紫荆花粉离体萌发条件的研究

以紫荆(Cercis chinensis Bunge)花粉为材料,采用人工培养法研究了紫荆花粉离体萌发的最适条件.结果表明:蔗糖、硼酸在一定质量浓度范围内能促进花粉的萌发,最适花粉萌发的质量浓度分别为蔗糖50 mg/L以及硼酸20 mg/L,最佳萌发温度20℃.正交试验设计结果表明:花粉萌发的最佳质量浓度分剐为70 mg/L蔗糖以及18mg/L硼酸,最佳萌发温度为22℃,此时的萌发率可达60.51％.     

培养条件及贮藏温度和时间对木麻黄花粉萌发率的影响

用离体培养的方法研究了不同蔗糖、硼酸浓度,以及不同贮藏温度和贮藏时间对木麻黄(Casuarina)花粉萌发的影响.结果表明:15%的蔗糖是木麻黄花粉萌发的最佳浓度;在15%蔗糖培养基上添加硼酸显著促进木麻黄花粉萌发,250 mg kg-1硼酸是木麻黄花粉萌发的最佳浓度;添加了琼脂的固体培养基更有利于木麻黄花粉萌发;在常温下木麻黄生活力丧失很快,但低温下花粉的萌发力可保持较长时间.     

悬铃木花粉生活力及贮藏力的研究

以30~40年生悬铃木(Platanus acerifolia)的花粉为试材,研究了不同培养基对其萌发的作用,同时探讨了不同贮藏条件和贮藏时间对花粉生活力的影响。结果表明:悬铃木花粉在15%蔗糖 0.01%硼酸的培养基上培养24 h后萌发率最高;附加琼脂的固体培养基对花粉的萌发影响不大;50 mg/L的赤霉素对悬铃木花粉的萌发没有明显的抑制或促进作用;花粉干燥后在低温4℃下贮藏能保持较长的生活力,比未经干燥25℃和4℃下贮藏分别长35 d和20 d。     

光皮桦花粉离体萌发试验

设置若干温度的培养环境以及各种浓度蔗糖、蔗糖+硼酸、蔗糖+硝酸钙、蔗糖+硼酸+硝酸钙培养基,研究温度以及蔗糖、硼、钙对光皮桦花粉离体萌发的影响,探明光皮桦花粉萌发的适宜温度和最佳培养基。结果表明:合适浓度的蔗糖、硼酸和硝酸钙均能显著促进光皮桦花粉萌发,而高浓度的蔗糖、硼和钙均抑制其花粉萌发;光皮桦花粉离体萌发的合适培养基为10%蔗糖+200mg.L-1硼酸+200mg.L-1硝酸钙,适宜培养温度为30℃;在此条件下培养4h后花粉萌发率基本稳定,培养6h后花粉管长度亦趋于稳定。     

百合不同杂交系品种花粉贮藏特性分析

百合花粉贮藏是解决育种过程中花期不遇以及种质资源保存的重要环节,该试验以亚洲百合、东方百合和OT杂种系列的12个品种为材料,筛选出适合大部分品种花粉萌发的培养基及萌发率的观测时间,探讨花蕾发育时期[完全显色(-1级)、2/3显色(-2级)]、花粉收集后处理方式[离心管(处理Ⅰ)、离心管口加棉花(处理Ⅱ)、离心管口加棉花和管底添加干燥剂(处理Ⅲ)]、贮藏温度(常温、4℃、-20℃和-80℃)对花粉活力的影响。结果显示:(1)5%蔗糖+100(150)mg/L硼酸+30(50)mg/L氯化钙为适合大部分品种花粉萌发的液体培养基配方,百合花粉培养24h后测定萌发率为宜。(2)-1级花粉的萌发率比-2级的高且保持生命力的时间更长,如‘Tresor’-1级新鲜花粉的萌发率可达到83.2%,但其-2级只有21%。常温条件最不利于花粉保存,20d时大部分花粉萌发率为0;4℃与-20℃下较利于花粉短期贮藏且差别不显著。(3)经过4℃、120d贮藏,亚洲百合4个品种花粉萌发率最低能保持24.7%,最高能有55.9%左右;2个东方百合品种4℃下花粉萌发率为6.8%～12.7%;花粉在-80℃条件能较长时间保持活力,亚洲百合和东方百合花粉萌发率分别能保持26.7%～61.9%和7.1%～16.2%。(4)各个品种在不同温度条件下,大部分在处理Ⅲ下花粉萌发率较其他两种处理稍高。因此,-80℃结合在离心管口加棉花和管底添加干燥剂(处理Ⅲ)适合百合花粉的长期贮藏。     

