International Journal of Molecular Sciences

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12 pages, 1922 KiB

Open AccessArticle

Quantification of Species-Preferential Micropylar Chemoattraction in Arabidopsis by Fluorescein Diacetate Staining of Pollen Tubes

by Takuya T. Nagae, Hidenori Takeuchi and Tetsuya Higashiyama

Int. J. Mol. Sci. 2022, 23(5), 2722; https://doi.org/10.3390/ijms23052722 - 28 Feb 2022

Viewed by 3417

Abstract

Sexual reproduction between males and females of the same species is essential for species maintenance. Ovular micropylar guidance, the last step of pollen tube guidance in angiosperms, contributes to species-preferential reproduction. Previous studies using semi-in vivo attraction assays showed that species-preferential attractant peptides [...] Read more.

Sexual reproduction between males and females of the same species is essential for species maintenance. Ovular micropylar guidance, the last step of pollen tube guidance in angiosperms, contributes to species-preferential reproduction. Previous studies using semi-in vivo attraction assays showed that species-preferential attractant peptides are secreted from the ovule through its micropyle. However, conventional semi-in vivo assays usually depend on transgenic pollen tubes expressing a fluorescent protein to determine whether the tubes are attracted to the ovule to precisely penetrate the micropyle. Here, we found that fluorescein diacetate (FDA) staining was suitable for evaluating the micropylar guidance rate of non-transgenic pollen tubes in semi-in vivo conditions. Micropylar guidance was quantified for ovules and pollen tubes of Arabidopsis thaliana and Arabidopsis lyrata by combining FDA staining with modified semi-in vivo assays. Our results using the simple staining method showed that the ovules of each species secrete species-preferential attractants, and that pollen tubes respond more strongly to attractants of their own species compared with those of closely related species. LURE-type CRP810 attractant peptides were shown to be responsible for micropylar attraction of A. thaliana in the semi-in vivo assay. The POLLEN-SPECIFIC RECEPTOR-LIKE KINASE 6 (PRK6) receptor for LURE1, as well as an unidentified receptor for other LURE-type attractants, are involved in the species-preferential response of these two Arabidopsis species. Full article

(This article belongs to the Special Issue Signaling in Plant Reproduction)

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13 pages, 3411 KiB

Open AccessArticle

Cyclanilide Induces Lateral Bud Outgrowth by Modulating Cytokinin Biosynthesis and Signalling Pathways in Apple Identified via Transcriptome Analysis

by Juanjuan Ma, Lingling Xie, Qian Zhao, Yiting Sun and Dong Zhang

Int. J. Mol. Sci. 2022, 23(2), 581; https://doi.org/10.3390/ijms23020581 - 6 Jan 2022

Cited by 9 | Viewed by 2800

Abstract

Cyclanilide (CYC), a plant growth regulator, is a potent shoot branching agent in apple. However, its mechanism remains unclear. The current study revealed that CYC treatment resulted in massive reprogramming of the axillary bud transcriptome, implicating several hormones in the response. We observed [...] Read more.

Cyclanilide (CYC), a plant growth regulator, is a potent shoot branching agent in apple. However, its mechanism remains unclear. The current study revealed that CYC treatment resulted in massive reprogramming of the axillary bud transcriptome, implicating several hormones in the response. We observed a marked increase (approximately 2-fold) in the level of zeatin riboside and a significant decrease (approximately 2-fold) in the level of abscisic acid (ABA). Zeatin metabolism gene cytokinin (CTK) oxidase 1 (CKX 1) was down-regulated at 168 h after CYC treatment compared with the control. Weighted gene co-expression network analysis of differentially expressed genes demonstrated the turquoise module clusters exhibited the highest positive correlation with zeatin riboside (r = 0.92) and the highest negative correlation with ABA (r = −0.8). A total of 37 genes were significantly enriched in the plant hormone signal transduction pathway in the turquoise module. Among them, the expressions of CTK receptor genes WOODEN LEG and the CTK type-A response regulators genes ARR3 and ARR9 were up-regulated. ABA signal response genes protein phosphatase 2C genes ABI2 and ABI5 were down-regulated in lateral buds after CYC treatment at 168 h. In addition, exogenous application of 6-benzylaminopurine (6-BA, a synthetic type of CTK) and CYC enhanced the inducing effect of CYC, whereas exogenous application of lovastatin (a synthetic type of inhibitor of CTK biosynthesis) or ABA and CYC weakened the promoting effect of CYC. These results collectively revealed that the stimulation of bud growth by CYC might involve CTK biosynthesis and signalling, including genes CKX1 and ARR3/9, which provided a direction for further study of the branching promoting mechanism of CYC. Full article

