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。     

兰属、兜兰属、石斛属植物叶片的扫描电镜观察

对兰科植物的兰属、兜兰属及石斛属１６个种折叶片及其横断面进行了扫描电镜的观察。兰属各种叶片上表皮细胞均为矩形,上表皮细胞表面具小乳突或不明显突起。石斛属及兜兰属的各个种上下表皮细胞均为多边形,但石斛属表皮细胞表面无坦无纹饰,而兜兰属花叶类上表皮细胞表面明显呈乳突状,绿叶类呈龟背状隆起。兰属及石斛属叶片叶肉组织没有栅栏组织及海绵组织的分化,而兜兰属的绿叶类叶肉不分化;花叶类叶肉有分化。     

小麦低温种质的器官结构特征

通过对小麦冠层温度的长期观测,发现自然界存在株温持续偏低的低温种质,与其相对应,也有株温持续偏高的高温种质存在。应用光学显微镜和电子显微镜研究了小麦低温种质叶片显微和超微结构,测量统计了叶肉细胞长度、单位面积叶肉细胞数目、单个叶肉细胞中的叶绿体数目、叶肉细胞层数和叶绿体基粒片层数。结果表明,低温小麦种质较高温种质叶肉细胞小,排列紧密,叶肉细胞层数较多;叶绿体数量多,叶绿体基粒片层丰富;叶片维管束密集;随着生育期向成熟趋近,叶肉细胞、叶绿体、籽粒腹沟区有色层细胞等结构衰老缓慢。     

扇叶铁线蕨叶片对岩溶环境的生态适应

地理环境的不同造就了植物不同的适生机制。本研究对岩溶区和非岩溶区的扇叶铁线蕨(Adiantum flabellulatum)的叶片进行了比较, 结果表明, 二者在显微结构和亚显微结构方面都存在明显区别。在显微结构方面: 岩溶区生长的扇叶铁线蕨的叶片具有旱生植物叶片特点, 即叶片为等面叶, 叶肉细胞排列较 为紧密以及叶片维管组织发达等; 而非岩溶区生长的扇叶铁线蕨的叶片为异面叶, 特点为叶肉细胞排列相对疏松, 维管组织不发达。扫描电镜分析显示: 非岩溶区扇叶铁线蕨叶片表面具有很多明显的凹槽状结构, 而岩溶区扇叶铁线蕨的叶片与之有明显不同, 其叶片表面特别是叶脉位置具有明显的刺状结构, 超 薄切片发现这些刺状膨大部分细胞内存在液泡结构, 并且这些刺状结构在叶片抽真空的过程中变瘪, 说明这些刺状结构可能具有储存水分的功能。岩溶区扇叶铁线蕨特有的显微和亚显微结构保证了该种植物在岩溶干旱环境中可以正常生长。     

扇叶铁线蕨叶片对岩溶环境的生态适应

地理环境的不同造就了植物不同的适生机制。本研究对岩溶区和非岩溶区的扇叶铁线蕨（Adiantum flabellulatum）的叶片进行了比较,结果表明,二者在显微结构和亚显微结构方面都存在明显区别。在显微结构方面：岩溶区生长的扇叶铁线蕨的叶片具有旱生植物叶片特点,即叶片为等面叶,叶肉细胞排列较为紧密以及叶片维管组织发达等：而非岩溶区生长的扇叶铁线蕨的叶片为异面叶,特点为叶肉细胞排列相对疏松,维管组织不发达。扫描电镜分析显示：非岩溶区扇叶铁线蕨叶片表面具有很多明显的凹槽状结构,而岩溶区扇叶铁线蕨的叶片与之有明显不同,其叶片表面特别是叶脉位置具有明显的刺状结构,超薄切片发现这些刺状膨大部分细胞内存在液泡结构,并且这些刺状结构在叶片抽真空的过程中变瘪,说明这些刺状结构可能具有储存水分的功能。岩溶区扇叶铁线蕨特有的显微和亚显微结构保证了该种植物在岩溶干旱环境中可以正常生长。     

