光质对设施葡萄叶片衰老与内源激素含量的影响

以设施延迟栽培条件下叶片衰老速度不同的意大利和无核白鸡心2个葡萄品种为试材,分别进行补充红光和蓝光处理,研究不同光质对叶片衰老过程中叶绿素含量、净光合速率和内源激素含量的影响.结果表明: 与未补光对照相比,红光能够显著提高叶片的叶绿素含量和净光合速率,降低了内源赤霉素(GA₃)含量,但明显减缓了脱落酸(ABA)含量的增加和玉米素核苷(ZR)总含量的减少,从而显著提高了(GA₃+ZR)/ABA值,延缓叶片衰老.叶片衰老前期,蓝光处理叶片叶绿素含量、净光合速率和(GA₃+ZR)/ABA值均低于对照,加速了植株的衰老进程;但在叶片衰老后期,蓝光处理叶绿素含量、净光合速率和(GA₃+ZR)/ABA值逐渐高于对照,在一定程度上延缓了叶片衰老.植物内源激素生长素(IAA)则表现出叶片衰老前期促进叶片生长发育、叶片衰老后期加速衰老的双重作用.意大利叶片衰老速度较无核白鸡心慢.在本试验条件下,红光处理效果最好,有效延缓了叶片衰老进程,延长了叶片的生理功能期.     

通过转PSAG12-IPT基因培育延缓叶片衰老水稻

利用农杆菌介导的遗传转化方法将PSAG12-IPT导入籼稻品种明恢63.在获得的61个独立的转基因植株中,有一些表现出叶片衰老显著延缓,对选择的两个纯合转基因株系的小区试验的结果显示:(1)转基因植株倒三叶的持绿性极显著延长;(2)两个纯合转基因株系比原品种的结实率极显著提高,株高极显著降低;(3)两个纯合转基因株系的有效穗数比原品种极显著或显著提高.     

转PSAG12-ipt基因水稻延衰性能的初步研究

研究了叶片衰老抑制基因PSAG1 2 ipt经基因枪导入籼稻不育系中A后 ,转化植株农艺性状和生理特性的变化。结果显示 ,在水稻生育期 ,转化植株相对于对照而言 ,叶绿素、蛋白质含量和SOD(超氧物歧化酶 )活性下降以及MDA(丙二醛 )相对含量上升趋势较缓 ,表现在农艺性状上是单株有效穗数、千粒重明显高于对照。说明叶片衰老抑制基因PSAG1 2 ipt确实具有延缓叶片衰老的功能 ,延长了水稻叶片利用光能的时间 ,使之积累了大量的光合产物 ,增加了产量     

不同绿豆品种生育后期叶片衰老的研究

以夏播绿豆品种‘冀绿2号’和‘泰来’为材料,研究其开花至成熟期间主茎开花节叶片的叶绿素含量、净光合速率、酶促防御系统的保护酶SOD、CAT、POD活性和MDA积累量的动态变化规律。结果表明,两品种各功能叶片的叶绿素含量、净光合速率、SOD、CAT活性均在其开花15 d后逐渐下降,但POD活性和MDA含量随着叶片的衰老而升高。虽然两品种叶片衰老的总体变化趋势一致,但衰老进程存在着显著差异。与‘泰来’绿豆相比,‘冀绿2号’各功能叶片衰老过程中SOD、CAT活性下降较慢,叶片功能期持续时间长,生育后期仍能保持相对较高的净光合速率,籽粒产量显著高于‘泰来’绿豆。综合分析表明,在绿豆开花结荚期间,有效控制或延缓开花节叶片的衰老进程,维持叶片生理功能,对籽粒产量形成具有重要作用。     