(This article belongs to the Special Issue Signaling in Plant Reproduction)

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22 pages, 7588 KiB

Open AccessArticle

Hormonal Regulatory Patterns of LaKNOXs and LaBEL1 Transcription Factors Reveal Their Potential Role in Stem Bulblet Formation in LA Hybrid Lily

by Yue Zhang, Zhen Zeng, Yubing Yong and Yingmin Lyu

Int. J. Mol. Sci. 2021, 22(24), 13502; https://doi.org/10.3390/ijms222413502 - 16 Dec 2021

Cited by 7 | Viewed by 2599

Abstract

In lily reproduction, the mechanism of formation of bulbs has been a hot topic. However, studies on stem bulblet formation are limited. Stem bulblets, formed in the leaf axils of under- and above-ground stems, provide lilies with a strong capacity for self-propagation. First, [...] Read more.

In lily reproduction, the mechanism of formation of bulbs has been a hot topic. However, studies on stem bulblet formation are limited. Stem bulblets, formed in the leaf axils of under- and above-ground stems, provide lilies with a strong capacity for self-propagation. First, we showed that above-ground stem bulblets can be induced by spraying 100 mg/L 6-BA on the LA hybrid lily ‘Aladdin’, with reduced endogenous IAA and GA₄ and a higher relative content of cytokinins. Then, expression patterns of three potential genes (two KNOTTED1-like homeobox (KNOX) and one partial BEL1-like homeobox (BELL)), during stem bulblet formation from our previous study, were determined by RT-qPCR, presenting a down-up trend in KNOXs and a rising tendency in BELL. The partial BELL gene was cloned by RACE from L. ‘Aladdin’ and denoted LaBEL1. Physical interactions of LaKNOX1-LaBEL1 and LaKNOX1-LaKNOX2 were confirmed by yeast two-hybrid and bimolecular fluorescence complementation assays. Furthermore, hormonal regulatory patterns of single LaKNOX1, LaKNOX2, LaBEL1, and their heterodimers, were revealed in transgenic Arabidopsis, suggesting that the massive mRNA accumulations of LaKNOX1, LaKNOX2 and LaBEL1 genes during stem bulblet formation could cause the dramatic relative increase of cytokinins and the decline of GAs and IAA. Taken together, a putative model was proposed that LaKNOX1 interacts with LaKNOX2 and LaBEL1 to regulate multiple phytohormones simultaneously for an appropriate hormonal homeostasis, which suggests their potential role in stem bulblet formation in L. ‘Aladdin’. Full article

(This article belongs to the Special Issue Signaling in Plant Reproduction)

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17 pages, 4099 KiB

Open AccessArticle

Molecular Analysis Uncovers the Mechanism of Fertility Restoration in Temperature-Sensitive Polima Cytoplasmic Male-Sterile Brassica napus

by Qing Xiao, Huadong Wang, Hui Chen, Xiaohan Chen, Jing Wen, Cheng Dai, Chaozhi Ma, Jinxing Tu, Jinxiong Shen, Tingdong Fu and Bin Yi

Int. J. Mol. Sci. 2021, 22(22), 12450; https://doi.org/10.3390/ijms222212450 - 18 Nov 2021

Cited by 4 | Viewed by 2618

Abstract

Temperature-sensitive male sterility is a heritable agronomic trait affected by genotype-environment interactions. In rapeseed (Brassica napus), Polima (pol) temperature-sensitive cytoplasmic male sterility (TCMS) is commonly used for two-line breeding, as the fertility of pol TCMS lines can be partially [...] Read more.

