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Science (New York, N.Y.) Jan 2022Fertilization of an egg by multiple sperm (polyspermy) leads to lethal genome imbalance and chromosome segregation defects. In , the block to polyspermy is facilitated...
Fertilization of an egg by multiple sperm (polyspermy) leads to lethal genome imbalance and chromosome segregation defects. In , the block to polyspermy is facilitated by a mechanism that prevents polytubey (the arrival of multiple pollen tubes to one ovule). We show here that FERONIA, ANJEA, and HERCULES RECEPTOR KINASE 1 receptor-like kinases located at the septum interact with pollen tube-specific RALF6, 7, 16, 36, and 37 peptide ligands to establish this polytubey block. The same combination of RALF (rapid alkalinization factor) peptides and receptor complexes controls pollen tube reception and rupture inside the targeted ovule. Pollen tube rupture releases the polytubey block at the septum, which allows the emergence of secondary pollen tubes upon fertilization failure. Thus, orchestrated steps in the fertilization process in are coordinated by the same signaling components to guarantee and optimize reproductive success.
Topics: Arabidopsis; Arabidopsis Proteins; Fertilization; Ligands; Ovule; Peptides; Phosphotransferases; Pollen; Pollen Tube; Pollination; Protein Kinases; Signal Transduction
PubMed: 35050671
DOI: 10.1126/science.abl4683 -
Molecular Plant Jun 2022Haploid induction (HI) is an important tool in crop breeding. Phospholipase A1 (ZmPLA1)/NOT LIKE DAD (NLD)/MATRILINEAL (MTL) is a key gene controlling HI in maize;...
Haploid induction (HI) is an important tool in crop breeding. Phospholipase A1 (ZmPLA1)/NOT LIKE DAD (NLD)/MATRILINEAL (MTL) is a key gene controlling HI in maize; however, the underlying molecular mechanism remains unclear. In this study, to dissect why loss of ZmPLA1 function could mediate HI we performed a comprehensive multiple omics analysis of zmpla1 mutant anthers by integrating transcriptome, metabolome, quantitative proteome, and protein modification data. Functional classes of significantly enriched or differentially abundant molecular entities were found to be associated with the oxidative stress response, suggesting that a reactive oxygen species (ROS) burst plays a critical role in HI. In support of this, we further discovered that a simple chemical treatment of pollen with ROS reagents could lead to HI. Moreover, we identified ZmPOD65, which encodes a sperm-specific peroxidase, as a new gene controlling HI. Taken together, our study revealed a likely mechanism of HI, discovered a new gene controlling HI, and created a new method for HI in maize, indicating the importance of ROS balance in maintaining normal reproduction and providing a potential route to accelerate crop breeding.
Topics: Haploidy; Plant Breeding; Pollen; Reactive Oxygen Species; Zea mays
PubMed: 35395409
DOI: 10.1016/j.molp.2022.04.001 -
Annual Review of Plant Biology Jun 2021The gametophyte represents the sexual phase in the alternation of generations in plants; the other, nonsexual phase is the sporophyte. Here, we review the evolutionary... (Review)
Review
The gametophyte represents the sexual phase in the alternation of generations in plants; the other, nonsexual phase is the sporophyte. Here, we review the evolutionary origins of the male gametophyte among land plants and, in particular, its ontogenesis in flowering plants. The highly reduced male gametophyte of angiosperm plants is a two- or three-celled pollen grain. Its task is the production of two male gametes and their transport to the female gametophyte, the embryo sac, where double fertilization takes place. We describe two phases of pollen ontogenesis-a developmental phase leading to the differentiation of the male germline and the formation of a mature pollen grain and a functional phase representing the pollen tube growth, beginning with the landing of the pollen grain on the stigma and ending with double fertilization. We highlight recent advances in the complex regulatory mechanisms involved, including posttranscriptional regulation and transcript storage, intracellular metabolic signaling, pollen cell wall structure and synthesis, protein secretion, and phased cell-cell communication within the reproductive tissues.
