Floral induction in longan (Dimocarpus longan, Lour.) trees: IV. The essentiality of mature leaves for potassium chlorate induced floral induction and associated hormonal changes

This study was conducted to elucidate the function of leaves and their role in the alteration of plant hormone homeostasis during potassium chlorate (KClO₃) induced “off season” floral induction (FI) of longan. KClO₃ application had almost no effect on the concentration of gibberellins in receptive apical and lateral shoot meristems, whereas the auxin IAA initially decreased, but later remarkably increased. The most significant changes caused by KClO₃ treatments was an increase in zeatin/zeatin-riboside (Z/ZR) type cytokinins (CKs) 8 days after treatment in the shoot apical and close by lateral buds as well as in the tissue beneath these buds. The 6–7-fold increase in CK concentrations were greatly reduced in the absence of leaves (leaves removed between the apical bud and a girdle). A significant exception was a strong accumulation of isopentenyl adenine/isopentenyl adenosine (iP/iPA) type CKs in wood and bark beneath the bud of defoliated shoots that were isolated against the rest of functional leaves of the tree by a girdle. This accumulation of iP/iPA, the immediate precursors of Z/ZR, together with the strong increase of Z/ZR in the shoot apical bud (SAB) after KClO₃ application indicate that leaves may be involved in the biosynthesis of CKs. Overall, the results suggest that cytokinins play a significant role in KClO₃ induced “off season” floral induction in longan. This role may not be restricted to the biosynthesis of these hormones but also to their mobilization and accumulation in the SAB of newly flushing shoots.     

Floral induction (FI) in longan (Dimocarpus longan, Lour.) trees: Part I. Low temperature and potassium chlorate effects on FI and hormonal changes exerted in terminal buds and sub-apical tissue

Floral induction (FI) in longan (Dimocarpus longan, Lour.) trees was achieved in controlled greenhouse experiments by low temperature (LT) and by the application of potassium chlorate at high temperature (HT + KClO₃) during two consecutive seasons. The latter treatment was successful also at temperatures above 20 °C. The present experiment was conducted to investigate possible alterations in the concentrations of plant hormones exerted by these two methods and to relate them to the floral induction process. The following hormones were examined by radioimmunoassay in the shoot apical buds (SAB), and in sub-apical bark and wood: the auxin indole-3-acetic acid (IAA); gibberellins (GAs); and the cytokinins zeatin/zeatin riboside (Z/ZR) and isopentenyl-adenine/isopentenyl-adenosine (iP/iPA).     

Floral induction (FI) in longan (Dimocarpus longan, Lour.) trees. III: Effect of shading the trees on potassium chlorate induced FI and resulting hormonal changes in leaves and shoots

Previous experiments demonstrated that treatment of longan trees with potassium chlorate (KClO₃) induces “off season floral induction” (FI) even in the absence of the naturally required cool temperature [Manochai, P., Sruamsiri, P., Wiriya-alongkorn, W., Naphrom, D., Hegele, M., Bangerth, F., 2005. Year around off season flower induction in longan (Dimocarpus longan, Lour.) trees by KClO₃ applications: potentials and problems. Sci. Hortic. 104, 379–390]. Potassium chlorate, however, cannot replace the presence of functional mature leaves and sufficient light intensity. Here we examined in more detail the effect of shade (about 10% of natural sunlight) on KClO₃ affected hormone concentrations/transport of leaves and shoot apical buds (SAB) and their interactions with FI.     

Water deficits promote flowering in Rhododendron via regulation of pre and post initiation development

Flowering is generally considered to be advanced by water deficits in many woody perennial species. A long-standing paradigm being that as a plant senses severe environmental conditions resources are diverted away from vegetative growth and towards reproduction before death. It is demonstrated that in Rhododendron flowering is promoted under water deficit treatments. However, the promotion of flowering is not achieved via an increase in floral initiation, but through separate developmental responses. If regulated deficit irrigation (RDI) is imposed prior to the time of initiation, fewer vegetative nodes are formed before the apical meristems switch to floral initiation, and chronologically, floral initiation occurs earlier. Both RDI and partial rootzone drying (PRD) treatments stimulate the development of more flowers on each inflorescence if the treatments are continued after the plant has undergone floral initiation. However, floral initiation is inhibited by soil water deficits. If the soil water deficit continues beyond the stages of floral development then anthesis can occur prematurely on the fully formed floral buds without a need for a winter chilling treatment. It is hypothesised that inhibition of floral initiation in plants experiencing severe soil water deficits results from the inhibitory action of ABA transportation to the apical meristem from stressed roots. It is demonstrated that ABA applications to well-watered Rhododendron inhibit floral initiation.     

