Stigma-surface Esterase Activity and Stigma Receptivity in Some Taxa Characterized by Wet Stigmas

Stigma-surface esterase activity and stigma receptivity througha sequence of developmental stages of the pistil have been studiedin four taxa characterized by having wet stigmas — Petuniahybrida, Nicotiana tabacum, Crinum defixum and Amaryllis vittata.The style is solid in the first two and hollow in the lattertwo taxa. In all the taxa, stigma—surface esterase couldbe detected in a thin surface layer (pellicle) from a very earlystage of pistil development, irrespective of the presence orabsence of the exudate. However, the taxa showed variation instigma receptivity. In Petunia and Nicotiana, stigmas from pistilsof all the stages supported pollen germination and tube growth.In Amaryllis and Crinum, stigmas of only the mature pistils,when the exudate is present on the stigma, supported normalpollen germination and tube growth. It is inferred that in taxacharacterized by a wet stigma and solid style, the factors requiredfor pollen germination are present from an early stage of pistildevelopment and the exudate per se is not involved in pollengermination. In taxa characterized by a wet stigma and hollowstyle, however, the pellicle does not carry the factors requiredfor pollen germination and tube growth; they appear to be presentin the exudate. Petunia hybrida Vilm, Nicotiana tabacum L., Crinum defixum, Ker-Gawl, Amaryllis vittata Ait., tobacco, pollination, pollen germination, stigmatic exudate, stigma receptivity, stigma-surface esterase, esterase activity     

Reversible inhibition of the pollen germination and the stigma penetration in Crocus vernus ssp. vernus (Iridaceae) following fumigations with NO2, CO, and O3 Gases

We assessed the pollen hydration, the pollen germination, and the stigma papilla penetration of CROCUS VERNUS subsp. VERNUS (Iridaceae) after 2 h fumigations with O (3), NO (2), and CO gases within humidified (90 - 100 % RH) box experiments. When the pollen and the pistil were separately fumigated, the pollen retained the capacity to emit a tube which penetrated papilla, and the stigma papillae retained the receptivity; when the pistils were first pollinated and then fumigated, the capacity of pollen to hydrate was not affected, but the germination was significantly reduced. The vulnerability to gases became evident at 0.3 ppm O (3), 0.2 ppm NO (2), and 0.5 ppm CO. The inhibition curves as a function of the gas concentrations were of an exponential type, and they saturated at 2 ppm NO (2), 25 ppm CO, and 0.5 ppm O (3), with germination percentages of 17 %, 27 %, and 60 %, respectively. Both the pollen germination and the papilla penetration were fully restored by prolonging for 60 - 90 min the incubation at 90 - 100 % RH, after the cessation of fumigations. The vulnerability of the pollen-papilla system is discussed.     

SD-RLK28 positively regulates pollen hydration on stigmas as a PCP-Bβ receptor in Arabidopsis thaliana

Pollen hydration on dry stigmas is strictly regulated by pollen–stigma interactions in Brassicaceae. Although several related molecular events have been described, the molecular mechanism underlying pollen hydration remains elusive. Multiple B-class pollen coat proteins(PCP-Bs) are involved in pollen hydration. Here, by analyzing the interactions of two PCP-Bs with three Arabidopsis thaliana stigmas strongly expressing S-domain receptor kinase(SD-RLK), we determined that SD-RLK28 directly intera...     

Breakdown of self-incompatibility during pistil development in Lycopersicon peruvianum by modified bud pollination

Summary Stylar self-incompatibility barriers in L. peruvianum can be avoided if pollen germination and growth through immature pistils is promoted under specific environmental conditions approximately 2–3 days before the initiation of anthesis. Since immature stigmas lack sufficient exudate for pollen germination, the sandwiching of a thin layer of pollen germination medium between the stigma and a mineral oil layer containing pollen allows precocious pollen germination and some compatible pollen tube growth through the style. This procedure is rapid, inexpensive, applicable in the field, and makes efficient use of pollen. Consistent though low seed yields have been obtained. A high proportion of aborted seed, seedling lethals, and aberrant seedling phenotypes in selfed progeny indicate the presence of strong post-zygotic barriers to such selfing. No evidence for a reduction in the strength of the SI response with increasing pistil age was observed.     

