The characteristics of light in floral induction in vitro of Cichorium intybus. The possible role of phytochrome

The action of light in the initiation of floral buds in vitro has been studied using monochromatic light qualities on root explants of a long day plant, Cichorium intybus L. cv. Witloof. Red light (660 nm, 0.30 W m^-2) promotes flowering, while far-red (730 nm, 0.31 W m^-2) and irradiation with combined red + far-red (0.20 + 0.41 W m^-2) have no effect. In short day conditions floral response can be obtained in two ways: 1) by interrupting the dark period with 5 brief irradiations of red light (0.45 W m^-2, 12 min) at regular intervals, although these are counteracted by far-red irradiations of equal intensity and duration; 2) by interrupting the long night with 5 h red light applied during the second third of the night, while at the beginning or at the end it is ineffective. Red light efficiency appears to depend on the photosynthetic activity of the tissues, so that flowering increases with increasing intensity of white light and is suppressed if no white light is supplied. The reproductive development is determined by the coordination of proper irradiation conditions with sufficient sensitivity of the perceiving meristematic cells. The period of highest sensitivity to environmental light conditions in the life cycle of a Cichorium root explant occurs between the 8th and the 16th day after the start of the culture. The data strongly suggest that phytochrome is involved in flower induction of Cichorium in vitro.     

Evolutionary breakdown of distyly to homostyly is accompanied by reductions of floral scent in Primula oreodoxa

Reproductive traits that function in pollinator attraction may be reduced or lost during evolutionary transitions from outcrossing to selfing. Although floral scent plays an important role in attracting pollinators in outcrossing species, few studies have investigated associations between floral scent variation and intraspecific mating system transitions. The breakdown of distyly to homostyly represents a classic example of a shift from outcrossing to selfing and provides an opportunity to test whether floral fragrances have become reduced and/or changed in composition with increased selfing. Here, we evaluate this hypothesis by quantifying floral volatiles using gas chromatography-mass spectrometry in two distylous and four homostylous populations of Primula oreodoxa Franchet, a perennial herb from SW China. Our analysis revealed significant variation of volatile organic compounds (VOCs) among populations of P. oreodoxa. Although there was no difference in VOCs between floral morphs in distylous populations as predicted, we detected a substantial reduction in VOC emissions and the average number of scent compounds in homostylous compared with distylous populations. A total of 12 compounds, mainly monoterpenoids and sesquiterpenoids, distinguished homostylous and distylous morphs; of these, (E)-β-ocimene was the most important in contributing to the difference in volatiles, with significantly lower emissions in homostyles. Our findings support the hypothesis that the transition from outcrossing to selfing is accompanied by the loss of floral volatiles. The modification to floral fragrances in P. oreodoxa associated with mating system change might occur because high selfing rates in homostylous populations result in relaxed selection for floral attractiveness.     

二乔玉兰开花过程中花色变化的生理生化机制

以4年生二乔玉兰不同花期外层花瓣为试材,测定其在开花过程中花瓣色度值、花色苷、类黄酮、可溶性糖含量、细胞pH值以及相关酶活性的变化,以探讨二乔玉兰花色呈色机理。结果显示:(1)随着花期的推移,苯丙氨酸解胺酶(PAL)和查尔酮异构酶(CHI)活性逐渐减弱,细胞pH值逐渐变大,可溶性糖、花色苷、类黄酮含量不断降低,而花瓣明亮度增强,红色度以及彩色度减弱,且不同花期各参数值之间差异显著。(2)花瓣可溶性糖含量、PAL和CHI的活性与其花色素苷、类黄酮含量变化之间呈显著正相关关系,花瓣pH值的变化、明亮度L*值与花色素苷、类黄酮含量之间呈显著负相关,色相值a*与花色苷含量的变化呈显著正相关。研究表明,二乔玉兰花瓣花色苷和类黄酮含量的高低可以影响其花色的深浅,可溶性糖含量、PAL和CHI活性、细胞pH通过参与一定的生理代谢来调节花色素的形成,进而引起二乔玉兰花色色调的改变。     