Strawberry Growth and Flowering

Abstract

Strawberry is an herbaceous perennial that can be easily propagated by stolons or by crown division. Seedlings have a few months in the juvenile period. The growth is determined with a terminal inflorescence as a modified stem or cyme. Flower induction is sensitive to thermo-photoperiod and to several agronomic and nutritional factors. The strawberry plant is highly adapted to diverse temperate climates and to production under forced artificial growing conditions. In the present study, a dynamic architectural model of growth is described and discussed in order to reveal strawberry development under different cultivation systems. The aim is to improve the cultural knowledge and understanding of the physiological control of axillary meristems, which can enhance the Strawberry fruit production.     

Year around off season flower induction in longan (Dimocarpus longan,Lour.) trees by KClO3 applications: potentials and problems

Off season induction of flowering and fruit production is a desirable economical and scientific goal with many subtropical fruit trees. Both objectives have been accomplished by the application of gibberellin biosynthesis inhibitors with mango and a few other fruit trees. Recently the same was achieved with longan trees (Dimocarpus longan, Lour.) after treatment with potassium chlorate. This treatment allows the efficient induction of flowering and fruit production all over the year in an obviously species-specific manner.Experiments are described that investigated several aspects of this KClO₃ treatments, such as methods of application, seasonal effects, reactiveness of different cvs. toward the chemical, influence of leaf age, etc. The results are discussed with respect to the practical application of KClO₃ for off season fruit production, but also under the aspect of its use for more basic investigations into the endogenous regulation of the flowering induction process in perennial fruit trees.     

‘三月红’荔枝不同温度处理的成花效应

利用控温室研究‘三月红’荔枝(Litchi chinensis Sonn.)成花诱导期和形态分化期不同的温度对成花的影响。结果表明,诱导期较低温(15℃/8℃,昼12h/夜12h),或者中度低温(18℃/13℃)处理,转移到高温(28℃/23℃)条件下,植株成花枝率低,而且也减少了每穗花的小花数和雌花质量。诱导期18℃/13℃,形态分化期15℃/8℃有利于成花。与18℃/13℃和15℃/8℃下发育的花芽相比,28℃/23℃下发育的花芽玉米素(ZRs)含量较低,而生长素(IAA)含量较高。高温处理下花芽中荔枝LEAFY同源基因(LcLFY)表达明显弱于低温处理。对不同温度下的成花与激素,以及与LcLFY表达的关系进行了分析讨论。     

桃花芽休眠解除SSH文库构建及相关基因表达分析

 为了深入研究桃花芽休眠的分子机制,利用抑制差减杂交技术（SSH）,以解除休眠期的花芽的RNA为实验方Tester,以休眠期花芽的RNA为驱动方Driver,构建休眠解除cDNA文库,测定分析了180 个上调表达的cDNA 片段,测序成功128个,除去冗余序列,得到28个单一序列。对序列进行BLAST比对及功能注释,发现这些序列分别属于新陈代谢、氧化还原、信号转导、抗性相关等类别基因。运用qRT-PCR 技术对HisH3、Dhn 和Metallothionein基因进行检测,结果表明它们在花芽休眠解除过程中均上调表达。     

荔枝树成花与碳水化合物器官分布的关系研究

 选择荔枝不同末端梢抽生期的植株, 于成花诱导期间取样分析, 比较了高成花树与低成花树可溶性糖和淀粉含量的变化。‘桂味’荔枝末端秋梢抽生早的树(10 月5 日抽梢) 成花枝率为95.8% , 而抽生晚的树(11月15 日抽梢) 为18.0% ,‘妃子笑’荔枝10月1日抽梢树和‘糯米糍’荔枝两个抽梢期树(10 月15 日和11 月5 日) 的成花枝率均在99%以上。从11月中旬到1月中旬, 各器官可溶性糖含量一般先上升而后下降; 淀粉含量则不同程度地提高。低温来临前各器官淀粉含量差异不大, 到花发端之前, 3个品种高成花率树的淀粉含量以小枝(粗度1 cm) 为最高, 形成从小枝到末端秋梢和叶片的下降梯度, 而低成花率的桂味荔枝树的淀粉含量则未见这种梯度。认为这种淀粉含量分布可能是荔枝枝梢接受成花诱导、反映诱花效果的一个标志。     

