Season and Nitrogen Effects on Activities of Three Hydrolytic Enzymes in Soils of the Gurbantunggut Desert,Northwest China

The activities of three extracellular hydrolytic enzymes, soil invertase, urease, and alkaline phosphatase (AlP), were measured across seasons and with the experimental addition of nitrogen (N) in the soil of the Gurbantunggut Desert, Northwest China. Seasonal fluctuations in hydrolytic enzyme activities were not correlated with seasonal variations in soil temperature, water content, pH, conductance, and organic carbon. Invertase and AlP activities increased with low rates of N addition, peaked at a N addition rate of 3.0 g N m^?2 y^?1, and then decreased at higher N addition rates. Urease activity decreased with increasing N addition. Higher organic matter content in the upper depths of soil resulted in higher hydrolytic enzyme activity at depths of 0–5 cm in soil samples and hydrolytic enzyme activity at that depth was more sensitive to N addition and seasonal environmental factors than that at depths of 5–10 cm in soil samples.     

甘薯细胞壁蔗糖转化酶基因IbCWIN家族成员鉴定及表达分析

甘薯是重要的粮食、饲料、工业原料作物和新型的生物能源作物,细胞壁蔗糖转化酶是植物源、库组织蔗糖代谢的关键酶,但关于甘薯细胞壁蔗糖转化酶基因IbCWIN家族成员的研究尚未见报道。本研究测定供试品种不同组织部位的蔗糖淀粉含量,利用生物信息学方法对IbCWIN基因家族的理化性质、保守结构域、系统进化关系、启动子作用元件、组织特异性表达模式进行分析。结果表明,甘薯茎中蔗糖含量最高,须根和叶次之,块根最低;块根淀粉含量最高,极显著高于其他部位。甘薯中含有10个IbCWIN基因,编码氨基酸442~1115个,蛋白质分子量范围49.56~124.44kD,等电点为5.0~9.1。分布在8条染色体上,都含有Glyco_32保守结构域及相同或相似的保守基序motif,属于糖基水解酶基因家族GH32。IbCWIN与木薯MeCWINV同源性高,IbCWIN基因家族启动子区域含有多种类型的顺式作用元件。qRT-PCR结果表明,IbCWIN基因家族在甘薯不同组织中均有表达且有多种表达模式,其中IbCWIN2和IbCWIN9在块根中表达量显著高于其他组织部位。本研究为下一步探索甘薯IbCWIN基因家族的功能及调控甘薯源、库关系机制提供理论指导。     

不同产地南丰蜜桔果实品质和蔗糖代谢相关酶研究

[目的]探索不同产地南丰蜜桔果实品质的差异及其与蔗糖代谢相关酶活性的关系,为指导南丰蜜橘的适度生产、保持地域产品声誉以及科学发展名贵稀有物种提供参考依据。[方法]研究分析了6个不同产地南丰蜜桔果实的主要品质特性和蔗糖代谢相关酶活性特征。[结果]南丰原产地的南丰蜜桔中总糖含量、尤其还原糖含量、糖酸比、固酸比均优于其他产地的果品,故体现出品质优异;不同产地南丰蜜桔中积累的可溶性糖种类含量存在差异;通过对蔗糖中性转化酶(NI)活性与还原糖含量、蔗糖合成酶(SS)活性和蔗糖磷酸合成酶(SPS)活性与蔗糖含量的相关性分析发现,还原糖与NI活性存在极显著正相关,蔗糖含量与SPS和SS活性之和存在显著相关性。[结论]该研究结果为南丰蜜桔引种种植范围的界定及品质的保证提供了参考依据。     

玉米籽粒发育的调控研究：Ⅲ.离体条件下的化学调控机理探讨

筛选出一种改良培养基，建立起有效的实验室内玉米果穗器官离体培养系统，可将授粉后３天带有３０￣５０个籽粒的果穗顶部器官培养至籽粒生理成熟。并应用此法研究了添加不同浓度赤霉酸（ＧＡ３）、脱落酸（ＡＢＡ）等生长调节剂对籽粒发育的影响。结果表明：对授粉后３￣７天取样培养的离体果穗顶部，１￣２５ｍｇ／Ｌ的ＧＡ３处理均表现出籽粒发育不良，而添加０．５ｍｇ／Ｌ浓度的ＡＢＡ可促进籽粒的发育，添加１０￣５０ｍｇ／Ｌ     

不同激素对红花子叶外植体过氧化物酶、酯酶同工酶和过氧化物酶、转化酶活性的影响

在 IAA、2,4-D 和 BA 作用下,红花子叶外植体过氧化物酶活性发生变化而同工酶谱带无显著改变,2,4-D 和 BA 显示对酶活性的累加促进效果。不同激素均可诱导红花子叶产生特异的酯酶同工酶酶谱。转化酶与激素所诱导的子叶外植体膨胀生长有密切联系。     

光照强度昼变化对烟叶蔗糖转化酶和蛋白酶活性的影响

为探索光照强度昼变化对植物叶片水解酶活性的影响,以烟草叶片为材料,对蔗糖转化酶和可溶性糖含量,蛋白酶活性和蛋白质、游离氨基酸含量与光照强度昼变化之间的关系进行研究.结果表明,光照强度的昼变化对蔗糖转化酶和蛋白酶活性有较大影响,随光照强度增强,蔗糖转化酶活性在11:00达到最高点3.933 mg/(g.h),之后开始逐步下降;蛋白酶活性在午后大幅度上升,17:00达到最大值125.33 mg/(g.h),之后迅速下降.对烟叶蔗糖转化酶和蛋白酶活性进行分析时,前者应在11:00左右取样测定;后者应在15:00之后取样测定.     

