花烛离体培养叶色变异株系的相关性状

以花烛（Anthurium andraeanum）间接器官发生途径中再生出的一株花叶变异植株为原始材料,进行增殖并对得到的3个叶色变异株系的叶色相关性状进行了初步研究。结果表明：通过愈伤组织器官发生途径和腋芽增殖途径对这一花叶苗进行增殖,均分离到3种变异株系,即花叶苗、黄化苗和天鹅绒绿色叶片苗;天鹅绒绿色苗叶片中的叶绿素含量比正常离体苗的含量低;叶片解剖结构表明,叶绿体在叶肉细胞中的分布与其叶片表现型相同,天鹅绒绿色叶片与正常叶片在解剖结构上无明显差异。花烛原套只具有1层细胞,无明显的L2层分生结构,因此叶肉的薄壁细胞完全由向各个方向分裂的原体细胞发育而来,这种组织结构导致花叶叶片中含有叶绿体的细胞和不含有叶绿体的薄壁细胞呈不规则分布。这种花叶株系可以作为育种材料或直接作为盆栽花烛进行推广。     

花烛离体培养叶色变异株系的相关性状

以花烛(Anthurium andraeanum)间接器官发生途径中再生出的一株花叶变异植株为原始材料, 进行增殖并对得到的3个叶色变异株系的叶色相关性状进行了初步研究。结果表明: 通过愈伤组织器官发生途径和腋芽增殖途径对这一花叶苗进行增殖, 均分离到3种变异株系, 即花叶苗、黄化苗和天鹅绒绿色叶片苗; 天鹅绒绿色苗叶片中的叶绿素含量比正常离体苗的含量低; 叶片解剖结构表明, 叶绿体在叶肉细胞中的分布与其叶片表现型相同, 天鹅绒绿色叶片与正常叶片在解剖结构上无明显差异。花烛原套只具有1层细胞, 无明显的L2层分生结构, 因此叶肉的薄壁细胞完全由向各个方向分裂的原体细胞发育而来, 这种组织结构导致花叶叶片中含有叶绿体的细胞和不含有叶绿体的薄壁细胞呈不规则分布。这种花叶株系可以作为育种材料或直接作为盆栽花烛进行推广。     

气生凤梨叶片结构研究

我们以地生凤梨(Guzmnania‘Denise’)作为对照,利用扫描电镜技术、石蜡切片技术对3种气生凤梨(Til-landsia stricta‘Hard leaf’、T.stricta‘Cotton candy’与T.filifolia)的叶片表面和内部结构进行了研究。结果表明所有凤梨叶片表面均分布着葵花状的鳞片,鳞片由碟状细胞、环状细胞和翼状细胞3类细胞构成,最内部的碟状细胞通过柄状细胞与叶片内部的叶肉细胞相连。气生凤梨叶片表面鳞片白色、蜡质、密度很大,但气孔很少或不可见,暗示鳞片除吸收水分和养分外,还可能具有减少光呼吸、排水及反射阳光等功能。另外,不同的气生凤梨之间叶片表面鳞片的形态、大小和密度也不同,反映了它们对其不同起源地及现生存环境的适应。     

NaCl胁迫对5个桂花品种叶片超微结构的影响

该研究以5个桂花品种为材料,以Hoagland培养液为对照,设计2个NaCl含量(70、100 mmol/L)处理10 d后利用透射电镜和扫描电镜观察各处理不同品种的叶片超微结构特征,以明确桂花品种对耐NaCl胁迫的解剖结构响应机制。结果显示：(1)透射电镜观察发现：随NaCl 胁迫程度的加强,5个桂花品种叶肉细胞中叶绿体结构受到不同程度地破坏;70 mmol/L NaCl处理后,5个品种的细胞核基本保持正常,而100 mmol/L NaCl处理后核内染色质发生降解;随着NaCl胁迫程度的加强,5个桂花品种的类囊体片层结构中嗜锇颗粒明显增多;在膜结构方面,大叶银桂的叶肉细胞被破坏程度最为严重,叶绿体膜被破坏,叶绿体形状基本不能辨认。(2)扫描电镜观察结果显示：随着NaCl浓度的增大,5个品种叶片表面的气孔密度不断增大,而张开气孔的密度却不断减小,且叶肉细胞体积均缩小;‘大叶银桂’、‘笑秋风’、‘晚籽银桂’的栅栏组织占叶厚的比重随NaCl胁迫浓度的增大而升高,‘潢川金桂’和‘紫梗籽银桂’的栅栏组织占叶厚的比重则随NaCl胁迫浓度的增大而呈先升高后降低的趋势。研究表明,NaCl胁迫对桂花叶片细胞叶绿体、细胞核等的超微结构会造成损伤,且NaCl胁迫浓度越高损伤越明显。该试验可初步判断‘大叶银桂’、‘笑秋风’、‘晚籽银桂’的耐盐性略高于‘潢川金桂’和‘紫梗籽银桂’。     

