玉米灌浆期水分差异供应对籽粒淀粉积累及其酶活性的影响

利用普通玉米(Zay mays)‘掖单22’和高油玉米‘高油115’,研究了灌浆期水分差异供应对籽粒淀粉及其组分积累、相关酶活性动态变化的影响。结果表明,两种类型玉米淀粉积累和酶活性动态变化趋势基本一致,但对水分的反应有差异。缺水提高了‘掖单22’籽粒中淀粉、支链淀粉含量,而直链淀粉含量下降,‘高油115’则是籽粒中的淀粉含量、支链淀粉和直链淀粉含量提高;充分供水使淀粉及其组分产量提高;叶片中蔗糖合成酶(SS)、磷酸蔗糖合成酶(SPS)活性随水分供应水平而提高,尤其在授粉后10~30 d增幅更加明显。充分供水明显提高籽粒中腺苷二磷酸葡萄糖焦磷酸化酶(ADPG-PPase)、尿苷二磷酸葡萄糖焦磷酸化酶(UDPG-PPase)、可溶性淀粉合成酶(SSS)和淀粉粒结合淀粉合成酶(GBSS)活性,缺水使籽粒中酶活性下降较早且迅速;SPS、ADPG-PPase、SSS酶活性对缺水反应比较敏感。     

糯性和非糯性小麦灌浆期胚乳直/支链淀粉积累及其相关酶活性研究

选用3份糯性和2份非糯性小麦材料,通过田间试验在灌浆过程中分别检测了各材料的籽粒直链和支链淀粉积累量、淀粉积累速率及淀粉合成关键酶活性的动态变化过程,探讨籽粒淀粉累积与相关酶活性的关系.结果表明:(1)非糯小麦在花后7 d前均未检测到直链淀粉存在,而此时已经检测到支链淀粉含量,并且糯小麦仅含有支链淀粉,支链淀粉早于直链淀粉合成.(2)糯性和非糯性小麦灌浆期籽粒的直、支链淀粉积累速率均呈先增加后降低的趋势,且直、支链淀粉最终积累量取决于最大积累速率和平均积累速率的大小,而积累活跃期的调节作用较小;糯性和非糯性小麦在淀粉合成过程中的腺苷二磷酸葡萄糖焦磷酸化酶(AGPP)、可溶性淀粉合成酶(SSS)、颗粒结合型淀粉合成酶(GBSS)和淀粉分支酶(SEB)活性均呈单峰曲线变化,活性峰值基本上都出现在花后20～25 d左右.(3)直链淀粉积累速率与AGPP、SSS、GBSS和SBE活性变化显著或极显著正相关,而支链淀粉积累速率仅与SSS活性变化极显著正相关,总淀粉积累速率与AGPP和SSS活性变化显著或极显著正相关.     

硫营养对小麦籽粒淀粉合成及相关酶活性的影响

在田间条件下,研究了施硫对小麦籽粒淀粉合成及相关酶活性的影响.结果表明:在0～20 cm土层土壤有效硫含量为5.84 mg/kg的地块上施硫不仅提高了小麦籽粒中蔗糖的含量,而且催化蔗糖降解代谢的蔗糖合成酶(SS)活性提高,利于籽粒蔗糖的降解.施硫显著提高了灌浆期间籽粒可溶性淀粉合成酶(SSS)活性,并使腺苷二磷酸葡萄糖焦磷酸化酶(ADPGPPase)和束缚态淀粉合成酶(GBSS)活性在灌浆中、后期维持在较高水平,对直链和支链淀粉的合成都起促进作用, 使总淀粉积累增加,千粒重提高,产量增加.     

灌浆前期高温和干旱胁迫对小麦籽粒蛋白质含量和氮代谢关键酶活性的影响

为探讨花后逆境胁迫影响小麦籽粒氮代谢及蛋白质合成的生理机制,采用盆栽和人工气候室模拟花后高温的方式,研究了灌浆前期短暂高温和干旱胁迫对两个不同品质类型小麦品种籽粒蛋白质含量、组分及谷氨酰胺合成酶(GS)、谷丙转氨酶(GPT)活性的影响。结果表明,灌浆前期高温、干旱及其复合胁迫均显著提高两品种籽粒蛋白质及组分含量,但降低谷/醇比。逆境胁迫使蛋白质积累量和粒重显著下降,其中高温处理使两品种蛋白质产量分别下降20.7%和12.4%,粒重下降23.2%和24.0%;干旱胁迫使两品种蛋白质产量分别下降16.2%和11.9%,粒重下降18.0%和16.0%;复合胁迫使两品种蛋白质产量分别下降26.1%和15.8%,粒重下降29.9%和28.9%。高温、干旱及其复合胁迫下两品种籽粒氮代谢关键酶活性升高。花后8,17,23,29 d的GS活性和花后11,17 d的GPT活性与蛋白质含量呈显著或极显著正相关,花后23,35 d的GS和花后8,17,23 d的GPT活性与蛋白质产量呈显著或极显著负相关,花后8,17,23,29,35 d的GS和花后8,11,17,23 d的GPT活性与籽粒产量呈显著或极显著负相关。试验条件下,高温处理对籽粒蛋白质合成的影响大于干旱胁迫,二者具有叠加效应,强筋小麦品种郑麦366受逆境胁迫的影响较大。     

