Interaction between Hormones, Light, and Nutrition on Extension of Lateral Buds in Phaseolus vulgaris L.

Gibberellic acid (GA₃), kinetin, and indol-3yl-acetic acid (IAA)contained in lanolin were applied in various combinations andconcentrations to decapitated stems and petioles and to budsof Phaseolus vulgaris L. GA₃ applied alone usually promotedgrowth of main stems and laterals but this was by no means consistentand occasionally it acted in the opposite way. IAA applied alonereduced lateral bud extension slightly, but not consistently;however, when applied with GA₃ or GA₃ plus kinetin, it oftenmarkedly inhibited the promotion caused by these compounds.On occasions, however, GA₃ and IAA acted synergistically topromote and sometimes to inhibit lateral shoot growth. Kinetinalone showed few significant effects on lateral shoot growthbut applied with GA₃ it often dramatically increased GA₃-inducedgrowth of main stems and laterals. The diversity of these results,which parallels that found in the literature, was shown to bepartly dependent on the point of hormone application and ageof the plant or bud, on concentration of hormone and on lightintensity or nutrition. However, no meaningful relationshipswere found and it is concluded that growth of laterals and mainstems is dependent on a hormone balance which can be criticallymodified by a wide range of internal and external factors thenature of which is still to be determined.     

Regulation of Branching in Decussate Species with Unequal Lateral Buds

In the decussate plants Alternanthera philoxeroides and Hygrophilasp. the opposite axillary bud primordia are of unequal sizefrom the time of their inception; the larger or + buds lie alongone helix and the smaller or – buds along another (helicoidalsystem). In decapitated plants of Alternanthera both buds grewout, but unequally; if the node was vertically split growthof the two shoots was more equal, and if the + buds were excisedgrowth of the – shoots approximately equalled that ofcontrol + shoots. In decapitated shoots of Hygrophila grownin sterile culture only one bud, the + or larger one, grew outat each of the upper nodes. In excised cultured nodes, also,only the + bud grew out; but if the nodes were split longitudinallyboth buds grew out, initially rather unequally. These experimentssupport the view that the regulation of branching in these specieshas two components, apical dominance and the dominance of thelarger (+) bud over the smaller (–) bud at the same node.The restriction of growth potentiality imposed on the –bud is not permanent but can be modified. Further correlativeeffects on bud outgrowth include those of the subtending leavesand of buds at other nodes.     

The Effect of the Apical Bud on the Growth of Lateral Buds on Subterranean Shoots

The influence of the apical bud on the growth of the lateral buds on subterranean shoots was studied in Stachys sieboldiiMig. and Helianthus rigidus(Gass.) Desv. Removing and damaging the apical parts of subterranean shoots or their treatment with 2% chlorocholine chloride shoot enhanced shoot branching. The response to light of the apical bud was invariably negative: the stolons, which came out or were extracted from the soil, grew back into the ground (negative phototropism). The response to light of lateral buds was autonomous and depended on the conditions of their initiation. The lateral buds developed in darkness manifested negative phototropism when withdrawn from the soil and exposed to the light, whereas the buds developed in the light showed positive phototropism. The author concludes that the concept of apical dominance, thoroughly studied in aboveground shoots, is also valid for subterranean shoots. However, in contrast to the former, in the latter case, the apical bud does not control the growth orientation of the lateral buds.     

Proteomic Analysis of Chrysanthemum Lateral Buds after Removing Apical Dominance Based on Label-Free Technology