氯酸钾诱导龙眼成花与叶片蛋白质及核酸含量变化的关系

用氯酸钾(KClO3)诱导龙眼成花及成花过程中成花母枝叶片蛋白质和核酸含量的变化,结果表明:经KClO3诱导处理的植株能在60d左右开花,添加植物细胞分裂素(CTK)比单独使用KClO3对促进龙眼成花效果更明显;在成花诱导后,成花母枝叶片中蛋白质和核酸的含量在成花诱导期迅速增加,之后逐渐下降,而对照树蛋白质和核酸含量始终保持在较低水平,其中RNA峰值出现比DNA晚10d左右;RNA/DNA的比值在成花后一直呈上升的趋势,在花芽形态分化前达到最大值。     

Temperature and photoperiod control of morphology and flowering time in two greenhouse grown Hydrangea macrophylla cultivars

Knowledge of the factors involved, and tools to control morphology and flowering are important in intensive and cost-efficient greenhouse production. Hydrangea macrophylla is an important flowering pot plant in Norway and is produced year-around in greenhouses. Due to problems in scheduling, a study was conducted to compare floral transition and morphology of two commercially important cultivars of Hydrangea (‘Early Blue’ and ‘Schneeball’) under different flower initiating treatments in growth chambers. Plants were grown with high pressure sodium lamps (HPS) at moderate temperature (17 °C) (MT) and high (24 °C) temperature. At high temperature, the effect of (1) irradiance under long day conditions (16 h lighting with 70 or 200 μmol m⁻² s⁻¹), and (2) short day (8 h lighting) was investigated. The short day treatment had similar light integral as the low irradiance long day treatment (SD: 8 h × 140 μmol m⁻² s⁻¹ and LD: 16 h × 70 μmol m⁻² s⁻¹ = 4.0 mol m⁻² d⁻¹). The intention was to test the effect of irradiance and SD on flower transition and morphology under high temperatures. The results clearly showed that MT is the strongest signal for floral transition. MT resulted in a rapid floral transition of the terminal buds and lateral flower buds. A short forcing period was required and the plants became short and compact without any use of chemical growth retardants. At high temperatures only SD had a promotive effect on flower transition and the response was found to be stronger in ‘Schneeball’ than ‘Early Blue’. In general, all the treatments under high temperatures required a long forcing time and the plants tended to be very tall with a low number of lateral flower buds.     

The effect of high temperature interruptions during inductive period on the extent of flowering and on metabolic responses in olives (Olea europaea L.)

The effect of the duration of high temperature interruption and the timing of its occurrence during inductive period on the extent of inhibition of inflorescence production in ‘Arbequina’ olive trees was investigated. Trees kept under inductive conditions in different growth chambers were subjected to high daytime temperature (26 ± 1 °C) interruptions for 3, 6, and 12 days. There was no significant difference in the extent of flowering between trees given an uninterrupted induction period and the trees where inductive period was interrupted with high daytime temperatures for three days. Inflorescence production was significantly reduced by both 6 and 12 days high temperature interruptions. Number of flowers per inflorescence was significantly reduced only with 12 days high temperature interruption. Since there was no significant difference between the extent of inhibition of inflorescence by 6 and 12 days high temperature interruption, therefore, 6 days high temperature interruption was used in subsequent experiments to study the effect of timing of interruption. A six day interruption of high temperature produced significant reduction (more than 83%) in inflorescence production irrespective of the time of interruption (i.e., 40 or 50 days after the start of induction) or number of interruptions. None of these treatments had any significant effect on the number of flowers per inflorescence. Higher levels of free arginine were found in trees that had greatest number of inflorescences produced under inductive conditions without any high temperature interruption.     