大麦和玉米叶片叶绿体中Rubisco及其活化酶的免疫金标记定位

运用免疫金标记电镜技术研究了禾本科C3植物大麦(Hordeum vulgare L.)和C4植物玉米(Zea mays L.)叶片中Rubisoo及其活化酶(RCA)的细胞定位,结果表明:两种植物叶片解剖结构及叶绿体超微结构差别明显.在大麦叶细胞中,只有一种叶肉细胞叶绿体,Rubisoo和RCA主要分布于叶绿体的间质中.在玉米叶细胞中,存在着维管束鞘细胞和叶肉细胞两种类型叶绿体,Rubisco主要分布于鞘细胞叶绿体的基质中,但在叶肉细胞叶绿体中亦有少量特异性标记;RCA在鞘细胞叶绿体和叶肉细胞叶绿体的基质中都有分布.两种植物叶绿体结构及光合作用关键酶定位的不同,体现了C3植物和C4植物在光合器结构与功能上的差异.     

盐胁迫对玉米叶片叶肉细胞生物膜超微结构的影响

研究了NaCl胁迫对玉米叶肉细胞生物膜超微结构的影响. 结果表明：NaCl胁迫破坏了玉米叶片叶肉细胞生物膜的正常结构,50 mmol·L^-1 NaCl处理胁迫下,玉米叶肉细胞核膜,线粒体膜,细胞膜,叶绿体膜,液泡膜都受到不同程度的破坏,叶绿体基粒类囊体膨胀,间质片层空间增大,片层紊乱。100 mmol·L^-1 NaCl处理胁迫下,质膜,液泡膜,线粒体,叶绿体都受到严重的破坏。细胞质膜破坏,破损的叶绿体充斥在细胞间隙中;叶绿体外膜破坏,甚至解体消失,叶肉细胞中充满膜结构,基粒排列方向改变,垛叠层数减少,基粒和基质片层界限模糊不清,有的基粒解体消失,甚至叶绿体完全解体;核膜破坏、解体,核中的染色质高度凝缩;线粒体的数量增多,线粒体膜破坏,脊的数量减少,甚至整个线粒体破损解体;液泡膜破坏;由于各种生物膜的破坏,使细胞内充满许多囊状小泡、多泡体或斑层小体;叶肉细胞发生严重的质壁分离,严重时发生细胞壁断裂;甚至整个细胞溶解。     

杂交兰‘紫妍氏’叶艺性状的生理生化与细胞结构分析

该研究以杂交兰‘紫妍氏’(K21)及其3个叶色变异(叶艺)新品系(K21-1、K21-2、K21-3)为材料,分析叶片光合色素含量、叶绿素合成前体物质含量、叶绿素合成相关酶活性及叶绿素荧光参数变化,并进一步观察叶片显微结构和叶绿体超微结构,以探讨其叶色变异的生理基础。结果表明:(1)3个叶艺品系叶片叶艺区域的叶绿素a、叶绿素b、类胡萝卜素含量均显著低于其相应的绿色区域和亲本绿叶;相较于相应的叶片绿色区域,K21-1、K21-2叶片叶艺区域的UrogenⅢ大量积累,K21-3叶片叶艺区域的PBG大量积累;3个叶艺品系叶片叶艺区域中的光系统Ⅱ最大光化学效率(F_v/F_m)和实际光化学效率[Y(Ⅱ)]均显著低于叶片绿色区域,三者的光化学淬灭系数(qP)则显著高于叶片绿色区域。(2)在显微结构和叶绿体超微结构比较中,相较于叶片绿色区域,叶片叶艺区域的细胞中含较少的叶绿体,且叶绿体的发育成熟程度较低,其中K21-3呈现出一种空腔化的结构。研究推测,叶绿素前体物质合成受阻、叶绿体结构发育不良和叶绿素含量下降是杂交兰3个叶艺品系叶艺形成的原因。该研究从生理和细胞层面初步解释了杂交兰叶艺形成的可能原因,为进一步开展相关分子机理研究及合理利用种质资源奠定了理论基础。     