烟草质体分裂相关基因NtFtsZ1和NtFtsZ2对叶绿体分裂和形态的影响

质体作为植物细胞中一类重要的细胞器,控制其分裂的分子机制一直都不清楚。最近的研究表明,植物细胞中与原核细胞分裂基因fisZ类似的同源基因控制着质体的分裂过程。通过正反义转化分析了两个烟草的ftsZ基因（NtFtsZ1和NtFtsZ2)在转基因烟草中的功能。二的反义表达并未对转化烟草细胞中叶绿体的分裂和形态产生明显影响,但二过表达转化植株中叶绿体的数目和形态都发生了明显的变化,在某些转化植株的叶肉细胞中甚至只有1－2个巨大的叶绿体存在。对不同转化植株的电镜观察和叶绿素含量分析认为,NtFtsZs基因可能对叶绿体的正常发育和功能没有影响,叶绿体形态的变化是对其数目减少的一种补偿。正反义转化植株中叶绿体的不同表型暗示高等植物中同一家族的ftsZ基因可能在控制质体分裂方面具有相同的功能。同时,过表达植株中叶绿体形态的变化被认为是高等植物的FtsZ质体骨架功能的体现。     

光强对人参叶片显微和超微结构的影响

在５％、２０％和３５％３种透光率棚下,人参叶片的比叶重、叶厚度,单位叶面积的叶肉细胞数目,叶肉细胞表面积和细胞层数随着光强的增加而增加,５０％透光率棚下叶片开始减少,５％和２０％透光率棚下叶片叶肉细胞主要呈横向排列,胞间隙较大,３５％透光率棚下叶片叶肉细胞排列致密,胞间隙变小,靠近上一有皮形成一层呈纵向排列的栅栏状细胞;５０５透光率棚下叶片叶肉细胞为大而圆形,胞间隙变大,排列也不规则。５％透光率棚     

烟草质体分裂相关基因NtFtsZ1和NtFtsZ2对叶绿体分裂和形态的影响

质体作为植物细胞中一类重要的细胞器,控制其分裂的分子机制一直都不清楚.最近的研究表明,植物细胞中与原核细胞分裂基因ftsZ类似的同源基因控制着质体的分裂过程.通过正反义转化分析了两个烟草的ftsZ基因(NtFtsZ1和NtFtsZ2)在转基因烟草中的功能.二者的反义表达并未对转化烟草细胞中叶绿体的分裂和形态产生明显影响,但二者过表达转化植株中叶绿体的数目和形态都发生了明显的变化,在某些转化植株的叶肉细胞中甚至只有1～2个巨大的叶绿体存在.对不同转化植株的电镜观察和叶绿素含量分析认为,NtFtsZs基因可能对叶绿体的正常发育和功能没有影响,叶绿体形态的变化是对其数目减少的一种补偿.正反义转化植株中叶绿体的不同表型暗示高等植物中同一家族的ftsZ基因可能在控制质体分裂方面具有相同的功能.同时,过表达植株中叶绿体形态的变化被认为是高等植物FtsZ质体骨架功能的体现.     

辣椒彩色斑叶突变体叶片显微结构及超微结构研究

以彩色斑叶辣椒突变体、紫叶辣椒、白色斑叶辣椒突变体功能叶为试验材料,利用光学显微镜和透射电子显微镜,通过观察叶片不同斑区的显微结构及超微结构,分析彩色斑叶的显色部位、显色特征、细胞器数量及形态变化,从细胞水平上探讨彩色斑叶辣椒复杂叶色的成因。结果表明：(1)彩色斑叶辣椒突变体子叶为紫色,自第一片真叶展开出现异色斑块,斑块位置、频率、色彩深度无明显规律。(2)叶肉细胞内叶绿体少甚至缺失形成白斑,花色素苷在叶肉细胞和保卫细胞均有分布,其在叶肉细胞不均匀分布是紫色深度不同的主因。(3)辣椒彩色斑叶突变体绿斑区内细胞形态良好,细胞器结构较好;紫色斑区和白色斑区细胞呈中度肿胀,细胞器明显异常。(4)叶肉细胞内叶绿体少甚至缺失、花色素苷不均匀分布是叶片呈现彩色的原因,该叶斑类型属于色素型。     

Expression of soybean nodulin 26 in transgenic tobacco. Targeting to the vacuolar membrane and effects on floral and seed development.

