甜高粱蔗糖合成酶基因（Susy2）的克隆及结构和功能分析

本研究以甘蔗蔗糖合成酶基因(susy2)cDNA序列为探针,对高粱EST数据库进行同源检索,将获得的4条与甘蔗相似性很高的EST序列进行拼接,后经基因组PCR、分子克隆和序列分析验证获得了甜高粱(sorghum bicofor)蔗糖合成酶基因DNA序列(Susy2,GenBank登录号为FJ513325).该序列全长4587 bp,起始密码子至终止密码子序列长4350 bp,包含一个2409 bp的开放读码框.该序列包含15个外显子和14个内含子,剪接方式都为GU/AG模式.Susy2编码的蛋白由802个氨基酸组成,分子量大小为91.7 kD,等电点pI为6.15.保守结构域分析表明,此蛋白含有一个475个氨基酸的GTI糖基化酶保守结构域(275～759),有4个ADP结合位点,能催化6-磷酸果糖和UDPG形成6-磷酸蔗糖.     

甘蔗新品种桂辐98-296的选育（简报）

桂辐98-296系采用辐射诱变技术选育而成的甘蔗新品系,全期生长快,中茎,宿根性好,抗逆性强。在广西不同蔗区生产适应性试验中,其单位面积产蔗量118.95t/hm2、含糖量16.65t/hm2,分别比当家品种ROC22增产32.98%和29.07%,差异性均达极显著水平,蔗糖分与ROC22相近。在国家第6轮甘蔗品种区域试验所有11个参试品种(系)中,其蔗产量名列第4, 蔗糖含量名列第3,分别比对照种ROC16增产11.41%和12.69%,差异性达显著水平, 蔗糖分比ROC16高0.11个百分点。桂辐98-296全期生长快,中茎,宿根性好,抗逆性强。     

胡杨果糖-1,6-二磷酸醛缩酶的定位及功能研究

将从胡杨中克隆的果糖-1,6-二磷酸醛缩酶基因（PeALD）构建到pGEX-4T—1载体上,经IPTG诱导成功获得融合蛋白GST：PeALD,并将蛋白进行纯化,其大小约为52kD,转化大肠杆菌的耐盐性实验表明,PeALD基因的成功表达有利于提高大肠杆菌菌株的耐盐性。为研究该基因编码蛋白在植物细胞中的定位,将基因的ORF区构建到定位表达载体pMDC85上,通过PEG介导的拟南芥瞬时转化法观察融合蛋白PeALD：GFP在细胞中的定位情况,结果显示该蛋白定位于胞质中,由此说明实验克隆得到的该胡杨果糖-1,6-二磷酸醛缩酶基因编码的是胞质蛋白。烟草种子在盐培养基上的萌发实验结果显示转基因烟草具有更高的耐盐性;烟草水培苗经200mmol／LNaCl处理一周后,可溶性糖的质谱检测结果显示转基因植株中葡萄糖的含量有很大提高。表明胡杨果糖-1,6-二磷酸醛缩酶通过促进糖酵解和有氧呼吸途径来提高植物对盐胁迫的适应性。     

酵母单杂交方法初步鉴定甘蔗SPSⅢ启动子区域调控序列

蔗糖磷酸合成酶(SPS,EC 2.4.1.14)是植物糖分积累的关键酶基因,在甘蔗中其家族成员SPSⅢ在成熟蔗茎中表达量高,是禾本科作物的特异成员.本研究应用酵母在甘蔗中单杂交系统,筛选SPSⅢ5’侧翼-1410～-1181 bp的光响应元件ATCT-motif和分生组织特异性元件CAT-box的调控序列,获得了54个含有cDNA片段的文库质粒,测序分析显示,14个cDNA序列为非重复性.NCBI的Blast同源性结果显示,除E1-3、E9-1和E0-3外,其余克隆都与甘蔗(Sacharum spp.)近缘物种的蛋白有很高的同源性,达到90％以上.通过SMART和SBASE,对推演的氨基酸序列进行蛋白质功能结构域预测与分析,显示编号为E0-3、E2-3、F2-1、F4-2和G8-2的5个克隆对应的氨基酸序列具有转录因子特征结构域.研究结果为分离调控SPSⅢ基因表达的转录因子提供了候选基因.     

