Activation of floral homeotic genes in Arabidopsis

The identity of floral organs in Arabidopsis thaliana is determined by homeotic genes, which are expressed in specific regions of the developing flower. The initial activation of homeotic genes is accomplished at least in part by the products of two earlier acting genes with overlapping functions. These are the floral meristem-identity genes LEAFY and APETALA1. The requirements of LEAFY and APETALA1 activity vary for different homeotic genes.     

Nitric oxide represses the Arabidopsis floral transition

The correct timing of flowering is essential for plants to maximize reproductive success and is controlled by environmental and endogenous signals. We report that nitric oxide (NO) repressed the floral transition in Arabidopsis thaliana. Plants treated with NO, as well as a mutant overproducing NO (nox1), flowered late, whereas a mutant producing less NO (nos1) flowered early. NO suppressed CONSTANS and GIGANTEA gene expression and enhanced FLOWERING LOCUS C expression, which indicated that NO regulates the photoperiod and autonomous pathways. Because NO is induced by environmental stimuli and constitutively produced, it may integrate both external and internal cues into the floral decision.     

两个大白菜FT基因的生物信息学解析

本文利用比较基因组学的方法从大白菜的基因组中解析出两个成花素基因brft1和brft2,并对这两个基因的结构、顺式调控元件以及遗传进化进行了分析。结果表明,brft1和brft2都含有4个外显子,编码区大小均为528 bp,二者预测编码蛋白的序列一致性为90.29%, 说明这两个基因序列存在某种程度的分化。进化分析表明这两个基因应为拟南芥ft和tsf基因的直系同源基因。另外,这两个基因都含有响应激素和逆境信号的顺式调控元件,而且不尽相同,说明这两个基因的表达调控有所不同,可能在功能上存在一定分化。本研究为进一步揭示大白菜ft基因在开花和逆境响应中的功能奠定了基础。     

百合花器官的组织培养

以帝伯、西伯利亚、铁炮、金百合4个品种的花器官为外植体,进行不同品种花器官及同一品种花器官不同部位的组培难易程度试验。结果表明,品种间诱导率存在差异,从易到难的排序为帝伯、西伯利亚、铁炮、金百合;同一品种不同部位的诱导率也存在差异,从易到难的排序为花丝、花托、子房、花冠、花柱、花药。在初代诱导培养基中,以M S 6-BA 0.5m g/L NAA 0.5m g/L和M S 6-BA 1.0m g/L NAA 0.5m g/L较好;在继代增殖培养基中,帝伯和西伯利亚的最适培养基均为M S 6-BA 1.0m g/L NAA 0.2m g/L,而铁炮百合为M S 6-BA 1.0m g/L NAA 0.5m g/L。     

雷竹开花生物学特性研究

对浙江省临安市的开花雷竹林的花芽分化、开花征兆、开花林相、开花类型、花器官结构、小花开放及结实情况等开花生物学特性进行了系统观察与研究。结果表明,雷竹为零星开花竹种,开花类型复杂多样;雷竹花序属于典型的无限制花序或称假花序,基本单位为假小穗;雷竹结实率低。     

Milkoscan FT120对原料乳中三聚氰胺快速分析

为了建立一种快速测定原料乳中掺假物质的方法,利用红外光谱,采用主成分分析(PCA)回归方法,以本地区具有代表性原料乳样品集为基础建立标准数据模型.在原料乳中加入三聚氰胺模拟牛奶掺假.通过总结原料乳成分数据的变化规律及调整控制因素以达到预判原料乳掺假和确定掺假物质的检出限的目的.结果表明,该方法具有快速、准确的特点.     

An antagonistic pair of FT homologs mediates the control of flowering time in sugar beet

Cultivated beets (Beta vulgaris ssp. vulgaris) are unable to form reproductive shoots during the first year of their life cycle. Flowering only occurs if plants get vernalized, that is, pass through the winter, and are subsequently exposed to an increasing day length (photoperiod) in spring. Here, we show that the regulation of flowering time in beets is controlled by the interplay of two paralogs of the FLOWERING LOCUS T (FT) gene in Arabidopsis that have evolved antagonistic functions. BvFT2 is functionally conserved with FT and essential for flowering. In contrast, BvFT1 represses flowering and its down-regulation is crucial for the vernalization response in beets. These data suggest that the beet has evolved a different strategy relative to Arabidopsis and cereals to regulate vernalization.     