Temperature-sensitive male sterility is a heritable agronomic trait affected by genotype-environment interactions. In rapeseed (Brassica napus), Polima (pol) temperature-sensitive cytoplasmic male sterility (TCMS) is commonly used for two-line breeding, as the fertility of pol TCMS lines can be partially restored at certain temperatures. However, little is known about the underlying molecular mechanism that controls fertility restoration. Therefore, we aimed to investigate the fertility conversion mechanism of the pol TCMS line at two different ambient temperatures (16 °C and 25 °C). Our results showed that the anthers developed and produced vigorous pollen at 16 °C but not at 25 °C. In addition, we identified a novel co-transcript of orf224-atp6 in the mitochondria that might lead to fertility conversion of the pol TCMS line. RNA-seq analysis showed that 1637 genes were significantly differentially expressed in the fertile flowers of 596-L when compared to the sterile flower of 1318 and 596-H. Detailed analysis revealed that differentially expressed genes were involved in temperature response, ROS accumulation, anther development, and mitochondrial function. Single-molecule long-read isoform sequencing combined with RNA sequencing revealed numerous genes produce alternative splicing transcripts at high temperatures. Here, we also found that alternative oxidase, type II NAD(P)H dehydrogenases, and transcription factor Hsfs might play a crucial role in male fertility under the low-temperature condition. RNA sequencing and bulked segregant analysis coupled with whole-genome sequencing identified the candidate genes involved in the post-transcriptional modification of orf224. Overall, our study described a putative mechanism of fertility restoration in a pol TCMS line controlled by ambient temperature that might help utilise TCMS in the two-line breeding of Brassica crops. Full article

(This article belongs to the Special Issue Signaling in Plant Reproduction)

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21 pages, 6196 KiB

Open AccessArticle

Transcriptome and Metabolome Analyses Provide Insights into the Stomium Degeneration Mechanism in Lily

by Ling He, Xinyue Liu, Ze Wu and Nianjun Teng

Int. J. Mol. Sci. 2021, 22(22), 12124; https://doi.org/10.3390/ijms222212124 - 9 Nov 2021

Cited by 8 | Viewed by 2194

Abstract

Lily (Lilium spp.) is a widely cultivated horticultural crop that has high ornamental and commercial value but also the serious problem of pollen pollution. However, mechanisms of anther dehiscence in lily remain largely unknown. In this study, the morphological characteristics of the [...] Read more.

Lily (Lilium spp.) is a widely cultivated horticultural crop that has high ornamental and commercial value but also the serious problem of pollen pollution. However, mechanisms of anther dehiscence in lily remain largely unknown. In this study, the morphological characteristics of the stomium zone (SZ) from different developmental stages of ‘Siberia’ lily anthers were investigated. In addition, transcriptomic and metabolomic data were analyzed to identify the differentially expressed genes (DEGs) and secondary metabolites involved in stomium degeneration. According to morphological observations, SZ lysis occurred when flower buds were 6–8 cm in length and was completed in 9 cm. Transcriptomic analysis identified the genes involved in SZ degeneration, including those associated with hormone signal transduction, cell structure, reactive oxygen species (ROS), and transcription factors. A weighted co-expression network showed strong correlations between transcription factors. In addition, TUNEL (TdT-mediated dUTP nick-end labeling) assays showed that programmed cell death was important during anther SZ degeneration. Jasmonates might also have key roles in anther dehiscence by affecting the expression of the genes involved in pectin lysis, water transport, and cysteine protease. Collectively, the results of this study improve our understanding of anther dehiscence in lily and provide a data platform from which the molecular mechanisms of SZ degeneration can be revealed. Full article

(This article belongs to the Special Issue Signaling in Plant Reproduction)

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14 pages, 3140 KiB

Open AccessArticle

Identification of DELLA Genes and Key Stage for GA Sensitivity in Bolting and Flowering of Flowering Chinese Cabbage

by Hongling Guan, Xinmin Huang, Yunna Zhu, Baoxing Xie, Houcheng Liu, Shiwei Song, Yanwei Hao and Riyuan Chen

Int. J. Mol. Sci. 2021, 22(22), 12092; https://doi.org/10.3390/ijms222212092 - 9 Nov 2021

Cited by 27 | Viewed by 3010

Abstract

Flowering Chinese cabbage (Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee) is an important and extensively cultivated vegetable in south China, and its stalk development is mainly regulated by gibberellin (GA). DELLA proteins negatively regulate GA signal transduction and may [...] Read more.