盐胁迫对转AtNHX1基因杨树光合特性与叶绿体超微结构的影响

以欧美107杨(Populus×euramericana ‘Neva',Wt)和转拟南芥液泡膜Na~+/H~+逆向转运蛋白基因AtNHX1的欧美107杨新品系(Tr) 幼苗为材料,研究了高低度盐胁迫对两品系幼苗光合色素含量、光合参数和叶绿体超微结构的影响,以阐明转AtNHX1基因杨树的耐盐性与其光合作用及叶绿体结构之间的关系.结果表明:(1)盐处理后,两品系叶片叶绿素含量、类胡萝卜素含量、净光合速率、蒸腾速率和气孔导度均下降,且高盐度处理下降幅度更大;同等盐度处理下,Tr品系叶片叶绿素含量、净光合速率和气孔导度的下降幅度显著低于Wt品系,且在高盐度处理间差异更大;两品系杨树叶片P_n下降的原因在低盐处理时以气孔限制为主,而在高盐下则是气孔限制和非气孔限制共同作用的结果.(2)盐胁迫对T_r 品系叶片叶绿体超微结构的影响较轻,其在高盐下仍保持了较好的内部结构;盐胁迫Wt品系叶绿体则缩皱成球形,内部结构趋向简单,以至解体,脂质球显著增多.可见,盐胁迫导致杨树叶绿体结构破坏而引起叶绿体色素含量下降,最终降低其光合作用效率;同等盐度胁迫下,转AtNHX1基因品系叶片保持了较完整的叶绿体超微结构、更高的叶绿素含量,能维持较好的光合状态,从而表现出较高的耐盐能力.     

PSAG12-ipt基因转化植株研究进展

叶片衰老是一种程序性死亡过程;ipt(isopentenyl transferas)基因转化植株,可以催化调控内源细胞分裂素合成,延缓转化株叶片衰老.SAG12基因启动子能够控制ipt基因在植株下部衰老叶片中表达.介绍了ipt基因和SAG12基因启动子的来源和应用,以及PSAG12-ipt基因的产生和转化植株在国内的研究概况.     

干旱胁迫对转LeFAD7基因番茄光合作用的影响

以‘天津白果’番茄品种的野生株系(WT)和转正义叶绿体ω-3脂肪酸去饱和酶基因(LeFAD7)株系T( )-12为试材,通过盆栽实验测定了它们在PEG-6000模拟干旱胁迫下的叶片类囊体膜脂脂肪酸组成,以及干旱胁迫后的光合参数、叶绿素荧光参数,以探讨类囊体膜脂LeFAD7基因在干旱胁迫下对番茄叶片光合作用的影响。结果表明:与WT株系相比,转正义基因番茄植株类囊体膜脂中亚麻酸(18∶3)含量升高12.67%,亚油酸(18∶2)含量下降26.98%,导致膜脂脂肪酸不饱和度升高;10%、20%和30%PEG干旱胁迫下,转正义基因番茄植株的实际光化学效率(ΦPSⅡ)、净光合速率(Pn)和叶绿素a(Chl a)含量分别比相应对照下降0.36%~5.11%、19.97%~28.13%、13.27%~23.66%,降幅均小于WT株系,且Pn和Chl a在转基因和野生株间大多存在显著差异。可见,LeFAD7基因能增加番茄叶片膜脂脂肪酸不饱和度,从而减轻干旱胁迫对细胞膜的伤害性,保持干旱逆境下光合系统结构和功能的相对稳定,维持较高的光合速率。     

转TPSP融合基因小麦的耐旱相关特性

在获得转TPSP基因小麦纯合株系的基础上,对3个转基因株系的耐旱相关生理特性进行了分析。脯氨酸含量测定显示,干旱胁迫过程中小麦叶片中脯氨酸含量逐渐增加,且3个转基因株系叶片中脯氨酸的积累速度和积累量均显著高于非转基因对照;叶绿素荧光参数测定显示,3个转基因株系的Fv/Fm值在胁迫过程中均略高于非转基因对照,转基因株系4-4-4的Fv/Fo值显著高于非转基因对照,表明转基因株系在水分胁迫条件下光合系统II（PSII）的光合效率有所增强;转基因小麦耐旱性鉴定显示：模拟干旱胁迫100h时对照小麦叶片几乎全部萎蔫,而3个转基因株系均表现出较强的耐旱性;复水24h后转基因株系4-9-1、4-4-4和30-1-2的叶片黄化率分别为25.2%、23.3%和27.6%,显著低于非转基因对照（48.8%）。上述研究结果表明转TPSP基因小麦具有较强的耐旱能力,为转基因材料进一步应用于小麦抗旱育种提供了依据。     

