Pollen Tube Pathway Research Articles

Gynoecium structure and pollen tube pathway in the cactus family with emphasis on tribe Trichocereeae (Cactaceae: Cactoideae)

Abstract The structural details of the gynoecium are key to understanding the reproductive systems and successful diversification of flowering plants. However, the gynoecium morpho-anatomy in South American species of Cactaceae that evolved in the Andean region remains largely unknown. Here we selected 18 species, most of them of evolutionarily related genera of Cactaceae tribe Trichocereeae, to conduct a detailed comparative study. Observations were made using light, fluorescence, differential interference contrast and scanning electron microscopy. Most of the characters of the ovary and ovule were typical of the family, except for the nucellar beak in Echinopsis aurea and E. haematantha, here reported for the first time in cacti. We found evidence suggesting that the stigmatic surface covered with multiseriate trichomes, the semi-closed style type and the pollen tube transmitting tract are conserved characters among species of Trichocereeae; this finding may be explained by a phylogenetic conservatism of the investigated genera of the tribe. We integrated the available information about structural and histological characters of the gynoecium in the family, taking into account the current phylogenetic context of the examined genera. Our results reinforce the significance of floral anatomical traits for the systematics of Cactaceae.

Analysis of Main Characters of Rice Progenies by Injecting Sorghum DNA into Rice

In this study, the whole genome DNA of sorghum apomixes line SSA-1 (Shanxi sorghum apomict-1) was injected into two rice varieties of ‘Liaoyan 28’ and ‘Liaoyan 6’ using the pollen tube pathway method. The genetic characters of the progeny changed obviously. By self-selection and identification, 27 phenotypic stable D 4  generation lines were obtained. Through field planting, the phenotypes of agronomic traits such as heading date, tiller number, plant height, and 1 000-grain weight of the introduced lines were statistically analyzed. The results showed that the agronomic traits of the D 4  generation lines were widely varied, some D 4  generation lines were more inclined to donor sorghum in culm and panicle color, which indicated that the whole genome DNA of sorghum was successfully introduced into the receptor cells, and the expression of the receptor gene was affected. Compared with the recipient parents, the introduced lines showed significant variations in the main traits such as heading date, tiller number, plant height, grain number per ear, grain weight per ear, ear length, and thousand grain weights. Further analysis and selection of mutant lines is helpful to discover new germplasm materials and provide abundant germplasm resources for breeding new rice varieties.

Transformation and functional verification of Cry5Aa in cotton

Most of the cotton bollworm-resistant genes applied in cotton are more than 20 years and they all belong to Cry1Ab/c family, but the insect-resistant effects of Cry5Aa on cotton were rarely reported. The possible risk of resistance is increasing. The study synthesized a novel bollworm-resistant gene Cry5Aa artificially based on preferences of cotton codon. The new gene was transferred to cotton through the method of pollen tube pathway. The transgenic strains were identified by kanamycin test in field and laboratory PCR analysis. Meanwhile, an insect resistance test was conducted by artificial bollworm feeding with transgenic leaves and GK19 was used as a control in this study. Results showed that rate of positive transgenic strains with kanamycin resistance in the first generation (T1), the second generation (T2) and the third generation (T3) respectively were 7.76%, 73.1% and 95.5%. However, PCR analysis showed that the positive strain rate in T1, T2 and T3 were 2.35%, 55.8% and 94.5%, respectively. The resistant assay of cotton bollworm showed that the mortality rate of the second, third and fourth instar larva feed by the transgenic cotton leaves, were 85.42%, 73.35% and 62.79%, respectively. There was a significant difference between transgenic plant of Cry5Aa and GK19 in insect resistance. Finally, we also conducted the further analysis of gene expression patterns, gene flow and the effect on non-target pest in the study. The results showed that Cry5Aa gene had less environmental impact, and Cry5Aa has been transferred successfully and expressed stably in cotton. Therefore, the novel bollworm resistance gene can partially replace the current insect-resistance gene of Lepidoptera insects.