Studying the genetic basis and regulatory mechanism of chrysanthemum lateral bud outgrowth is of great significance for reduction the production cost of cut chrysanthemum. To clarify the molecular basis of lateral bud elongation after removal of apical dominance in chrysanthemum, label-free quantification analysis was used to analyze the proteome changes after apical bud removal. Quantitative real-time PCR (qPCR) was used to analyze the changes in the expression of three plant hormone-related genes. A total of 440 differentially expressed proteins were successfully identified at three time points during the lateral bud elongation. The number of differentially expressed proteins in the three stages (24 h/0 h, 48 h/0 h, 48 h/24 h) were 219, 332, and 97, respectively. The difference in expressed proteins in the three comparison stages mainly involves RNA processing and modification; translation, ribosomal structure and biogenesis; Posttranslational modification, protein turnover, and chaperones. Path analysis showed that there was various physiological activities in the process of lateral bud dormancy breaking and elongation, which involved energy metabolism, biosynthesis, signal transduction and stress response in the growth process of lateral buds. qPCR indicated that the expression of cytokinin synthesis related gene was significantly increased after the removal of apical dominance, while the expression of strigolactones synthesis related gene experiences a dramatic fall to promote the development of the lateral buds. However, there was a drop before a slight increase in the expression of the auxin synthesis related gene, which was mainly due to the removal of apical dominance that led to the loss of indoleacetic acid in the main stem. However, with formation of the new apical source, indoleacetic acid can be released again.     

Determination of the Pattern of Winter Dormancy in Lateral Buds of Apples

Controlled environmental conditions and decapitation treatmentswere used to distinguish and determine the relative importanceof environmentally-imposed dormancy, correlative inhibitionand rest on the imposition of winter dormancy of lateral budson detached shoots and potted seedlings of apples. It is establishedthat the winter dormancy of lateral buds follows a pattern similarto that previously proposed for buds in general. The minimum procedure for the assessment of dormancy in lateralbuds is discussed. Malus sylvestris L, apple, bud dormancy, winter dormancy     

光周期对菊花花芽分化及其叶片和芽内源多胺含量的影响

以切花菊品种神马为材料,研究不同光周期(16h昼/8h夜;12h昼/12h夜;8h昼/16h夜)对菊花花芽分化过程中叶片和芽内腐胺(Put)、亚精胺(Spd)和精胺(Spm)含量的影响.结果显示:(1)16h/8h处理植株始终没有花芽分化,8h/16h处理的花芽分化开始和完成分别在处理后第13.9天和第23.1天出现,比12h/12h处理的分别提前1.7d和2.8d.(2)16h/8h处理叶片和芽中Put、Spd和Spm含量始终都没有明显变化,而8h/16h和12h/12h处理的叶片和芽中Put、Spd、Spm含量都比16h/8h处理的明显增加,而且8h/16h和12h/12h处理的叶片Put和Spd含量在处理第10天和第20天时出现2个高峰,芽中Put和Spd含量在处理第15天时出现一个高峰;另外,8h/16h处理的叶片和芽中Put、Spd含量比12h/12h处理的有所增加,但差异不显著.结果表明,菊花神马是质型短日照植物,短日照可诱导神马叶片和芽内合成多胺,而且日照时数越短,越有利于叶片和芽内Put、Spd、Spm的积累和促进花芽分化.     

Effect of Abscisic Acid and Other Plant Hormones on Growth of Apical and Lateral Buds of Seedlings

The effect of abscisic acid (AbA) on the growth of lateral and apical buds was studied in seedlings of Pisum sativum and some other species. The hormone was applied in three different ways: 1) directly to the lateral bud on the second node of decapitated pea seedlings as 5 μI droplets in an ethanolic solution; 2) to the cut surface of decapitated seedlings: 3) to the apical bud of intact plants. AbA directly applied in amounts of 5 to 0.1 μg to the lateral bud of the second node of decapitated seedlings had a strong inhibitory effect on the bud. Application to the cut surface of seedlings decapitated about 5 mm above the second node resulted in slight inhibition of the lateral bud on the second node and in growth promotion of the bud on the first node. When AbA at 10 to 0.1 μg was applied to the apical bud of intact seedlings, the growth of this bud was inhibited but the lateral buds grew out. It is concluded that the release of the lateral buds from apícal dominance is the result of the inhibitory effect of AbA on growth of the apical bud and of low transport of AbA. This conclusion is supported by application of GA₃ and IAA, individually and each combined with AbA.     