Topics: Biological Evolution; Magnoliopsida; Pollen; Pollen Tube; Reproduction; Signal Transduction
PubMed: 33900787
DOI: 10.1146/annurev-arplant-080620-021907 -
Current Opinion in Insect Science Apr 2021Microbes (fungi, bacteria and viruses) living within flowers are hypothesized to affect pollination. We evaluate current support for this idea at each stage of the... (Review)
Review
Microbes (fungi, bacteria and viruses) living within flowers are hypothesized to affect pollination. We evaluate current support for this idea at each stage of the pollination process. Evidence to date is convincing that microbes influence pollinator attraction, but data are heavily weighted toward bumblebees and the effects of nectar yeasts. Effects of microbes on the efficacy of pollinator visits is understudied and variable outcomes from field studies suggest quality of pollinator visits, not only quantity, are likely involved. The effect of microbes on pollen performance is underappreciated. Beyond the effect of pathogenic viruses, the impacts of pollen-transmitted endophytic microbes on pollen viability or tube growth are unknown but could affect the outcome of pollen receipt. Future research integrating microbes into pollination should broaden taxonomic diversity of microbes, pollinators and plants and the processes under study.
Topics: Animals; Behavior, Animal; Endophytes; Flowers; Host-Pathogen Interactions; Pollen; Pollination
PubMed: 33248285
DOI: 10.1016/j.cois.2020.11.002 -
The International Journal of... 2020Professor Panchanan Maheshwari served as Professor and Head of the Department of Botany, University of Delhi, from 1950 to 1966 and built an internationally reputed... (Review)
Review
Professor Panchanan Maheshwari served as Professor and Head of the Department of Botany, University of Delhi, from 1950 to 1966 and built an internationally reputed School of integrated plant embryology. Studies carried out during and after Maheshwari's period from this School have enormously advanced our knowledge of the structural, developmental and functional aspects of embryological processes. This review covers studies carried out at the Delhi School on the developmental biology of dispersed pollen grains which operate from pollen dispersal from the anthers until pollen tubes discharge the male gametes in the embryo sac for fertilization. These events include pollen viability and vigour, pollen germination and pollen tube growth, structural details of the pistil relevant to pollen function, pollination and pollen-pistil interaction.
Topics: Developmental Biology; Flowers; Gene Expression Regulation, Plant; Germination; Plant Proteins; Pollen; Pollen Tube
PubMed: 32659021
DOI: 10.1387/ijdb.190166ks -
The Science of the Total Environment Dec 2023Aeroallergens or inhalant allergens, are proteins dispersed through the air and have the potential to induce allergic conditions such as rhinitis, conjunctivitis, and... (Review)
Review
Aeroallergens or inhalant allergens, are proteins dispersed through the air and have the potential to induce allergic conditions such as rhinitis, conjunctivitis, and asthma. Outdoor aeroallergens are found predominantly in pollen grains and fungal spores, which are allergen carriers. Aeroallergens from pollen and fungi have seasonal emission patterns that correlate with plant pollination and fungal sporulation and are strongly associated with atmospheric weather conditions. They are released when allergen carriers come in contact with the respiratory system, e.g. the nasal mucosa. In addition, due to the rupture of allergen carriers, airborne allergen molecules may be released directly into the air in the form of micronic and submicronic particles (cytoplasmic debris, cell wall fragments, droplets etc.) or adhered onto other airborne particulate matter. Therefore, aeroallergen detection strategies must consider, in addition to the allergen carriers, the allergen molecules themselves. This review article aims to present the current knowledge on inhalant allergens in the outdoor environment, their structure, localization, and factors affecting their production, transformation, release or degradation. In addition, methods for collecting and quantifying aeroallergens are listed and thoroughly discussed. Finally, the knowledge gaps, challenges and implications associated with aeroallergen analysis are described.
Topics: Allergens; Pollen; Asthma; Particulate Matter; Europe; Air Pollutants
PubMed: 37709071
DOI: 10.1016/j.scitotenv.2023.167042 -
Plant Biology (Stuttgart, Germany) Apr 2024Floral colours represent a highly diverse communication signal mainly involved in flower visitors' attraction and guidance, but also flower discrimination, filtering... (Review)
Review
Floral colours represent a highly diverse communication signal mainly involved in flower visitors' attraction and guidance, but also flower discrimination, filtering non-pollinators and discouraging floral antagonists. The divergent visual systems and colour preferences of flower visitors, as well as the necessity of cues for flower detection and discrimination, foster the diversity of floral colours and colour patterns. Despite the bewildering diversity of floral colour patterns, a recurrent component is a yellow UV-absorbing floral centre, and it is still not clear why this pattern is so frequent in angiosperms. The pollen, anther, stamen, and androecium mimicry (PASAM) hypothesis suggests that the system composed of the flowers possessing such yellow UV-absorbing floral reproductive structures, the flowers displaying central yellow UV-absorbing structures as floral guides, and the pollen-collecting, as well as pollen-eating, flower visitors responding to such signals constitute the world's most speciose mimicry system. In this review, we call the attention of researchers to some hypothetical PASAM systems around the globe, presenting some fascinating examples that illustrate their huge diversity. We will also present new and published data on pollen-eating and pollen-collecting pollinators' responses to PASAM structures supporting the PASAM hypothesis and will discuss how widespread these systems are around the globe. Ultimately, our goal is to promote the idea that PASAM is a plausible first approach to understanding floral colour patterns in angiosperms.