The synstigma turns the fig into a large flower

Abstract The synstigma is a structure formed by clusters of two to several stigmas, whether in the same or between different flowers. Although rare in angiosperms, synstigmas are found in c. 500 out of the c. 750 Ficus spp. (Moraceae). This floral structure is associated with fig-fig wasp pollinating mutualism. The synstigma structure and pollen tube pathways were studied in six Ficus spp. from Ficus section Americanae to test the hypothesis that the synstigma allows pollen grains deposited on a stigma to emit pollen tubes that can grow laterally and fertilize surrounding flowers. Syconia containing recently pollinated stigmas were collected and dissected, and the stigmas were processed for analyses with light and scanning and transmission electron microscopy. The arrangement of the synstigmas across species can be spaced or congested, with the number of stigmas per synstigma ranging from two to 20. Contact between the stigmas in a synstigma occurs by the intertwining of the stigmatic branches and papillae; their union is firm or loose. The pollen tube grows through live cells of the transmitting tissue until reaching the ovule micropyle. Curved pollen tubes growing from one stigma to another were observed in five out of the six species studied. The curvilinear morphology of pollen tubes probably results from competition by pollen between the stigmas composing a synstigma via chemotropic signals. The synstigma appears to be a key adaptation that ensures seed production by flowers not exploited by the fig wasps in actively pollinated Ficus spp.

Reproductive ecology and postpollination development in the hydrophilous monocot Ruppia maritima.

Water-pollination (hydrophily) is a rare but important pollination mechanism that has allowed angiosperms to colonize marine and aquatic habitats. Hydrophilous plants face unique reproductive challenges, and many have evolved characteristic pollen traits and pollination strategies that may have downstream consequences for pollen performance. However, little is known about reproductive development in the life history stage between pollination and fertilization (the progamic phase) in hydrophilous plants. The purpose of this study was to characterize reproductive ecology and postpollination development in water-pollinated Ruppia maritima L. Naturally pollinated inflorescences of R. maritima were collected from the field. Experimental pollinations using both putatively outcross and self pollen were conducted in the greenhouse and inflorescences were collected at appropriate intervals after pollination. Pollen reception, pollen germination, pollen tube growth, and carpel morphology were characterized. Ruppia maritima exhibits incomplete protogyny, allowing for delayed selfing. Pollen germinated within 15 min after pollination. The average shortest possible pollen tube pathway was 425 μm and pollen tubes first reached the ovule at 45 min after pollination. The mean adjusted pollen tube growth rate was 551 μm/h. Ruppia pollen is adapted for rapid pollen germination, which is likely advantageous in an aquatic habitat. Small effective pollen loads suggest that pollen competition intensity is low. Selection for traits such as a long period of stigma receptivity, fast pollen germination, and carpel morphology likely played a larger role in shaping postpollination reproductive development in Ruppia than evolution in pollen tube growth rates.

Transformation of the rolB gene via the pollen-tube pathway to obtain transgenic pomegranate plants

Transformation of the <i>rolB</i> gene via the pollen-tube pathway to obtain transgenic pomegranate plants

Траектории роста пыльцевых трубок в гинецее однодольных

В работе приведен обзор известных паттернов роста пыльцевых трубок в гинецее однодольных растений. Рассмотрены тип проводникового тракта и особенности формирования компитума.

Arabinogalactan proteins mediate intercellular crosstalk in the ovule of apple flowers.

AGP-rich glycoproteins mediate pollen-ovule interactions and cell patterning in the embryo sac of apple before and after fertilization. Glycoproteins are significant players in the dialog that takes place between growing pollen tubes and the stigma and style in the angiosperms. Yet, information is scarce on their possible involvement in the ovule, a sporophytic organ that hosts the female gametophyte. Apple flowers have a prolonged lapse of time between pollination and fertilization, offering a great system to study the developmental basis of glycoprotein secretion and their putative role during the last stages of the progamic phase and early seed initiation. For this purpose, the sequential pollen tube elongation within the ovary was examined in relation to changes in arabinogalactan proteins (AGPs) in the tissues of the ovule before and after fertilization. To evaluate what of these changes are developmentally regulated, unpollinated and pollinated flowers were compared. AGPs paved the pollen tube pathway in the ovules along the micropylar canal, and the nucellus entrance toward the synergids, which also developmentally accumulated AGPs at the filiform apparatus. Glycoproteins vanished from all these tissues following pollen tube passage, strongly suggesting a role in pollen-ovule interaction. In addition, AGPs marked the primary cell walls of the haploid cells of the female gametophyte, and they further built up in the cell walls of the embryo sac and developing embryo, layering the interactive walls of the three generations hosted in the ovule, the maternal sporophytic tissues, the female gametophyte, and the developing embryo.