光合磷酸化偶联机制的研究——C_4植物鞘细胞与叶肉细胞叶绿体光合磷酸化与高能态的关系

用去除类囊体膜内外质子梯度(⊿H~+)的解联剂氯化铵(NH_4Cl)或尼日利亚菌素(nigericin+KCl),以及去除膜电位(⊿φ)的载离子体短杆菌肽(gramicidin D)和缬氨霉素(valinomycin+KCl)等解联剂,观察和比较了它们对玉米鞘细胞和叶肉细胞叶绿体光合磷酸化(PSP)反应的影响。在恒态照光下,发现氯化铵对叶肉细胞叶绿体光合磷酸化反应的抑制作用比鞘细胞叶绿体光合磷酸化反应要强烈得多。gramicidla D对这两种叶绿体的作用与NH_4Cl作用则相反,它对鞘细胞叶绿体磷酸化反应的抑制远比对叶肉细胞叶绿体磷酸化反应的抑制作用强烈。缬氨霉素对叶肉细胞叶绿体PSP活力无显著的影响,但对鞘细胞叶绿体PSP活力有明显的抑制作用。说明在恒态下这种叶肉细胞叶绿体的PSP反应中驱使ATP形成的PMF主要由(⊿H~+)组成,鞘细胞叶绿体中推动ATP形成的PMF主要组成为⊿φ。叶肉细胞叶绿体在氯化铵和短杆菌肽共同作用下它的PSP反应几乎完全被抑制,而鞘细胞叶绿体的PSP反应还残留为对照的23％。在⊿H~+和⊿φ完全消失的情况下,鞘细胞叶绿体仍能形成相当数量的ATP。这种现象再次说明可能还有一种不以膜内外势差(⊿H~+,⊿φ)形式的膜上高能态存在,这种高能态可直接推动ATP形成。     

CO2加富对丹尼斯凤梨(Guzmania ‘Denise’)叶片显微超微结构的影响

对CO2大气浓度(ck:360±30μmol.mol-1)和CO2加富(T1:600±40μmol.mol-1,T2:900±40μmol.mol-1)条件下,丹尼斯凤梨(Guzmania‘Denise’)叶片的显微和超微结构等进行了比较研究。在透射电镜下的观测结果表明:CO2加富可促进丹尼斯凤梨叶片叶肉厚度的增加,叶绿体与叶绿体中淀粉粒数量增多、体积增大,而叶绿体光合膜的结构却受到很大破坏。     

保卫细胞的光合作用在光调节的气孔运动中的功能

本文介绍植物叶片上保卫细胞中叶绿体在光诱导气孔开放过程中的作用等研究进展,并对叶肉细胞中的光合作用与气孔运动之间的关系也作简要分析和讨论。     

Gibberellin indirectly promotes chloroplast biogenesis as a means to maintain the chloroplast population of expanded cells