Asynchronous development of stigmatic receptivity in the pear (Pyrus communis; Rosaceae) flower

While stigma anatomy is well documented for a good number of species, little information is available on the acquisition and cessation of stigmatic receptivity. The aim of this work is to characterize the development of stigma receptivity, from anthesis to stigma degeneration, in the pentacarpellar pear (Pyrus communis) flower. Stigma development and stigmatic receptivity were monitored over two consecutive years, as the capacity of the stigmas to offer support for pollen germination and pollen tube growth. In an experiment where hand pollinations were delayed for specified times after anthesis, three different stigmatic developmental stages could be observed: (1) immature stigmas, which allow pollen adhesion but not hydration; (2) receptive stigmas, which allow proper pollen hydration and germination; and (3) degenerated stigmas, in which pollen hydrates and germinates properly, but pollen tube growth is impaired soon after germination. This developmental characterization showed that stigmas in different developmental stages coexist within a flower and that the acquisition and cessation of stigmatic receptivity by each carpel occur in a sequential manner. In this way, while the duration of stigmatic receptivity for each carpel is rather short, the flower has an expanded receptive period. This asynchronous period of receptivity for the different stigmas of a single flower is discussed as a strategy that could serve to maximize pollination resources under unreliable pollination conditions.     

棉花竹花形态与结构研究

棉花竹（Fargesia fungosa）是箭竹属重要经济竹种,有关其花器官的形态与解剖结构研究至今尚无报道。本文通过对棉花竹花器官的形态与解剖结构进行观察和分析,结果显示棉花竹花序为“混合花序”,小穗基部具潜伏芽,由单个叶片形成的“佛焰苞”包裹多枚小穗。小穗单次发生,均长3.05±0.390 cm,每枚小穗具有3~7朵小花,小花均长1.85±0.167 cm,颖片2枚。每朵小花皆具有内、外稃各1片,3枚浆片,雄蕊3枚,雌蕊1枚组成。未成熟花药具有4药室,花药壁由外到内依次为表皮、药室内壁、中层和绒毡层。花药成熟后纵裂散粉。成熟花粉粒为2或3细胞型,且具有1个萌发孔。子房1室,上位,侧膜胎座,倒生胚珠,雌蕊具2分叉羽毛状柱头。花药发育异常,导致出现大量败育现象。     

The extracellular lipase EXL4 is required for efficient hydration of Arabidopsis pollen

Pollination in species with dry stigmas begins with the hydration of desiccated pollen grains on the stigma, a highly regulated process involving the proteins and lipids of the pollen coat and stigma cuticle. Self-incompatible species of the Brassicaceae block pollen hydration, and while the early signaling steps of the self-incompatibility response are well studied, the precise mechanisms controlling pollen hydration are poorly understood. Both lipids and proteins are important for hydration; loss of pollen coat lipids and proteins results in defective or delayed hydration on the stigma surface. Here, we examine the role of the pollen coat protein extracellular lipase 4 (EXL4), in the initial steps of pollination, namely hydration on the stigma. We identify a mutant allele, exl4-1, that shows a reduced rate of pollen hydration. exl4-1 pollen is normal with respect to pollen morphology and the downstream steps in pollination, including pollen tube germination, growth, and fertilization of ovules. However, owing to the delay in hydration, exl4-1 pollen is at a disadvantage when competed with wild-type pollen. EXL4 also functions in combination with GRP17 to promote the initiation of hydration. EXL4 is similar to GDSL lipases, and we show that it functions in hydrolyzing ester bonds. We report a previously unknown function for EXL4, an abundant pollen coat protein, in promoting pollen hydration on the stigma. Our results indicate that changes in lipid composition at the pollen–stigma interface, possibly mediated by EXLs, are required for efficient pollination in species with dry stigmas.     

