POLLEN TUBE GROWTH AND INCOMPATIBILITY FOLLOWING INTRA- AND INTER-SPECIFIC POLLINATIONS IN LILIUM LONGIFLORUM

The growth of pollen tubes of a sampling of Lilium species in styles of L. longiflorum incubated at 24 C for 48 hr after pollination indicated two types of interspecific incompatibility. Pollen tubes of two self-compatible species of section Leucolirion, the section including L. longiflorum, stopped growth abruptly upon reaching the stylar canal, were of abnormal morphology, and were incapable of continued growth with longer incubation. Pollen tubes of self-compatible or self-incompatible species of sections Sinomartagon, Pseudolirium, Liriotypus, and Daurolirion approached but did not exceed the length of intraspecific incompatible pollen tubes in styles of L. longiflorum. Pollen tube morphology was normal and tubes were capable of continued growth with additional incubation. Unilateral interspecific incompatibility occurred in reciprocal crosses between self-incompatible L. longiflorum and self-compatible L. regale and L. formosanum, but exceptions occurred in Aurelian hybrids. Incubation of interspecifically pollinated L. longiflorum styles at 39 C, which removes the self-incompatibility reaction, had no effect on interspecific incompatibility.     

GROWTH OF POLLEN TUBES OF OENOTHERA ORGANENSIS THROUGH OTHERWISE INCOMPATIBLE STYLES

Hecht , A. (Washington State U., Pullman.) Growth of pollen tubes of Oenothera organensis through otherwise incompatible styles. Amer. Jour. Bot. 47(1) : 32—36. Illus. 1960.–It has previously been reported that pollen tubes of Oenothera organensis fail to grow from compatible stylar tissue into a graft of stylar tissue containing the same “S” alleles as are present in the pollen tubes. Upon this basis it has been assumed that the incompatibility reaction in this species is equally effective at all levels of the stigma and style. Results contrary to these were obtained by employing a new culturing and grafting technique: styles with attached stigmas were excised from their ovaries and cultured in large Petri dishes. The styles were cut usually 15 mm. below the stigmas, then grafted to similarly cut styles from a plant of another incompatibility class and held together by means of a “splint” made of lactose-gelatin and a square of moistened lens paper. This “splint” was generally effective in keeping the cut ends in contact and in allowing pollen tubes to grow through the scion portion into the stock. In the 95 grafts involving a scion having no “S” alleles in common with those of the pollen and a stock containing the “S” allele of the pollen, tubes grew an average of 22.1 mm. into the stock during a 15-hr. period at 27°C., with some growing as far as 55 mm. under these conditions. These results suggest the possibility of 3 alternative mechanisms: (1) the incompatibility reaction is stronger in the stigma than in the style; (2) in the growth of pollen tubes through compatible tissue some stimulus is received or some substance is formed. which allows continued growth into the otherwise incompatible tissue of the stock; or (3) some of the stylar, inhibitory substance is lost by diffusion into the gelatin mixture at the graft juncture.     

FINE STRUCTURE AND CYTOCHEMISTRY OF LILIUM POLLEN TUBES

Growth of the Lilium longiflorum pollen tube in vitro is restricted to a zone extending back 3–5 μ from the tip. Electron micrographs of cross and longitudinal thin sections of L. longiflorum and L. regale pollen tubes reveal that the cytoplasm of the nongrowing region of the tube contains an abundance of mitochondria, amyloplasts, Golgi bodies, endoplasmic reticulum, lipid bodies, and vesicles. In contrast, the growing tip is characterized by an abundance of vesicles and an absence of other cytoplasmic elements. The vesicles appear to be of 2 types. One is spherical, about 0.1 μ in diameter, stains strongly with phosphotungstic acid, apparently arises from the Golgi apparatus and appears to contribute to tube wall and plasmalemma formation. The other type is irregular in shape, 0.01-0.05 μ in diameter, stains strongly with lead hydroxide, and is of unknown origin and function. Cytochemical analysis indicates that the tips of L. longiflorum pollen tubes are singularly rich in ribonucleic acid, protein, and carbohydrate. These findings are discussed in relation to tube growth.     

FINE-STRUCTURAL STUDY ON THE FORMATION OF THE GENERATIVE CELL WALL AND INTINE-3 LAYER IN A GROWING POLLEN GRAIN OF LILIUM LONGIFLORUM

At the end of mitosis in the lily pollen microspore, the fan-shaped cell plate gives rise to a cell wall delineating a hemispherical cell. At first, the cell wall of the newly formed generative cell and the intine-3 layer of the pollen grain wall are inseparable. Gradually, the wall of the generative cell near the pollen grain wall becomes thicker and wall segments are formed between the thickened zones, and these make a network system by which the generative cell becomes suspended and separated from the pollen grain wall. After the separation, the intine-3 layer is formed inside the intine 2. The generative cell wall and the intine-3 layer are formed by coated vesicles, polysaccharide particles and rough ER.     