Insights into secrets along the pollen tube pathway in need to be discovered.

The process of plant fertilization provides an outstanding example of refined control of gene expression. During this elegant process, subtle communication occurs between neighboring cells, based on chemical signals, that induces cellular mechanisms of patterning and growth. Having faced an immediate issue of self-incompatibility responses, the pathway to fertilization starts once the stigmatic cells recognize a compatible pollen grain, and it continues with numerous players interacting to affect pollen tube growth and the puzzling process of navigation along the transmitting tract. The pollen tube goes through a guidance process that begins with a preovular stage (i.e. prior to the influence of the target ovule), with interactions with factors from the transmitting tissue. In the subsequent ovular-guidance stage a specific relationship develops between the pollen tube and its target ovule. This stage is divided into the funicular and micropylar guidance steps, with numerous receptors working in signalling cascades. Finally, just after the pollen tube has passed beyond the synergids, fusion of the gametes occurs and the developing seed-the ultimate aim of the process-will start to mature. In this paper, we review the existing knowledge of the crucial biological processes involved in pollen-pistil interactions that give rise to the new seed.

Different factors involved in the low fruit set of mango (Mangifera indica)

Mango (Mangifera indica) is a tropical fruit tree originated in southeastern Asia, which is cultivated in regions with tropical and subtropical climates worldwide. Mango cultivation has significantly increased in the last decades, often spreading to areas where environmental conditions are not the most favorable for optimal fruit set. In this work, we describe the reproductive biology of mango in the coastal areas of southern Spain, the furthest region from the equator where mango is produced commercially at a significant scale. As in other regions, mango trees produced several inflorescences per tree with hundreds to thousands of male and hermaphrodite flowers, depending on the cultivar, but only a very small percentage of the flowers are able to set fruits due to a massive drop of flowers and fruitlets. Although about half of the flowers in the inflorescence are male flowers and, consequently, contribute to this massive drop, a high proportion of the hermaphrodite flowers were not receptive to pollen germination. In receptive flowers, the characterization of the pollen tube pathway within the pistil showed chalazogamy. A detailed study of the ovules indicates that a high proportion of them showed degenerated embryo sacs, both before and after fertilization. Paternity analysis with molecular markers showed a high proportion of embryos resulting from self-pollination in orchards planted with a single cultivar. However, without pollination restrictions, the offspring shows a higher proportion of genotypes resulting from cross-pollination, suggesting preferential cross-fertilization. The variable response of this parameter, together to the variable proportion of hermaphrodite/male flower ratio, also obtained in response to environmental conditions, suggests a reproductive plasticity in this species.

Evolution of development of pollen performance.

With the origin of pollination in ancient seed plants, the male gametophyte ("pollen") began to evolve a new and unique life history stage, the progamic phase, a post-pollination period in which pollen sexual maturation occurs in interaction with sporophyte-derived tissues. Pollen performance traits mediate the timing of the fertilization process, often in competition with other pollen, via the speed of pollen germination, sperm development, and pollen tube growth. Studies of pollen development rarely address the issue of performance or its evolution, which involves linking variation in developmental rates to relative fitness within populations or to adaptations on a macroevolutionary scale. Modifications to the pollen tube pathway and changes in the intensity of pollen competition affect the direction and strength of selection on pollen performance. Hence, pollen developmental evolution is always contextual-it involves both the population biology of pollen reaching stigmas and the co-evolution of sporophytic traits, such as the pollen tube pathway and mating system. For most species, performance evolution generally reflects a wandering history of periods of directional selection and relaxed selection, channeled by developmental limitations, a pattern that favors the accumulation of diversity and redundancy in developmental mechanisms and the genetic machinery. Developmental biologists are focused on finding universal mechanisms that underlie pollen function, and these are largely mechanisms that have evolved through their effects on performance. Here, we suggest ways in which studies of pollen performance or function could progress by cross-fertilization between the "evo" and "devo" fields.