钾对小麦茎和叶鞘碳水化合物含量及子粒淀粉积累的影响

田间条件下研究了钾素对冬小麦品种鲁麦22茎和叶鞘中碳水化合物含量变化以及灌浆过程中子粒淀粉积累的影响。结果表明,钾素有利于提高茎中果聚糖、蔗糖、果糖和葡萄糖在灌浆期间的积累,促进了灌浆后期果聚糖的降解及蔗糖、果糖和葡萄糖的输出。其中以K2处理的作用为最大;有利于提高灌浆过程中叶鞘果聚糖、果糖、蔗糖和葡萄糖的积累,但提高幅度小于茎中的提高幅度;同时钾素亦提高了灌浆期间子粒中可溶性总糖和蔗糖的供应,加速了淀粉积累速率,其中以K2处理为最高,最终获得了最高的产量(9411 15kg/hm2)和最大的钾素生产效率。     

土壤紧实胁迫对黄瓜碳水化合物代谢的影响

用容重分别为1.25 g/cm3(疏松土壤,即对照)和1.55 g/cm3(紧实土壤)的土壤进行盆栽试验,研究了土壤紧实胁迫对“津春4号”黄瓜(Cucumis sativusL.)不同生育期叶片和根系碳水化合物代谢的影响,以探讨土壤紧实胁迫对黄瓜生长产生影响的机理.结果表明,在土壤紧实胁迫条件下,黄瓜不同生育期叶片的净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)均显著下降,胞间CO2浓度(Ci)显著升高,光合作用受到抑制;叶片中蔗糖磷酸合成酶(SPS)活性显著降低,蔗糖合成酶(SS)、酸性转化酶(AI)和中性转化酶(NI)活性显著增强,蔗糖、葡萄糖、果糖和淀粉含量显著增加,蔗糖的合成与输出受到抑制;不同生育期根系SPS、AI和NI活性显著下降,而SS活性显著增强,蔗糖、葡萄糖和果糖含量显著增加,淀粉含量基本不变.这表明,土壤紧实胁迫抑制了黄瓜叶片中同化物的合成和输出,降低了碳水化合物向根系中的输入,阻碍了根系对碳水化合物的利用,使植株矮小,产量下降.     

乙烯利对甘蔗生化特性和品质的效应研究

用200ppm 乙烯利喷施伸长期的甘蔗,施用量为227.3mg/m~2.结果叶片硝酸还原酶,苹果酸酶.Mg~(++)-ATP 酶活性均减弱,水分含量减少,光合色素总量降低,而过氧化物酶和中性蔗糖酶等活性增强;蔗汁糖分增加,重力纯度提高,蔗汁品质改善.     

玉米碳水化合物分配机制研究进展与展望

源-库互作是重要的产量决定因子,源库间碳水化合物的转运与分配机制是生命科学领域研究热点。玉米作为同化能力较强的C4植物,是研究植物碳水化合物分配的理想模型。为给玉米碳水化合物分配机制及源-库互作研究提供理论支持,通过大量文献资料的整理,分析了蔗糖长距离运输和瞬时淀粉转化形成蔗糖相关基因的调控作用,论述了同化产物分配的调控机制,对影响共质体运输基因、质外体运输基因、韧皮部结构基因和机制调控未知基因对玉米碳水化合物分配调控的分子功能方面的研究进展进行了综述,并对玉米碳水化合物分配机制研究进行了展望。     

