Project description:Pollen germination, along with pollen tube growth, is an essential process for the reproduction of flowering plants. The germinating pollen with tip-growth characteristics provides an ideal model system for the study of cell growth and morphogenesis. As an essential step towards a detailed understanding of this important process, the objective of this study was to comprehensively analyze the transcriptome changes during pollen germination and pollen tube growth. Using Affymetrix Arabidopsis ATH1 Genome Arrays, this study is the first to show the changes in the transcriptome from desiccated mature pollen grains to hydrated pollen grains and then to pollen tubes of Arabidopsis thaliana. The number of expressed genes, either for total expressed genes or for specifically expressed genes, increased significantly from desiccated mature pollen to hydrated pollen and again to growing pollen tubes, which is consistent with the finding that pollen germination and tube growth was significantly inhibited in vitro by a transcriptional inhibitor. The results of GO analyses showed that expression of genes related to cell rescue, transcription, signal transduction and cellular transport were significantly changed, especially for up-regulation, during pollen germination and tube growth, respectively. In particular, genes of the CaM/CML, CHX and Hsp families showed the most significant changes during pollen germination and tube growth. These results demonstrate that the overall transcription of genes, both in the number of expressed genes and in the levels of transcription, was increased. Furthermore, the appearance of many novel transcripts during pollen germination as well as tube growth indicates that these newly expressed genes may function in this complex process. SUBMITTER_CITATION: Yi Wang, Wen-Zheng Zhang, Lian-Fen Song, Jun-Jie Zou, Zhen Su, and Wei-Hua Wu. Transcriptome analyses show changes in gene expression to accompany pollen germination and tube growth in Arabidopsis. Plant Physiol. September 5, 2008; 10.1104/pp.108.126375 Experiment Overall Design: Three samples are analyzed in this experiment. They are desiccated mature pollen grains (MP), hydrated pollen grains (HP) and growing pollen tubes (PT) of Arabidopsis thaliana, respectively. Each sample has two biological replicates, so that there are 6 data sets of ATH1 array in this experiment.
Project description:Pollen germination, along with pollen tube growth, is an essential process for the reproduction of flowering plants. The germinating pollen with tip-growth characteristics provides an ideal model system for the study of cell growth and morphogenesis. As an essential step towards a detailed understanding of this important process, the objective of this study was to comprehensively analyze the transcriptome changes during pollen germination and pollen tube growth. Using Affymetrix Arabidopsis ATH1 Genome Arrays, this study is the first to show the changes in the transcriptome from desiccated mature pollen grains to hydrated pollen grains and then to pollen tubes of Arabidopsis thaliana. The number of expressed genes, either for total expressed genes or for specifically expressed genes, increased significantly from desiccated mature pollen to hydrated pollen and again to growing pollen tubes, which is consistent with the finding that pollen germination and tube growth was significantly inhibited in vitro by a transcriptional inhibitor. The results of GO analyses showed that expression of genes related to cell rescue, transcription, signal transduction and cellular transport were significantly changed, especially for up-regulation, during pollen germination and tube growth, respectively. In particular, genes of the CaM/CML, CHX and Hsp families showed the most significant changes during pollen germination and tube growth. These results demonstrate that the overall transcription of genes, both in the number of expressed genes and in the levels of transcription, was increased. Furthermore, the appearance of many novel transcripts during pollen germination as well as tube growth indicates that these newly expressed genes may function in this complex process.
Project description:- Pollen tube growth is important process for successful double fertilization, which is critical for grain yield in crop plants. Despite much progress in identification of rapid alkalization factors (RALFs) which serve as ligand for signaling transduction during fertilization in Arabidopsis, there is no functional study of RALF in mono-cotyledon plant. - We functionally characterized two pollen specific RALF in rice (Oryza sativa) using multiple CRISPR/Cas9 induced loss-of-function mutants, peptide treatment, expression analyses, tag reporter lines. - OsRALF17 is specifically expressed in pollen and pollen tube as the strongest level among 41 RALF members in rice. Exogenously applied OsRALF17 inhibits pollen tube germination and elongation at high concentration, but enhances tube elongation at low concentration, indicating the regulation of growth balance. Double mutant of OsRALF17 with OsRALF19 exhibit almost male sterile, with defect on pollen germination and tube elongation. - Our study revealed that functionally-redundant OsRALF17 and 19 peptides binds to the OsMTD2, CrRLK1L family member, and transmits ROS signal for pollen tube germination and integrity maintenance in rice. We provide new insights into the role of RALF and expanding our understanding of the biological role of RALF in regulating rice fertilization.
Project description:Upon germination, pollen forms a tube that elongates dramatically through female tissues in order to reach and fertilize ovules. While essential for the life cycle of higher plants, the genetic basis underlying most of the process is not well understood. We used Affymetrix Arabidopsis ATH1 Genome Arrays covering more than 80% of the Arabidopsis genome to compare transcriptomes of cell-sorted, hydrated pollen grains with those of flowers, leaves, seedlings and siliques (all samples with duplicates). This comparison revealed that pollen expresses a reduced set of genes with increased proportions of enriched and selectively-expressed transcripts. Relative gene ontology (GO) category representations in pollen and vegetative tissues revealed a functional skew of the pollen transcriptome towards signaling, vesicle transport and cytoskeleton, suggestive of a commitment towards germination and tube growth. Relative gene ontology (GO) category representations in pollen and vegetative tissues reveal a functional skew of the pollen transcriptome towards signaling, vesicle transport and cytoskeleton, suggestive of a commitment towards germination and tube growth. Relative gene ontology (GO) category representations in pollen and vegetative tissues reveal a functional skew of the pollen transcriptome towards signaling, vesicle transport and cytoskeleton, suggestive of a commitment towards germination and tube growth. Gene family and pathway analysis allowed formulation of novel hypotheses for the role of non-classical MADS-box genes, small RNA pathways and cell cycle components in pollen.
