties and the molecular structure of starch are discussed. Results indicate that taro starches from tubers planted in summer had the largest granule size, a low uniformity of gelatinization, and a high tendency to swell and collapse when heated in water. Taro starch planted in summer also showed an elasticity during gelatinization that was higher than that of starches planted in the other seasons. In addition to the planting season and the variety, rheological and pasting properties of taro starches studied are influenced not only by the amylose content but also by the chain-length distribution of amylopectin, whereas swelling power and solubility only depend on the amylose content of starch. Taro starch with relatively high amylose content, high short-to-long-chain ratio, and long average chain length of long-chain fraction of amylopectin displayed high elasticity and strong gel during heating.     

Molecular Size Distribution and Amylase Resistance of Maize Starch Nanoparticles Prepared by Acid Hydrolysis

The molecular size distribution of maize starch nanoparticles (SNP) prepared by acid hydrolysis (3.16M H₂SO₄) and their amylase‐resistant counterparts, before and after debranching, was investigated. The weight average molecular weight (M_w) and linear chain length distribution were determined by high‐performance size‐exclusion chromatography (HPSEC) and high‐performance anion‐exchange chromatography (HPAEC), respectively. The objective was to understand the role of amylose involvement in the formation of SNP showing different crystalline structures (A‐ and B‐types). The HPSEC profiles of SNP before debranching from waxy, normal, and high‐amylose maize starches showed broad monomodal peaks. Debranched SNP from waxy maize eluted in a single narrow peak, whereas those from nonwaxy starches showed a multimodal distribution. Similar trends were also observed for the chain length distribution patterns, for which the longest detectable chains (degree of polymerization [DP] 31) in waxy maize were significantly lower than those of nonwaxy maize starches (DP 55–59). This indicated the potential amylose involvement in the SNP structure of normal and high‐amylose starches. Further evidence of amylose involvement was ascribed to the resistance of SNP toward amylolysis (Hylon VII > Hylon V > normal > waxy). The amylase‐resistant residues of SNP from high‐amylose maize starches were composed of both low M_w linear and branched chains.