基于结构方程模型的玉米施氮量-光合产物-产量关系研究

玉米是重要的粮食作物,其最终产量与吐丝期穗的发育密切相关,而玉米穗发育受到土壤水分、氮素和其他养分营养调控。但是,不同施氮水平下,玉米幼穗中碳水化合物含量如何变化,怎样影响产量及其构成因子,至今还缺乏综合分析。该研究通过2 a的田间试验,比较了3个施氮处理下(0,150和300 kg/hm2,以N计),玉米吐丝期幼穗中葡萄糖、果糖、蔗糖和淀粉含量的差异,并通过结构方程模型综合分析它们与2个重要的产量构成因子穗粒数和穗粒质量,以及最终产量的关系。结果发现,施氮显著增加了籽粒产量、穗粒数和百粒质量。在吐丝期,氮肥施用提高了幼穗干质量和穗轴上的小花原基数。同时,玉米幼穗中的葡萄糖和果糖含量随施氮量增加而增加,而蔗糖和淀粉含量随施氮量增加呈下降趋势。结构方程模型的结果显示,在不同氮水平处理下,穗粒数和百粒质量能够解释产量变异的91%,其中,穗粒数对最终产量的影响较大,标准化路径系数为0.66,而百粒质量对产量的路径系数只有0.34。同时,碳水化合物含量的变化显著影响穗粒数和百粒质量,分别解释二者变异的82%和59%。其中,单糖(葡萄糖和果糖之和)对二者的影响大致相同,标准化路径系数分别为0.47和0.52;而淀粉主要影响了穗粒数,路径系数为-0.51;相对而言,对百粒质量的影响较小,路径系数为-0.31。蔗糖含量对穗粒数和百粒质量都没有显著影响。综上,玉米吐丝期幼穗中碳水化合物含量受到土壤氮素有效性的影响,并对玉米最终产量及其构成因子具有重要的指示作用。该研究对揭示玉米产量形成对施氮的响应有一定参考价值。     

甘蔗尿苷二磷酸葡萄糖焦磷酸化酶基因(UGPase)转化拟南芥及转基因植株的生理特性分析

尿苷二磷酸葡萄糖焦磷酸化酶(UDP-glucose pyrophosphorylase,UGPase)是植物糖代谢的主要参与酶之一,在植物的生长发育过程中起着重要作用。本研究将甘蔗(Saccharum officinarum)UGPase基因cDNA片段连接至载体pBI121,通过BamHⅠ和SacⅠ酶切鉴定及测序验证,结果表明,植物表达载体成功构建;通过农杆菌(Agrobacterium tumefaciens)的介导,采用浸花法转化拟南芥(Arabidopsis thaliana)。结合卡那霉素抗性筛选和PCR检测,获得了5株T0代转基因植株。对T1代转基因植株进行PCR及Southern blot分析,结果表明,目的基因已成功转入拟南芥中,并且不同的转化植株含有目的基因的拷贝数不同。对T2代转基因植株进行PCR和RT-PCR检测,结果表明,目的基因不仅能在自交系后代中稳定遗传,而且在RNA水平也有表达。同时,对T2代转基因植株的可溶性总糖、蔗糖及淀粉含量进行测定,结果表明,与野生型相比,转基因植株中可溶性总糖含量没有明显的变化,但蔗糖含量有所提高,并且差异明显,比野生型植株提高了50.85%~96.99%,而淀粉含量都较野生型植株的低,降低了9.69%~36.76%。说明UGPase在蔗糖与淀粉的转换过程中起着较为重要的作用,其催化的反应方向影响着组织中这两种产物(蔗糖和淀粉)的分配。     

缺硼对绿豆叶片光合特性和碳水化合物含量的影响

本试验以绿豆为指示植物,采用溶液培养法研究了缺硼对叶片光合功能和碳水化合物含量的影响,以明确缺硼是否影响光合作用进而影响作物生长。在绿豆第二片真叶出现后的第二天,一半植株供给 50 mol/L 硼（高硼）,另一半植株供给0.2 mol/L 硼（低硼）,在叶片生长过程中动态监测叶绿素含量、 气体交换和碳水化合物含量。结果表明,缺硼对叶片叶绿素含量没有影响,缺硼降低了光合速率（Pn）和气孔导度（Gs）,但对胞间二氧化碳浓度（Ci）没有影响; 缺硼提高了气孔限制率（Ls）。虽缺硼降低了Pn,但提高了叶片中可溶性糖,特别是葡萄糖和淀粉的含量。本研究结果表明缺硼对植物生长的影响并非是由于碳水化合物缺乏的缘故,而是因降低库活力导致了Pn的降低。     