Nodulin 26 is an integral membrane protein of the symbiosome membrane of nitrogen-fixing soybean nodules. We expressed a nodulin 26 cDNA in transgenic tobacco (TN26 tobacco) under the control of the cauliflower mosaic virus 35S promoter to study subcellular targeting and the physiological effect(s) of its expression. Based on Northern and Western blots, the expression of nodulin 26 mRNA and protein in transgenic plants is high in apical shoot sections, flowers, and stems, low in mature leaves, and absent in roots. Western blot analysis revealed high levels of transgenic nodulin 26 protein in tonoplast membranes. In contrast, nodulin 26 protein was not found in isolated plasma membranes, the soluble fraction, nor in chloroplast and mitochondria-enriched membrane fractions. About 50-60% of the flowers and pods from TN26 tobacco plants abscised prematurely. Seed capsule size and seed fill per capsule from the remainder of surviving flowers were about 50% of that of control plants. Pollen viability was found to be normal, but flowers from TN26 tobacco plants showed shorter anther filaments compared with control plants. Normal seed production and capsule size was restored by manually crossing the stigmas from TN26 plants with isolated pollen from either transgenic or control plants. Thus, the aberrant filament growth could have resulted in the reproductive defects associated with the plants.     

Down-regulation of TM29, a tomato SEPALLATA homolog,causes parthenocarpic fruit development and floral reversion

We have characterized the tomato (Lycopersicon esculentum Mill.) MADS box gene TM29 that shared a high amino acid sequence homology to the Arabidopsis SEP1, 2, and 3 (SEPALLATA1, 2, and 3) genes. TM29 showed similar expression profiles to SEP1, with accumulation of mRNA in the primordia of all four whorls of floral organs. In addition, TM29 mRNA was detected in inflorescence and vegetative meristems. To understand TM29 function, we produced transgenic tomato plants in which TM29 expression was down-regulated by either cosuppression or antisense techniques. These transgenic plants produced aberrant flowers with morphogenetic alterations in the organs of the inner three whorls. Petals and stamens were green rather than yellow, suggesting a partial conversion to a sepalloid identity. Stamens and ovaries were infertile, with the later developing into parthenocarpic fruit. Ectopic shoots with partially developed leaves and secondary flowers emerged from the fruit. These shoots resembled the primary transgenic flowers and continued to produce parthenocarpic fruit and additional ectopic shoots. Based on the temporal and spatial expression pattern and transgenic phenotypes, we propose that TM29 functions in floral organ development, fruit development, and maintenance of floral meristem identity in tomato.     

Phenotypic effects of overexpression of Agrobacterium rhizogenes T-DNA ORF13 in transgenic tobacco plants are mediated by diffusible factor(s)

Nicotiana tabacum cv. Xanthi transgenic plants expressing ORF13 of Agrobacterium rhizogenes 8196 T-DNA under the 35S RNA promoter from the cauliflower mosaic virus displayed developmental abnormalities. They were small, with short and variable internodal lengths, their root systems were poorly developed; leaves were small, asymmetric, rounded, wrinkled and dark green; flowers were short, and irregularly shaped. They exhibited reduced apical dominance and regularly produced offshoots at the base of the plant. This phenotype was also exhibited by offshoots of normal N. tabacum cv. Xanthi stock grafted with a transgenic scion indicating that expression of ORF13 influences plant development via diffusible factor(s).     

Reorganization of the chloroplast thylakoid system during decay of acquired thermotolerance of photosynthesis and aging of wheat leaves

A 3 hours heating at 39 degrees C of 14-day old wheat plants increases the termotolerance of photosynthesis, and also the length and number of thylakoids in chloroplast in mature leaves. The acquired termotolerance disappears within 10 days. Simultaneously the intensity of photosynthesis and the length of thylakoids decrease. Reduction of photosynthesis ability and of thylakoid membranes occurs in the first leaves of non-hardened plants during 14-29 days after sowing. The intensity of photosynthesis in plants of both variants positively correlates with the length of grana membranes and with the total length of membranes of all thylakoids. Besides, a positive correlation was detected between the intensity of photosynthesis and the share of small (2-7 thylakoids) grana and the length of their membranes in non-hardened plants. The level of thermotolerance of photosynthesis in leaves in heat hardened plants correlates positively with the length of grana membranes and with the total length of all thylakoid membranes and the share of small grana.     