Project description:cDNA microarray analysis of gene expression changes during pollen germination and tube growth in Lilium longiflorum L. Keywords: other
Project description:Pollen grains are coated with a pollen wall which protects the microspore from various biotic and abiotic stresses, as well as facilitates male-female interaction. During pollen wall development, many compounds are transported from the tapetum to the developing pollen wall via tapetum-specific membrane transporters, and male sterility is often observed when membrane transporter’s function or localization is altered. Here, we show that mutating AP1/2β1 and AP1/2β2, two homologous genes of AP1/2β which encodes a large subunit shared by adaptor protein 1 (AP-1) and adaptor protein 2 (AP-2) complexes in Arabidopsis, impair pollen exine formation and cause reduced pollen germination rate and slowed pollen tube growth. However, the shared theory of AP1/2β is not proved in Arabidopsis.
Project description:Arabinogalactan proteins are proteoglycans known to have important roles during cell growth and development, namelly during pollen tube growth. A microarray experiment was performed on agp6 agp11 pollen tubes to search for genetic interactions in the context of pollen tube growth. RNA from wt and mutant pollen tubes was extracted after 8h of in vitro germination and hybridized on Affimetrix microarrays.
Project description:Pollen development from the microspore involves a series of coordinated cellular events, and the resultant mature pollen is specialized in function that it can quickly germinate and produces a polar-growth pollen tube derived from the vegetative cell to deliver two sperms for fertilization. Understanding the molecular program underlying pollen development and germination still remains a major challenge for plant biology. We used Affymetrix GeneChip Rice Genome Array to comprehensively analyzed the dynamic changes in the transcriptomes of rice pollen at five sequential developmental stages from microspores to germinated pollen. Among the 51,279 transcripts on the array, we found 25,062 pollen-preferential transcripts, among which 2,203 were development stage-enriched. The diversity of transcripts decreased greatly from microspores to mature and germinated pollen, whereas the number of stage-enriched transcripts displayed a U-type change, with the lowest at the bicellular pollen stage; and a transition of overrepresented stage-enriched transcript groups associated with different functional categories, which indicates a shift in gene expression program at the bicellular pollen stage. About 54% of the now-annotated rice F-box protein genes were expressed preferentially in pollen. The transcriptome profile of germinated pollen was significantly and positively correlated with that of mature pollen. Analysis of expression profiles and coexpressed features of the pollen-preferential transcripts related to cell cycle, transcription, the ubiquitin/26S proteasome system, phytohormone signalling, the kinase system and defense/stress response revealed five expression patterns, which are compatible with changes in major cellular events during pollen development and germination. A comparison of pollen transcriptomes between rice and Arabidopsis revealed that 56.6% of the rice pollen preferential genes had homologs in Arabidopsis genome, but 63.4% of these homologs were expressed, with a small proportion being expressed preferentially, in Arabidopsis pollen. Rice and Arabidopsis pollen had non-conservative transcription factors each. These results supply novel insights into the molecular program and key components of the regulatory network regulating pollen development and germination. KEYWORDS: rice (Oryza sativa L.), pollination and fertilization, stigma, molecular functions, signaling, microarray, stress response
Project description:Pollen grains of Arabidopsis thaliana contain two haploid sperm cells enclosed in a haploid vegetative cell. Upon germination, the vegetative cell extrudes a pollen tube that carries the sperm to an ovule for fertilization. Knowing the identity, relative abundance, and splicing patterns of pollen transcripts will improve understanding of pollen and allow investigation of tissue-specific splicing in plants. Most Arabidopsis pollen transcriptome studies have used the ATH1 microarray, which does not assay splice variants and lacks specific probe sets for many genes. To investigate the pollen transcriptome, we performed high-throughput sequencing (RNA-Seq) of Arabidopsis pollen and seedlings for comparison. Gene expression was more diverse in seedling, and genes involved in cell wall biogenesis were highly expressed in pollen. RNA-Seq detected at least 4,172 protein coding genes expressed in pollen, including 289 assayed only by non-specific probe sets. Additional exons and previously unannotated 5’ and 3’ UTRs for pollen-expressed genes were revealed. We detected regions in the genome not previously annotated as expressed; 14 were tested and 12 confirmed by PCR. Gapped read alignments revealed 1,908 high-confidence new splicing events supported by 10 or more spliced read alignments. Alternative splicing patterns in pollen and seedling were highly correlated. For most alternatively spliced genes, the ratio of variants in pollen and seedling was similar, except for some encoding proteins involved in RNA splicing. This study highlights the robustness of splicing patterns in plants and the importance of on-going annotation and visualization of RNA-Seq data using interactive tools such as Integrated Genome Browser.