氮肥基追比对弱筋小麦宁麦9号籽粒淀粉合成及相关酶活性的影响

 为研究弱筋小麦籽粒淀粉形成的机制，以弱筋小麦宁麦9号为材料，对不同氮肥基追比对其籽粒淀粉合成及相关酶活性的影响及相关生理基础研究表明，氮肥基追比7∶1∶2处理与5∶1∶4处理相比，花后7～28 d籽粒直、支链淀粉及总淀粉积累速率低，成熟籽粒直链淀粉含量低，支链淀粉、总淀粉含量高，剑叶蔗糖磷酸合成酶(SPS)活性和蔗糖含量低，籽粒蔗糖合成酶（SS）活性低，籽粒蔗糖含量高，籽粒ADPG焦磷酸化酶(AGPP)、可溶性淀粉合成酶(SSS)、束缚态淀粉合成酶(GBSS)活性低，淀粉积累量低。相关分析表明，籽粒中AGPP、SSS、GBSS与直、支链及总淀粉积累速率、籽粒灌浆速率呈极显著正相关，说明这几种酶对促进籽粒淀粉的积累起重要作用。     

糯小麦种质资源宁W0065的评价与利用

为了解引进的糯小麦新品系宁W0065的利用价值,对其农艺性状、抗病性和支链淀粉含量进行了分析鉴定。研究结果表明,宁W0065具有株高偏高、穗长偏短、千粒重偏轻、生育期偏晚及易感白粉病等缺点,不能在四川生产上直接利用。不过,宁W0065具有分蘖力强、成穗率高及纯糯的特点,可作为优异种质资源加以利用。     

两个直链淀粉含量不同的小麦品种籽粒淀粉合成酶活性与淀粉积累特征的比较

以均含有3个Waxy蛋白亚基的普通小麦品种济麦20（低直链淀粉含量）和鲁麦21（高直链淀粉含量）为材料，对灌浆期籽粒淀粉合成相关酶活性的变化及淀粉积累特征进行了研究，并分析了两者之间的关系。结果表明，蔗糖合成酶(SS)、腺苷二磷酸葡萄糖焦磷酸化酶(AGPP)、束缚态淀粉合成酶(GBSS)、可溶性淀粉合成酶(SSS)和淀粉分支酶(SBE)活性均呈单峰曲线变化。鲁麦21的上述酶活性均高于济麦20。相关分析表明，支链淀粉积累速率与SS、AGPP、SSS和SBE呈显著或极显著正相关；直链淀粉积累速率与SS、AGPP和GBSS呈极显著正相关。Logistic方程拟合淀粉积累过程发现，支、直链淀粉最终积累量的高低取决于积累启动时间的早晚和积累速率的高低，而积累持续期的调节作用较小。直链淀粉的积累速率除受GBSS活性影响外，还受SS和AGPP活性的影响，其中，GBSS活性的变化与2品种籽粒直链淀粉积累量的变化情况基本吻合。籽粒灌浆后期的GBSS活性对直链淀粉最终积累量的调节作用大于灌浆前期，说明对同时具有3个Waxy蛋白亚基的不同品种，Waxy蛋白亚基表达量(GBSS活性)的差异可能是导致品种间籽粒直链淀粉含量较大差异的一个关键原因。     

Identification of allelic variations of puroindoline genes controlling grain hardness in wheat using a modified denaturing PAGE

The amount of long chains (LC) of amylopectin in high-amylose rice is thought to be one of the important determinants of its quality when cooked. A wide range of differences in LC content have been reported in rice varieties, which can be clearly divided into four classes based on LC and apparent amylose content: namely, amylose and LC-free, low or medium-amylose and low-LC, high-amylose and medium-LC, high-amylose and high-LC. However, genetic factors controlling LC content have not been fully understood. Here, we performed quantitative trait loci (QTL) analysis of LC content using 157 recombinant inbred lines (RILs) derived from a cross of a low-LC cultivar, Hyogokitanishiki, and a high-LC line, Hokuriku 142. By analyzing randomly selected 15 RILs, it was shown that high LC content (≥11%) was associated with high setback viscosity (≥200 RVU), and that low LC (≤ 3%) was associated with low setback viscosity (≤ 130 RVU), as measured by a Rapid Visco Analyzer. With setback viscosity as an indicator for LC content, QTL analysis was conducted using 60 DNA markers including a CAPS marker that distinguished Wx a and Wx b alleles coding for granule-bound starch synthase I (GBSSI or Wx protein), the enzyme working for amylose biosynthesis. Only one QTL with a peak log of likelihood score at the wx locus was detected, and no line showing setback viscosity corresponding to the medium-LC class appeared. The fact that wx mutants of Hokuriku 142 lacked LC in their rice starch supports the view that the functional Wx allele is indispensable for LC synthesis in addition to amylose synthesis in rice endosperm. We suggest three possible reasons why no line with medium-LC content was observed. First, the locus (loci) responsible for generation of medium-LC may be located very close to the wx locus and not able to be dissected by the population and DNA markers we used. Second, there may be special QTLs for medium-LC cultivars that do not exist in low- or high-LC cultivars. Third, medium-LC cultivars may have an as-yet unidentified Wx allele with lower capability in LC synthesis compared to the Wx allele in high-LC cultivars.     