Engineering cytoplasmic male sterility via the chloroplast genome by expression of {beta}-ketothiolase

While investigating expression of the polydroxybutyrate pathway in transgenic chloroplasts, we addressed the specific role of beta-ketothiolase. Therefore, we expressed the phaA gene via the chloroplast genome. Prior attempts to express the phaA gene in transgenic plants were unsuccessful. We studied the effect of light regulation of the phaA gene using the psbA promoter and 5' untranslated region, and evaluated expression under different photoperiods. Stable transgene integration into the chloroplast genome and homoplasmy were confirmed by Southern analysis. The phaA gene was efficiently transcribed in all tissue types examined, including leaves, flowers, and anthers. Coomassie-stained gel and western blots confirmed hyperexpression of beta-ketothiolase in leaves and anthers, with proportionately high levels of enzyme activity. The transgenic lines were normal except for the male-sterile phenotype, lacking pollen. Scanning electron microscopy revealed a collapsed morphology of the pollen grains. Floral developmental studies revealed that transgenic lines showed an accelerated pattern of anther development, affecting their maturation, and resulted in aberrant tissue patterns. Abnormal thickening of the outer wall, enlarged endothecium, and vacuolation affected pollen grains and resulted in the irregular shape or collapsed phenotype. Reversibility of the male-sterile phenotype was observed under continuous illumination, resulting in viable pollen and copious amount of seeds. This study results in the first engineered cytoplasmic male-sterility system in plants, offers a new tool for transgene containment for both nuclear and organelle genomes, and provides an expedient mechanism for F(1) hybrid seed production.     

The Commelina Yellow Mottle Virus Promoter Is a Strong Promoter in Vascular Tissue of Transgenic Gossypium hirsutum Plants

Explants of cotton (Gossypium hirsutum L. cv. Jingmian 7) were transformed with Agrobacterium tumefaciens (Smith et Townsend ) Conn LBA4404 harboring an expression cassette composed of CoYMV (Commelina Yellow Mottle Virus) promoter-gus-nos terminator on the plant expression vector pBcopd2. Transgenic plants were regenerated and selected on a medium containing kanamycin. GUS (β-glucuronidase) activity assays and Southern blot analysis confirmed that the chimerical gus gene was integrated into and expressed in the regenerated cotton plants. Plant expression vector pBI121 was also transferred into the same cotton variety and the regenerated transgenic plants were used as a positive control in GUS activity analysis. Evidences from histochemical analysis of GUS activity demonstrated that under the control of a 597 bp CoYMV promoter the gus gene was highly expressed in the vascular tissues of leaves, petioles, stems, roots, hypocotyls, bracteal leaves and most of the flower parts while GUS activity could not be detected in stigma, anther sac and developing cotton fibers of the transgenic cotton plants. GUS specific activity in various organs and tissues from transgenic cotton lines was determined and the results indicated that the CoYMV promoter-gus activities were at the same level or higher than that of CaMV 35S promoter-gus in leaf veins and roots where the vascular tissues occupy a relatively larger part of the organs, but in other organs like leaves, cotyledons and hypocotyls where the vascular tissues occupy a smaller part of the organs the CoYMV promoter-gus activity was only 1/3-1/5 of the CaMV 35S promoter-gus activity. The GUS activity ratio between veins and leaves was averaged 0.5 for 35S-GUS plants and about 2.0 for CoYMV promoter-gus transgenic plants. These results further demonstrated the vascular specific property of the promoter in transgenic cotton plants. An increasing trend of GUS activity in leaf vascular tissues of transgenic cotton plants developing from young to older was observed.     

拟南芥AtLH基因过量表达引起叶向下性卷曲和晚开花

AtLH基因是BcpLH基因在拟南芥(Arapsis thaliana L.)中的同源基因,含有两个编码双链RNA结合蛋白的结构域.在大白菜叶球发育过程中,BcpLH基因与包叶的卷曲有关.为研究AtLH的基因对叶卷曲这一重要生物学现象的调控作用,构建了35S:AtLH基因的正义表达载体并转化拟南芥.与野生型比较页言,转基因植株的花和叶中AtLH的表达量有显著增加,成为AtLH基因过量的植株.这些植株的莲座叶向外或向下卷曲,呈现明显的偏上性生长;而且抽苔和开花时间延迟;在营养生长期其短缩茎的叶腑处着生数个侧茎,表现为顶端优势减弱;在生殖生长期二级花序减少使得主花序更加发达,表现为顶端优势增强,转基因植株对激素的敏感性改变,IAA剌激根生长的作用增强,ABA抑制根生长的作用减弱.由此可见,AtLH基因的过量表达可引起转基因植株的叶片向下卷曲.