Early tagging of cortical networks is required for the formation of enduring associative memory

Although formation and stabilization of long-lasting associative memories are thought to require time-dependent coordinated hippocampal-cortical interactions, the underlying mechanisms remain unclear. Here, we present evidence that neurons in the rat cortex must undergo a "tagging process" upon encoding to ensure the progressive hippocampal-driven rewiring of cortical networks that support remote memory storage. This process was AMPA- and N-methyl-D-aspartate receptor-dependent, information-specific, and capable of modulating remote memory persistence by affecting the temporal dynamics of hippocampal-cortical interactions. Post-learning reinforcement of the tagging process via time-limited epigenetic modifications resulted in improved remote memory retrieval. Thus, early tagging of cortical networks is a crucial neurobiological process for remote memory formation whose functional properties fit the requirements imposed by the extended time scale of systems-level memory consolidation.     

Transient floral change and rapid global warming at the Paleocene-Eocene boundary

Rapid global warming of 5 degrees to 10 degrees C during the Paleocene-Eocene Thermal Maximum (PETM) coincided with major turnover in vertebrate faunas, but previous studies have found little floral change. Plant fossils discovered in Wyoming, United States, show that PETM floras were a mixture of native and migrant lineages and that plant range shifts were large and rapid (occurring within 10,000 years). Floral composition and leaf shape and size suggest that climate warmed by approximately 5 degrees C during the PETM and that precipitation was low early in the event and increased later. Floral response to warming and/or increased atmospheric CO2 during the PETM was comparable in rate and magnitude to that seen in postglacial floras and to the predicted effects of anthropogenic carbon release and climate change on future vegetation.     

The mRNA of the Arabidopsis gene FT moves from leaf to shoot apex and induces flowering

Day length controls flowering time in many plants. The day-length signal is perceived in the leaf, but how this signal is transduced to the shoot apex, where floral initiation occurs, is not known. In Arabidopsis, the day-length response depends on the induction of the FLOWERING LOCUS T (FT) gene. We show here that local induction of FT in a single Arabidopsis leaf is sufficient to trigger flowering. The FT messenger RNA is transported to the shoot apex, where downstream genes are activated. These data suggest that the FT mRNA is an important component of the elusive "florigen" signal that moves from leaf to shoot apex.     

杏花器官抗寒性初步研究

以杏盛开花朵为试材,利用人工模拟霜箱,对花器官抗寒性进行了研究。结果表明:杏花器官的过冷却点为:花瓣-4.0~-5.2℃,雄蕊-3.3~-4.1℃,雌蕊-2.8~-3.2℃。低温胁迫条件下,杏花器官褐变程度加剧,相对电导率增高,质膜透性增强,膜保护酶SOD、POD的活性在低温胁迫前期均逐渐升高,在达到一定的临界低温后,呈现下降的趋势。花器官抗寒性表现为花瓣>雄蕊>雌蕊,品种间抗寒性有差异。     

不同矮牵牛品种花香成分差异分析研究

[目的]矮牵牛花色丰富、花香芬芳,是重要的园林花卉种类,深入阐明不同品种矮牵牛花香特征的差异可进一步明确矮牵牛花香特征多样性的原因,为矮牵牛香花育种提供明确的思路。[方法]本研究以8个系列12个矮牵牛品种为材料,利用嗅觉对其香味浓淡程度进行分类,同时采用顶空-固相微萃取(HS-SPME)与气相色谱-质谱联用(GCMS)技术,鉴定并定量分析不同品种的挥发成分,并进行主成分分析和聚类分析。[结果]12个品种矮牵牛中共检测出66种挥发物,依据花香浓淡程度分为芳香型、清香型、淡香型3类。‘地毯’系列关键挥发物为酯类(苯甲酸甲酯);‘海市蜃楼’系列关键挥发物为烯类((S)-(-)-柠檬烯);‘轻浪’系列关键挥发物为烯萜类(三环萜、β-蒎烯)和酯类(2-甲基丁酸甲酯、苯甲酸甲酯);其余4个系列关键挥发成分分别为三环萜、β-蒎烯、2-甲基丁酸甲酯、苯甲酸甲酯等,聚类分析表明挥发成分相近的品种其遗传关系较为接近。[结论]不同品种矮牵牛挥发成分间存在显著差异,矮牵牛花挥发物主要种类为酯类、萜烯类,关键挥发物主要有(S)-(-)-柠檬烯、三环萜、β-蒎烯、2-甲基丁酸甲酯、苯甲酸甲酯等。苯甲酸苯甲酯是本研究芳香型矮牵牛品种的特征芳香成分。     