Flowering Chinese cabbage (Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee) is an important and extensively cultivated vegetable in south China, and its stalk development is mainly regulated by gibberellin (GA). DELLA proteins negatively regulate GA signal transduction and may play an important role in determining bolting and flowering. Nevertheless, no systematic study of the DELLA gene family has been undertaken in flowering Chinese cabbage. In the present study, we found that the two-true-leaf spraying of gibberellin A3 (GA₃) did not promote bolting but did promote flowering, whereas the three-true-leaf spraying of GA₃ promoted both bolting and flowering. In addition, we identified five DELLA genes in flowering Chinese cabbage. All five proteins contained DELLA, VHYNP, VHIID, and SAW conserved domains. Protein-protein interaction results showed that in the presence of GA₃, all five DELLA proteins interacted with BcGID1b (GA-INSENSITIVE DWARF 1b) but not with BcGID1a (GA-INSENSITIVE DWARF 1a) or BcGID1c (GA-INSENSITIVE DWARF 1c). Their expression analysis showed that the DELLA genes exhibited tissue-specific expression, and their reversible expression profiles responded to exogenous GA₃ depending on the treatment stage. We also found that the DELLA genes showed distinct expression patterns in the two varieties of flowering Chinese cabbage. BcRGL1 may play a major role in the early bud differentiation process of different varieties, affecting bolting and flowering. Taken together, these results provide a theoretical basis for further dissecting the DELLA regulatory mechanism in the bolting and flowering of flowering Chinese cabbage. Full article

(This article belongs to the Special Issue Signaling in Plant Reproduction)

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25 pages, 11454 KiB

Open AccessArticle

The Rab Geranylgeranyl Transferase Beta Subunit Is Essential for Embryo and Seed Development in Arabidopsis thaliana

by Joanna Rojek, Matthew R. Tucker, Michał Rychłowski, Julita Nowakowska and Małgorzata Gutkowska

Int. J. Mol. Sci. 2021, 22(15), 7907; https://doi.org/10.3390/ijms22157907 - 24 Jul 2021

Cited by 3 | Viewed by 3608

Abstract

Auxin is a key regulator of plant development affecting the formation and maturation of reproductive structures. The apoplastic route of auxin transport engages influx and efflux facilitators from the PIN, AUX and ABCB families. The polar localization of these proteins and constant recycling [...] Read more.

Auxin is a key regulator of plant development affecting the formation and maturation of reproductive structures. The apoplastic route of auxin transport engages influx and efflux facilitators from the PIN, AUX and ABCB families. The polar localization of these proteins and constant recycling from the plasma membrane to endosomes is dependent on Rab-mediated vesicular traffic. Rab proteins are anchored to membranes via posttranslational addition of two geranylgeranyl moieties by the Rab Geranylgeranyl Transferase enzyme (RGT), which consists of RGTA, RGTB and REP subunits. Here, we present data showing that seed development in the rgtb1 mutant, with decreased vesicular transport capacity, is disturbed. Both pre- and post-fertilization events are affected, leading to a decrease in seed yield. Pollen tube recognition at the stigma and its guidance to the micropyle is compromised and the seed coat forms incorrectly. Excess auxin in the sporophytic tissues of the ovule in the rgtb1 plants leads to an increased tendency of autonomous endosperm formation in unfertilized ovules and influences embryo development in a maternal sporophytic manner. The results show the importance of vesicular traffic for sexual reproduction in flowering plants, and highlight RGTB1 as a key component of sporophytic-filial signaling. Full article

(This article belongs to the Special Issue Signaling in Plant Reproduction)