杜鹃红山茶花粉萌发力及贮藏耐性的研究

以2～3年生嫁接的杜鹃红山茶(Camellia azalea)花粉为实验材料,研究了不同培养基、不同培养温度对其萌发的影响,同时探讨了不同贮藏条件和贮藏时间下花粉生活力的差异。结果表明:杜鹃红山茶花粉在不同培养时间下其萌发率呈抛物线型,花粉在15%蔗糖+0.02%硼酸的培养基上萌发率最高,30℃的培养温度比25℃、20℃更适合杜鹃红山茶花粉萌发。-20℃冷冻保存和液氮保存都是适合杜鹃红山茶花粉长期保存的方式。     

桃花粉离体萌发和花粉管生长特性研究

采用花粉离体萌发法研究不同培养基组分和培养条件对桃花粉萌发和花粉管生长的影响,同时对不同贮藏温度下的桃花粉寿命进行研究.结果表明:固体培养基与液体培养基对桃的花粉萌发率和花粉管长度影响差异不显著;10%蔗糖是大多数桃品种花粉的最适萌发条件;硼能提高桃花粉的萌发率,但对花粉管的生长没有促进作用;桃花粉在20℃～25℃的培养温度下萌发率最高,花粉管最长;桃花粉萌发率和花粉管长度在培养前3 h内上升最快,3～5 h上升趋势减弱,5 h后基本停止;随着贮藏温度的升高和贮藏时间的延长,花粉生活力呈降低的趋势.     

凯特杏花粉的离体培养及影响因子分析

采用离体培养法,在不同培养基组分含量、pH值、温度及植物生长调节物质的培养条件下,对凯特杏(Prunus armeniacaL.cv Katy)花粉的离体萌发和花粉管生长状况进行观察研究。结果表明:(1)凯特杏花粉离体萌发及花粉管生长的适宜培养基为20%蔗糖 0.04%硼酸 0.01?Cl2,最适pH为6.0,最适温度为20℃,培养20 h后,花粉的萌发率达68.76%,花粉管长度达1 083.53μm。(2)不同植物生长调节物质对花粉萌发和花粉管生长作用不同,赤霉素浓度为5~8 mg/L、矮壮素浓度为10~150 mg/L、多效唑浓度为5~10 mg/L时对凯特杏花粉萌发和花粉管生长都有促进作用,但国光丁酰肼对凯特杏花粉萌发和花粉管生长均有抑制作用。     

天女木兰花粉形态特征及其生活力

对天女木兰（Magnolia sieboldii）花粉的采集时期、形态以及培养的温度和培养基进行了研究,并探讨贮存温度和时间对花粉生活力的影响。结果表明,扫描电镜观察到的花粉形状和萌发孔与其他已报道的木兰科植物相同,但大小和花粉外壁的纹理不同。在花瓣刚刚展开的初花期采集的花粉生活力最高。25℃下最适于花粉的萌发;花粉在含10％蔗糖＋0．1％硼酸的培养基上培养14h的萌发率最高,0．01％～0．05％的氯化钙对花粉的萌发影响不显著,0．1％的氯化钙对花粉的萌发有抑制作用。随着贮存时间的延长,花粉萌发率不断降低。不同贮存温度下花粉萌发率的降低速度依次为-10℃〈4℃〈25℃,-10％下贮藏5d的花粉萌发率降低了48．8％,10d后萌发率降低为0。     