Influence of elevated CO2 and mild water stress on nonstructural carbohydrates in field-grown cotton tissues

Root, stem and leaf tissues, from cotton plants exposed to CO₂ at ambient (370 μmol mol⁻¹ (control)) or elevated (550 μmol mol⁻¹ (FACE; free-air carbon dioxide enrichment)) levels in the field during the 1990 and 1991 growing seasons, were analyzed for nonstructural carbohydrates (glucose, fructose, sucrose and starch). Besides the FACE treatment, these plants were also exposed to two irrigation levels: 100% and 67% replacement of evapotranspiration. FACE had a greater effect upon cotton plant nonstructural carbohydrates than did irrigation treatments. Leaf carbohydrate content was increased by FACE, but this increase was much more pronounced in the stems and roots. Starch and soluble sugars in leaves in FACE plots tended to be consistently greater than in control leaves, without much change in carbohydrate content during the growing season. In contrast, root and stem, starch and soluble sugar pools were strongly increased by FACE and fluctuated strongly during the growing season. In both seasons, stem and taproot nonstructural carbohydrate content passed through a minimum during periods of heavy boll set. The fluctuations in stem and root carbohydrate content were therefore probably caused by the varying metabolic demands of the developing plant. These results suggest that a significant effect of CO₂ enrichment on starch-accumulating plants is an increase of nonstructural carbohydrate, especially starch, in nonleaf storage pools. This buildup occurs somewhat independently of the water status of the plant, and these enlarged pools can be drawn upon by the growing plant to maintain growth during periods of high metabolic demand.     

石蒜鳞茎膨大过程中碳水化合物代谢相关基因的差异表达研究

为探讨石蒜[Lycoris radiata (L’Her.) Herb.]鳞茎膨大过程中碳水化合物积累的变化规律,本研究依据前期已构建的材料,分析了石蒜鳞茎膨大过程中碳水化合物含量、相关酶活性以及碳水化合物代谢相关基因的表达变化。结果表明,随着石蒜鳞茎的膨大,蔗糖含量不断升高,蔗糖代谢酶SUS以及淀粉合成酶AGPase、SSS和GBSS的活性不断增强,从而加快淀粉的合成,这一过程可能受到编码蔗糖代谢及淀粉合成相关酶基因的正向调控,如SUS1、SUS2、SUS4、UGPA、AGPS2、AGPL2、SS2、SS3、GBSS1、SBE1、SBE2、SBE3等。另外,本研究还发现分别在AMY3和BAMY7、BAMY8、BAMY9基因的调控作用下,石蒜鳞茎膨大过程中α-淀粉酶和β-淀粉酶的活性也增强,从而加速淀粉的分解,提高鳞茎中可溶性糖含量,并可能在糖转运相关基因的作用下加快向鳞茎发育部位的转运,为鳞茎的后续膨大过程提供能量。本研究初步揭示了石蒜鳞茎膨大过程中碳水化合物代谢活动的变化规律,并挖掘到一些可能在此过程中发挥重要作用的调控基因,为后续利用分子生物学等手段加速石蒜鳞茎的膨大提供了理论依据。     