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11 pages, 2217 KiB

Open AccessArticle

Homology-Based Interactions between Small RNAs and Their Targets Control Dominance Hierarchy of Male Determinant Alleles of Self-Incompatibility in Arabidopsis lyrata

by Shinsuke Yasuda, Risa Kobayashi, Toshiro Ito, Yuko Wada and Seiji Takayama

Int. J. Mol. Sci. 2021, 22(13), 6990; https://doi.org/10.3390/ijms22136990 - 29 Jun 2021

Cited by 5 | Viewed by 2579

Abstract

Self-incompatibility (SI) is conserved among members of the Brassicaceae plant family. This trait is controlled epigenetically by the dominance hierarchy of the male determinant alleles. We previously demonstrated that a single small RNA (sRNA) gene is sufficient to control the linear dominance hierarchy [...] Read more.

Self-incompatibility (SI) is conserved among members of the Brassicaceae plant family. This trait is controlled epigenetically by the dominance hierarchy of the male determinant alleles. We previously demonstrated that a single small RNA (sRNA) gene is sufficient to control the linear dominance hierarchy in Brassica rapa and proposed a model in which a homology-based interaction between sRNAs and target sites controls the complicated dominance hierarchy of male SI determinants. In Arabidopsis halleri, male dominance hierarchy is reported to have arisen from multiple networks of sRNA target gains and losses. Despite these findings, it remains unknown whether the molecular mechanism underlying the dominance hierarchy is conserved among Brassicaceae. Here, we identified sRNAs and their target sites that can explain the linear dominance hierarchy of Arabidopsis lyrata, a species closely related to A. halleri. We tested the model that we established in Brassica to explain the linear dominance hierarchy in A. lyrata. Our results suggest that the dominance hierarchy of A. lyrata is also controlled by a homology-based interaction between sRNAs and their targets. Full article

(This article belongs to the Special Issue Signaling in Plant Reproduction)

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16 pages, 2973 KiB

Open AccessArticle

Spatial and Temporal Distribution of Arabinogalactan Proteins during Larix decidua Mill. Male Gametophyte and Ovule Interaction

by Katarzyna Rafińska, Katarzyna Niedojadło, Michał Świdziński, Janusz Niedojadło and Elżbieta Bednarska-Kozakiewicz

Int. J. Mol. Sci. 2021, 22(9), 4298; https://doi.org/10.3390/ijms22094298 - 21 Apr 2021

Cited by 8 | Viewed by 2538

Abstract

The role of ArabinoGalactan Proteins (AGPs) in the sexual reproduction of gymnosperms is not as well documented as that of angiosperms. In earlier studies, we demonstrated that AGPs play important roles during ovule differentiation in Larix decidua Mill. The presented results encouraged us [...] Read more.

The role of ArabinoGalactan Proteins (AGPs) in the sexual reproduction of gymnosperms is not as well documented as that of angiosperms. In earlier studies, we demonstrated that AGPs play important roles during ovule differentiation in Larix decidua Mill. The presented results encouraged us to carry out further studies focused on the functions of these unique glycoproteins during pollen/pollen tube and ovule interactions in Larix. We identified and analyzed the localization of AGPs epitopes by JIM4, JIM8, JIM13 and LM2 antibodies (Abs) in male gametophytes and ovule tissue during pollination, the progamic phase, and after fertilization and in vitro growing pollen tubes. Our results indicated that (1) AGPs recognized by JIM4 Abs play an essential role in the interaction of male gametophytes and ovules because their appearance in ovule cells is induced by physical contact between reproductive partners; (2) after pollination, AGPs are secreted from the pollen cytoplasm into the pollen wall and contact the extracellular matrix of stigmatic tip cells followed by micropylar canal cells; (3) AGPs synthesized in nucellus cells before pollen grain germination are secreted during pollen tube growth into the extracellular matrix, where they can directly interact with male gametophytes; (4) in vitro cultured pollen tube AGPs labeled with LM2 Abs participate in the germination of pollen grain, while AGPs recognized by JIM8 Abs are essential for pollen tube tip growth. Full article