三种栽培模式下不同基因型冬小麦旗叶衰老代谢比较

为了探索冬小麦在不同栽培模式下功能叶片衰老代谢的生理机制,以cp02(213)、cp99(1)和陕农512为材料,比较研究了常规栽培、覆草栽培、地膜覆盖3种栽培模式下小麦旗叶衰老代谢特性.结果表明,覆草栽培叶面积、旗叶功能期、叶绿素含量、叶片保护酶活性(SOD、POD、CAT)显著高于常规栽培,膜脂过氧化程度较低,叶片衰老速度缓慢,代谢强度旺盛,有利于籽粒灌浆和光合产物的积累.灌浆前期,地膜覆盖叶面积、旗叶功能期、叶绿素含量、叶片保护性酶活性(SOD、POD、CAT)显著高于常规栽培,膜脂过氧化程度低于常规栽培;灌浆后期,叶绿素含量急剧下降,叶片衰老速度加快,膜脂过氧化程度加剧.参试品种(系)中陕农512叶片衰老速度缓慢,保绿性好.     

杂交春性小麦开花结实期间叶片的衰老

用杂交春性小麦901和常规小麦品种陕229为材料,研究了杂交春性小麦901叶片衰老的进程及叶片衰老延迟的原因。研究表明,杂交春性小麦901冠层3叶片叶绿素含量,光合速率,可溶性蛋白质含量在小麦灌浆后期均高于对照常规小麦品种陕229。保护酶SOD活性高且稳定,使活性氧,自由基对细胞膜的伤害减轻,膜结构能较长时间保持健康完整,维持细胞的正常供谢,叶片的功能期延长,同化能力增强。叶片向籽粒和其它器官提供充盈的同化产物,使作物的产量和抗逆性提高。     

转基因(SAG12-IPT)青菜的迟衰特性

利用根癌农杆菌感染方法将融合基因SAG12 IPT导入青菜 ,转基因植株明显表现出衰老延迟的生理现象。SAG12 IPT的抗衰老作用表现为 :在衰老过程中转基因青菜叶片中叶绿素含量高于未转基因的青菜 ,PCR分析结果表明该融合基因已经转入青菜中。激素检测结果表明转基因青菜叶片中细胞分裂素含量高于未转基因植株 ,说明抗衰老与叶片内细胞分裂素含量提高有关。另外 ,转基因植株不仅表现出活体植株衰老延迟 ,而且长在植株上的与离体的叶片滞绿时间延长。这些为蔬菜的耐储存育种提供了新的思路 ,同时为该融合基因在十字花科经济作物中的应用提供了理论依据。     

Effects of P(SAG12)-IPT gene expression on development and senescence in transgenic lettuce

An ipt gene under control of the senescence-specific SAG12 promoter from Arabidopsis (P(SAG12)-IPT) significantly delayed developmental and postharvest leaf senescence in mature heads of transgenic lettuce (Lactuca sativa L. cv Evola) homozygous for the transgene. Apart from retardation of leaf senescence, mature, 60-d-old plants exhibited normal morphology with no significant differences in head diameter or fresh weight of leaves and roots. Induction of senescence by nitrogen starvation rapidly reduced total nitrogen, nitrate, and growth of transgenic and azygous (control) plants, but chlorophyll was retained in the lower (outer) leaves of transgenic plants. Harvested P(SAG12)-IPT heads also retained chlorophyll in their lower leaves. During later development (bolting and preflowering) of transgenic plants, the decrease in chlorophyll, total protein, and Rubisco content in leaves was abolished, resulting in a uniform distribution of these components throughout the plants. Homozygous P(SAG12)-IPT lettuce plants showed a slight delay in bolting (4-6 d), a severe delay in flowering (4-8 weeks), and premature senescence of their upper leaves. These changes correlated with significantly elevated concentrations of cytokinin and hexoses in the upper leaves of transgenic plants during later stages of development, implicating a relationship between cytokinin and hexose concentrations in senescence.     