柑桔转化酶基因家族新成员的克隆和序列分析

分析植物可溶性转化酶基因的保守区序列，设计一对PCR引物，以甜橙基因组DNA为模板。采用PCR方法扩增出长约1000bp的DNA片段。克隆入pUCm-T载体，测序结果表明获得柑桔酸性转化酶基因家族的一个新的成员。基因片段长1096bp。包括4个外显子和3个内含子，其序列已在GenBank中登记（登记号为AF433643）。在GenBank中进行同源性检索的结果表明，该成员编码的氨基酸与植物可溶性酸性转化酶的氨基酸同源性较高。与宽皮柑桔（GenBank登记号，AF312229）可溶性酸性转化酶基因编码的氨基酸具有77%的同源性，而与定位于细胞壁的（不溶性）酸性转化酶同源性较低。最高权33%（Fragaria ananassa,GenBankAF000521)。聚类分析结果表明该成员与我们已报道的2个柑桔酸性转化酶基因不同，推测我们获得的基因是转化酶基因家族的又一新成员（CS-VI1）。它与CU-AI1和CSCWI-1的核苷酸同源性分别为45.28%和44.85%。氨基酸同源性分别为27.58%和10.35%。3个成员间核苷酸和氨基酸序列较低的同源性，不会在South-ern,Northern和Western杂交中产生交叉干扰反应。     

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.     

Acid invertase as a serious candidate to control the balance sucrose versus (glucose + fructose) of banana fruit during ripening

Six banana varieties: 3 ‘dessert’ ones: ‘IDN 110’; ‘Kirun’; and ‘Grande Naine’, and 3 ‘cooking’ ones: ‘Galéo’; ‘Sowmuk’; and ‘French’ were used to investigate the relationship between sugar profiles and activities of sucrose-phosphate synthase (SPS, EC 2.4.1.14), sucrose synthase (SuSy, EC 2.4.1.13) working in the hydrolytic way, invertases (EC 3.2.1.26) (neutral (NIV) and acid (AIV)). Expression of a Musa cell-wall invertase (MaCwINV1/pBANUU103) gene was additionally studied during fruit development and ripening ex planta after ethylene treatment of two of these varieties. Close amounts of soluble sugars (sucrose + glucose + fructose) were measured in the different varieties at ripe stage. SPS activity was either almost constant or increased continuously or transitorily during ripening of all varieties, concomitantly to total soluble sugar (sucrose + glucose + fructose) accumulation. Together with previous data obtained from ‘Cavendish’, our data lead us, (i) to strengthen the hypothesis that this enzyme is likely to have a major role in the synthesis of sucrose during ripening of banana and (ii) to underline the complexity of the mode of SPS activity regulation already pointed out. Interestingly, for the first time in banana, two diploid and cooking varieties: ‘Galéo’ and ‘Sowmuk’ were found almost sucrose-free, in good agreement with a 6.4-fold higher mostly vacuolar AIV activity than that of the two desserts and diploid ones. Otherwise, expression of a MaCwINV1/pBANUU103 (cell wall) gene was followed in the two most contrasted varieties in matter of sucrose content: ‘Sowmuk’ almost sucrose-free, and ‘IDN 110’ accumulating high level of sucrose. Compared to ‘IDN110’, the mRNA level of MaCwINV1/pBANUU103 gene was higher (up to 173-fold) in ‘Sowmuk’ concomitantly with the low level of sucrose of ‘Sowmuk’. Our data let us to conclude that the AIV is probably one of the main determinants involved in the regulation of sucrose level during banana fruit ripening, even if the form, vacuolar or cell wall-linked is not determined yet. Otherwise, the MaCwINV1/pBANUU103 gene appears as a putative candidate gene that could contribute to regulate this level.     

兰州百合鳞茎可溶性酸性转化酶活性检测体系的建立

 为深入研究百合鳞茎蔗糖代谢生理机制,以兰州百合（Lilium davidii var. unicolor）鳞茎外层鳞片为试材,研究了不同种类和pH值的缓冲液、反应时间和反应温度对可溶性酸性转化酶（Soluble acid invertase,SAI,EC 3.2.1.26）活性的影响,建立了SAI活性的最佳检测体系。结果表明,最适提取缓冲液为pH 8.0的Hepes-NaOH;最佳反应缓冲液为pH 4.8的HAc-K3PO4,最适反应温度为40 ℃,最适反应时间为30 min。