魔芋ADP-葡萄糖焦磷酸化酶大亚基cDNA片段的克隆

 利用ADP - 葡萄糖焦磷酸化酶的保守序列设计引物, 采用RT-PCR 方法, 从白魔芋球茎组织的总RNA 中扩增出目标cDNA 片段, 并克隆到pUC18 载体中。序列分析后确认该片段属于一新的ADP - 葡萄糖焦磷酸化酶大亚基基因。     

烤烟大田生长期烟叶中淀粉合成的酶活性变化

对K326、红花大金元(HD)2个烤烟品种在云南常规施肥情况下烟叶中ADPG焦磷酸化酶、淀粉合成酶、Q酶活性的变化及可溶性总糖、还原糖和淀粉含量的变化进行了研究。结果表明：K326,HD的ADPG焦磷酸化酶、淀粉合成酶活性在移栽后第40d开始升高,都在生理成熟期第90d达到高峰,以后迅速下降。2个品种的Q酶活性高峰在移栽后80d出现,但2个品种的Q酶活性变化规律不一致。K326的Q酶活性移栽后第60d开始先下降,65d以后迅速上升,移栽后80d达到高峰后又下降IHD的Q酶活性移栽后第柏d开始一直上升,移栽后第80d达到高峰后缓慢下降。2个品种可溶性总糖、还原糖含量都在移栽后第40d迅速升高,持续稳定20d以后下降,移栽后90d又迅速上升。2个品种淀粉含量都在移栽后60d上升,在生理成熟期达到最高(HD在移栽后90d,K326在移栽后110d)。     

Sucrose synthase dominates carbohydrate metabolism and relative growth rate in growing kiwifruit (Actinidia deliciosa, cv Hayward)

Changes in fruit growth rate, carbohydrate content (glucose, fructose, sucrose and starch) and enzyme activity (sucrose synthase, UDPglucose pyrophosphorylase, fructokinase, glucokinase, sucrose phosphate synthase, ADPglucose pyrophosphorylase and invertases), in the external pericarp of kiwifruit, were measured throughout the growing season. Sucrose synthase showed the highest activity among the sucrose cleaving enzymes during large part of the growing season. The activity of invertases were much lower than that of sucrose synthase until ripening started. Sucrose synthase showed a tight although not linear relationship with the fruit RGR. Furthermore, sucrose synthase showed linear and significant correlations with the activities of both fructokinase and UDPglucose pyrophosphorylase indicating a strong co-regulation of the activities of these three enzymes involved in sucrose cleavage and sink strength, in kiwifruit. Sucrose synthase is suggested to be the dominating enzyme in the cleavage of imported carbon in kiwifruit, in tight coordination with fructokinase and UDPglucose pyrophosphorylase.     

Molecular approaches for enhancing sweetness in fruits and vegetables

The quality of fruits and vegetables is mainly dependant on the sweetness determined by the level of soluble sugars such as glucose, fructose and sucrose. Other fruit quality parameters include Brix content, acidity, aroma, color, size and shape. Total sugar content in fruits and vegetables is a function of genetic, nutritional, environmental and developmental factors. Understanding the factors controlling sweetness is important to design strategies for enhancing quality of fruits and vegetables. Modifying the activity of enzymes in carbohydrate metabolism such as sucrose synthase (SuSy), acid invertase, ADP-glucose pyrophosphorylase (AGPase), sucrose phosphate synthase (SPS) and sucrose transporters were found to influence carbohydrate partitioning and sucrose accumulation in sink tissues of several food crops. Plant based taste-modifying sweet proteins such as brazzein, cucurmin, mabinlin, monellin, miraculin, neoculin and thaumatin have potential application for developing transgenic plants to improve the sweetness and quality of fruits and vegetables. The present review envisages various cultural, breeding and molecular approaches used for enhancing sugar content and sweetness in fruits and vegetables.     

Pre-anthesis non-structural carbohydrate reserve in the stem enhances the sink strength of inferior spikelets during grain filling of rice

Sink strength plays an important role in grain filling of cereals but how it is related to the pre-anthesis non-structural carbohydrate (NSC) reserves is not clear. This study investigated if and how an increase in NSC reserves could enhance sink strength, and consequently improve grain filling of later-flowering inferior spikelets (in contrast to the earlier flowering superior spikelets) for rice varieties with large panicles. Two “super” rice varieties (the recently bred high-yielding rice) and two New Plant Type (NPT, named in IRRI for the extra-large panicle) rice lines were compared with two elite inbred varieties under field-grown conditions. Three nitrogen (N) treatments, applied at the stages of panicle initiation, spikelet differentiation or both, were adopted with no N application during the mid-season as control. Both super rice and NPT rice showed a greater yield capacity as a result of a larger panicle than the elite inbred rice. However, a lower percentage of filled grains limited the realization of higher yield potential in super rice and especially in NPT rice, due to their lower grain filling rate and the smaller grain weight of their inferior spikelets. The low grain filling rate and small grain weight of inferior spikelets are mainly attributed to a poor sink strength as a result of small sink size (small number of endosperm cells) and low sink activity, e.g. low activities of sucrose synthase (SuSase) and adenosine diphosphoglucose pyrophosphorylase (AGPase). The amounts of NSC in the stem and NSC per spikelet at the heading time are significantly and positively correlated with sink strength (number of endosperm cells and activities of SuSase and AGPase), grain filling rate, and grain weight of inferior spikelets. Nitrogen application at the spikelet differentiation stage significantly increased, whereas N application at the panicle initiation or at both panicle initiation and spikelet differentiation stages, significantly reduced, NSC per spikelet at the heading time, sink strength, grain filling rate, and grain weight of inferior spikelets in super rice. The results suggest that pre-anthesis NSC reserves in the stem are closely associated with the sink strength during grain filling of rice, and N application at the spikelet differentiation stage would be a good practice to increase pre-anthesis NSC reserves, and consequently to enhance sink strength for rice varieties with large panicles, such as super rice varieties.     

