冬小麦幼苗中玉米赤霉烯酮的免疫组织学定位

应用免疫组化方法结合共聚焦激光扫描显微技术,研究了小麦春化幼苗的根尖和茎尖中玉米赤霉烯酮的存在及分布。结果表明,玉米赤霉烯酮在根中集中存在于根尖最前端约1mm长的区域,即根冠和分生组织区,至伸长区逐渐减少。在茎尖中,生长锥下方的分蘖节中的玉米赤霉烯酮含量很高,与生长锥相邻的叶原基内侧也有较高量的分布。顶端分生区的荧光反应较弱,侧芽(分蘖)原基呈负反应。     

植物茎端分生组织CLV/WUS信号途径的研究进展

高等植物的最终形态主要依赖于茎端分生组织的发育调控,拟南芥CLV/WUS途径是茎端分生组织最重要的调控机制之一。CLV途径促进器官发生,WUS途径诱导分生组织细胞增殖,它们构成了负反馈调节环,保证了拟南芥分生组织的正常增殖与分化。利用突变体基因克隆和系统发育比较,证实了CLV和WUS的同源基因也存在于以水稻和玉米为代表的禾本科作物中,说明CLV/WUS信号途径在禾本科作物中很可能是保守的。由于禾本科作物茎端分生组织的发育最终关系到作物的产量和品质,因此,深入研究禾本科作物的CLV/WUS信号途径将有助于禾本科作物的遗传改良。     

美洲黑杨木质素生物合成转录因子PdLiml基因的克隆、表达及植物表达载体构建

在植物体内,Liml基因与木质素生物合成酶基因启动子区域富含AC的Pal盒结合,转录调控木质素的生物合成过程.该研究组合利用生物信息学和realtime PCR方法,首次从美洲黑杨形成层cDNA中分离出PdLimlcDNA全长,并进行了测序和序列分析.结果表明,克隆的美洲黑杨PdLimlcDNA片段总长为952 bp,基因内部含有完整的开放阅读框架,大小为594 bp,可编码长度为197个氨基酸残基的蛋白质,所推导的蛋白质氨基酸序列与拟南芥AtLiml和水稻OsLiml蛋白的同源性分别为82.1%和78.2%.组织特异性realtime PCR结果显示,PdLiml基因在场树根、茎、叶片和顶端分生组织中均有表达,但其表达模式却不同:PdLiml在成熟叶片和成熟木质部中表达丰度最高,在树皮、根部、韧皮部和形成层表达丰度较高,在未成熟木质部有少量表达,在顶端分生组织中表达丰度最低.在此基础上,以pBI121为表达载体,构建了在CaMV35S启动子驱动下,PdLiml基因的正义(pBI121-CaMV35S-sensePdLiml)和反义(pBI121-CaMV35S-antisense PdLiml)类型的双元植物表达载体.该研究为杨树PdLiml的基因工程改良木材纤维品质性状提供了重要的理论依据,具有潜在的应用价值.     

拟南芥干旱敏感突变体的筛选及其对干旱胁迫的响应

采用质量浓度为5 g/L的PEG - 6000进行渗透胁迫,利用弯根法筛选拟南芥T-DNA插入突变体库,得到干旱敏感突变体36 -1.该突变体在PEG - 6000渗透胁迫下,种子萌发率、根系长度均低于野生型;盆栽试验表明:水分正常条件下,突变体36 -1与野生型幼苗形态、根冠比、叶片含水量等并无明显差异;干旱条件下,...     

Arabidopsis CLV3 peptide directly binds CLV1 ectodomain

CLV1, which encodes a leucine-rich repeat receptor kinase, and CLV3, which encodes a secreted peptide, function in the same genetic pathway to maintain stem cell populations in Arabidopsis shoot apical meristem. Here, we show biochemical evidence, by ligand binding assay and photoaffinity labeling, that the CLV3 peptide directly binds the CLV1 ectodomain with a dissociation constant of 17.5 nM. The CLV1 ectodomain also interacts with the structurally related CLE peptides, with distinct affinities depending on the specific amino acid sequence. Our results provide direct evidence that CLV3 and CLV1 function as a ligand-receptor pair involved in stem cell maintenance.     