Topics: Pollination; Reproduction; Flowers; Pollen; Magnoliopsida
PubMed: 38407440
DOI: 10.1111/plb.13628 -
Annual Review of Plant Biology Jun 2021Pollen-pistil interactions serve as important prezygotic reproductive barriers that play a critical role in mate selection in plants. Here, we highlight recent progress...
Pollen-pistil interactions serve as important prezygotic reproductive barriers that play a critical role in mate selection in plants. Here, we highlight recent progress toward understanding the molecular basis of pollen-pistil interactions as reproductive isolating barriers. These barriers can be active systems of pollen rejection, or they can result from a mismatch of required male and female factors. In some cases, the barriers are mechanistically linked to self-incompatibility systems, while others represent completely independent processes. Pollen-pistil reproductive barriers can act as soon as pollen is deposited on a stigma, where penetration of heterospecific pollen tubes is blocked by the stigma papillae. As pollen tubes extend, the female transmitting tissue can selectively limit growth by producing cell wall-modifying enzymes and cytotoxins that interact with the growing pollen tube. At ovules, differential pollen tube attraction and inhibition of sperm cell release can act as barriers to heterospecific pollen tubes.
Topics: Flowers; Pollen; Pollen Tube; Pollination; Reproduction
PubMed: 34143652
DOI: 10.1146/annurev-arplant-080620-102159 -
Trends in Plant Science Dec 2019Understanding the molecular basis of pollen germination in cereals holds great potential to improve yield. Pollen, a highly specialized haploid male gametophyte,... (Review)
Review
Understanding the molecular basis of pollen germination in cereals holds great potential to improve yield. Pollen, a highly specialized haploid male gametophyte, transports sperm cells through a pollen tube to the female ovule for fertilization, directly determining grain yield in cereal crops. Although insights into the regulation of pollen germination and gamete interaction have advanced rapidly in the model Arabidopsis thaliana (arabidopsis), the molecular mechanisms in monocot cereals remain largely unknown. Recently, pollen-specific genome-wide and mutant analyses in rice and maize have extended our understanding of monocot regulatory components. We highlight conserved and diverse mechanisms underlying pollen hydration, germination, and tube growth in cereals that provide ideas for translating this research from arabidopsis. Recent developments in gene-editing systems may facilitate further functional genetic research.
Topics: Arabidopsis; Arabidopsis Proteins; Edible Grain; Germination; Pollen; Pollen Tube
PubMed: 31610991
DOI: 10.1016/j.tplants.2019.08.005 -
Current Protein & Peptide Science 2023Allergic diseases have increased worldwide during the last century and are a major disease burden globally. Several substances can induce allergic sensitization and... (Review)
Review
Allergic diseases have increased worldwide during the last century and are a major disease burden globally. Several substances can induce allergic sensitization and elicit allergic symptoms in sensitized individuals. Pollen grains are one of the main causes of allergic rhinitis and asthma, and the prevalence of different pollen species depends on the climate, geographical regions, flora, and seasons. In addition to avoiding exposure to pollens, anti-allergic drugs are commonly used to mitigate the symptoms of allergies. However, these drugs need to be administered repeatedly as long as the symptoms prevail, usually life-long. Allergen immunotherapy (AIT) is currently the only disease-modifying approach that can prevent the natural progression of the disease (also known as an allergic march), provide a long-lasting therapeutic effect, and prevent the worsening of the symptoms and the occurrence of new sensitizations in allergic individuals. Since the pioneering clinical studies conducted more than 100 years ago using subcutaneously administered pollen extract to treat hay fever, significant advances have been made in the field of AIT. Starting from this pioneering approach, in this review, we have discussed the evolution of the products used for AIT with particular emphasis on pollen allergoids, the chemically modified pollen extracts characterized by lower allergenicity and comparable immunogenicity, and the different routes of administration used for AIT.
Topics: Humans; Rhinitis, Allergic, Seasonal; Allergens; Pollen; Asthma; Desensitization, Immunologic
PubMed: 36872361
DOI: 10.2174/1389203724666230303091754