Chloroplast biogenesis needs to be well coordinated with cell division and cell expansion during plant growth and development to achieve optimal photosynthesis rates. Previous studies showed that gibberellins (GAs) regulate many important plant developmental processes, including cell division and cell expansion. However, the relationship between chloroplast biogenesis with cell division and cell expansion, and how GA coordinately regulates these processes, remains poorly understood. In this study, we showed that chloroplast division was significantly reduced in the GA‐deficient mutants of Arabidopsis (ga1‐3) and Oryza sativa (d18‐AD), accompanied by the reduced expression of several chloroplast division‐related genes. However, the chloroplasts of both mutants exhibited increased grana stacking compared with their respective wild‐type plants, suggesting that there might be a compensation mechanism linking chloroplast division and grana stacking. A time‐course analysis showed that cell expansion‐related genes tended to be upregulated earlier and more significantly than the genes related to chloroplast division and cell division in GA‐treated ga1‐3 leaves, suggesting the possibility that GA may promote chloroplast division indirectly through impacting leaf mesophyll cell expansion. Furthermore, our cellular and molecular analysis of the GA‐response signaling mutants suggest that RGA and GAI are the major repressors regulating GA‐induced chloroplast division, but other DELLA proteins (RGL1, RGL2 and RGL3) also play a role in repressing chloroplast division in Arabidopsis. Taken together, our data show that GA plays a critical role in controlling and coordinating cell division, cell expansion and chloroplast biogenesis through influencing the DELLA protein family in both dicot and monocot plant species.     

A putative plastidial adenine nucleotide transporter,BRITTLE1-3, plays an essential role in regulating chloroplast development in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

Differentiation from proplastids into chloroplasts is a light- and energy-dependent process. How this process is regulated is still poorly understood at the molecular level. We herein report a new putative plastidial adenine nucleotide transporter, BRITTLE1-3 (referred to as OsBT1-3), encoded by the rice (Oryza sativa) White Stripe Leaf 2 (WSL2) gene. Loss of OsBT1-3 function results in defective chloroplast biogenesis, severely reduced photosynthetic efficiency, and finally a white stripe leaf phenotype in the first four leaves. The expression levels of genes related to chlorophyll biosynthesis and photosynthesis are drastically reduced, accompanied with over accumulation of reactive oxygen species (ROS) in the wsl2 mutant. OsBT1-3 is targeted to the chloroplasts and it expresses in almost all tissues in plants, especially in young leaves. OsBT1-3 consists of 419 amino acids and exhibits features of all mitochondrial carrier proteins, including a typical transmembrane-spanning domain and a highly conserved sequence motif designated as the ‘mitochondrial energy transfer signatures’. Phylogenetic analysis shows that OsBT1-3 is a putative plastidial adenine nucleotide transporter and is most closely related to ZmBT1-2. Together, these observations suggest that the new putative adenine nucleotide transporter, OsBT1-3, plays an essential role in regulating chloroplast biogenesis and maintenance of ROS homeostasis during rice seedling de-etiolation.     

Effects of light quality on the chloroplastic ultrastructure and photosynthetic characteristics of cucumber seedlings

To understand how light quality influences plant photosynthesis, we investigated chloroplastic ultrastructure, chlorophyll fluorescence and photosynthetic parameters, Rubisco and chlorophyll content and photosynthesis-related genes expression in cucumber seedlings exposed to different light qualities: white, red, blue, yellow and green lights with the same photosynthetic photon flux density of 100 μmol m^?2 s^?1. The results revealed that plant growth, CO₂ assimilation rate and chlorophyll content were significantly reduced in the seedlings grown under red, blue, yellow and green lights as compared with those grown under white light, but each monochromatic light played its special role in regulating plant morphogenesis and photosynthesis. Seedling leaves were thickened and slightly curled; Rubisco biosynthesis, expression of the rca, rbcS and rbcL, the maximal photochemical efficiency of PSII (Fv/Fm) and quantum yield of PSII electron transport (Ф_PSII) were all increased in seedlings grown under blue light as compared with those grown under white light. Furthermore, the photosynthetic rate of seedlings grown under blue light was significantly increased, and leaf number and chlorophyll content of seedlings grown under red light were increased as compared with those exposed to other monochromatic lights. On the contrary, the seedlings grown under yellow and green lights were dwarf with the new leaves etiolated. Moreover, photosynthesis, Rubisco biosynthesis and relative gene expression were greatly decreased in seedlings grown under yellow and green light, but chloroplast structural features were less influenced. Interestingly, the Fv/Fm, Ф_PSII value and chlorophyll content of the seedlings grown under green light were much higher than those grown under yellow light.     