农杆菌浸种处理对小麦种子萌发及幼苗生长发育的影响

以小麦品种(系)郑9023、中13和西农1376为主区,分别以农杆菌菌液浓度、农杆菌生长阶段和农杆菌侵染时间为副区,研究了农杆菌浸种处理后小麦种子萌发及幼苗生理生化特性变化.结果表明,小麦品种(系)分别与农杆菌菌液浓度、农杆菌生长阶段和侵染时间的互作效应不显著;随着农杆菌菌液浓度的增加,小麦种子发芽率、幼苗株高、鲜重、叶绿素含量呈下降趋势,MDA含量、白化苗率、卡那霉素抗性苗率则呈上升趋势,而POD活性则呈先升后降的趋势,小麦种子及幼苗受到的伤害逐渐增大,尤其是农杆菌菌液浓度超过1.5 OD后小麦幼苗受到的伤害更为明显;对数生长阶段的农杆菌活性最高,该阶段处理的小麦种子发芽率、幼苗株高、鲜重、叶绿素含量达到最低,而POD活性、MDA含量、白化苗则达到最大,小麦种子及幼苗受到的伤害也最为明显;随着农杆菌侵染时间的延长,小麦种子萌发及幼苗生长发育的各项指标表现出与农杆菌菌液浓度处理相同的变化趋势,尤其是侵染时间超过1.5 h时,小麦种子萌发及幼苗生长发育受到了显著抑制;各小麦不同品种(系)对农杆菌的反应存在一定基因型差异.研究发现,依据小麦种子萌发及幼苗生理生化特性影响和卡那霉素抗性苗率表现,浸种转化法中的农杆菌菌液浓度应控制在1.5 OD左右,生长阶段宜选用对数生长期,侵染时间以1.5 h较为适宜.     

Senescence-induced ectopic expression of the A. tumefaciens ipt gene in wheat delays leaf senescence, increases cytokinin content, nitrate influx, and nitrate reductase activity, but does not affect grain yield

The manipulation of cytokinin levels by senescence-regulated expression of the Agrobacterium tumefaciens ipt gene through its control by the Arabidopsis SAG12 (senescence-associated gene 12) promoter is an efficient tool for the prolongation of leaf photosynthetic activity which potentially can affect plant productivity. In the present study, the efficiency of this approach was tested on wheat (Triticum aestivum L.)-a monocarpic plant characterized by a fast switch from vegetative to reproductive growth, and rapid translocation of metabolites from leaves to developing grains after anthesis. When compared with the wild-type (WT) control plants, the SAG12::ipt wheat plants exhibited delayed chlorophyll degradation only when grown under limited nitrogen (N) supply. Ten days after anthesis the content of chlorophyll and bioactive cytokinins of the first (flag) leaf of the transgenic plants was 32% and 65% higher, respectively, than that of the control. There was a progressive increase in nitrate influx and nitrate reductase activity. However, the SAG12::ipt and the WT plants did not show differences in yield-related parameters including number of grains and grain weight. These results suggest that the delay of leaf senescence in wheat also delays the translocation of metabolites from leaves to developing grains, as indicated by higher accumulation of ((15)N-labelled) N in spikes of control compared with transgenic plants prior to anthesis. This delay interferes with the wheat reproductive strategy that is based on a fast programmed translocation of metabolites from the senescing leaves to the reproductive sinks shortly after anthesis.     

水稻叶色突变体叶绿体发育规律研究

从温敏核不育系水稻'810S'中筛选出一个生长发育正常的淡黄绿叶色自然突变株'标810S',其叶绿素含量约为'810S'的50%,光合速率比野生型高.以'810S'为对照,对'标810S'进行叶片形态、叶肉细胞和叶绿体超微结构以及叶绿体蛋白研究.结果显示,'标810S'的叶长、宽和面积与'810S'相似;叶肉细胞和叶绿体发育稍迟缓,片层结构减少;叶绿体蛋白约为对照的55%,并初步鉴定出与光合作用相关的差异蛋白点13个,其中4个缺失蛋白,包括1个RuBP大亚基缺失.推测该水稻突变体叶色变浅与叶绿体基粒片层减少有关.     