Evidence for a translocatable florigenic promoter in mango

Movement of a putative florigenic promoter from leaves to buds was investigated in two cultivars of mango (Mangifera indica L.) over two flowering seasons through examination of the minimum number of leaves on each stem necessary for floral induction and movement of this component over various distances from stem to stem in isolated branches. The minimum number of leaves on individual stems necessary to induce flowering was less than 1/4 of a cross-cut leaf per stem. The putative florigenic promoter moved from donor stems bearing as few as one leaf to induce flowering in five receiver stems located as far down branches as 100 cm from the donor stem. Evidence suggests that movement of the putative florigenic promoter occurs in phloem and that far more of this component is available in trees than is necessary for floral induction of initiating shoots during cool, floral-inductive conditions of the subtropics.     

干旱胁迫对果树开花的诱导及对生理生化性状的影响

干旱胁迫是许多热带、亚热带果树花芽诱导的有效措施,现就干旱胁迫对果树开花诱导的效果以及对果树生理生化过程的影响进行讨论.认为干旱胁迫明显降低果树的营养生长,影响果树体内碳水化合物以及含氮化合物的含量水平和相对比例,明显调节果树体内内源激素含量状况,并有效促进部分果树的开花.同时对干旱诱导的时间、强度以及今后控水促花研究中尚需解决的问题进行了讨论.     

Mango (Mangifera indica L.) flowering physiology

Mango flowering is an important physiological event that sets the start of fruit production. Initiation is the first event that takes place for mangoes to flower. Coincident with shoot initiation, induction occurs based on the conditions present at the time of initiation. Numerous studies with mango trees support the existence of a florigenic promoter (FP) that is continuously synthesized in mango leaves and induces flowering. Translocation experiments suggest that the FP is carried from leaves to buds in phloem. Induction appears to be governed by the interaction of the FP and a vegetative promoter (VP). The FP is translocated as far as 100 cm in subtropical conditions and 52 cm in tropical conditions. In the tropics, floral induction occurs in stems that have attained sufficient time in rest since the previous flush. The age of the last flush is the primary factor governing flowering in the tropics as evidenced by experiments in Colombia. Tip pruning is ideal to synchronize vegetative flush events in the canopy. Potassium nitrate (KNO₃) has been shown to stimulate flowering in sufficiently mature stems. Tip pruning and foliar applied KNO₃ are effective methodologies that induce synchronous flowering especially in Colombia. Cool temperatures are important for mango floral induction under subtropical conditions. Mangoes grown in the low-latitude tropics rely less on low temperature. Soil and leaf analyses should be conducted to evaluate the nutrient status of trees.     

Inhibition of flowering of Mexican- and Guatemalan-type avocados under tropical conditions

Avocado trees of a range of cultivars growing in Darwin, northern Australia (average yearly maximum 33°C, minimum 23°C), were observed for flower and shoot development. Terminal buds of the cultivars ‘Fuerte’, ‘Rincon’ and ‘Edranol’ sampled in July were not floral. Buds which did not burst were sampled in September and they contained developing flowers with perianth primordia. Vegetative extension growth resulted from laterals proximal to the inhibited terminal buds.Avocado trees of the cultivars ‘Fuerte’ and ‘Hass’ which had initiated floral buds were transferred to controlled environment chambers with 33°C day, 23°C night ($\text{33}\text{23}$) or 25°C day, 15°C night ($\text{25}\text{15}$) with a 12-h photoperiod and photon flux density of 400 μmol m^?2 s^?1 (400–700 nm). At $\text{33}\text{23}$ the trees had fewer flowers and a shorter flowering period than at $\text{25}\text{15}$. Inhibited floral buds and lateral vegetative extension resulted at $\text{33}\text{23}$, as observed in northern Australia. The unburst buds had developing flowers with perianth and stamen primordia.The controlled environment experiments showed that the abnormal flushing behaviour of Mexican- and Guatemalan-type avocados growing in northern Australia was due to high temperature. Floral development was inhibited at the stage of stamen differentiation.     