Impaired Chloroplast Biogenesis in Immutans,an Arabidopsis Variegation Mutant,Modifies Developmental Programming,Cell Wall Composition and Resistance to Pseudomonas syringae

The immutans (im) variegation mutation of Arabidopsis has green- and white- sectored leaves due to action of a nuclear recessive gene. IM codes for PTOX, a plastoquinol oxidase in plastid membranes. Previous studies have revealed that the green and white sectors develop into sources (green tissues) and sinks (white tissues) early in leaf development. In this report we focus on white sectors, and show that their transformation into effective sinks involves a sharp reduction in plastid number and size. Despite these reductions, cells in the white sectors have near-normal amounts of plastid RNA and protein, and surprisingly, a marked amplification of chloroplast DNA. The maintenance of protein synthesis capacity in the white sectors might poise plastids for their development into other plastid types. The green and white im sectors have different cell wall compositions: whereas cell walls in the green sectors resemble those in wild type, cell walls in the white sectors have reduced lignin and cellulose microfibrils, as well as alterations in galactomannans and the decoration of xyloglucan. These changes promote susceptibility to the pathogen Pseudomonas syringae. Enhanced susceptibility can also be explained by repressed expression of some, but not all, defense genes. We suggest that differences in morphology, physiology and biochemistry between the green and white sectors is caused by a reprogramming of leaf development that is coordinated, in part, by mechanisms of retrograde (plastid-to-nucleus) signaling, perhaps mediated by ROS. We conclude that variegation mutants offer a novel system to study leaf developmental programming, cell wall metabolism and host-pathogen interactions.     

基于联合测序分析技术挖掘红苞凤梨lncRNA信息

为了揭示lncRNA在红苞凤梨嵌合叶片形成和生长发育过程中的调控作用机制,该文以金边红苞凤梨为材料,采用Hiseq2500测序和SMRT三代全长转录组测序联合测序分析技术,分析挖掘红苞凤梨lncRNA信息。结果表明:(1)鉴定得到6 018条lncRNA,包含3 298个基因间lncRNA,870个反义lncRNA,717个内含子lncRNA和1 109个正义lncRNA,数据量较二代测序有了极大的提高。(2)结构分析表明,红苞凤梨lncRNA的总体表达丰度低于mRNA;序列长度在400~1 200 nt区间比例高于mRNA,而在1 600 nt区间,lncRNA分布的比例显著小于mRNA; lncRNA中的外显子数量总体少于mRNA,开放阅读框长度总体上也短于mRNA。(3)差异表达分析表明,在全绿、全白叶片发育过程中鉴定到1 710个差异表达lncRNA。(4)靶基因预测结果表明,5 441个lncRNA通过cis作用方式预测到靶基因,1 544个lncRNA通过trans方式预测到靶基因。(5)靶基因的功能注释和富集分析显示,差异表达lncRNA的靶基因主要作为酶蛋白参与调节叶片代谢活动和信号转导等方面,与叶片的颜色形成、光合作用和生长发育密切相关。该文鉴定出的lncRNA信息以及对其结构和功能的分析,为红苞凤梨以及凤梨科其他植物的lncRNA表观遗传调控机理研究提供了数据基础,筛选出的差异表达lncRNA在金边红苞凤梨叶片嵌合性状的形成和生长发育中具有重要的调控作用。     

OsHAP3 genes regulate chloroplast biogenesis in rice

We have isolated three genes that potentially encode a HAP3/nuclear factor-YB (NF-YB)/CCAAT binding factor-A (CBF-A) subunit of a CCAAT-box binding complex in rice (Oryza sativa), and named them OsHAP3A, OsHAP3B and OsHAP3C. These genes were expressed in various organs including leaves. In the transgenic rice plants with antisense or RNAi construct of OsHAP3A, reduced expression of not only OsHAP3A but also OsHAP3B and OsHAP3C was observed. These plants had pale green leaves, in which the amount of chlorophyll was reduced and chloroplasts were degenerated. Lamella was not well developed and accumulation of starch was not detected. The degenerated chloroplast formation was accompanied by reduced expression of nuclear-encoded photosynthesis genes such as RBCS and CAB, while expression of chloroplast-encoded genes was not affected or rather increased. These results suggest that one or more OsHAP3 genes regulate the expression of nuclear-encoded chloroplast-targeted genes and normal development of chloroplasts.