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Plant Physiology and Biochemistry : PPB Mar 2024In staple crops, such as rice (Oryza sativa L.), pollen plays a crucial role in seed production. However, the molecular mechanisms underlying rice pollen germination and...
In staple crops, such as rice (Oryza sativa L.), pollen plays a crucial role in seed production. However, the molecular mechanisms underlying rice pollen germination and tube growth remain underexplored. Notably, we recently uncovered the redundant expression and mutual interaction of two rice genes encoding cyclic nucleotide-gated channels (CNGCs), OsCNGC4 and OsCNGC5, in mature pollen. Building on these findings, the current study focused on clarifying the functional roles of these two genes in pollen germination and tube growth. To overcome functional redundancy, we produced gene-edited rice plants with mutations in both genes using the CRISPR-Cas9 system. The resulting homozygous OsCNGC4 and OsCNGC5 gene-edited mutants (oscngc4/5) exhibited significantly lower pollen germination rates than the wild type (WT), along with severely reduced fertility. Transcriptome analysis of the double oscngc4/5 mutant revealed downregulation of genes related to receptor kinases, transporters, and cell wall metabolism. To identify the direct regulators of OsCNGC4, which form a heterodimer with OsCNGC5, we screened a yeast two-hybrid library containing rice cDNAs from mature anthers. Subsequently, we identified two calmodulin isoforms (CaM1-1 and CaM1-2), NETWORKED 2 A (NET2A), and proline-rich extension-like receptor kinase 13 (PERK13) proteins as interactors of OsCNGC4, suggesting its roles in regulating Ca channel activity and F-actin organization. Overall, our results suggest that OsCNGC4 and OsCNGC5 may play critical roles in pollen germination and elongation by regulating the Ca gradient in growing pollen tubes.
Topics: Oryza; Cyclic Nucleotide-Gated Cation Channels; Germination; Pollen; Pollen Tube; Calmodulin; Phosphotransferases; Nucleotides, Cyclic
PubMed: 38493663
DOI: 10.1016/j.plaphy.2024.108522 -
Plant Reproduction Mar 2024Pollen tubes from closely related species and mutants lacking pollen tube MYB transcription factors are able to initiate FER/LRE-dependent synergid cell calcium...
Pollen tubes from closely related species and mutants lacking pollen tube MYB transcription factors are able to initiate FER/LRE-dependent synergid cell calcium oscillations. Reproductive isolation leads to the evolution of new species; however, the molecular mechanisms that maintain reproductive barriers between sympatric species are not well defined. In flowering plants, sperm cells are immotile and are delivered to female gametes by the pollen grain. After landing on the stigmatic surface, the pollen grain germinates a polarized extension, the pollen tube, into floral tissue. After growing via polar extension to the female gametes and shuttling its cargo of sperm cells through its cytoplasm, the pollen tube signals its arrival and identity to synergid cells that flank the egg. If signaling is successful, the pollen tube and receptive synergid cell burst, and sperm cells are released for fusion with female gametes. To better understand cell-cell recognition during reproduction and how reproductive barriers are maintained between closely related species, pollen tube-initiated synergid cell calcium ion dynamics were examined during interspecific crosses. It was observed that interspecific pollen tubes successfully trigger synergid cell calcium oscillations-a hallmark of reproductive success-but signaling fails downstream of key signaling genes and sperm are not released. This work further defines pollen tube-synergid cell signaling as a critical block to interspecific hybridization and suggests that the FERONIA/LORELEI signaling mechanism plays multiple parallel roles during pollen tube reception.
Topics: Arabidopsis; Calcium Signaling; Seeds; Reproduction; Pollen Tube; Arabidopsis Proteins
PubMed: 37934279
DOI: 10.1007/s00497-023-00483-6 -
Plant Reproduction Jun 2024ARID-HMG DNA binding protein, AtHMGB15, regulates pollen development and pollen germination in Arabidopsis. Previous studies have shown that ARID-HMG DNA binding...
ARID-HMG DNA binding protein, AtHMGB15, regulates pollen development and pollen germination in Arabidopsis. Previous studies have shown that ARID-HMG DNA binding protein, AtHMGB15 regulate pollen development and pollen germination in Arabidopsis. Here, we performed transcriptome and cytological studies to understand the role of AtHMGB15 in regulating pollen wall morphology and the pollen tube germination rate. Our result showed abnormal vacuolization in the tapetal cells during anther maturation and prolonged PCD in AtHMGB15 loss-of-function mutant. The tapetum has the ability to perform both secretory and biosynthetic activities critical for pollen maturation and pollen viability. Interestingly, expression of PCD executer genes CEP1, MC9 and RNS3 were significant down-regulation of in athmgb15-4. The growth of pollen tubes is regulated by the actin cytoskeleton dynamics. To address the defect in pollen tube growth of athmgb15, we monitored the actin network in growing pollen tubes of wildtype and athmgb15-4 using Rhodamine-phalloidin fluorescence. Our results indicate a highly fragmented actin distribution in athmgb15-4 pollen tubes with a lesser number of long actin fibers and significantly low f-actin concentration at the apex. q-RTPCR further indicates significant downy-regulation of actin regulatory proteins VLN2 and PRF4. Collectively, our results suggest that AtHMGB15 being a nuclear architectural protein orchestrates high-order chromatin organization to promote the transcription of genes responsible for pollen development and pollen germination.