两个ADP-葡萄糖焦磷酸化酶α亚基基因在甘薯中的超量表达

ADP-葡萄糖焦磷酸化酶(AGPase)催化ADP-葡萄糖合成反应,是淀粉生物合成的限速酶之一。为研究甘薯AGPase与块根淀粉合成的关系,从高淀粉甘薯品种川薯34中克隆了AGPase基因的两个α亚基编码序列AGPa1和AGPa2;构建植物表达载体pC-AGPa1和pC-AGPa2后经根癌农杆菌EHA105介导分别导入甘薯品种西成薯007;获得表达了GUS的7株AGPa1和5株AGPa2转基因甘薯植株。RT-PCR和AGPase活性检测表明,AGPa1和AGPa2基因在转基因植株中表达水平高于对照,并引起甘薯叶片中AGPase活性显著增加。     

魔芋GDP甘露糖焦磷酸化酶基因及其启动子的克隆与分析

以花魔芋和白魔芋为材料,通过魔芋5个转录组高通量测序数据库,与拟南芥进行tBlastn比对、拼接,得到魔芋中的GDP-甘露糖焦磷酸化酶基因GMP的推定全长,设计基因特异性引物,克隆得到魔芋GMP基因的部分cDNA序列,长度为1 233 bp,其中基因编码区长度为1 086 bp,编码的氨基酸为361个.在此基础上运用FNPI-PCR技术得到了魔芋GDP-甘露糖焦磷酸化酶基因GMP上游启动子2 116 bp,经生物信息学分析,该序列具有典型的TATA-box、 CAAT-box及与胁迫相关的元件和光应答元件.     

种植密度对玉米籽粒淀粉粒分布及相关酶活性的影响

以玉米品种隆平206和郑单958为材料,设置3个种植密度D1(57 000株/hm~2)、D2(67 500株/hm~2)、D3(78 000株/hm~2),分析成熟期玉米淀粉粒分布特征和籽粒灌浆阶段ADPG焦磷酸化酶的活性变化。结果表明:玉米淀粉粒粒径范围为0.4～30.0μm,平均粒径随种植密度增加而逐渐增加;玉米淀粉粒体积分布呈双峰曲线,表面积分布呈三峰曲线,随种植密度的增加,中型淀粉粒(3μm≤粒径≤18μm)的体积、表面积百分比显著下降,大型淀粉粒(粒径18μm)则显著升高;淀粉粒数量分布呈单峰曲线,种植密度对2个品种的淀粉粒数量分布无显著影响;2个玉米品种灌浆阶段ADPG焦磷酸化酶活性随种植密度的增大而降低。     

小麦腺苷二磷酸葡萄糖焦磷酸化酶同工酶基因型与酶活性及淀粉含量的关系

采用非变性聚丙烯酰胺凝胶电泳鉴定了我国60个代表性小麦品种的腺苷二磷酸葡萄糖焦磷酸化酶(AGP)同工酶基因型, 并测定了AGP活性及总淀粉含量, 以明确小麦籽粒AGP同工酶基因型组成及其与AGP活性和淀粉含量的关系。结果表明, AGP有AGPa、AGPb、AGPc和AGPd 4个等位基因位点, 其出现频率分别为96.7%、80.0%、86.7%和16.7%; 共检测到5种基因型, 其中基因型AGPabc出现频率最高, 为46.7%。不同基因型的品种间AGP活性和总淀粉含量差异显著(P<0.05)。其中具有基因型AGPabcd的品种酶活性及总淀粉含量最高, 表明小麦籽粒中不同AGP同工酶基因型对酶活性及淀粉含量有不同遗传效应。     

节水灌溉条件下饲料稻不同施氮水平碳代谢关键酶活性及产量表现

节水条件下,采用田间小区试验研究"氮中量施肥法"(N,P2O5,K2O施用量分另4为190,90,100kg/hm2)、"氮高量施肥法"(N,P2O5,K2O为210,90,100 kg/hm2)、"氮低量施肥法"(N,P2O5,K2O为170,90,100kg/hm2)对饲料稻威优198蔗糖磷酸合成酶(SPS)、蔗糖合成酶(SUS)、腺苷二磷酸葡萄糖焦磷酸化酶(ADPase)活性、光合特性以及产量的影响.结果表明,氮中量施肥法处理水稻旗叶和粒籽中的SPS、SUS、ADPase活性较高;旗叶净光合作用速率较快;叶和籽粒中蔗糖含量较高,蔗糖转化成淀粉的能力较强.氪中量施肥法处理能显著增加水稻的有效德和籽粒产量,有效穗分别比氮高量栽培法和氪低量施肥法提高了7.70%和10.32%,籽粒产量分别比氮高量栽培法和氮低量施肥法提高了12.02%和8.47%.