3种稻米淀粉成分的分离

采用化学方法分离稻米粉,得到了除直链淀粉、支链淀粉以外的中间成分和非淀粉成分,初步测定了它们的含量,并观察了其形态结构的不同,可能会为揭示稻米品质的差异提供一个新的方向。     

多波长分光光度法测定稻米中的直链与支链淀粉

稻米中的直链和支链淀粉组成直接影响稻米的品质和米饭的食味。稻米中合适的直链与支链淀粉比例是衡量稻米品质优劣的一个重要指标。在酸性条件下,直链淀扮与碘反应,其络合物在630～670nm范围内有最大吸收峰,而支链淀粉与碘的络合物在530～590nm范围内有最大吸收峰。吸收峰波长差为△入=40～140nm。由此,利用DU-7紫外/可见分光光度计,建立了多波长分光光度法测定稻米中直链与支链淀粉含量的方法,此法与传统方法比较,具有迅速、简单、重现性好的特点。     

The effect of gluten on the retrogradation of wheat starch

The retrogradation of amylopectin in a wheat starch and a wheat starch/gluten (10:1) blend prepared by extrusion and containing 34% water (wet weight basis) was studied using X-ray diffraction, differential scanning calorimetry and NMR relaxometry during storage at constant water content and temperature (25 °C). For both samples, amylopectin ‘fully’ retrograded after 2–3 days storage, i.e. the different parameters monitored with time to follow the retrogradation had reached their maximum value, and crystallised predominantly into the A polymorph. Under the experimental conditions used, there was no evidence of any significant effects of the presence of gluten on the kinetics, extent or polymorphism of amylopectin retrogradation.     

施氮量对超级稻南粳9108产量、淀粉RVA谱特征值和理化特性的影响

为探明施氮量对水稻RVA谱特征值、稻米淀粉结构和理化特性的影响,以超级稻品种南粳9108为材料,在大田种植,设置3个施氮水平,分别为全生育期不施氮（N0）、施纯氮180kg/hm²（N180）和360kg/hm²（N360）,研究了淀粉结构和理化性质与RVA谱特征值的关系。结果表明,与N0相比,N180和N360处理下南粳9108的产量显著增加,氮肥利用率则逐渐降低。与N0相比,N180处理下南粳9108的崩解值、热浆黏度、峰值黏度、糊化温度和胶稠度提升,消减值和直链淀粉含量降低;提高了支链淀粉中短中链含量、淀粉的无序结构、溶解度和膨胀度,降低了糊化焓和结晶度。N360处理的结果与上述结果相反。相关性分析表明,支链淀粉短中链含量与崩解值、淀粉的无序结构、溶解度和膨胀度呈显著或极显著正相关,与糊化焓、结晶度和消减值呈显著或极显著负相关。综上可得,全生育期施纯氮180kg/hm²时南粳9108支链淀粉结构和淀粉理化性质得到改善,优化了RVA谱特征值,使蒸煮食味品质变优。     

Effects of Variations in Starch Synthase on Starch Properties and Eating Quality of Rice

Abstract

We evaluated the effects of functional variation in three starch synthases in rice (Oryza sativa L.)?granule-bound starch synthase I (GBSSI, wx), starch synthase I (SSI, SSI), and starch synthase IIa (SSIIa, alk)?between indica cultivar Kasalath and japonica cultivar Nipponbare on starch properties and eating quality. We used three near-isogenic lines?NIL(Wx^a), NIL(SSI ^k), and NIL(Alk)?containing chromosomal segments of Kasalath on a Nipponbare genetic background. The Wx^a allele explained most of the difference in amylose content between the two cultivars, and decreased the peak viscosity and breakdown to less than half of those of Nipponbare. These changes reduced the quality of cooked rice both just after cooking and after storage at 5ºC. The variation in SSIIa also affected the eating quality after storage of cooked rice at 5ºC : NIL(Alk) became harder and less sticky than Nipponbare, although the rices were comparable just after cooking. Differential scanning calorimetry revealed faster retrogradation of the once-gelatinized starch in NIL(Alk). The variation in SSI alleles hardly affected these properties.     

强、中、弱筋小麦籽粒中淀粉、蛋白质积累和淀粉体发育的比较

以强、中、弱筋小麦品种烟农19、扬麦16和宁麦13为试验材料,研究了籽粒中淀粉和蛋白质积累动态及差异,比较了三者胚乳细胞中淀粉体发育的异同。结果表明,小麦成熟籽粒中总淀粉、直链淀粉、支链淀粉含量由高到低依次为宁麦13、扬麦16、烟农19。蛋白质含量积累变化“V”形曲线,表现为烟农19>扬麦16>宁麦13。在籽粒发育过程中,胚乳中大、小淀粉体的发生具有严格的时序性,发育前期大淀粉体比例高,后期小淀粉体比例高。3种类型小麦相比,细胞中大淀粉体数目由多到少依次为烟农19、扬麦16、宁麦13,而小淀粉体数目的排序恰好相反。总淀粉、直链淀粉、支链淀粉积累量均呈“S”型曲线变化,积累速率呈抛物曲线变化,积累量和积累速率表现为烟农19>扬麦16>宁麦13。在成熟胚乳细胞中烟农19大淀粉体多,小淀粉体少,且结合紧密,而宁麦13大淀粉体少,小淀粉体多,胚乳结构疏松。扬麦16结构介于两者之间。