花后高温对不同耐热性小麦品种籽粒淀粉形成的影响

以耐热性不同的2个小麦品种济麦20和鲁麦21为材料,分别于花后5～9d（T1）和15～19d（T2）进行高温处理,研究了小麦花后不同阶段高温对籽粒淀粉积累、淀粉粒分布及相关酶活性的影响。结果表明,花后高温显著降低籽粒淀粉积累量;显著降低籽粒淀粉及支链淀粉含量,但提高直链淀粉含量、直／支链淀粉比例。处理间比较,他处理对籽粒淀粉积累的影响程度较T1处理大。品种间比较,高温对济麦20的影响程度较鲁麦21大。高温使A型淀粉粒的体积、数量和表面积比例显著增加,B型淀粉粒的体积、数量和表面积比例显著降低。T1处理后,两品种籽粒蔗糖含量、蔗糖合酶（SS）和腺苷二磷酸葡萄糖焦磷酸化酶（AGPP）、可溶性淀粉合酶（SSS）、束缚态淀粉合酶（GBSS）和淀粉分支酶（SBE）活性均略高于对照;但济麦20、鲁麦21上述指标分别于花后15、20d开始低于对照。他处理后,两品种籽粒蔗糖含量、SS、AGPP、SSS、GBSS和SBE活性显著低于对照,济麦20上述指标的降幅较鲁麦21大。与其它淀粉合成相关酶相比,高温对籽粒GBSS活性的影响程度较小。两品种处理间籽粒蔗糖含量、SS、AGPP、SSS、GBSS及SBE活性的变化趋势,与淀粉积累量的变化趋势基本一致。说明灌浆期高温使籽粒淀粉积累量降低,一方面是由于籽粒蔗糖供应较低引起糖源不足;另一方面则是由于灌浆中后期淀粉合成相关酶活性下降使淀粉合成受抑所致。     

不同穗型冬小麦品种蔗糖和淀粉合成中关键性酶的活性变化

灌浆期间的豫麦66和豫麦49旗叶中蔗糖磷酸合成酶(SPS)和籽粒中蔗糖合成酶(SS)活性均呈单峰曲线变化,峰值分别出现在花后20和15 d,整个灌浆期内豫麦66 SPS与SS活性均高于豫麦49;豫麦66籽粒中腺苷二磷酸葡萄糖焦磷酸化酶(AGPP)和淀粉分支酶(SBE)活性均呈单峰曲线变化,峰值出现在花后20 d,而可溶性淀粉合成酶(SSS)活性则呈双峰曲线变化,峰值分别出现在花后10和20 d,且第二个峰值显著高于第一个.     

‘台农1号’芒果果实发育过程中的糖分积累与相关酶活性研究

以‘台农1号’芒果为材料,测定了果实生长发育过程中淀粉、蔗糖、葡萄糖和果糖含量以及淀粉酶、蔗糖代谢相关酶———酸性转化酶(AI)、中性转化酶(NI)、蔗糖合成酶(SS)和蔗糖磷酸合成酶(SPS)的活性,并对果实中糖组分与酶活性的关系进行了分析.结果显示,(1)台农1号芒果果实属于单S型生长曲线,发育前期主要积累淀粉、葡萄糖和果糖,果实成熟软化时,淀粉酶活性降至最低,淀粉水解,蔗糖快速积累.(2)酸性转化酶活性在果实整个发育过程中维持最高,完熟时略有降低;蔗糖磷酸合成酶在果实发育前期略有降低,完熟时升至最高;蔗糖合成酶和中性转化酶活性在整个发育期一直很低且较稳定.(3)淀粉含量与淀粉酶活性呈显著正相关,与SPS活性呈极显著负相关,蔗糖、葡萄糖含量均与SPS、SS呈显著、极显著的正相关;果糖含量与SS呈极显著的正相关.研究表明,芒果成熟时淀粉分解、酸性转化酶活性的降低,且蔗糖合成酶和蔗糖磷酸合成酶活性的增加是引起果实蔗糖积累的主要因子.     