Correlative Inhibition of Lateral Bud Growth in Phaseolus vulgaris L.--Influence of the Environment

The influence of various environmental factors upon main stemand lateral bud growth has beeninvestigated using Phaseolusvulgaris, with the object of discovering why there is variabilityin the response of lateral buds on decapitated plants to apically-appliedIAA. Light intensity, light quality and temperature had differentand specific effects on main stem and lateral bud growth inintact plants and on the effectiveness of IAA in inhibitingprimary leaf axillary bud growth in decapitated plants. Photoperiod,on the other hand, was apparently ineffective. It is concluded that environmental factors, as well as contributingto the normal regulation of apical dominance, could also partlyor wholly account for the variation in effectiveness of appliedIAA found by different workers. IAA was least effective whenthe temperature was lower at night than during the day.     

Effects of Temperature on Cold Acclimation and Deacclimation in Flower Buds of Evergreen Azaleas

The effects of various storage temperature/duration combinations(5, 10 and 17°/4, 8, 12 and 16 weeks) on cold acclimationand deacclimation of flower buds were studied in four speciesof evergreen azaleas having different natural distribution andcold hardiness. The freezing process and the exotherm temperaturedistribution of florets in excised whole buds determined bydifferential thermal analysis were used as the diagnostics todetermine the degree of bud acclimation and deacclimation. Theacclimation in buds lasted for as long as 12 to 16 weeks at5°C storage, and from 8 to 12 weeks at 10°C, and itappeared to be maintained after the chilling requirement forbreaking bud dormancy had been satisfied. Therefore, bud acclimationseems to be maintained independently from bud dormancy. Thedehardening effect on acclimated buds occurred as a result ofshort exposures to higher temperatures or long exposures tolower temperatures, and there was no relation between the rateof deacclimation and the degree of hardiness in each species.Among three storage temperatures examined, 5°C was the mosteffective for the maintenance of cold acclimation in flowerbuds and the small difference of floret water contents at 5and 10°C storage is not significant. (Received August 28, 1982; Accepted February 4, 1983)     

Experiments on growth interactions between two invasive macrophyte species

Abstract. The success of invasive species has been attributed to the ability to displace other species by direct competition. We studied growth and possible competition between the two macrophyte species Elodea nuttallii and E. canadensis, because the former has been observed to replace the latter in the field. Additional experiments were conducted in aquaria with mixed plantings of Elodea species. Species growth was measured and competitive abilities of each species determined by applying the reciprocal yield model to mean plant weight and length. In monocultures the growth rates of the two species were similar, while in mixtures the growth rate of E. canadensis was significantly lower than that of E. nuttallii. E. canadensis was more sensitive to intraspecific than to interspecific neighbours, whereas E. nuttallii was indifferent to the presence of neighbours. Differential growth characteristics of Elodea species can explain the displacement of E. canadensis by E. nuttallii under eutrophic field conditions.     

Effects of Ultraviolet Radiation on Amphibians: Field Experiments

SYNOPSIS. Numerous reports suggest that populations of amphibiansfrom a wide variety of locations are experiencing populationdeclines and/or range reductions. In some cases, unusually highegg mortality has been reported. Field experiments have beenused with increasing frequency to investigate ultraviolet radiationas one of the potential factors contributing to these declines.Results from field experiments illustrate that hatching successof eggs is hampered by ultraviolet radiation in a number ofspecies, while other species appear to be unaffected. Continuedmortality in early life-history stages may ultimately contributeto a population decline. Although UV-B radiation may not contributeto the population declines of all species, it may play a rolein the population decline of some species, especially thosethat lay eggs in open shallow water subjected to solar radiationand in those that have a poor ability to repair UV-induced DNAdamage.     