异型花柱植物喀什补血草的传粉者功能群与花粉转移效率

异型花柱是受遗传控制的花柱多态现象, 被达尔文认为是植物通过在传粉者体表不同部位滞落花粉以促进型间花粉准确传递的一种适应。该现象虽已受到广泛关注, 但在一些花型变异较大且不稳定的传粉系统中, 不同传粉者对各花型繁殖所产生的影响仍知之甚少。该研究以分布于新疆天山南坡的一个有同长花柱共存的异型花柱植物喀什补血草(Limonium kaschgaricum)种群为研究对象, 对其花型构成及频率、传粉者及花粉转移效率等进行了调查分析。结果表明: 1)种群中除了存在雌/雄蕊长度交互对应的长(L)/短(S)花柱型花外, 还有雌/雄蕊同长的花(H型), 且各花型花的花冠口直径、花冠筒长及花粉量等参数间无差异, 但花粉纹饰和柱头乳突细胞形态具二型性。其中, H型花的花粉和柱头形态与L型花(或S型花)的一致。2)花型内和自花授粉均不亲和; 型间授粉时, 花粉和柱头形态不同的花型间亲和, 反之不亲和。3)种群内存在长/短吻两类传粉昆虫。在以短吻传粉者为主的盛花初、中期, L和H型花柱头上的异型花粉数均显著高于S型花的, 且L和S型花高位性器官间的异型花粉传递效率高于低位性器官间的; 而在以长吻传粉者为主的盛花后期, L和S型花的柱头间异型花粉数无显著差异, 且高/低位性器官间具有相同的异型花粉转移效率; 与传粉者出现时期相对应的、在花期不同阶段开放花的结实率也明显不同。4)长/短吻昆虫具明显不同的传粉功能, 短吻昆虫只能对L和H型花进行有效传粉, 且访花频率和型间花粉转移效率较低, 为低效传粉者; 而长吻昆虫对各花型均能有效传粉, 具高的访花频率和型间花粉转移效率, 为高效传粉者。因为长吻昆虫的阶段性出现所形成的不稳定传粉系统, 使低效的短吻昆虫可能会成为种群中花型变异的驱动力, 并使S型花受到更大的选择压力。H型花克服了柱头缩入的弊端, 可能会成为不稳定传粉系统下的一个替代花型而持续存在。     

Sulfinylated azadecalins act as functional mimics of a pollen germination stimulant in Arabidopsis pistils

Polarized cell elongation is triggered by small molecule cues during development of diverse organisms. During plant reproduction, pollen interactions with the stigma result in the polar outgrowth of a pollen tube, which delivers sperm cells to the female gametophyte to effect double fertilization. In many plants, pistils stimulate pollen germination. However, in Arabidopsis, the effect of pistils on pollen germination and the pistil factors that stimulate pollen germination remain poorly characterized. Here, we demonstrate that stigma, style, and ovules in Arabidopsis pistils stimulate pollen germination. We isolated an Arabidopsis pistil extract fraction that stimulates Arabidopsis pollen germination, and employed ultra‐high resolution electrospray ionization (ESI), Fourier‐transform ion cyclotron resonance (FT‐ICR) and MS/MS techniques to accurately determine the mass (202.126 Da) of a compound that is specifically present in this pistil extract fraction. Using the molecular formula (C₁₀H₁₉NOS) and tandem mass spectral fragmentation patterns of the m/z (mass to charge ratio) 202.126 ion, we postulated chemical structures, devised protocols, synthesized N‐methanesulfinyl 1‐ and 2‐azadecalins that are close structural mimics of the m/z 202.126 ion, and showed that they are sufficient to stimulate Arabidopsis pollen germination in vitro (30 μm stimulated approximately 50% germination) and elicit accession‐specific response. Although N‐methanesulfinyl 2‐azadecalin stimulated pollen germination in three species of Lineage I of Brassicaceae, it did not induce a germination response in Sisymbrium irio (Lineage II of Brassicaceae) and tobacco, indicating that activity of the compound is not random. Our results show that Arabidopsis pistils promote germination by producing azadecalin‐like molecules to ensure rapid fertilization by the appropriate pollen.     

Floral morphology and anatomy of Pittosporum tobira (Pittosporaceae)

Comparative studies are made on floral morphology and anatomy of female and male flowers of Pittosporum tobira. The two types of flower differ little from each other in structure at the early stage of floral development, but appear dimorphic towards anthesis. The male flower becomes cryptically bisexual, although its pistil is slender compared to that of the female flower. The stigmas of the male flower are receptive and can induce pollen germination. The structure of the style in the male flower is identical to that in the female flower. Ovules are produced on the protruded parietal placenta in the male flower, but their development is arrested at the stage of the 4–nucleate embryo sac. The female flower is clearly unisexual, with obviously aborted and sagittate anthers. Its pistil is rather plump and can produce darkish red seeds immersed in sticky pulp. The male and female flowers are similar in vascular anatomy. A conspicuous difference between the two types of flower lies in the stamens. Variation of sexual organs in the genus Pittosporum is reviewed. We assume that the flowers of Pittosporum are derived from the hermaphrodite-flowered ancestor and the female flower has become unisexual through partial reduction of sexual organs at a faster rate than the male flower.     