不同类型玉米发育籽粒中淀粉合成及相关酶活性比较

以普通玉米、爆裂玉米、甜玉米和糯玉米为试材,分析和比较不同类型的玉米品种之间籽粒发育过程中淀粉合成及相关酶活性的变化。结果表明,淀粉合成速率和蔗糖合成酶(SS)、可溶性淀粉合成酶(SSS)、束缚态淀粉合成酶(GBSS)、淀粉分支酶(SBE)、去分支酶(DBE)活性都呈单峰曲线变化。30～40 DAP,普通玉米的SS活性显著高于其他3种类型;类型间平均和最大SSS活性水平的顺序为普通玉米>糯玉米>爆裂玉米>甜玉米;30～40 DAP,普通玉米GBSS活性最高,糯玉米GBSS活性最低;20～40 DAP,糯玉米SBE活性最高;甜玉米的DBE活性很低,并且在40 DAP完全丧失。淀粉合成速率与SS、SSS、GBSS和SBE活性相关程度比较高,与腺苷二磷酸葡萄糖焦磷酸化酶(AGP酶)和DBE活性相关不显著。推测AGP酶虽然为淀粉合成提供直接前体ADPG,但可能SS活性过低致使其限速作用比AGP酶的还强,AGP酶潜在的限速作用无法表现,SS成为玉米籽粒淀粉合成的限速因子。GBSS对直链淀粉积累起重要的促进作用;SSS和SBE对支链淀粉积累起重要的促进作用。     

两种穗型冬小麦籽粒淀粉积累动态及其有关酶活性变化

花后25d内,大穗型品种豫麦66籽粒中淀粉积累比多穗型品种豫麦49慢,但花后25d后情况则相反。2个品种籽粒中淀粉积累速率的变化均呈单峰曲线,豫麦49峰值出现在花后15～20d,而豫麦66峰值则出现在花后20～25d。灌浆期豫麦66和豫麦49籽粒中蔗糖合成酶(SS)活性变化呈单峰曲线,峰值分别出现在花后20d和15d,整个灌浆期内豫麦66籽粒中SS活性高于豫麦49;2个品种籽粒中腺苷二磷酸葡萄糖焦磷酸化酶(AGPP)和淀粉分支酶(SBE)活性变化均呈单峰曲线,峰值出现在花后20d,而可溶性淀粉合成酶(SSS)活性变化则呈双峰曲线,峰值分别出现在花后10d和20d,且第二个峰值显著高于第一个。相关分析表明,SS、AGPP、SSS和SBE是影响小麦籽粒淀粉积累的关键酶。     

淀粉含量不同的玉米自交系籽粒淀粉积累及其关键酶活性

以2个高淀粉和2个低淀粉玉米自交系为材料,分析了玉米籽粒淀粉的动态积累规律,同时对高低淀粉玉米籽粒灌浆过程中淀粉生物合成关键酶活性的动态变化及其与淀粉积累动态的相关性进行讨论分析。研究结果表明:灌浆过程中4个自交系淀粉含量变化趋势均呈sigmoid型曲线。灌浆过程中ADPG-PPase(腺苷二磷酸葡萄糖焦磷酸化酶)、SSS(可溶性淀粉合成酶)、GBSS(颗粒结合淀粉合成酶)活性均呈单峰曲线变化,峰值都出现在20～30DAP(授粉后天数)。2个高淀粉自交系的Q酶(淀粉分支酶)活性也呈单峰曲线变化,峰值也出现在20DAP,而2个低淀粉自交系的Q酶活性则呈双峰曲线变化,2个峰值分别出现在15～20DAP和30～35DAP。4个自交系籽粒淀粉的积累速率与各自交系ADPG-PPase、SSS和GBSS的活性变化呈极显著正相关。各自交系关键酶活性之间,ADPG-PPase、SSS和GBSS三者间活性变化呈极显著正相关,这3种酶活性变化与Q酶活性变化也呈不同程度的正相关。     

Regulation of Starch and Protein Synthesis in Wheat Grains by Feeding Sucrose and Glutamine to Detached Ears Cultured in vitro