Pollen Tube Pathway-Mediated Cotton Transformation.

Although many gene transfer methods have been employed for successfully obtaining transgenic cotton, the major constraint in cotton improvement is the limitation of genotype because the majority of transgenic methods require plant regeneration from a single transformed cell which is limited by cotton tissue culture. Comparing with other plant species, it is difficult to induce plant regeneration from cotton; currently, only a limited number of cotton cultivars can be cultured for obtaining regenerated plants. Thus, developing a simple and genotype-independent genetic transformation method is particularly interested for cotton. In this chapter, we present a simple, cost-efficient, and genotype-independent cotton transformation method - pollen tube pathway-mediated transformation. This method uses pollen tube pathway to deliver transgene into cotton embryo sacs and then insert foreign genes into cotton genome. There are three major steps for pollen tube pathway-mediated genetic transformation, which include injection of foreign genes into pollen tube, integration of foreign genes into plant genome, and selection of transgenic plants.

Development of Transgenic CryIA(c) + GNA Cotton Plants via Pollen-Tube Pathway Method Confers Resistance to Helicoverpa armigera and Aphis gossypii Glover.

Elite cotton cultivar Sumian16 was transformed with p7RPSBK-mGNA-NPTII containing Bt (CryIA(c)), Galanthus nivalis agglutinin (GNA) resistance genes, and selectable marker NptII gene via the pollen-tube pathway method, and two fertile transgenic Bt+GNA plants were obtained in the present study. The integration and expression of the Bt and GNA genes were confirmed by molecular biology techniques and insect bioassays. Insect bioassays showed that the transformed plants were highly toxic to bollworm larvae as well as obviously retarding development of aphid populations. PCR analyses and identification of resistance to kanamycin and bollworm showed that the resistance to bollworm for the two transgenic plants was dominantly inherited in a Mendelian manner and the two resistance genes and selectable marker co-segregated from primary transformed parents to the first self-fertilized progeny plants.

Molecular breeding of water lily: engineering cold stress tolerance into tropical water lily

Water lilies (order Nymphaeales) are rich in both economic and cultural values. They grow into aquatic herbs, and are divided into two ecological types: tropical and hardy. Although tropical water lilies have more ornamental and medicinal values compared to the hardy water lily, the study and utilization of tropical water lilies in both landscaping and pharmaceutical use is greatly hindered due to their limited planting area. Tropical water lilies cannot survive the winter in areas beyond 24.3°N latitude. Here, the transgenic pipeline through the pollen-tube pathway was generated for water lily for the first time. To improve cold stress tolerance of tropical water lilies, a gene encoding choline oxidase (CodA) driven by a cold stress-inducible promoter was transformed into a tropical water lily through the pollen-tube transformation. Six independent transgenic lines were tested for survival rate during two winter seasons from 2015 to 2017 in Hangzhou (30.3°N latitude). PCR and southern blot detection revealed that the CodA gene had been integrated into the genome. Reverse transcription PCR showed that CodA gene was induced after cold stress treatment, and further quantitative real-time PCR revealed different expressions among six 4 lines and line 3 had the highest expression. Multiple physiological experiments showed that after cold stress treatment, both the conductivity and malondialdehyde (MDA) levels from transgenic plants were significantly lower than those of non-transgenic plants, whereas the content of betaine and the activity of superoxide dismutase, catalase, and peroxidase were higher than those from non-transgenic plants. These results suggest that expression of exogenous CodA gene significantly improved the cold stress tolerance of tropical water lilies through a wide range of physiological alterations. Our results currently expanded a six-latitude cultivating area of the tropical water lilies. These results not only illuminate the bright future for water lily breeding but will also facilitate the functional genomic studies.