Grafting between tobacco plants to enhance salinity tolerance

We analysed the technique of grafting as a tool to increase salt-stress resistance in tobacco plants. With this aim, we performed two experiments. First, we selected, from among 6 commercial tobacco cultivars (cv. BB-162, cv. H-20, cv. Jarandilla, cv. ZB-3, cv. Havana II and cv. Havana 307) those most tolerant and sensitive to salinity, studying the response of certain nutritional and biochemical indicators of resistance in these plants. In the second experiment, we analysed the response to salinity in grafted tobacco plants using the rootstock of the most tolerant plants, and the scion of the most sensitive ones. In addition, these plants were subjected to salinity to test the viability and efficiency of this grafting technique, assessing the production of foliar biomass and the different quality parameters in this crop. In the first experiment, we found that the most tolerant tobacco cultivars were cv. BB-162 and cv. H-20, which were characterized by reduced uptake and foliar accumulation of Na⁺ and Cl⁻, together with greater synthesis of sucrose and proline, thereby reducing lipid peroxidation and thus oxidative damage, reflected in higher foliar biomass with respect to the other cultivars studied (primarily cv. Jarandilla, defined as the most salt-sensitive). In the second, we demonstrated that the grafting of salt-sensitive tobacco scions to salt-tolerant rootstocks improves the production and quality of tobacco leaves under conditions of saline stress. Our results show that the rootstocks cv. BB-162 and cv. H-20 best induced salt resistance in tobacco cv. Jarandilla, registering the lowest foliar concentrations of Na⁺ and Cl⁺, the lowest lipid peroxidation, and the highest proline and sugar concentrations. Overall, this is reflected in better biomass production and quality of the aerial part of the plant.     

Effects of Lateral Inhibition on Fluctuations of the Impulse Rate

Inhibition from neighboring eccentric cells has an effect on the variability of firing of a given eccentric cell. The reduction in the average impulse rate which is caused by inhibition decreases the variance of the impulse rate. However, this reduction of the average rate increases the coefficient of variation of the impulse rate. Inhibitory synaptic noise should add to the low frequency portion of the variance spectrum of the impulse rate. This occurs because of the slow time course of inhibitory synaptic potentials. As a consequence, inhibition decreases the signal-to-noise ratio for low frequency modulated stimuli.     

Exogenous Auxin Effects on Lateral Bud Outgrowth in Decapitated Shoots

In 1933 Thimann and Skoog demonstrated exogenous auxin repressionof lateral bud outgrowth in decapitated shoots ofVicia faba. This evidence has given strong support for a role of auxinin apical dominance. Most, but not all, investigators have confirmedThimann and Skoog's results. In the present study, auxin treatmentswere carried out on ten different species or plant types, manyof which were treated with auxin in different forms, media andunder different light conditions. The Thimann–Skoog experimentdid work for most species (i.e. exogenous auxin did repressbud outgrowth) including thedgt tomato mutant which is knownto be insensitive to auxin in certain responses. Toxic auxinsymptoms were observed in some but not all species. The Thimann–Skoogexperiment did not work for greenhouse-grownColeus or forArabidopsis. Light was shown to reduce apical dominance inColeus andIpomoeanil . apical dominance; lateral bud outgrowth; axillary bud; auxin; IAA; decapitation; Vicia faba ; Ipomoea nil ; Pisum sativum ; Phaseolus vulgaris ; Lycopersion exculentum ; dgt ; Coleus blumei ; Arabidopsis thaliana ; Helianthus annuus ; Thimann–Skoog     

石灰氮催芽对葡萄芽内源物质含量的影响(英文)

用15%石灰氮对巨峰葡萄(Kyoho grapevine)进行催芽后,于葡萄休眠解除过程中对芽内源激素含量、蛋白质含量以及淀粉酶活性的动态变化进行测定分析,以探讨石灰氮解除葡萄休眠的生理机制.结果显示:(1)用15%石灰氮催芽5 d后葡萄芽解除休眠而萌发,比对照提前5～8 d,处理21 d后休眠已经被打破;(2)处理后葡萄芽内ABA含量急剧下降了86.48%,而GA_3、ZR和IAA分别升高了461.70%、107.24%和1 020.41%;(3)IAA的急剧升高,伴随着淀粉酶活性加强,加速淀粉降解为可溶性糖;而蛋白质含量则先下降后升高.可见,石灰氮催芽后,葡萄芽内的生长抑制类激素ABA含量降低的同时生长促进类激素IAA、ZR和GA_3含量急剧增加,内源激素平衡被打破,加强了葡萄芽内有机物质的代谢,为葡萄芽的萌发提供了物质基础.因此,石灰氮处理促进葡萄休眠芽萌发的主要原因可能是调节了葡萄芽内各种激素平衡关系,从而加速了葡萄芽内有机物质的代谢而最终解除芽体休眠.