Three experiments of in vitro ear culture were conducted to evaluate how the substrates of C (carbon) and N (nitrogen) supply in liquid medium regulate the grain growth and synthesis of protein and starch in two winter wheat cultivars. Increasing glutamine supply with constant sucrose concentration increased the contents of total protein and protein components of albumin and globulin in grain, and the activity of glutamate pyruvate transaminase (GPT) across most treatments, while markedly reducing the contents of total starch and components of amylose and amylopectin as well as the activities of soluble starch synthase (SSS) and granule bounded starch synthase (GBSS). The opposite patterns were observed in the experiment of increasing sucrose supply at constant glutamine concentration. When simultaneously increasing sucrose and glutamine supply at constant ratio, the contents of total protein, albumin and globulin in grain were slowly enhanced, whereas the contents of total starch, amylose and amylopectin and the activities of SSS, GBSS and GPT increased only to a certain extent and then decreased. Negative correlations were found between the contents of protein or protein components in grains and the relative ratio of sucrose to glutamine concentrations in the culture medium, while positive correlations were seen between the contents of total starch or starch components and the ratio of sucrose to glutamine. These results implied that the composition of protein and starch in wheat grain could be readily manipulated by varying the concentrations of sucrose and glutamine and their ratio in the culture medium.     

Activities of key enzymes for starch synthesis in relation to growth of superior and inferior grains on winter wheat (Triticum aestivum L.) spike

Weight of individual grains is a major yield component in wheat. The non-uniform distribution of single grain weight on a wheat spike is assumed to be closely associated with starch synthesis in grains. The present study was undertaken to determine if the enzymes involved in starch synthesis cause the differences in single grain weight between superior and inferior grains on a wheat spike. Using two high-yield winter wheat (Triticum aestivum L.) varieties differing in grain weight and three nitrogen rates for one variety, the contents of amylose and amylopectin, and activities of enzymes involved in starch synthesis in both superior and inferior grains were investigated during the entire period of grain filling. Superior grains showed generally higher starch accumulation rates and activities of enzymes including SS (sucrose synthase), UDPGPPase (UDP-glucose pyrophosphorylase), ADPGPPase (ADP-glucose pyrophosphorylase), SSS (soluble starch synthase) and GBSS (starch granule bound starch synthase) and subsequently produced much higher single grain weight than inferior grains. Nitrogen increased enzyme activities and starch accumulation rates, and thus improved individual grain weight, especially for inferior grains. The SS, ADPGPPase and SSS were significantly correlated to amylopectin accumulation, while SS, ADPGPPase, SSS and GBSS were significantly correlated to amylose accumulation. This infers that SS, ADPGPPase and starch synthase play key roles in regulating starch accumulation and grain weight in superior and inferior grains on a wheat spike.     

冬小麦籽粒淀粉合成相关酶活性的日变化

蔗糖向淀粉的转化是决定小麦籽粒产量的重要因素.田间条件下研究了两个小麦(Triticum aestivum L.)品种"鲁麦22"和"鲁麦14"籽粒淀粉合成相关酶:蔗糖合酶(sucrose synthase,SS)、腺苷二磷酸葡萄糖焦磷酸化酶(ADP-glucose pyrophosphorylase,ADPGPPase)、可溶性淀粉合酶(soluble starch synthase,SSS)、束缚态淀粉合酶(starch granule-bound synthase,GBSS)的活性以及籽粒ATP含量的日变化.结果表明,上述酶活性呈现明显的昼夜变化特征,酶活性一般在白天较低,而在夜间呈现较高活性,而籽粒ATP含量趋势相反.相关分析表明,白天较低的酶活性可能与气温超过其适宜温度有关.对籽粒淀粉合成相关酶活性日变化的可能因子进行了讨论.     

The effect of water stress on the activities of key regulatory enzymes of the sucrose to starch pathway in wheat

Developmental changes in the starch and sucrose content of grains andthe activities of enzymes of starch synthesis in wheat were studied under waterstress conditions. Water stress caused a marked reduction in the sucrose andstarch content of the grains. Sucrose synthase (SS) and UDP-glucosepyrophosphorylase (UDP-Gppase), showed higher catalytic activity and moreresistance to water stress compared with amyloplastic enzymes. ADP-glucosepyrophosphorylase (ADP-Gppase) activity was reduced to a low level under bothin situ and osmotic stress conditions in which grainsfailed to accumulate dry matter in vivo. Granule-boundstarch synthase (GBSS) also responded rapidly to in situwater stress treatments as did ADP-Gppase. Reduction in GBSS activity at thetime of growth cessation in situ was less than that ofADP-Gppase and the enzyme did not respond to severe osmotic stress. Solublestarch synthase (SSS) was the enzyme most sensitive to water stress in that itresponded earlier, and to a greater extent, than the other enzymes. However,under severe dehydration conditions, leading to cessation of growth, thedeclinein SSS activity was less than that for ADP-Gppase. SSS showed the lowestin vitro activity followed by GBSS. These results suggestthat SSS is the site of response to water stress by which the rate of graingrowth can be affected, whereas growth cessation is due mainly to theinactivation of ADP-Gppase.     