The Panax ginseng PgTIP1 gene confers enhanced salt and drought tolerance to transgenic soybean plants by maintaining homeostasis of water, salt ions and ROS

The Panax ginseng PgTIP1 gene has been demonstrated to have high water channel activity by its heterologous expression in Xenopus laevis oocytes and in yeast, and it also plays significant roles in enhancing the salt/drought tolerance of PgTIP1-transgenic Arabidopsis plants and salt adaptation of PgTIP1-transformed Glycine max. In this work, PgTIP1 gene was transformed into the hybrid soybean strain 4076 (F5), which was selected for salt tolerance generation by generation from the cross assembly of G. max N23674 cultivar × G. soja BB52 accession. The PgTIP1-transgenic soybean plants mediated by the pollen tube pathway, represented by lines L19 and L29, were simultaneously analyzed at physiological and molecular levels for enhanced salt and drought tolerance. The results showed that the salt-stressed PgTIP1-transgenic lines L19 and L29 acquired better leaf stomatal movement and water-gas exchange capacity; less absorption, transport and accumulation of Na+, Cl−; a lower Na+/K+ ratio; and enhanced antioxidase activities of SOD, POD, CAT, and APX than WT in the roots and leaves. Under PEG-induced drought stress, the PgTIP1-transgenic plants showed greater leaf water-retention capacity and reduced cell membrane damage in roots and leaves. Therefore, the PgTIP1-transgenic soybean lines showed both salt and drought tolerance, which are related not only to the primary functions of the PgTIP1 gene in terms of water status regulation but also to its secondary roles in up-regulating the expression of stress-related genes (GmNHX1, GmSOS1, GmCLC1, GmCAT1, GmAPX1, GmNCED1 and GmP5CS1), which are involved in homeostasis of Na+, K+, and Cl−; ROS scavenging; and synthesis of ABA, proline, etc.

The unusual gynoecium structure and extragynoecial pollen-tube pathway in Phytolacca (Phytolaccaceae)

The fusion of carpels into a unified compound gynoecium is considered a dominant feature of angiosperm evolution and it also occurs by postgenital fusion during the gynoecium development in some apocarpous species. However, we found the reverse process, the separation of carpels from combined carpel primordia, during the development of the gynoecium in Phytolacca. Semithin sectioning and scanning electron microscopy were utilised to observe the structure and development of the gynoecia in Phytolacca acinosa and Phytolacca americana, fluorescence microscopy was utilised to observe the pollen tube growth in the gynoecia of the two species, and the topology method was applied to analyze the relationship between the gynoecium structure and pollen tube pathway. Although the gynoecia of P. acinosa and P. americana are both syncarpous, the degree of carpel fusion in the mature gynoecia of the two syncarpous species is different as a result of variant developmental processes. However, change in the degree of carpel fusion during the development of gynoecia in Phytolacca does not affect pollen tube growth because of the existence of the extragynoecial pollen-tube pathway. Thus, the change in the degree of carpel fusion in Phytolacca is primarily the result of diversification of developmental processes related to selection pressure.

Over-expression of transcription factor GhWRI1 in upland cotton

Transcription factors are involved in lipid metabolism, and in present study, the transcription factor WRINKLED 1 (GhWRI1) was cloned from Gossypium hirsutum L. cv. Coker 201 by reverse transcription (RT)-PCR and rapid amplification of cDNA ends. The Pro35S:WRI1 vector was constructed and transformed into upland cotton cv. Sumian 20 using the pollen tube pathway method. After PCR and Southern blot verification of the positive transgenic plants, T2 transgenic lines derived from T1 individuals with the insertion gene in a single copy were chosen for further dissection. Semi-quantitative and quantitative RT-PCR analyses indicated that GhWRI1 gene expression increased in transgenic plants compared with that in the wild-type. Seed lipid content increased at most transgenic plants, and at the same time, protein content decreased. Compared to the control, major agronomical traits were not affected by overexpression of GhWRI1 in transgenic plants.