培养基组分及培养条件对蜡梅花粉萌发及花粉管生长的影响

采用液体培养法研究不同培养基组分和培养条件对蜡梅花粉萌发和花粉管生长的影响。结果表明:(1)PEG-4000是蜡梅花粉离体培养所必需的培养基成分,当培养基中无PEG-4000时,花粉不能正常萌发。(2)培养基内低浓度蔗糖对花粉萌发和花粉管的生长无显著影响,但随着蔗糖浓度的升高,则对花粉萌发和花粉管生长表现出强烈的抑制作用,且浓度越高,抑制效应越强。(3)培养基内其它组分分别在一定浓度范围(0～250g/L PEG-4000、0～50mg/L硼酸、0～30mg/L硝酸钙)内对花粉萌发及花粉管生长有促进作用,但超过上述高限值时则起抑制作用。(4)培养基内镁和钾的浓度对花粉萌发及花粉管生长影响不显著。研究表明,蜡梅最适花粉液体培养基组分为250g/L PEG-4000+50mg/L H3BO3+30mg/L Ca(NO3)2.4H2O,且在pH 5.5、温度15℃和600lx的光照培养条件下蜡梅花粉萌发和花粉管生长最佳。     

Class B β-expansins are needed for pollen separation and stigma penetration

Group 1 grass pollen allergens comprise a distinctive clade within the β-expansin family of cell wall-loosening proteins and are divided by sequence divergence into two phylogenetically separable classes (A and B). They have been proposed to loosen the walls of the stigma and style. Supporting this idea, we recently showed that a transposon insertion in one of the maize group-1 allergen genes reduces the ability of pollen to effect fertilization under conditions of pollen competition. In this work, we provide additional information on the phenotype of this mutant, showing that pollen deficient in β-expansin gene expression tended to form large aggregates, leading to poor pollen dispersal on anther dehiscence, and that emerging pollen tubes had difficulties entering the silk. In addition, a silencing construct was created to reduce expression of all the class B genes with results that are consistent with those seen with the transposon insertional line, including reduced transgene transmission through the pollen. Our results provide a more detailed understanding of the role of group 1 allergens (pollen β-expansins) in maize pollen development, pollen dispersal, pollen tube penetration into the style, and pollen tube growth through the transmitting tract. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Storage of pollen grains of Crotalaria retusa in oils

Summary Attempts were made to store pollen grains of Crotalaria retusa L. in a mineral oil (paraffin oil) and two vegetable oils (soybean oil and olive oil). Under laboratory conditions pollen grains not stored in oil lost in vitro germinability within 15–30 days, while those stored in oils maintained some degree of germinability even after 60 days. Pollen samples stored in oils at –20° C did not show any decline in germinability or pollen tube vigour even after 6 months of storage. The results amply demonstrate the feasibility of using oils for short- and long-term pollen storage.     

The role of the pistil in screening compatible pollen

Summary Results of in vitro studies on pollen germination and tube growth in the presence of leachates from bisected pistils in Crotalaria retusa provide evidence for the operation of selection pressure during pollen-pistil interaction — a process which stimulates growth of a limited number of pollen tubes giving them an advantage over others in effecting fertilization.     