STUDIES ON THE SELF-INCOMPATIBILITY RESPONSE OF LILIUM LONGIFLORUM

Removal of substances loosely associated with the wall of Lilium longiflorum pollen did not affect in vitro germination and tube growth, tube growth within compatible styles, or production of viable seeds. Nor was growth of pollen tubes within incompatible styles enhanced by prior removal of the loosely bound materials. Hence, these materials appear not to be recognition factors in the gametophytic self-incompatibility system of Lilium and to have no role in pollen germination. Heat treatment of selected portions of lily pistils prior to pollination indicated that the incompatibility factor(s) was located in the lower half of the style, and that the stigma plays no role in incompatibility.     

荞麦亲和与不亲和授粉后柱头和花粉管中ATP酶的超微细胞化学定位

利用磷酸铅沉淀技术对荞麦(Fagopyrum esculentum Month.)pin型植株分别进行亲和授粉和不亲和授粉后的柱头、花粉粒、花粉管进行了ATPase的超微细胞化学定位。结果表明(1)亲和授粉和不亲和授粉后0.5h,柱头细胞的ATPase活性反应水平较低或基本无酶活性;柱头表面、柱头上附着的花粉粒内ATPase活性在不亲和授粉时较低,亲和授粉时较高,花粉粒内ATPase主要定位于线粒体和精子细胞;(2)授粉后1.5h,不亲和授粉的柱头细胞及花粉管的ATPase活性均较低,花粉管停止生长,细胞质开始解体;而亲和授粉的柱头细胞及花粉管的ATPase活性均较高,ATPase主要定位于柱头细胞的质膜、胞基质以及花粉管的壁、质体的膜、高尔基体、线粒体上。根据不同时期不同部位ATPase活性的差异,我们认为荞麦发生自交不亲和时,花粉管在花柱中停止生长不仅是因为花粉管得不到花柱中的营养物质而引起的,可能也与花粉管自身物质代谢发生障碍有关。     

A STUDY OF THE RELIABILITY OF SYNCHRONY IN THE DEVELOPMENT OF POLLEN MOTHER CELLS OF LILIUM LONGIFLORUM AT THE FIRST MEIOTIC PROPHASE

Lilium longiflorum anthers have been used by a number of investigators as a source of supposedly synchronous cells for studying genetic, chromosomal and molecular events of meiotic prophase I. Because of questions raised by the literature as to the reliability of such synchrony, new baseline data were obtained for L. longiflorum ‘Croft’ in preparation for experiments requiring homogeneity or synchrony. Homogeneity was found to be reliable at the same level of locules of the same anther and of anthers from the same bud up to the onset of diplotene. Synchrony deteriorates rapidly from diplotene on. Less than half the anthers examined had PMC's at the same stage from apex to base. Hence experiments requiring complete homogeneity within anthers would call for rigorous monitoring of each anther included in the sample. Synchrony between buds of the same length was insufficient to allow bud length to be used as a reliable index of meiotic stage.     

SECRETIONS FROM THE PISTIL OF LILIUM LONGIFLORUM

The pistil of Lilium longiflorum secretes two forms of exudate, one from the stigma surface and the other from the canal cavity. Electrophoretic studies of these exudates have revealed quantitative and qualitative differences in protein profiles. The exudatic components which are transferred to the cell wall by endoplasmic reticulum and Golgi vesicles, are stored within the cell wall of the secretive tissues and secreted from the cell walls directly. The cell wall structure of these secretive tissues differs. The canal cell wall has thick characteristic ingrowths that are supplied mainly from Golgi vesicles, while the papilla cell wall of the stigma is thinner, lacks ingrowths, and is supplied from ER vesicles.     

类整合素在烟草花粉萌发和花粉管生长中的作用

本文研究了动物整合素VnR抗血清及动物整合素专一性抑制剂含RGD的多肽对体外及半体内培养条件下烟草花粉萌发及花粉管生长的影响。结果表明在体外培养条件下,VnR抗血清及GRGDSP肽对花粉的萌发及花粉管的生长没有明显的抑制作用,但可抑制钙调素促进的花粉萌发和花粉管的生长;两者对柱头上进行的花粉萌发及在花柱里进行的花粉管生长也有一定程度的抑制。对类整合素在花粉萌发及花粉管生长中的作用进行了讨论。     