Pembentukan Buah dan Perkecambahan Tanaman Jarak Pagar pada Transformasi Langsung Melalui Jalur Tabung Polen

&lt;em&gt;&lt;em&gt;The genetic transformation via pollen-tube pathway in jatropha is the first alternative method that was applied in this plant. The objective of the research was to study fruit set and germination of three genotypes of jatropha following direct transformations via pollen-tube pathways. The research was conducted during April 2014 until January 2015 at jatropa’s experimental field, Pasuruan, and at green house of ICABIOGRAD, Bogor. Three genotypes of jatropha i.e., IP3A, IP3P and JcUMM18 were used. In the first experiment, split plot design was used where 3 levels of DNA plasmid concentration as a main plot and 5 levels of stigma-drip time of DNA plasmid as a subplot. In the second experiment randomized block design was used with single factor consisting of 15 combinations of concentration and stigma-drip time of DNA plasmid as treatments and control. The results demonstrated that interaction between concentration and application time of DNA plasmid did not significantly affect fruit and seeds formation of three Jatropha genotypes. Combination of DNA plasmid concentration with time of stigma-drip had significant effect on seed germination rate of IP3A genotype, but not significant on the other variables. The concentration of 0.05-0.5 µg µL-1 and application time of DNA plasmid at 1-10 hours after pollination could be applied on jatropha genetic transformation via pollen-tube pathways.&lt;br /&gt;&lt;br /&gt;Keywords: DNA plasmid, Jatropha curcas, pCAMBIA1301, pollen-tube, stigma-drip&lt;br /&gt;&lt;br /&gt;&lt;/em&gt;&lt;/em&gt;

Plant gene regulation algorithm mediated by agrobacterium tumefaciens Atu4860

At present, the effect of plant gene regulation algorithm based on pollen tube pathway is not obvious. Therefore, a plant gene regulation algorithm based on Agrobacterium tumefaciens Atu4860 is proposed. Firstly, the Agrobacterium tumefaciens Atu4860 is analyzed, then the structure of gene regulatory algorithm is analyzed and formalized, and the basic elements of the algorithm are analyzed. By introducing Agrobacterium tumefaciens Atu4860 into the gene regulation algorithm, a plant gene regulation algorithm based on Agrobacterium tumefaciens Atu4860 is realized. Experiments show that the proposed algorithm can effectively improve the quality of plant transgene, and the implementation process is relatively easy.

Efficiency of Genetic Transformation via Pollen-Tube Pathway of Jatropha (Jatropha curcas L.) Based on Histochemical and Molecular Analysis

The genetic transformation via pollen-tube pathway is an alternative method to overcome the constraints imposed by genotype specificity in transformation and regeneration in jatropha (Jatropha curcas L.) tissue culture. Therefore, it is necessary to establish important parameters for efficient genetic transformation of jatropha via pollen-tube pathway. The objective of the research was to study the efficiency of direct transformation of jatropha via pollen-tube pathway based on histochemical and molecular analysis. Solution of purified pCAMBIA1301 DNA plasmid carrying a hptII marker gene and a gus reporter gene with concentration level of 0.05, 0.25, 0.50 µg µl-1 were applied to stigma of flowers at 1, 2, 4, 7, 10 h after pollination. Seedling of IP3A, IP3P and JcUMM18 jatropha’s genotypes derived from 15 combination treatments of plasmid DNA concentration and application time, also wild type was subjected to histochemical and molecular analyses. Based on those analyses, the efficiency of transformation via pollen-tube pathway of three jatropha genotypes ranged from 1.5-16.7%. PCR analysis showed that a number of positive plants were identified by using specific primers hptII and gus, i.e. 1-3 and 3-7 plants of the 15 combined treatments, respectively. It indicated that the transformation efficiency via the pollen-tube pathway varied in each jatropha genotype.&lt;br /&gt;&lt;br /&gt;Keywords: Jatropha curcas L., pCAMBIA1301, plasmid DNA, stigma-drip&lt;br /&gt;&lt;br /&gt;