簇枝补血草花的二态性及繁育系统研究

白花丹科被列为异型花柱较多的科,该文以补血草属簇枝补血草为材料,通过对野外居群的花部特征、花期物候和繁育系统等研究,探讨花部形态多态性及其对生殖的影响。簇枝补血草具有两种类型植株,具玉米状柱头和A型花粉的植株称为C型植株;具乳头状柱头和B型花粉的植株称为P型植株,且A/B型花粉的大小、外壁纹饰不同。单花发育过程中两型植株的花萼、雌蕊大小差异明显,随着花的成熟差异逐渐消失。两型植株都为雌蕊高于雄蕊,柱头探出式雌雄异位;C型植株的花期较P型植株长约2 d。一天当中,A型花粉活力高峰期为13:00,B型花粉在11:00和15:00都表现为高峰期;玉米状柱头可授性最强时期在13:00～15:00,乳头状柱头则在15:00。两型花粉可育性在盛花期最高,终花期时B型花粉可育性明显高于A型。荧光染色观察发现花粉萌发和花粉管的生长速度都为:异型授粉＞同型授粉,B型花粉在乳头状柱头上不能完成受精。此外,人工授粉实验也表明异型授粉结实率显著高于同型,P型植株经同型授粉结实现象并不明显,存在少量无融合生殖。研究表明簇枝补血草花部具二态性,繁育系统为兼性异交,其中乳头状柱头对A型花粉亲和,对B型花粉不亲和,但玉米状柱头却对A/B型花粉都亲和,这打破了该科的异型自交不亲和的例证。     

敦煌‘李光杏’花芽发育过程中雌蕊败育观察及生物学特性调查

为克服杏生产中雌蕊败育现象、提高坐果率,该研究以甘肃省敦煌市的‘李光杏’盛果期不同树势(强势树、中庸树和弱势树)和不同类型结果枝(花束状果枝、短果枝、中果枝、长果枝)的花芽为试材,对其开花物候期及生物学特性进行调查,采用石蜡切片观察易发生败育时期(花芽分化初期、雌蕊分化期、花粉细胞期和花蕾膨大期)的花芽内部组织结构形态,同时测定各主要败育时期叶片可溶性糖、淀粉含量及矿质元素的变化。结果表明:(1)弱树花芽的平均败育率最高(91.26%),中庸树最低(71.08%);不同类型结果枝中,花束状果枝花芽的败育率最低,长果枝的败育率最高。(2)不同结果枝类型的花粉生活力表现为花束状果枝>短果枝>中果枝>长果枝,花粉发芽率表现为短果枝>花束状果枝>中果枝>长果枝。各花型花粉生活力表现为雌蕊高于雄蕊>雌雄等长>雌蕊低于雄蕊>无雌蕊,发芽率的表现为雌雄等长>雌蕊高于雄蕊>雌蕊低于雄蕊>无雌蕊。(3)各树势花芽雌蕊分化期叶片可溶性糖与淀粉含量显著低于其他时期;叶片P、K、Ca含量在分化前期较高,但是雌蕊、雄蕊分化期显著下降。(4)与正常花相比,败育花主要表现为子房发育异常,多数生长点不均匀,子房萎缩,胚珠原基发育停滞;雌蕊的花柱低于花丝,且花粉粒急剧减少。研究发现,‘李光杏’树势的强弱会造成败育花比例和坐果率的差异,并以中庸树果实坐果率最高,且花败育率最低;雌蕊发育是否正常直接关系到‘李光杏’正常开花,雌蕊的发育受阻,最终成为整个花芽退化的主要形式;叶片碳水化合物和矿质元素等营养物质参与并保证了花器官的正常发育。     

有花植物触敏柱头的闭合行为及其适应意义

有花植物触敏柱头的闭合行为一直是传粉生态学和进化生物学研究的热点问题之一。植物花的多裂片柱头在传粉者接触后迅速闭合的现象主要存在于玄参目的一些类群中。早在上个世纪初,植物学家就对花的柱头闭合现象进行过初步的研究,认为柱头闭合主要是由于花粉在柱头上萌发时吸收水分导致柱头细胞膨压降低而引起的;并对柱头闭合的适应性提出了一些假说。近年来,许多学者研究证实柱头闭合能促进花粉萌发及花粉管伸长,或减少花粉散出与柱头接受花粉间的相互干扰,提高传粉者访问过程中花粉的散播量,并且柱头的状态会直接影响传粉者的取食行为。到目前为止,对柱头闭合的机制及其避免自交的假说还存在许多争议。关于触敏柱头的闭合行为,尤其是其适应机制及其生态学意义还有待更加系统和深入的研究。本文概述了触敏柱头的研究进展,并对研究中尚存在的一些问题进行了讨论。     