水稻裂颖突变体srg花器官突变的形态发生及遗传分析

在水稻Lemont×Dular的重组自交系群体(RILs,F10)中发现了裂颖突变体(split rice glume,srg).利用扫描电子显微镜观察野生型水稻和裂颖水稻的颖花原基分化情况,结果发现,突变体水稻的幼穗在形成内、外稃原基后,有些颖花在形成浆片后并不是直接发育形成雄蕊原基,而是在外稃或内稃原基内侧又分化出浆片原基;有些颖花原基从中间缢裂,缢裂的颖花原基又分别形成类稃片的结构,颖花发育后期,6枚雄蕊发育畸形,并且观察到不同数目的雄蕊.同时以突变体作母本,Dular、Lemont为父本配制杂交组合进行遗传分析,F2表型和χ2测验结果表明,该突变性状受单基因隐性控制.     

梨花蜜腺的解剖观察

梨花蜜腺位于子房上部的盘状结构上,属于下位子房上部的花盘蜜腺。蜜腺由分泌表皮和产蜜组织构成。分泌表皮具波纹状角质层,表皮上分布有气孔器。产蜜组织细胞7～10层,其下有5层左右大型薄壁细胞,与来自子房壁的维管束相毗邻。产蜜组织在发育过程中,其细胞中的淀粉粒呈现一定的消长规律。根据其结构及泌蜜前后的多糖物质分析,其原蜜汁来源于子房壁维管束的韧皮部,通过产密组织积聚加工成蜜汁。蜜汁通过气孔和表皮细胞泌出。     

Hyperspectral waveband selection for automatic detection of floral pear buds

Thinning of fruit-tree blossoms is used to regulate the yearly tree bearing and to increase the fruit yield and quality. While this is still mostly done by hand, the increasing costs of manual labor have created a demand for mechanization. This has recently led to the development of several prototype thinning machines. The main disadvantage of these machines is that they are not selective, while the fruit bearing capacity of different floral buds is not equal. On-line information about the position and distribution of the floral buds on the tree can improve the efficiency of mechanized thinning. Therefore, the aim of this study was to identify the most informative wavebands to develop a multispectral vision sensor for detection of the floral buds of the pear cultivar Conference. Hyperspectral scans were taken from tree samples in five early phenological stages to create a database of reflectance spectra for the different tree features. A stepwise algorithm was then applied to this training set to select the best combination of wavebands having the highest discriminating power between the components of interest. Subsequently, canonical correlation analysis was used to create discriminant functions out of the selected wavebands. It was possible to correctly classify 95 % of the (pixel) observations with six selected wavebands. The discrimination performance was also tested as a function of the number of used wavebands. Analysis showed that when only the two most important wavebands were used, still over 90 % of the (pixel) observations could be correctly classified.     

T-DNA标签技术及其在水稻基因克隆中的应用

T-DNA标签技术是一种高通量的分离和克隆植物功能基因的方法。本文介绍了T-DNA标签方法的基本原理和操作步骤,概述了该法的优缺点和在水稻基因克隆研究中的应用。     

Identification and molecular tagging of two Arabidopsis resistance genes to Botrytis cinerea

To map Arabidopsis resistance genes to Botrytis cinerea, Arabidopsis Col-0 ecotype resistant to B. cinerea BC18 isolate and Arabidopsis Ler ecotype susceptible to B. cinerea BC18 isolate were crossed. According to the resistant responses of the F₁, BC₁ and F₂ populations to B. cinerea, we identified two genes, named BC1 and BC2, responsible for the resistance of Arabidopsis Ler ecotype to B. cinerea. Through the method of map-based cloning, BC1 was linked to DNA markers CCR1 and DHS1 on the fourth chromosome of Arabidopsis with genetic distances of 1.2 cM and 1.6 cM for CCR1 and DHS1, respectively, and BC2 was linked to DNA markers CA72/NGA151 and NGA106 on the fifth chromosome with genetic distances of 1.4 cM and 2.4 cM for CA72/NGA151 and NGA106, respectively. Our results are beneficial for chromosome walking so that we can obtain the whole gene sequences, which will facilitate the understanding of their roles and manners of resistance to B. cinerea.