GoNe encoding a class VIIIb AP2/ERF is required for both extrafloral and floral nectary development in Gossypium

The floral nectary, first recognized and described by Carl Linnaeus, is a remarkable organ that serves to provide carbohydrate-rich nectar to visiting pollinators in return for gamete transfer between flowers. Therefore, the nectary has indispensable biological significance in plant reproduction and even in evolution. Only two genes, CRC and STY, have been reported to regulate floral nectary development. However, it is still unknown what genes contribute to extrafloral nectary development. Here, we report that a nectary development gene in Gossypium (GoNe), annotated as an APETALA 2/ethylene-responsive factor (AP2/ERF), is responsible for the formation of both floral and extrafloral nectaries. GoNe plants that are silenced via virus-induced gene silencing technology and/or knocked out by Cas9 produce a nectariless phenotype. Point mutation and gene truncation simultaneously in duplicated genes Ne₁Ne₂ lead to impaired nectary development in tetraploid cotton. There is no difference in the expression of the CRC and STY genes between the nectary TM-1 and the nectariless MD90ne in cotton. Therefore, the GoNe gene responsible for the formation of floral and extrafloral nectaries may be independent of CRC and STY. A complex mechanism might exist that restricts the nectary to a specific position with different genetic factors. Characterization of these target genes regulating nectary production has provided insights into the development, evolution, and function of nectaries and insect-resistant breeding.     

Cloning and characterization of PhPI9 involved in floral development from Phalaenopsis Orchid

In the attempt to discover new genes involved in the floral development in monoeotyledonousin species,we have cloned and characterized the homologous PISTALLATA-like (PI-like) gone from Phalaenopsis hybrid cultivar named PhPI9 (Phalaenopsis PI STILLATA # 9).The eDNA of PhPI9 has a fragment of 834 bp and has 60% identity with the PISTILATA from Arabidopsis.The deduced amino acid sequence of PhPI9 had the typical PI-motif.It also formed a subelade with other monoeot PI-type genes in phylogenetie analysis.Southern analysis showed that PhPI9 was present in the Phalaenopsis orchid genome as a single copy.Furthermore,it was expressed only in the lip of the Phalaenopsis flower and no expression was detected in vegetative organs.Thus,as a B-function MADS-box gone,PhP19 specifies floral organ identity in orchids.     

垂花青兰花蜜腺的发育解剖学研究

垂花青兰（Dracocephalum nutans Linn.）花蜜腺分布于子房基部的花托上,盘状蜜腺的上部裂成三小一大的四枚裂片,基部在膨大的花托外环绕一圈。蜜腺组织由分泌表皮、产蜜组织和维管束三部分组成,是典型的结构蜜腺;组织化学染色显示淀粉粒动态明显,因此又属淀粉蜜腺。在发育的过程中细胞液泡化动态明显,且淀粉粒和蛋白质具有明显的消长变化,蜜汁通过气孔器和表皮细胞的角质层泌出。     