干旱胁迫下钾素对甘薯碳水化合物及内源激素含量的影响

【目的】研究干旱胁迫下施钾量对不同生长时期甘薯碳水化合物及内源激素含量的影响,为甘薯的抗旱高产栽培提供理论依据。【方法】选用食用型甘薯品种‘泰中6号’为材料,以硫酸钾（K₂SO₄）为供试肥料,水分处理设土壤最大持水量的60%～70%和30%～40%,依次代表正常供水（W1）和干旱胁迫（W0）;钾肥设K0、K1、K2、K3四个水平,K₂O用量分别为0、120、240和360 kg/hm2。分析了不同生长时期甘薯干物质含量、淀粉和可溶性糖含量、内源激素含量及收获期块根产量。【结果】干旱胁迫下甘薯植株干物质含量、块根和淀粉产量显著降低,施钾有利于甘薯植株干物质含量的提高、块根的膨大和淀粉的生成和积累,甘薯植株和块根干物质含量、块根淀粉含量和积累量最大均为K2处理,较K0提高幅度最大分别达到31.7%、43.6%、10.6%和50.6%。相同钾用量条件下,干旱胁迫下块根单薯重显著高于正常灌水,单株结薯数显著低于正常灌水。正常灌水条件下施钾后甘薯叶片可溶性糖含量降低,而块根可溶性糖含量升高,干旱胁迫下施钾使甘薯叶片和块根可溶性糖含量增大,较K0提高幅度最高分别达到31.4%和36.0%。干旱胁迫下施钾后甘薯叶片和块根IAA、ABA、ZR和GA含量显著增大,较K0提高幅度最高分别达到12.7%、15.7%、12.0%、10.4%和21.4%、15.6%、65.7%、13.0%,促进了甘薯植株碳水化合物含量和干重的提高,块根淀粉积累速率增大。【结论】干旱胁迫下施钾促进了干物质向块根的分配,提高了甘薯块根单薯重,从而增加了单位面积甘薯块根产量。干旱胁迫下钾素提高甘薯块根和叶片内源激素（ABA、IAA、ZR、GA）含量,块根内源激素含量的增加促进了块根淀粉的合成和积累,叶片内源激素含量的增加促进了地上部茎叶生长、茎叶干物质积累和叶片可溶性糖含量的增加,增强了甘薯的抗旱性。     

Effects of selenium treatments on potato (Solanum tuberosum L.) growth and concentrations of soluble sugars and starch

The effect of selenium (Se) treatments on potato growth and Se, soluble sugar, and starch accumulation was investigated. Potato plants were cultivated in quartz sand without or with sodium selenate (0, 0.075, 0.3 mg Se kg(-1) sand). In young potato plants, Se treatment resulted in higher starch concentrations in upper leaves. The tuber yield of Se-treated potato plants was higher and composed of relatively few but large tubers. At harvest, the starch concentration in tubers did not differ significantly between treatments. The higher Se addition (0.3 mg Se kg(-1)) may have delayed the aging of stolons and roots, which was observed as high concentrations of soluble sugar and starch. Together with the earlier results showing elevated starch concentration in Se-treated lettuce, the findings of this research justify the conclusion that Se has positive effects also on potato carbohydrate accumulation and possibly on yield formation.     

Mild salinity improves sugar beet (Beta vulgaris L.) quality

Abstract

Sugar beet (Beta vulgaris L.) is cultivated mainly on saline soils. Low levels of salinity stimulate growth of this crop plant possibly due to production of broader leaves as sources of assimilates. In this work, six cultivars were studied under mild salinity (EC = 5.5 dS m^?1) in a field experiment to analyse its effect on growth parameters and yield of storage root and sugar accumulation. An attempt was also made to determine the contributing role of photosynthetic gas exchange in response of sugar beet plants to salinity. Production of greater leaf area in salinized plants occurred only transitionally in the early growth period; in progression of the growing season it was decreased, and at 3rd harvest (100 days after treatment) it was significantly lower compared with control plants without cultivar differences. Leaf chlorophyll fluorescence, net photosynthesis rate, and stomatal conductance did not change by salinity significantly. Although, at the end of growth season, leaf area and potential photosynthesizing component of salinized plants on the basis of leaf area (LAR) or weight (LWR) were significantly lower than for control plants, weight of storage root and sugar content were up to 90 and 37% higher than in control plants, respectively. Consequently, a considerable higher yield under mild salinity conditions in sugar beet is not attributable to higher leaf area or, therefore, higher photosynthetic capacity of whole plants. Indeed, the storage roots benefit from lower dry matter and surface production of shoot during the late growing season (because of lower nitrogen assimilation and a slight drought stress of salinized plants) and a change in dry-matter partitioning in favor of roots takes place. However, a possible special effect of Na on carbon allocation for storage and structure and involvement of growth regulators in the change of root-shoot allometry could not be excluded.     