PubMed: 38904831
DOI: 10.1007/s00497-024-00505-x -
Molecular Breeding : New Strategies in... Mar 2024Cold shock domain proteins (CSPs), initially identified in , have been demonstrated to play a positive role in cold resistance. Previous studies in wheat, rice, and...
UNLABELLED
Cold shock domain proteins (CSPs), initially identified in , have been demonstrated to play a positive role in cold resistance. Previous studies in wheat, rice, and have indicated the functional conservation of CSPs in cold resistance between bacteria and higher plants. However, the biological functions of PbrCSPs in pear pollen tubes, which represent the fragile reproductive organs highly sensitive to low temperature, remain largely unknown. In this study, a total of 22 CSPs were identified in the seven Rosaceae species, with a focus on characterizing four PbrCSPs in pear ( Rehder). All four PbrCSPs were structurally conserved and responsive to the abiotic stresses, such as cold, high osmotic, and abscisic acid (ABA) treatments. PbrCSP1, which is specifically expressed in pear pollen tubes, was selected for further research. PbrCSP1 was localized in both the cytoplasm and nucleus. Suppressing the expression of significantly inhibited the pollen tube growth in vitro. Conversely, overexpression of promoted the growth of pear pollen tubes under the normal condition and, notably, under the cold environment at 4 °C. These findings highlight an essential role of PbrCSP1 in facilitating the normal growth and enhancing cold resistance in pear pollen tubes.
SUPPLEMENTARY INFORMATION
The online version contains supplementary material available at 10.1007/s11032-024-01457-w.
PubMed: 38390031
DOI: 10.1007/s11032-024-01457-w -
Plant Reproduction Mar 2024In Araucaria angustifolia, the seed scale is part of the ovule, the female gametophyte presents a monosporic origin and arises from a coenocytic tetrad, and the pollen...
In Araucaria angustifolia, the seed scale is part of the ovule, the female gametophyte presents a monosporic origin and arises from a coenocytic tetrad, and the pollen tube presents a single axis. The seed cone of conifers has many informative features, and its ontogenetic data may help interpret relationships among function, development patterns, and homology among seed plants. We reported the seed cone development, from pollination to pre-fertilization, including seed scale, ovule ontogeny, and pollen tube growth in Araucaria angustifolia. The study was performed using light microscopy, scanning electron microscopy, and X-ray microcomputed tomography (μCT). During the pollination period, the ovule arises right after the seed scale has emerged. From that event to the pre-fertilization period takes about 14 months. Megasporogenesis occurs three weeks after ovule formation, producing a coenocytic tetrad. At the same time as the female gametophyte's first nuclear division begins, the pollen tube grows through the seed scale adaxial face. Until maturity, the megagametophyte goes through the free nuclei stage, cellularization stage, and cellular growth stage. Along its development, many pollen tubes develop in the nucellar tissue extending straight toward the female gametophyte. Our observations show that the seed scale came out of the same primordia of the ovule, agreeing with past studies that this structure is part of the ovule itself. The formation of a female gametophyte with a monosporic origin that arises from a coenocytic tetrad was described for the first time in conifers, and the three-dimensional reconstruction of the ovule revealed the presence of pollen tubes with only one axis and no branches, highlighting a new pattern of pollen tube growth in Araucariaceae.
Topics: Pollination; Pollen Tube; Araucaria; Araucariaceae; Plant Cone; Brazil; X-Ray Microtomography; Seeds; Ovule; Biology
PubMed: 37449999
DOI: 10.1007/s00497-023-00473-8 -
The Plant Journal : For Cell and... May 2024Low phytic acid (lpa) crop is considered as an effective strategy to improve crop nutritional quality, but a substantial decrease in phytic acid (PA) usually has...
Rice myo-inositol-3-phosphate synthase 2 (RINO2) alleviates heat injury-induced impairment in pollen germination and tube growth by modulating Ca signaling and actin filament cytoskeleton.
Low phytic acid (lpa) crop is considered as an effective strategy to improve crop nutritional quality, but a substantial decrease in phytic acid (PA) usually has negative effect on agronomic performance and its response to environment adversities. Myo-inositol-3-phosphate synthase (MIPS) is the rate-limiting enzyme in PA biosynthesis pathway, and regarded as the prime target for engineering lpa crop. In this paper, the rice MIPS gene (RINO2) knockout mutants and its wild type were performed to investigate the genotype-dependent alteration in the heat injury-induced spikelet fertility and its underlying mechanism for rice plants being imposed to heat stress at anthesis. Results indicated that RINO2 knockout significantly enhanced the susceptibility of rice spikelet fertility to heat injury, due to the severely exacerbated obstacles in pollen germination and pollen tube growth in pistil for RINO2 knockout under high temperature (HT) at anthesis. The loss of RINO2 function caused a marked reduction in inositol and phosphatidylinositol derivative concentrations in the HT-stressed pollen grains, which resulted in the strikingly lower content of phosphatidylinositol 4,5-diphosphate (PI (4,5) P) in germinating pollen grain and pollen tube. The insufficient supply of PI (4,5) P in the HT-stressed pollen grains disrupted normal Ca gradient in the apical region of pollen tubes and actin filament cytoskeleton in growing pollen tubes. The severely repressed biosynthesis of PI (4,5) P was among the regulatory switch steps leading to the impaired pollen germination and deformed pollen tube growth for the HT-stressed pollens of RINO2 knockout mutants.