茜草科二型花柱植物滇丁香传粉精确性研究

异型花柱是一种受遗传因素控制的花型多态性现象,其适应意义在于提高不同花型间传粉精确性,从而促进异交。为检验二型花柱植物滇丁香（Luculia pinceana）是如何促进异交并确定有效传粉者的类型,实验统计自然种群中长、短柱型的植株数量,测量花部特征,统计自然种群植株柱头上的型间花粉落置的数量和比例,比较型内、型间花粉的萌发率以及花粉管长度,比较不同人工授粉处理结实情况,观察传粉昆虫类型并测量虫体特征。结果表明（1）滇丁香自然居群中长、短柱型植株的数量没有显著性差异。长柱型的筒深、筒直径、开口直径、雄蕊长和柱头长均显著小于短柱型,而长柱型的叶片长和宽、雌蕊长、花药体积、花粉粒体积、柱头厚均显著大于短柱型。（2）自然种群植株柱头上型间花粉所占比例显著低于型内花粉的比例。（3）型间授粉的花粉萌发率以及花粉管长度均大于型内授粉和混合授粉。（4）型间授粉的结实率显著高于型内授粉的结实率,型内授粉具有一定的结实。（5）夜行性长喙条背天蛾（Cechenena lineosa）是滇丁香的有效传粉者,其吻长和滇丁香的花筒深相适应。本研究表明二型花柱植物滇丁香主要是通过与其花部特征相匹配的长喙天蛾实现有效的传粉,通过促进型间花粉的萌发和花粉管的伸长而有利于型间授粉结实,提高传粉精确性。     

Pollination Biology in a TropicalAcaciaHybrid (A. mangiumWilld. xA. auriculiformisA. Cunn. ex Benth.)

Floral biology and pollination mechanism of theAcaciahybrid(A. mangiumWilld. xA. auriculiformisA. Cunn. ex Benth.) growingin Thailand are investigated using light and electron microscopy.The hybrid is andromonoecious. A floral spike consists of about150 loosely arranged flowers. Flowers are cream coloured, fragrantand have no floral nectaries. The pistil has a solid style witha smooth, wet stigma and amphitropous ovules with immature integuments.The anther consists of eight loculi, each bearing only one 16-grainpolyad. The flowers are weakly protogynous. Anthesis is completeat 0500–0600 h but peak female receptivity begins at 0200–0300h and is completed that day. The stigmatic exudate is of thelipophilic type and is secreted from the stigmatic cells bya holocrine mechanism. Pollen is the main floral reward forthe insect pollinators. There are several floral characteristicswhich facilitate pollen transfer from anthers and depositionon stigmas.Apis melliferaandCeratinasp. are the most effectivepollinators because they are the most common visitors and carrya heavy load of hybrid polyads. However, their behaviour inforaging for pollen in the same tree and weak protogynous dichogamymay promote self-pollination in the hybrid. The hybrid has lowpollination success due to low pollinator number. An increasein exposure time of flowers to pollinators or pollinator numbermay increase pollination success but may not affect the rateof pollen deposition on stigmas due to the relatively smallsize of the stigma in relation to the polyad.Copyright 1998Annals of Botany Company Acaciahybrid,Acacia mangium, Acacia auriculiformis, pollination, pistil receptivity, anthesis, pollinators.     

Gametophyte–Sporophyte Interactions in the Pollen–Pistil System: 3. Hormonal Status at the Progamic Phase of Fertilization

The content of hormones, IAA, ABA, and cytokinins, as well as the rate of ethylene production in petunia (Petunia hybrida L.) pistils and their parts (stigma, style, and ovary) were determined over 8 h after compatible pollination. At the progamic phase of fertilization in the pollen–pistil system, the phytohormones were virtually absent from the ovary but were present in various proportions in stigma and style. The stigma was the main site of ethylene synthesis and contained 90% of ABA while the style contained 80% of cytokinins of their contents in the whole pollinated pistil. Stigma and style did not differ in their IAA levels. The interaction of the male gametophyte with the stigmatic tissues was accompanied by a threefold increase in the ethylene production and a 1.5-fold increase in the IAA content in the pollen–pistil system within 0–4 h. Growth of pollen tubes in the stylar tissues (4–8 h) was accompanied by a further increase in IAA content and a decrease in the ethylene production by stigmatic tissues, as well as by a decrease in the cytokinin content in the stylar tissues. The ethylene/auxin status of the stigma may be suggested to control the processes of adhesion, hydration, and germination of pollen grains during pollination, while the auxin/cytokinin status of the style controls the pollen tube growth.     

