scholarly journals Identification of a role for an E6-like 1 gene in early pollen-stigma interactions in Arabidopsis thaliana

2019 ◽  
Author(s):  
Jennifer Doucet ◽  
Christina Truong ◽  
Elizabeth Frank-Webb ◽  
Hyun Kyung Lee ◽  
Anna Daneva ◽  
...  

AbstractIn Arabidopsis, successful pollen-stigma interactions are dependent on rapid recognition of compatible pollen by the stigmatic papillae located on the surface of the pistil and the subsequent regulation of pollen hydration and germination, and followed by the growth of pollen tubes through the stigma surface. Here we have described the function of a novel gene, E6-like 1 (E6L1), that was identified through the analysis of transcriptome datasets, as one of highest-expressed genes in the stigma, and furthermore, its expression was largely restricted to the stigma and trichomes. The first E6 gene was initially identified as a highly-expressed gene during cotton fiber development, and related E6-like predicted proteins are found throughout the Angiosperms. To date, no orthologous genes have been assigned a biological function. Both the Arabidopsis E6L1 and cotton E6 proteins are predicted to be secreted, and this was confirmed using an E6L1:RFP fusion construct. To further investigate E6L1’s function, one T-DNA and two independent CRISPR-generated mutants were analyzed for compatible pollen-stigma interactions, and pollen hydration, pollen adhesion and seed set were mildly impaired for the e6l1 mutants. This work identifies E6L1 as a novel stigmatic factor that plays a role during the early post-pollination stages in Arabidopsis.Key MessageWe describe a function for a novel Arabidopsis gene, E6-like 1 (E6L1), that was identified as a highly-expressed gene in the stigma and plays a role in early post-pollination stages.


Author(s):  
Hyun Kyung Lee ◽  
Daphne R Goring

Abstract In flowering plants, cell–cell communication between the compatible pollen grain/growing pollen tube and the pistil is an essential component for successful sexual reproduction. In Arabidopsis thaliana, the later stages of this dialogue are mediated by several peptide ligands and receptors that guide pollen tubes to the ovules for the release of sperm cells. Despite a detailed understanding of these processes, a key gap remains regarding the nature of the regulators that function at the earlier stages which are essential steps leading to fertilization. Here, we report on new functions for A. thaliana Receptor-Like Kinase (RLK) genes belonging to the LRR-II and LRR-VIII-2 RLK subgroups in the female reproductive tract to regulate compatible pollen hydration and the early stages of pollen tube growth. Mutant pistils for the A. thaliana RKF1 gene cluster were observed to support reduced wild-type pollen hydration and, when combined with the SERK1 and SERK3/BAK1 mutations, reduced pollen tube travel distances occurred. As these mutant pistils displayed a wild-type morphology, we propose that the observed altered compatible pollen responses result from an impaired pollen–pistil dialogue at these early stages.



1995 ◽  
Vol 120 (2) ◽  
pp. 313-317 ◽  
Author(s):  
Thomas H. Boyle ◽  
Renate Karle ◽  
Susan S. Han

The reproductive biology of Schlumbergera truncata (Haworth) Moran and S. xbuckleyi (T. Moore) Tjaden was examined in a series of experiments. At anthesis, pollen grains are spherical, 54 to 62 μm in diameter, and tricellular. The receptive surface of the stigma is densely covered with elongated papillae and is devoid of exudate during the period of flower opening. When compatible pollen was applied to mature stigmas, germination occurred between 20 and 30 minutes after pollination and pollen tubes penetrated the stigma surface between 30 and 40 minutes after pollination. Pollen tubes exhibited a nonlinear pattern of growth in the upper two-thirds of the style, and the maximum rate of growth (≫1.9 mm·h-1) occurred between 12 and 18 hours after pollination. Full seed set was attained between 32 and 48 hours after pollination. Genotypic variation in the time required to achieve full seed set was partly attributable to differences in stylar length. Seeds were fully mature 6 months after pollination, but delaying fruit harvest until 8 months after pollination did not affect seed germination.



2021 ◽  
Vol 22 (12) ◽  
pp. 6287
Author(s):  
Hendrik Reuper ◽  
Benjamin Götte ◽  
Lucy Williams ◽  
Timothy J. C. Tan ◽  
Gerald M. McInerney ◽  
...  