Ultrastructural investigations on Lycopersicum peruvianum pollen activation and pollen tube organization after self-and cross-pollination

No differences have been observed in vivo between Lycopersicum peruvianum compatible and incompatible pollen during activation and pollen tube emission and organization, that is until 4 h and 30 min after pollination. During pollen activation the main events are the setting free of rough endoplasmic reticulum (RER) cisterns which were stacked in the mature pollen, the increase in the number of polysomes, and a great activity of the dictyosomes. Immediately after germination of the vegetative nucleus and the generative cell move into the tube, the generative cell diviting to form the male gametes; the tube then becomes organized in four zones. This series of changes is similar to what has already been observed in vitro except that in vitro the generative cell remains undivided and the whole process from seeding to tube organization takes 3 h instead of 4 h and 30 min after pollination, as it does in vivo. Our findings are compatible with the main models of the tube inhibition mechanism proposed till now.Abbreviations RER rough endoplasmic reticulum - GC generative cell - VN vegetative nucleus - GP germinative pore Research performed under C.N.R. (Italian National Research Council) program Biology of Reproduction     

Production of fertile tobacco pollen from microspores in suspension culture and its storage for in situ pollination

Summary A simple procedure is described for the in vitro production of tobacco (Nicotiana tabacum L.) pollen from microspores isolated just before entering mitosis. During a 3-day culture period in a liquid medium containing pyrimidine nucleosides these microspores develop into young pollen grains to the stage of starch deposition. Pollen maturation and transition to dormancy is achieved during a further 2- to 3-day culture period in the same medium stepwise supplemented by a concentrated solution of sucrose and l-proline. Upon transfer of the pollen to a simple germination medium containing sucrose and boric acid, up to 40% of the grains were observed to produce relatively long tubes. The in vitro-matured pollen grains can be stored at-20° C either suspended in 1.17 M sucrose and 100 mM l-proline or separated from the medium on filter paper discs. The stored pollen germinated both in vitro and on the stigma, the pollen tubes grew through the style into the ovary and pollination produced up to 300 viable seeds per pod. The procedure is of interest for pollen developmental studies and various fields of pollen manipulation, such as in vitro pollen selection.     

Behavioral responses by bumble bees to variation in pollen availability

Summary Pollen-collecting bumble bees (Bombus spp.) detect differences between individual flowers in pollen availability and alter their behavior to capitalize on rewarding flowers. Specific responses by bees to increased pollen availability included: longer visits to flowers; visits to more flowers within an inflorescence, including an increased frequency of revisits; an increased likelihood of grooming while the bee flow between flowers within the inflorescence; and more protracted inter-flower flights, probably because of longer grooming bouts. The particular suite of responses that a bee adopted depended on the pollen-dispensing mechanism of the plant species involved. Bees buzzed previously-unvisited Dode-catheon flowers longer than empty flowers. In contrast, pollen availability did not significantly affect the duration of visits to Lupinus flowers, which control the amount of pollen that can be removed during a single visit. Simulation results indicate that the observed movement patterns of bumble bees on Lupinus inflorescences would return the most pollen per unit of expended energy. The increased foraging efficiency resulting from facultative responses by bees to variation in pollen availability, especially changes in the frequency and intensity of grooming, could correspondingly decrease pollen dispersal between plants.     

Selection for tolerance to copper during pollen formation in Mimulus guttatus Fischer ex DC

In Mimulus guttatus, copper tolerance is determined largely by a single gene and is expressed in both the sporophyte and microgametophyte. This study explores the extent to which selection during pollen formation affects copper tolerance in the sporophytic generation. Two sets of plants heterozygous for copper tolerance, produced by reciprocal crosses between different copper-tolerant or sensitive families, and the plant on which the original observations were based, were cloned and grown in control or copper-supplemented solutions. Pollen viability and the number of tolerant progeny produced in backcrosses to sensitive plants were compared. In addition, the effect of copper treatment on pollen viability in vitro was compared for plants tolerant, sensitive and heterozygous for copper tolerance. The extent to which in vitro pollen viability decreased in response to copper treatment corresponded to the copper tolerance of the pollen source. When grown with added copper, four of the five plants showed significant reductions in pollen viability, ranging from 18% to 48% of control values. The reductions in pollen viability were correlated with an increase in tolerant progeny (r= 0.679, p=0.004). Increases in tolerant progeny could be large, ranging from 119% to 170% of that of controls, but were usually smaller than was predicted from the reductions in viable pollen. In addition, plants derived from reciprocal crosses differed significantly in the extent to which pollen viability was decreased and sporophytic tolerance increased. Thus, while selection during pollen formation could increase sporophytic tolerance, sporophytic factors, perhaps including cytoplasmic or epigenetic ones, moderated the effectiveness of pollen selection for copper tolerance.     