AUTORADIOGRAPHIC STUDIES OF NUCLEIC ACIDS AND PROTEINS DURING MEIOSIS IN LILIUM LONGIFLORUM

Taylor , J. Herbert (Columbia U., New York, N. Y.) Autoradiographic studies of nucleic acids and proteins during meiosis in Lilium longiflorum. Amer. Jour. Bot. 46(7): 477–484. Illus. 1959.—A study was made of the incorporation of glycine-C¹⁴, orotic acid-C¹⁴ and cytidine-H³ into nucleic acids and proteins of sporogenous and tapetal cells of lily anthers preceding and during meiosis. Methods for differential extraction of nucleic acids from tissue sections, which had been frozen, dehydrated by alcohol-substitution, and fixed in hot alcohol, were tested by chromatographic analysis of extracts. Both acid and enzyme hydrolysis were shown to be useful for quantitative or, at least, semi-quantitative work. DNA synthesis was shown to occur only during premeiotic interphase in sporogenous cells, but at two intervals in tapetal nuclei, once when the microsporocytes are in zygotene and again during pachytene. Each time the synthetic period was followed by a normal mitosis. Accumulation of RNA in microsporocytes occurred at stages up to late leptotene. After this period, labeled RNA accumulated almost exclusively in their nuclei and at a slower rate than in earlier stages. DNA synthesis, as measured by incorporation of glycine-C¹⁴ and orotic acid-C¹⁴, gave the same results and confirm earlier results with inorganic phosphate-P³². For RNA, glycine-C¹⁴ and orotic acid-C¹⁴ gave different results. When glycine-C¹⁴ was the source of label, incorporation of C¹⁴ in RNA stopped during DNA synthesis in sporogenous cells. Glycine-C¹⁴ was not utilized to a significant extent at any time by tapetal cells for RNA synthesis, but extensively for DNA and protein synthesis. Orotic acid-C¹⁴ was incorporated into RNA of both tapetum and sporogenous cells at various periods in development apparently including the interval of DNA synthesis. Protein synthesis as measured by incorporation of glycine is relatively rapid during premeiotic interphase and leptotene. It continues during the remainder of prophase, but at a much reduced rate. In tapetal cells the rate is rapid in the nuclei during periods of DNA synthesis, but even faster in both cytoplasm and nucleus after divisions are completed and the microsporocytes are in late prophase and division stages. This period of synthesis is perhaps necessary for the postmeiotic functioning of tapetum when it appears to secrete the wall materials for the microspores.     

EFFECT OF CROSSING DISTANCE AND MALE PARENT ON IN VIVO POLLEN TUBE GROWTH IN CHAMAECRISTA FASCICULATA

Gametophytic competition among pollen grains has been proposed as an important mechanism of sexual selection in plants. The purpose of this paper is to examine the contribution of pollen source on in vivo pollen tube growth in Chamaecrista fasciculata. We addressed two questions: 1) Is pollen tube growth affected by the genetic relatedness between the pollen source and the pollen recipient? 2) Is there significant phenotypic variation among pollen donors for pollen tube growth? We compared pollen tube growth by measuring the number of pollen tubes which germinated, reached quarter length of style, and reached the ovary resulting from self- and outcross-pollinations. The outcross pollinations included three interplant distance classes: near (within genetic neighborhood, ca. 1 m), far (between far neighborhoods and within subpopulation, ca. 20 m), and distant (between neighborhoods and adjacent subpopulations, ca. 50–100 m). Our results show that pollen tube growth was not affected by genetic relatedness, by differences between self and outcross, nor by differences due to phenotypic variation among pollen donors. In contrast, maternal environment had a strong impact on pollen tube growth. These results suggest a lack of gametophytic competition and indicate little opportunity for sexual selection on pollen tube growth in C. fasciculata.     

植物花粉管中类整联蛋白的免疫荧光定位研究

利用免疫荧光技术,分别用整联蛋白β_3、α_y亚基胞质域抗血清及整联蛋白VnR(Vitronectin的受体)的抗血清在百合花粉管中检测出荧光标记,且在花粉管尖端逐渐增强,而用FnR(纤粘连蛋白的受体)、LnR(层粘连蛋白的受体)的抗血清及非免疫血清对照实验在百合花粉管中则没有或仅有很弱的荧光。在萌发的碧桃花粉管中,用β_1、β_3亚基胞质域抗血清也能检测出荧光标记,初步结果显示花粉管在生长过程中,质膜上有可能存在类整联蛋白,并且在百合花粉管中这种类整联蛋白可能是由α_v和β_3两种亚基组成的Vn样蛋白的受体。     

THE ESSENTIAL ROLE OF CALCIUM ION IN POLLEN GERMINATION AND POLLEN TUBE GROWTH

Brewbaker, James L., and Beyoung H. Kwack. (U. Hawaii, Honolulu.) The essential role of calcium ion in pollen germination and pollen tube growth. Amer. Jour. Bot. 50(9): 859–865. Illus. 1963.—A pollen population effect occurs whenever pollen grains are grown in vitro. Small pollen populations germinate and grow poorly if at all, under conditions which support excellent growth of large pollen populations. The pollen population effect is overcome completely by a growth factor obtained in water extracts of many plant tissues. This factor is shown to be the calcium ion, and its action confirmed in 86 species representing 39 plant families. Other ions (K⁺, Mg⁺⁺, Na⁺) serve in supporting roles to the uptake or binding of calcium. The high requirement of calcium (300–5000 ppm, as Ca (NO₃)₂·4H₂O, for optimum growth) and low calcium content of most pollen may conspire to give calcium a governing role in the growth of pollen tubes both in vitro and in situ. It is suspected that ramifications of this role extend to the self-incompatibilities of plants and to the curious types of arrested tube growth distinguishing, for example, the orchids. A culture medium which proved its merit in a wide variety of pollen growth studies included, in distilled water, 10% sucrose, 100 ppm H₃BO₃, 300 ppm Ca (NO₃)₂·4H₂O, 200 ppm MgSO₄·7H₂O and 100 ppm KNO₃.