(This article belongs to the Special Issue Signaling in Plant Reproduction)

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21 pages, 6474 KiB

Open AccessArticle

Combined Transcriptome Analysis Reveals the Ovule Abortion Regulatory Mechanisms in the Female Sterile Line of Pinus tabuliformis Carr.

by Zaixin Gong, Rui Han, Li Xu, Hailin Hu, Min Zhang, Qianquan Yang, Ming Zeng, Yuanyuan Zhao and Caixia Zheng

Int. J. Mol. Sci. 2021, 22(6), 3138; https://doi.org/10.3390/ijms22063138 - 19 Mar 2021

Cited by 4 | Viewed by 2574

Abstract

Ovule abortion is a common phenomenon in plants that has an impact on seed production. Previous studies of ovule and female gametophyte (FG) development have mainly focused on angiosperms, especially in Arabidopsis thaliana. However, because it is difficult to acquire information about [...] Read more.

Ovule abortion is a common phenomenon in plants that has an impact on seed production. Previous studies of ovule and female gametophyte (FG) development have mainly focused on angiosperms, especially in Arabidopsis thaliana. However, because it is difficult to acquire information about ovule development in gymnosperms, this remains unclear. Here, we investigated the transcriptomic data of natural ovule abortion mutants (female sterile line, STE) and the wild type (female fertile line, FER) of Pinus tabuliformis Carr. to evaluate the mechanism of ovule abortion during the process of free nuclear mitosis (FNM). Using single-molecule real-time (SMRT) sequencing and next-generation sequencing (NGS), 18 cDNA libraries via Illumina and two normalized libraries via PacBio, with a total of almost 400,000 reads, were obtained. Our analysis showed that the numbers of isoforms and alternative splicing (AS) patterns were significantly variable between FER and STE. The functional annotation results demonstrate that genes involved in the auxin response, energy metabolism, signal transduction, cell division, and stress response were differentially expressed in different lines. In particular, AUX/IAA, ARF2, SUS, and CYCB had significantly lower expression in STE, showing that auxin might be insufficient in STE, thus hindering nuclear division and influencing metabolism. Apoptosis in STE might also have affected the expression levels of these genes. To confirm the transcriptomic analysis results, nine pairs were confirmed by quantitative real-time PCR. Taken together, these results provide new insights into ovule abortion in gymnosperms and further reveal the regulatory mechanisms of ovule development. Full article

(This article belongs to the Special Issue Signaling in Plant Reproduction)

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21 pages, 5298 KiB

Open AccessArticle

EPIP-Evoked Modifications of Redox, Lipid, and Pectin Homeostasis in the Abscission Zone of Lupine Flowers

by Emilia Wilmowicz, Agata Kućko, Wojciech Pokora, Małgorzata Kapusta, Katarzyna Jasieniecka-Gazarkiewicz, Timothy John Tranbarger, Magdalena Wolska and Katarzyna Panek

Int. J. Mol. Sci. 2021, 22(6), 3001; https://doi.org/10.3390/ijms22063001 - 16 Mar 2021

Cited by 11 | Viewed by 4103

Abstract

Yellow lupine is a great model for abscission-related research given that excessive flower abortion reduces its yield. It has been previously shown that the EPIP peptide, a fragment of LlIDL (INFLORESCENCE DEFICIENT IN ABSCISSION) amino-acid sequence, is a sufficient molecule to induce flower [...] Read more.