PubMed: 38761097
DOI: 10.1111/tpj.16802 -
Frontiers in Plant Science 2023Climate change and global warming represent the main threats for many agricultural crops. Tomato is one of the most extensively grown and consumed horticultural products... (Review)
Review
Climate change and global warming represent the main threats for many agricultural crops. Tomato is one of the most extensively grown and consumed horticultural products and can survive in a wide range of climatic conditions. However, high temperatures negatively affect both vegetative growth and reproductive processes, resulting in losses of yield and fruit quality traits. Researchers have employed different parameters to evaluate the heat stress tolerance, including evaluation of leaf- (stomatal conductance, net photosynthetic rate, Fv/Fm), flower- (inflorescence number, flower number, stigma exertion), pollen-related traits (pollen germination and viability, pollen tube growth) and fruit yield per plant. Moreover, several authors have gone even further, trying to understand the plants molecular response mechanisms to this stress. The present review focused on the tomato molecular response to heat stress during the reproductive stage, since the increase of temperatures above the optimum usually occurs late in the growing tomato season. Reproductive-related traits directly affects the final yield and are regulated by several genes such as transcriptional factors, heat shock proteins, genes related to flower, flowering, pollen and fruit set, and epigenetic mechanisms involving DNA methylation, histone modification, chromatin remodelling and non-coding RNAs. We provided a detailed list of these genes and their function under high temperature conditions in defining the final yield with the aim to summarize the recent findings and pose the attention on candidate genes that could prompt on the selection and constitution of new thermotolerant tomato plant genotypes able to face this abiotic challenge.
PubMed: 38259925
DOI: 10.3389/fpls.2023.1245661 -
WD40-domain protein GORI is an integrative scaffold that is required for pollen tube growth in rice.Plant Signaling & Behavior Dec 2023The pollen tube plays a critical role in angiosperm plants by delivering sperm gametes for double fertilization. Although the molecular mechanisms underlying pollen tube...
The pollen tube plays a critical role in angiosperm plants by delivering sperm gametes for double fertilization. Although the molecular mechanisms underlying pollen tube germination and growth are crucial to crop plants, they are poorly understood. Here, we describe recent advancements in the understanding of the role of the WD40-domain protein in regulating pollen germination and discuss future directions to investigate its role in rice. encodes a seven-WD40-motif protein that interacts with an AP180 N-terminal homology (ANTH)-domain protein, which modulates clathrin-mediated endocytosis (CME), and regulates Rac6 activity in the apical plasma membrane of elongating pollen tubes. Loss of function of GORI or Rac6 reduces pollen germination and tube growth, thereby resulting in male sterility in rice. In contrast, overexpression of Rac6 increases pollen tube elongation, with this effect being rescued by GORI overexpression. In the absence of ANTH, pollen germination was reduced, similar to the results observed after inhibitor treatment, indicating that pollen germination partially requires CME. Our findings demonstrated that the GORI protein is a positive regulator of pollen germination and tube growth, serving as a link between Rac6 activity regulation and ANTH-mediated endocytosis.
Topics: Pollen Tube; Oryza; Seeds; Arabidopsis Proteins; Plant Proteins; Germination
PubMed: 35642508
DOI: 10.1080/15592324.2022.2082678 -
Plant-environment Interactions... Jun 2024Food production and food security depend on the ability of crops to cope with anthropogenic climate change and successfully produce seed. To guarantee food production... (Review)
Review
Food production and food security depend on the ability of crops to cope with anthropogenic climate change and successfully produce seed. To guarantee food production well into the future, contemporary plant scientists in Latin America must carry out research on how plants respond to environmental stressors such as temperature, drought, and salinity. This review shows the opportunities to apply these results locally and abroad and points to the gaps that still exist in terms of reproductive processes with the purpose to better link research with translational work in plant breeding and biotechnology. Suggestions are put forth to address these gaps creatively in the face of chronic low investment in science with a focus on applicability.
PubMed: 38764600
DOI: 10.1002/pei3.10143 -
Current Biology : CB Oct 2023Flowering plants evolved glandular synergid cells assisting female gametes to attract pollen tubes carrying sperm cells. A recent study shows how central cells serve as...
Flowering plants evolved glandular synergid cells assisting female gametes to attract pollen tubes carrying sperm cells. A recent study shows how central cells serve as a back-up to ensure pollen tube attraction and reproductive success in the absence of the assistants.
Topics: Arabidopsis; Seeds; Pollen Tube; Reproduction; Fertilization; Ovule; Arabidopsis Proteins
PubMed: 37816321
DOI: 10.1016/j.cub.2023.08.078