In vitro morphogenesis and adventitious shoot mass regeneration of Vriesea reitzii from nodular cultures

Micropropagation systems based on nodular cultures (NCs), are considered as an intermediary in vitro morphogenetic route, diverging from regenerative systems based on organogenesis and somatic embryogenesis. The aim of this study was to establish a regenerative protocol based on the induction and development of NCs in Vriesea reitzii, an endangered bromeliad from the Atlantic forest which also has ornamental value. Additionally structural analyses were performed in order to better understand this in vitro morphogenetic route. NCs were regenerated in MSB culture medium free of PGR or supplemented with different levels of NAA alone or in combination with in combination with 2-iP. The subculture of these NCs on MSB medium supplemented with 10 μM of GA₃ promoted the synchronized shoot elongation. A regenerative efficiency of 12.4 g g⁻¹ of NCs was obtained, and this results in 5300 microshoots after 10 weeks in culture. The structural analyses of the NCs revealed that the regenerative process occurs from the proliferation of meristematic cell groups resulting in the development of multiple shoot meristems and buds. The development of NCs leads to the formation of monopolar structures called microshoots, which evolve to elongated shoots. Intermediary features shown in NCs are consistent with their classification as an intermediary system among organogenesis and somatic embryogenesis.     

Studies on the induction of flowering in juvenile Prunus avium L.

Juvenile Prunus avium shoot apices produced flowering shoots after grafting to mature trees irrespective of treatment of the apices in the season before grafting with G A or G A + cytokinin. Scions grown from mature shoot apices grafted to seedling stocks failed to flower, again irrespective of prior hormone treatment. Similar treatment of mature shoot apices with these hormones, or with zeatin, inhibited concurrent floral initiation, but G A or GA + zeatin treatments increased flowering of scions grown from the treated apices after grafting to untreated mature trees. Localized shoot tip or root drench treatment of one or two year old seedlings with (2RS, 3RS)-paclobutrazol failed to induce flowering, but treatment of three or four year old plants did stimulate flowering. Branch or stem girdling or root flooding applied alone or in combination to three year old plants did not affect flowering. Floral initiation by three or four year old plants was inhibited by treatment with GAs. The results were consistent with the presence in seedlings of a root- produced, xylem transported, graft-transmissible inhibitor(s), which control the initiation of otherwise competent meristems, and which could include factors other than GAs. Juvenile meristem competence to flower was not affected by prior GA treatment.     

植物细胞工程在菊花育种中的应用

综述了近几年来细胞工程应用于菊花辐射诱变、化学诱变、体细胞杂交和转基因育种方面研究进展,其中详细介绍了采用拯救性茎尖培养获得类病毒脱毒苗的研究,和薄层细胞培养减少转基因植株的嵌合体、提高转化率方面的研究。     

Influences of cold deprivation during dormancy on carbohydrate contents of vegetative and floral primordia and nearby structures of peach buds (Prunus persica L. Batch)

Endogenous carbohydrate contents and availability in structures near the meristematic zone (scales, cushion, part of stem) during winter with and without sufficient chilling were investigated. Insufficient chilling is known to provoke an abnormal pattern of budbreak and development in temperate zone fruit trees cultivated in warm climates. Mild temperatures applied during winter to strictly floral buds, as is the case in peach, are known to provoke the necrosis of flower primordia in the buds. One of the hypotheses to explain this is that carbohydrate fluxes to the buds are impeded and/or that internal reserves are completely used up. Carbohydrate availability and bud survival were compared between peach trees under natural temperate conditions and under complete deprivation of cold, by keeping trees in a greenhouse with temperature constantly above 15 °C from early October to the first sign of necrosis in flower buds. Concentrations and carbohydrate contents were compared during a little more than 2 months (beginning mid-December) before the first signs of necrosis in flower buds. Results showed that cold deprivation deeply disturbed carbohydrate dynamics, blocking the import of carbohydrates into vegetative and floral primordia, even though sucrose and sorbitol concentrations within these structures remained high. Conversely, soluble carbohydrates accumulated strongly in bud scales and in the cushion beneath the primordia. This suggests a strong diversion towards structures close to the primordia under cold deprivation. However, since sucrose and sorbitol concentrations in the floral primordia remained high, necrosis could be the consequence of the inability to use sucrose and sorbitol reserves rather than the result of a lack of available carbohydrates.