Arabinogalactan-protein secretion is associated with the acquisition of stigmatic receptivity in the apple flower

Background and Aims

Stigmatic receptivity plays a clear role in pollination dynamics; however, little is known about the factors that confer to a stigma the competence to be receptive for the germination of pollen grains. In this work, a developmental approach is used to evaluate the acquisition of stigmatic receptivity and its relationship with a possible change in arabinogalactan-proteins (AGPs).

Methods

Flowers of the domestic apple, Malus × domestica, were assessed for their capacity to support pollen germination at different developmental stages. Stigmas from these same stages were characterized morphologically and different AGP epitopes detected by immunocytochemistry.

Key Results

Acquisition of stigmatic receptivity and the secretion of classical AGPs from stigmatic cells occurred concurrently and following the same spatial distribution. While in unpollinated stigmas AGPs appeared unaltered, in cross-pollinated stigmas AGPs epitopes vanished as pollen tubes passed by.

Conclusions

The concurrent secretion of AGPs with the acquisition of stigmatic receptivity, together with the differential response in unpollinated and cross-pollinated pistils point out a role of AGPs in supporting pollen tube germination and strongly suggest that secretion of AGPs is associated with the acquisition of stigma receptivity.Key words: AGPs, arabinogalactan proteins, apple, Malus × domestica, pollen, pollen tube, stigma, stigmatic receptivity, flower receptivity     

Characterization of the pollen growth transition in self-incompatible <Emphasis Type="Italic">Petunia inflata</Emphasis>

In Petunia inflata, as in other species that shed bicellular pollen, early pollen tube growth in the pistil is slow, then increases 2- to 5-fold depending on the genotype of the female parent. We refer to the time point at which pollen tubes enter the accelerated phase of growth as the pollen growth transition (PGT). Here, we present evidence that pre-PGT and post-PGT growth are quantitatively and qualitatively different, and that the PGT is triggered when pollen tubes reach the transition zone (TZ) below the stigma. The capacity of various pistil zones to precipitate the PGT was tested through 'stump' pollinations: varying lengths of the pistil apex were excised, the cut surface of the remaining pistil (the stump) coated with stigmatic exudates then dusted with compatible pollen. Pollen applied to TZ tissues entered the PGT earlier than pollen growing in intact control pistils; the PGT was delayed in stylar stumps, largely because of delayed germination and reduced pre-PGT growth. In immature pistils, the PGT was delayed by several hours relative to its onset in mature pistils. The PGT fails to occur in pollen cultured in vitro. Collectively, the data suggest that pollen tubes become competent to enter the PGT when they reach a critical size, but the physicochemical environment of the transmitting tissue is necessary for triggering the cellular changes that result in accelerated growth. An analysis of the distribution of pollen tube tips before and after the PGT suggests that pollen competition is most intense during the pre-PGT phase.     

A novel pollen tube growth assay utilizing a transmitting tract-ablated Nicotiana tabacum style

Sexual plant reproduction requires multiple pollen–pistil interactions from the stigma (pollen adhesion, hydration, and germination) to the ovary (fertilization). Understanding the factors that regulate pollen tube growth is critical to understanding the processes essential to sexual reproduction. Many pollen tube growth assays (PTGAs) have shorter and slower pollen tube growth when compared to pollen tube growth through the style. The identification and study of factors that regulate pollen tube growth have been impeded by a lack of an efficient and reproducible PTGA. The objective of this research is to develop a robust assay for Nicotiana tabacum pollen tube growth in an environment that supports sustained and normal growth yet is amenable to testing the effects of specific factors. In this paper, we introduce a novel PTGA, which uses pistils from N. tabacum that lack a mature transmitting tract (TT) due to tissue-specific ablation. The TT-ablated style supports normal pollen tube growth and the hollow structure of the style allows modification of the growth environment by direct injection of test material. This PTGA is robust and allows for rapid and accurate measurement of pollen tube length and pollen tube morphology, supporting pollen tube growth from 20 to 35°C and at pH ranging from 4.8 to 7.6. Use of the ablated style for a PTGA is a novel method for the culture of pollen tubes with sustained growth in vivo while permitting the application of treatments to the growing pollen tubes.