Stem-cell homeostasis and growth dynamics can be uncoupled in the Arabidopsis shoot apex

The shoot apical meristem (SAM) is a collection of stem cells that resides at the tip of each shoot and provides the cells of the shoot. It is divided into functional regions. The central zone (CZ) at the tip of the meristem is the domain of expression of the CLAVATA3 (CLV3) gene, encoding a putative ligand for a transmembrane receptor kinase, CLAVATA1, active in cells of the rib meristem (RM), located just below the CZ. We show here that CLV3 restricts its own domain of expression (the CZ) by preventing differentiation of peripheral zone cells (PZ), which surround the CZ, into CZ cells and restricts overall SAM size by a separate, long-range effect on cell division rate.     

An optimized protocol using Steedman's wax for high-sensitivity RNA in situ hybridization in shoot apical meristems and flower buds of cucumber

In situ mRNA hybridization (ISH) is a powerful tool for examining the spatiotemporal expression of genes in shoot apical meristems and flower buds of cucumber. The most common ISH protocol uses paraffin wax; however, embedding tissue in paraffin wax can take a long time and might result in RNA degradation and decreased signals. Here, we developed an optimized protocol to simplify the process and improve RNA sensitivity. We combined embedding tissue in low melting-point Steedman's wax with processing tissue sections in solution, as in the whole-mount ISH method in the optimized protocol. Using the optimized protocol, we examined the expression patterns of the CLAVATA3 (CLV3) and WUSCHEL (WUS) genes in shoot apical meristems and floral meristems of Cucumis sativus (cucumber) and Arabidopsis thaliana (Arabidopsis). The optimized protocol saved 4–5 days of experimental period compared with the standard ISH protocol using paraffin wax. Moreover, the optimized protocol achieved high signal sensitivity. The optimized protocol was successful for both cucumber and Arabidopsis, which indicates it might have general applicability to most plants.     

Long-distance signaling in nodulation directed by a CLAVATA1-like receptor kinase

Proliferation of legume nodule primordia is controlled by shoot-root signaling known as autoregulation of nodulation (AON). Mutants defective in AON show supernodulation and increased numbers of lateral roots. Here, we demonstrate that AON in soybean is controlled by the receptor-like protein kinase GmNARK (Glycine max nodule autoregulation receptor kinase), similar to Arabidopsis CLAVATA1 (CLV1). Whereas CLV1 functions in a protein complex controlling stem cell proliferation by short-distance signaling in shoot apices, GmNARK expression in the leaf has a major role in long-distance communication with nodule and lateral root primordia.     

垃圾渗滤液暴露对拟南芥的毒效应研究

为研究垃圾渗滤液的综合毒性,通过盆栽实验探讨了渗滤液对拟南芥早期、成熟期和后期生长发育的影响。结果表明:垃圾渗滤液会影响拟南芥整个生命期的生长情况,低浓度(0.1%)、短时间(24 h)的渗滤液暴露会促进拟南芥早期的萌发及根系生长,分别为对照的256%和324%,而高浓度(10%)、长时间(≥48 h)暴露则产生抑制作用,48 h的抑制效应分别为对照的67%和36%;在相同暴露时间下,芽长随暴露浓度变化不明显,仅在48 h呈现出差异,说明拟南芥幼苗的根系比芽更为敏感。不同浓度的渗滤液还会影响成熟期拟南芥的生长发育,诱导叶片氧化损伤并呈现浓度和时间双重依赖性,进而损伤其抗氧化防御系统。此外,高浓度(20%)渗滤液对晚期阶段拟南芥抽薹率和角果数的抑制效应较为明显(P0.01),在暴露15 d后分别为对照的45%和43%。研究结果说明拟南芥可有效、简单、重复性地监测渗滤液的毒性,为渗滤液的植物监测提供理论依据。     

EMF, an Arabidopsis Gene Required for Vegetative Shoot Development

In higher plants, the transition from the vegetative to the; reproductive state in the shoot meristem initiates flowering. To study this floral transition, Constitutively flowering mutant of Arabidopsis thaliana ecotype columbia, embryonic flower (emf), was characterized. No vegetative shoots were produced from emf embryos or calli; the shoot apical meristems (SAMs) in the emf embryos were altered compared to wild-type SAMs. The mutant SAMs enlarged precociously and produced inflorescence meritems upon germination. These results suggest that the dominant, wild-type allele EMF is required for the vegetative state of the SAM. In the absence of EMF function, the mutant embryo assumes the reproductive state.     