Monocots

Green nectaries have been frequently mentioned in the literature, leading to the assumption that photosynthesis of nectaries can supply the carbohydrates secreted in the nectar, especially when storage of starch is seen in the plastids in nectaries and this starch disappears during secretion. Photosynthesis in nectaries can also provide reduction equivalents for the nectar–redox cycle and energy for secretion. However, quantitative data on the photosynthetic capacity of nectaries are largely missing. Therefore, in the present study, the photosynthetic capacity of green nectaries from a range of plants was screened; 20 floral nectaries (including six septal nectaries) and six extrafloral nectaries were studied. For the screening, chlorophyll fluorescence parameters were measured as depending on photosynthetic photon flux density (PPFD). Parameters measured were basic ground fluorescence (F) and quantum yield (Y₀) of the dark adapted sample at 0 PPFD. From the light saturation curves saturating PPFD (PPFD_sat), quantum yield at saturation (Y_sat) and maximum apparent photosynthetic electron transport rates (ETR_max) were obtained. For comparison, leaves of the plants were also measured. In most cases, the performance of the nectaries was lower than that of the leaves. F was lower in 14 floral and four extrafloral nectaries (69% of total), ETR_max was lower in 18 floral and four extrafloral nectaries (85%), Y_sat was lower in 15 floral and three extrafloral nectaries (69%). In 18 floral and two extrafloral nectaries (77%) Y₀ was well below 0.8, indicating photoinhibition. In contrast, the range of ETR_max for green nectaries was 25–140 μmol m^?2 s^?1 and overlaps well with that of green tissues in general. The lower end of the range of rates of photosynthetic carbon dioxide (CO₂) uptake of sun leaves in the literature is 10 μmol CO₂ m^?2 s^?1. Taking this value for sun‐adapted green nectaries, i.e. having a PPFD_sat > 1000 μmol m^?2 s^?1, with an area of nectar tissue measured as 3–50 mm² per flower, sugar secretion related to photosynthetic CO₂ fixation in the green nectaries is estimated at approximately 0.2–3.0 μmol hexose units flower^?1 day^?1. This is compares well in order of magnitude with the range of secretion given in the literature and clearly suggests that photosynthetic activity of green nectaries can explain a significant part, if not all, of the sugar secreted. In some nectaries ETR did not saturate with PPFD. This could be attributable to spillover from photosystem II to photosystem I and cyclic photosynthetic electron transport. It is in agreement with observations in the literature and my preliminary findings that nectary plastids often lack grana thylakoids where photosytem II is located. Cyclic photophosphorylation could provide adenosine triphosphate (ATP) energy for the nectaries. This needs further investigation. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 173 , 1–11.     

Biotic versus abiotic pollination in Oeceoclades maculata (Lindl.) Lindl. (Orchidaceae)

Geographical variation in the reproductive biology of widespread species often occurs at their distributional boundaries. We sought to determine whether such variation has occurred in an invasive orchid, Oeceoclades maculata, across its naturalized range. We compared its reproductive biology in a Brazilian population with that published for a population on the Caribbean island of Puerto Rico. In the state of São Paulo, O. maculata flowers between December and February, at the height of the rainy season. Similar fruit sets were observed in manual self (76%) and cross (70.4%) pollination treatments. The fruit set of plants protected from both pollinators and rainfall was 6.1%, whereas plants exposed only to rainfall had a fruit set of 41.4%, slightly less than the controls (48.3%). Like the Puerto Rico population, reproduction is primarily through rain‐assisted autogamy, but unlike observations made on the island, outcrossing can eventually occur. We observed two butterfly species (Heliconius ethilla narcaea and Heliconius erato phyllis) pollinating O. maculata. Secretory epidermal cells and trichomes of the spur lumen produced 0.7 µL of 25% (sucrose equivalents) nectar per flower each morning, which was stored in a dilated basal portion of the spur and reabsorbed by the afternoon. Thus, geographical variation in reproductive biology exists across the broad invasive range of O. maculata.     

热带滨海沙滩上森林植被的组成成分与土壤性质的研究

1　前　言在 1 96 3年张宏达提到分布在海南万宁海岸沙滩上的青梅林 (Ｖａｔｉｃａｍａｎ ｇａｃｈａｐｏｉｆｏｒｅｓｔ)时 ,就认为该森林缺乏雨林的结构[1 ],但仍把它归入平地及低山的原生植被里[2 ]。 1 981年 ,胡玉佳对海南龙脑香林进行比较研究后指出 ,这是一块分布在特殊环境里的热带雨林类型 ,由于土壤条件恶劣和常年受海风的影响 ,形成了这一特殊森林[3 ]。 1 987年王伯荪在讨论季雨林的概念时 ,进一步指出这块森林属于土壤顶极森林群落[4 ]。尽管前人未曾对这一块热带滨海沙滩上的森林植被性质与土壤性质的相互关系开展过详细的比…