Carbohydrate accumulation in leaves of plants treated with the herbicide chlorsulfuron or imazethapyr is due to a decrease in sink strength

Herbicides that inhibit branched chain amino acid biosynthesis produce a rapid carbohydrate increase in leaves of treated plants. The relationship between these processes is not known nor is the importance of carbohydrate accumulation in the growth inhibition caused by these herbicides. This work analyzes carbohydrate concentration in sources and sinks after herbicide treatments in pea (Pisum sativum L.), as well as photosynthetic carbon assimilation, using two classes of chemicals, chlorsulfuron and imazethapyr, applied to roots or leaves. The most remarkable result was that, in addition to carbohydrate accumulation in leaves, accumulation of sucrose and/or starch in roots was detected. This pattern of carbohydrate accumulation was similar for both herbicides and independent of whether the herbicides were applied to leaves or roots. This indicates that root growth inhibition was not caused by sugar starvation in sinks. Nevertheless, the results are consistent with a decrease in sink strength, leading to the inhibition of photoassimilate translocation.     

白浆型水稻土生物硅肥生理效应的研究

采用田间试验以基肥和返青肥两种施肥方式,施生物硅肥量为0、150、300、450、600、750 kg hm-2六个水平,研究了白浆型水稻土不同生物硅肥施用量对水稻生理指标的影响。结果表明,适宜的生物硅肥施用量(450 kg hm-2)对水稻叶片叶绿素含量有显著的影响,可使叶绿素的含量提高9.6%,从而延缓了水稻功能叶片的光合功能期;水稻叶片的保护酶(CAT、POD)在施用生物硅肥后可维持较高的活性或受到抑制程度较低,使所受膜脂过氧化程度(MDA的含量)相对较低,生物硅肥施用量为450 kg hm-2时水稻叶片的CAT、POD活性达最大值,MDA的含量达到最低值,这说明施用生物硅肥促进了膜脂脱氧化作用,延缓功能叶片的衰老;施用生物硅肥后提高了植株干物质的合成与积累,促进了可溶性糖向淀粉的转移和碳水化合物的运输,协调了源、库关系。在本试验中,生物硅肥施用量为450 kg hm-2效果最好,施肥效果各处理表现为:Si3>Si4>Si5>Si2>Si1>Si0,各处理间差异达到极显著,两种施肥方式做基肥的要比返青肥的效果好。     

Tuber yield and allocation of nutrients and carbohydrates in potato plants as affected by limestone type and magnesium supply

Abstract

Magnesium (Mg) is a nutrient that affects the development of plants and is mainly supplied through liming performed to correct soil acidity. By acting on photosynthesis and influencing carbohydrate partitioning in the plant, supplementary Mg supplied through soil or foliar application can increase the yield and quality of potato (Solanum tuberosum L.) tubers. The aim of this study was to evaluate the effect of supplemental Mg fertilization by soil or foliar application on plant nutritional status, tuber yield, and carbohydrate partitioning in potato crops in soil corrected with calcitic and dolomitic limestones. The experiment was carried out in pots under greenhouse conditions with a randomized block design in a 2?×?3 factorial scheme with four replications. Dolomitic limestone application and supplemental Mg fertilization via soil increased the concentrations of this nutrient in potato leaves. Liming with dolomitic limestone reduced the uptake of Ca and K by plants, but supplemental Mg fertilization did not alter the uptake of Ca, Mg or K. Supplemental Mg fertilization did not increase plant growth and tuber yield, even when calcitic limestone was used to elevate the base saturation to 60%; the exchangeable Mg concentration in soil was 9?mmol_c dm^?3, and the Ca:Mg relationship was 3.7. Liming with dolomitic limestone or providing supplemental Mg fertilization did not increase sugar and starch partitioning to the tubers.