冬小麦籽粒淀粉合成相关酶活性的日变化

蔗糖向淀粉的转化是决定小麦籽粒产量的重要因素。田间条件下研究了两个小麦(TriticumaestivumL.)品种“鲁麦22”和“鲁麦14”籽粒淀粉合成相关酶:蔗糖合酶(sucrosesynthase,SS)、腺苷二磷酸葡萄糖焦磷酸化酶(ADP-glucosepyrophosphorylase,ADPGPPase)、可溶性淀粉合酶(solublestarchsynthase,SSS)、束缚态淀粉合酶(starchgranule-boundsynthase,GBSS)的活性以及籽粒ATP含量的日变化。结果表明,上述酶活性呈现明显的昼夜变化特征,酶活性一般在白天较低,而在夜间呈现较高活性,而籽粒ATP含量趋势相反。相关分析表明,白天较低的酶活性可能与气温超过其适宜温度有关。对籽粒淀粉合成相关酶活性日变化的可能因子进行了讨论。     

Nitrogen fertiliser rate and post-anthesis waterlogging effects on carbohydrate and nitrogen dynamics in wheat

Waterlogging is predicted to increase in both magnitude and frequency along with global warming, and will become one of the most severe adversities for crop production in many regions. Nitrogen is considered to be an effective up-regulatory nutrient for crops grown under stress and non-stress conditions. In this study, we try to evaluate N fertiliser effects on contents of carbohydrate and N dynamics, dry matter accumulation in shoot, yield under post-anthesis waterlogging. Waterlogging after anthesis significantly reduced grain yield due to decrease in thousand-kernel-weight and in grain number per spike. High N fertiliser application aggravated grain yield loss due to post-anthesis waterlogging. These yield losses were related to the decreases in dry matter accumulation, redistribution of stored photosynthate to the grain, and the conversion capacity from carbohydrate to starch in grain. The decrease in dry matter accumulation could be attributed to the reduced activities of Pn (photosynthesis) and SPS (sucrose phosphate synthase) in the flag leaf, while the low capacity in starch synthesis could be explained by the reduced activities of sucrose synthase (SS) and soluble starch synthase (SSS) in grain. Total N uptake in shoot was also reduced, which could contribute to the losses in biomass and yield by waterlogging. The decrease in Pn was inconsistent with the increase in N content in the flag leaf at high N fertiliser application under post-anthesis waterlogging.     

Dynamic changes in carbohydrate metabolism and endogenous hormones during <Emphasis Type="Italic">Tulipa edulis</Emphasis> stolon development into a new bulb

The stolon is the main asexual reproductive organ of Tulipa edulis (Miq.) Baker. It has a special morphology and can develop into a new bulb for propagation. In the current greenhouse experiment, the dynamic changes in carbohydrates and related enzymes, protein and endogenous hormones during T. edulis stolon development were investigated. The results showed that soluble sugar levels were basically declining, whereas starch and protein content rose continuously during stolon development. The adenosine diphosphoglucose pyrophosphorylase (AGPase) activity peaked in the initial swelling stage and stayed a relative high level in the middle swelling stage; sucrose synthase (SS), soluble starch synthase (SSS) and granule-bound starch synthase (GBSS) activities followed the same law that showed rising trends during stolon development. SS activity was significantly inversely related to sucrose content but had significantly positive relations with starch content, SSS and GBSS activities. Gibberellin (GA), indole-3-acetic acid (IAA) and zeatin riboside (ZR) peaked in the initial swelling stage and maintained high levels in the middle swelling stage; they then decreased significantly in the later swelling stage. A substantial increase was observed in abscisic acid (ABA) content until the middle swelling stage, followed by a significant reduction in the later swelling stage. The ratios of ABA to IAA, GA and ZR reached their lowest levels in the initial swelling stage. In conclusion, T. edulis stolon development is a process of new bulb morphogenesis along with the starch accumulation catalyzed by AGPase, SSS and GBSS, using the product of sucrose cleavage caused by SS. Initial low ABA content and low ratios of ABA to IAA, GA and ZR, together with the GA, IAA and ZR of high-content, soluble sugars worked more efficiently to induce new bulb formation.