Subcellular distribution of arabinogalactan proteins in pollen grains and tubes as revealed with a monoclonal antibody raised against stylar arabinogalactan proteins

Summary Monoclonal antibody PCBC3, raised against stylar extracts fromNicotians, alata flowers, was deduced from enzyme-linked immunosorbent assays and inhibition of immuno-gold labelling on tissue sections to bind specifically to carbohydrate epitopes on arabinogalactan proteins (AGPs) but not to other arabinose-containing cell wall polysaccharides. When pollen grains ofN. tabacum were hydrated in fixative, PCBC3 bound to vesicles in the vicinity of the endoplasmic reticulum but, when grains were hydrated for 20 min in culture medium before fixation, binding was restricted to the plasma membrane. The generative-cell plasma membrane was also labelled in grains ofLycopersicon peruvianum. In pollen tubes ofN. tabacum grown in liquid culture, the AGPs detected by PCBC3 were located in several regions, including the plasma membrane, tubular-vesicular structures (plasmalemmasomes) at and under the plasma membrane, and multilamellar bodies within vacuoles, features generally associated with endocytosis. Labelling was not evident in secretory vesicles or the plasma membrane at the pollen-tube tip. The AGPs detected with PCBC3 were also present in pollen-tube walls, near the interface between the inner, callosic layer and the outer, fibrillar, pectic layer. Pollen tubes ofN. tabacum grown in medium lacking added CuSO₄ produce a wall with an abnormally thickened fibrillar layer, and this layer was uniformly labelled with PCBC3. The disposition of wall AGPs thus changes in pollen tubes of different morphologies.Abbreviations AGP arabinogalactan protein - -L-Araf -L-arabinofuranose - ELISA enzyme-linked immunosorbent assay - MAb monoclonal antibody - PBS phosphate-buffered saline     

Pollen-pistil interaction in Brassica oleracea

Quantitative studies of the adhesion of pollen grains to the stigma in Brassica oleracea revealed that self-pollen is initially less firmly bound than cross-pollen. The pollen grain tryphine, believed to be important in the adhesion process, has been shown to differ in mobility following self- and cross-pollination when observed using fluorescent probes. The hydration of the pollen grains has been investigated in vitro by measuring the changes in shape, volume and fresh weight of the imbibing grains. Whilst little change in volume could be detected there was a considerable increase in fresh weight together with a change of shape. The significance of these events, which occur prior to pollen germination, is discussed in relation to their effect upon subsequent germination and expression of self-incompatibility.Abbreviations RH relative humidity - SI self-incompatibility - ConA concanavalin A - I-ANS I-anilino-napthyl-sulfonic acid     

Oleosin-like proteins are not present on the surface of tobacco pollen

Pollen-stigma interactions on wet- and dry-type stigmas involve similar processes: the hydration of the pollen, followed by pollen tube growth and penetration of the stigma. Furthermore, in some species, identical molecules, namely lipids, are used to achieve this. In addition to lipids, oleosin-like proteins of the pollen coat of dry-type stigma plants have been shown to be involved in pollen-stigma interactions. However, little information is present about the proteins on the surface of pollen of wet-type stigma plants, in particular that of the Solanaceae. To analyze proteins from the surface of pollen of Nicotiana tabacum (tobacco), a solanaceous plant, we used an antiserum raised against Brassica pollen coat, a dry-type stigma plant of the Brassicaceae. In addition we used a molecular approach to identify tobacco homologues of oleosin-like genes. Our results show that no proteins similar to Brassica oleracea pollen coat proteins are present on the surface of tobacco pollen, and that oleosin-like genes are not expressed in tobacco anthers or stigmas.