Yellow lupine is a great model for abscission-related research given that excessive flower abortion reduces its yield. It has been previously shown that the EPIP peptide, a fragment of LlIDL (INFLORESCENCE DEFICIENT IN ABSCISSION) amino-acid sequence, is a sufficient molecule to induce flower abortion, however, the question remains: What are the exact changes evoked by this peptide locally in abscission zone (AZ) cells? Therefore, we used EPIP peptide to monitor specific modifications accompanied by early steps of flower abscission directly in the AZ. EPIP stimulates the downstream elements of the pathway—HAESA and MITOGEN-ACTIVATED PROTEIN KINASE6 and induces cellular symptoms indicating AZ activation. The EPIP treatment disrupts redox homeostasis, involving the accumulation of H₂O₂ and upregulation of the enzymatic antioxidant system including superoxide dismutase, catalase, and ascorbate peroxidase. A weakening of the cell wall structure in response to EPIP is reflected by pectin demethylation, while a changing pattern of fatty acids and acyl lipids composition suggests a modification of lipid metabolism. Notably, the formation of a signaling molecule—phosphatidic acid is induced locally in EPIP-treated AZ. Collectively, all these changes indicate the switching of several metabolic and signaling pathways directly in the AZ in response to EPIP, which inevitably leads to flower abscission. Full article

(This article belongs to the Special Issue Signaling in Plant Reproduction)

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13 pages, 1240 KiB

Open AccessReview

Paving the Way for Fertilization: The Role of the Transmitting Tract

by Ana Marta Pereira, Diana Moreira, Sílvia Coimbra and Simona Masiero

Int. J. Mol. Sci. 2021, 22(5), 2603; https://doi.org/10.3390/ijms22052603 - 5 Mar 2021

Cited by 17 | Viewed by 3922

Abstract

Angiosperm reproduction relies on the precise growth of the pollen tube through different pistil tissues carrying two sperm cells into the ovules’ embryo sac, where they fuse with the egg and the central cell to accomplish double fertilization and ultimately initiate seed development. [...] Read more.

Angiosperm reproduction relies on the precise growth of the pollen tube through different pistil tissues carrying two sperm cells into the ovules’ embryo sac, where they fuse with the egg and the central cell to accomplish double fertilization and ultimately initiate seed development. A network of intrinsic and tightly regulated communication and signaling cascades, which mediate continuous interactions between the pollen tube and the sporophytic and gametophytic female tissues, ensures the fast and meticulous growth of pollen tubes along the pistil, until it reaches the ovule embryo sac. Most of the pollen tube growth occurs in a specialized tissue—the transmitting tract—connecting the stigma, the style, and the ovary. This tissue is composed of highly secretory cells responsible for producing an extensive extracellular matrix. This multifaceted matrix is proposed to support and provide nutrition and adhesion for pollen tube growth and guidance. Insights pertaining to the mechanisms that underlie these processes remain sparse due to the difficulty of accessing and manipulating the female sporophytic tissues enclosed in the pistil. Here, we summarize the current knowledge on this key step of reproduction in flowering plants with special emphasis on the female transmitting tract tissue. Full article

(This article belongs to the Special Issue Signaling in Plant Reproduction)

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18 pages, 3092 KiB

Open AccessReview

The Importance of Cytokinins during Reproductive Development in Arabidopsis and Beyond

by Giada Callizaya Terceros, Francesca Resentini, Mara Cucinotta, Silvia Manrique, Lucia Colombo and Marta A. Mendes

Int. J. Mol. Sci. 2020, 21(21), 8161; https://doi.org/10.3390/ijms21218161 - 31 Oct 2020

Cited by 23 | Viewed by 5110

Abstract

Fertilization and seed formation are fundamental events in the life cycle of flowering plants. The seed is a functional unit whose main purpose is to propagate the plant. The first step in seed development is the formation of male and female gametophytes and [...] Read more.

Fertilization and seed formation are fundamental events in the life cycle of flowering plants. The seed is a functional unit whose main purpose is to propagate the plant. The first step in seed development is the formation of male and female gametophytes and subsequent steps culminate in successful fertilization. The detailed study of this process is highly relevant because it directly impacts human needs, such as protecting biodiversity and ensuring sustainable agriculture to feed the increasing world population. Cytokinins comprise a class of phytohormones that play many important roles during plant growth and development and in recent years, the role of this class of phytohormones during reproduction has become clear. Here, we review the role of cytokinins during ovule, pollen and seed formation at the genetic and molecular levels. The expansion of knowledge concerning the molecular mechanisms that control plant reproduction is extremely important to optimise seed production. Full article

(This article belongs to the Special Issue Signaling in Plant Reproduction)

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