PSAG12-ipt嵌合基因转化马铃薯体系的研究

以根癌农杆菌介导法将PSAG12-ipt嵌合基因导入马铃薯栽培品种,对影响马铃薯遗传转化的多种因素进行系统研究.结果表明:马铃薯茎段分化效率高于叶片,马铃薯愈伤诱导和芽分化最适培养基为MS+6-BA 0.25mg/L+NAA 0.25mg/L+2,4-D 0.25mg/L,添加1%Na2SO3能有效防止褐化;茎段愈伤诱导和分化苗生根最适的Kan浓度分别为50mg/L和75mg/L;外植体预培养2d,OD600为0.2～0.5的农杆菌浓度侵染8min、共培养3d后进行选择培养能有效地提高植株再生能力.用PSAG12和ipt双重PCR检测再生植株,阳性转化率为65.8%.Southern blotting结果表明,转基因植株多以单拷贝形式整合进马铃薯基因组中.     

Analysis of transgenic wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) harboring a maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) gene for plastid EF-Tu: segregation pattern,expression and effects of the transgene

We previously reported that transgenic wheat (Triticum aestivum L.) carrying a maize (Zea mays L.) gene (Zmeftu1) for chloroplast protein synthesis elongation factor, EF-Tu, displays reduced thermal aggregation of leaf proteins, reduced injury to photosynthetic membranes (thylakoids), and enhanced rate of CO₂ fixation following exposure to heat stress (18 h at 45°C) [Fu et al. in Plant Mol Biol 68:277–288, 2008]. In the current study, we investigated the segregation pattern and expression of the transgene Zmeftu1 and determined the grain yield of transgenic plants after exposure to a brief heat stress (18 h at 45°C). We also assessed thermal aggregation of soluble leaf proteins in transgenic plants, testing the hypothesis that increased levels of EF-Tu will lead to a non-specific protection of leaf proteins against thermal aggregation. The transgenic wheat displayed a single-gene pattern of segregation of Zmeftu1. Zmeftu1 was expressed, and the transgenic plants synthesized and accumulated three anti-EF-Tu cross-reacting polypeptides of similar molecular mass but different pI, suggesting the possibility of posttranslational modification of this protein. The transgenic plants also showed better grain yield after exposure to heat stress compared with their non-transgenic counterparts. Soluble leaf proteins of various molecular masses displayed lower thermal aggregation in transgenic than in non-transgenic wheat. The results suggest that overexpression of chloroplast EF-Tu can be beneficial to wheat tolerance to heat stress. Moreover, the results also support the hypothesis that EF-Tu contributes to heat tolerance by acting as a molecular chaperone and protecting heat-labile proteins from thermal aggregation in a non-specific manner.     

UV-B辐射增强对芦苇光合生理及叶绿体超微结构的影响

在UV-B辐照增强条件下,研究不同辐照梯度对芦苇光合特性、光合色素含量及叶绿体超微结构的影响. 结果表明: 与自然光照相比,UV-B辐照增强显著降低芦苇叶片净光合速率、气孔导度、蒸腾速率,且随辐照强度增大,降低程度加剧,胞间CO₂浓度升高,光合效率显著降低;与自然光照相比,UV-B辐照增强显著降低芦苇叶片光合色素含量(包括叶绿素a、叶绿素b、总叶绿素和类胡萝卜素),且随辐照强度增大,降低程度加剧;UV-B辐射增强条件下,叶绿体超微结构遭到破坏,表现为叶绿体结构变形,类囊体片层排列稀疏紊乱、膨胀甚至模糊不清,并且UV-B辐射强度越大,损伤越大,高强度UV-B辐射对叶绿体超微结构的影响大于低强度辐射.