A plant peptide encoded by CLV3 identified by in situ MALDI-TOF MS analysis

The Arabidopsis CLAVATA3 (CLV3) gene encodes a stem cell-specific protein presumed to be a precursor of a secreted peptide hormone. Matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) applied to in situ Arabidopsis tissues determined the structure of a modified 12-amino acid peptide (MCLV3), which was derived from a conserved motif in the CLV3 sequence. Synthetic MCLV3 induced shoot and root meristem consumption as cells differentiated into other organs, displaying the typical phenotype of transgenic plants overexpressing CLV3. These results suggest that the functional peptide of CLV3 is MCLV3.     

宽叶缬草短缩茎的结构及石细胞的分布与发育

对宽叶缬草短缩茎的结构及其石细胞分布和发育进行系统观察.结果表明,宽叶缬草短缩茎具有茎尖、腋芽、叶迹和根迹维管束等组织和器官,是完整的营养繁殖体.茎尖明显分为顶端分生组织、伸长区和成熟区,成熟区为初生结构,所占比例最大,成熟区的上、下部结构组成成分上有所不同.短缩茎的薄壁细胞中含有大量白色体、造油体,少数有橙黄色橙皮苷针簇状结晶,是缬草素等次生代谢产物的贮藏器官.短缩茎内茎节的髓部有堆状或带状分布的石细胞,由石细胞原基细胞快速侵入式生长,细胞壁木质化增厚,周围薄壁细胞随之继续增厚而形成.     

墨兰组织培养中原球茎的形态解剖研究

通过对墨兰（Ｃｙｍｉｄｉｕｍ ｓｉｎｅｎｓｅ）组织培养中原球茎外部形态、内部结构的观察研究,发现墨兰茎尖组织培养中产生的原球茎和丛生型原球茎虽外形差别较大,但内部结构都具有根的典型特征。牙的分生组织可以在原球茎表层、丛生型原球茎或其顶端发生。芽的顶端分生组织与随后产生的根的顶端分生组织共同构成胚状结构,其形态与种子胚相似。由于墨兰组培中先后产生的原球茎和丛生型原球茎其内部结构都属典型的根结构,故称     

葡萄试管苗绿枝扦插成活因素的研究

将经过移栽驯化的葡萄试管苗通过剪截绿枝进行扦插繁殖试验,结果表明:生长调节剂IAA对嫩枝扦条的生根促进作用明显强于IBA;在IAA生长剂处理下,处理时间以15~20 min为宜,绿枝带顶芽进行催根比剪截后不带顶芽的茎段成苗率高20%。     

大面积稻田病虫优化防治技术的研究

1997～1999年,在对湖南桃江县水稻主要病虫不同年度的灾变特点和病虫发生新动向调查的基础上,筛选出大面积稻田病虫优化防治技术,即县域统防,社区统治,分田施治,依据病虫发生的特征制定防治对策.初步筛选出一批低残留、高防效、有利保护天敌的新农药.采用优化防治技术与依据传统经验进行防治的方法相比,可节省防治费用21.31%,增加单产44 0 kg/hm2.     

Cloning and Characterization of Putative Hd6 Ortholog Associated with Zea mays L.Photoperiod Sensitivity

The photoperiod response of fowering is critical to the survival and successful reproduction in crops.The Hd6 gene,encoding a protein similar to the Arabidopsis α-subunit of CASEIN KINASE2α(CK2α)has been reported to affect flowering time through the photoperiodic pathway in rice.In this study,the maize ortholog,ZmHd6,has been cloned and its role in the photoperiodic pathway was investigated.ZmHd6 encodes 332 amino acids with six distinct domains: two CK2 active domains,a nuclear localization signal sequence,a N terminal domain,an ATP binding site,and an active site of serine/threonine protein kinase.ZmHd6 was constitutively expressed in the leaves and shoot apical meristem(SAM)with the highest expression in SAMs of plants with seven leaves under long and short day conditions.Delayed flowering time under long day(LD)conditions were observed in ZmHd6 overexpression transgenic Arabidopsis plants compared to the wild type.In transgenic Arabidopsis plants,ZmHd6 was expressed in a circadian oscillatory pattern,TOC1 peak expression was delayed,new G1,CO,and FT expressions reached to peak after 3 h while entering illumination period and oscillatory expression patterns of CO and FT were created during the dark phase.These results suggested that ZmHd6 might negatively regulate flowering time under LD conditions by delaying TOC1 peak expression and disrupting CO and FT expression in transgenic Arabidopsis plants.