Stress granules (SGs) are dynamic RNA–protein complexes localized in the cytoplasm that rapidly form under stress conditions and disperse when normal conditions are restored. The formation of SGs depends on the Ras-GAP SH3 domain-binding protein (G3BP). Formations, interactions and functions of plant and human SGs are strikingly similar, suggesting a conserved mechanism. However, functional analyses of plant G3BPs are missing. Thus, members of the Arabidopsis thaliana G3BP (AtG3BP) protein family were investigated in a complementation assay in a human G3BP knock-out cell line. It was shown that two out of seven AtG3BPs were able to complement the function of their human homolog. GFP-AtG3BP fusion proteins co-localized with human SG marker proteins Caprin-1 and eIF4G1 and restored SG formation in G3BP double KO cells. Interaction between AtG3BP-1 and -7 and known human G3BP interaction partners such as Caprin-1 and USP10 was also demonstrated by co-immunoprecipitation. In addition, an RG/RGG domain exchange from Arabidopsis G3BP into the human G3BP background showed the ability for complementation. In summary, our results support a conserved mechanism of SG function over the kingdoms, which will help to further elucidate the biological function of the Arabidopsis G3BP protein family.



2018 ◽  
Vol 93 (5) ◽  
pp. 209-220 ◽  
Author(s):  
Seiji Takeda ◽  
Kohki Ochiai ◽  
Yasuaki Kagaya ◽  
Wataru Egusa ◽  
Hiroaki Morimoto ◽  
...  


2020 ◽  
Author(s):  
Patrick Kenney ◽  
Subramanian Sankaranarayanan ◽  
Michael Balogh ◽  
Emily Indriolo

AbstractMembers of the Brassicaceae family have the ability to regulate pollination events occurring on the stigma surface. In Brassica species, self-pollination leads to an allele specific interaction between the pollen small cysteine-rich peptide ligand (SCR/SP11) and the stigmatic S-receptor kinase (SRK) that activates the E3 ubiquitin ligase ARC1 (Armadillo repeat-containing 1), resulting in proteasomal degradation of various compatibility factors including Glyoxalase I (GLO1) which is necessary for successful pollination. Suppression of GLO1 was sufficient to reduce compatibility, and overexpression of GLO1 in self-incompatible Brassica napus stigmas resulted in partial breakdown of the self-incompatibility response. Here, we verified if BnGLO1 could function as a compatibility factor in the artificial self-incompatibility system of Arabidopsis thaliana expressing AlSCRb, AlSRKb and AlARC1 proteins from A. lyrata. Overexpression of BnGLO1 is sufficient to breakdown self-incompatibility response in A. thaliana stigmas, suggesting that GLO1 functions as an inter-species compatibility factor. Therefore, GLO1 has an indisputable role as a compatibility factor in the stigma in regulating pollen attachment and pollen tube growth. Lastly, this study demonstrates the usefulness of an artificial self-incompatibility system in A. thaliana for interspecific self-incompatibility studies.



2020 ◽  
Vol 21 (19) ◽  
pp. 7404
Author(s):  
Yanqiao Zhu ◽  
Oliver Berkowitz ◽  
Jennifer Selinski ◽  
Andreas Hartmann ◽  
Reena Narsai ◽  
...  

Seed germination is a critical process for completion of the plant life cycle and for global food production. Comparing the germination transcriptomes of barley (Hordeum vulgare) to Arabidopsis thaliana revealed the overall pattern was conserved in terms of functional gene ontology; however, many oppositely responsive orthologous genes were identified. Conserved processes included a set of approximately 6000 genes that peaked early in germination and were enriched in processes associated with RNA metabolism, e.g., pentatricopeptide repeat (PPR)-containing proteins. Comparison of orthologous genes revealed more than 3000 orthogroups containing almost 4000 genes that displayed similar expression patterns including functions associated with mitochondrial tricarboxylic acid (TCA) cycle, carbohydrate and RNA/DNA metabolism, autophagy, protein modifications, and organellar function. Biochemical and proteomic analyses indicated mitochondrial biogenesis occurred early in germination, but detailed analyses revealed the timing involved in mitochondrial biogenesis may vary between species. More than 1800 orthogroups representing 2000 genes displayed opposite patterns in transcript abundance, representing functions of energy (carbohydrate) metabolism, photosynthesis, protein synthesis and degradation, and gene regulation. Differences in expression of basic-leucine zippers (bZIPs) and Apetala 2 (AP2)/ethylene-responsive element binding proteins (EREBPs) point to differences in regulatory processes at a high level, which provide opportunities to modify processes in order to enhance grain quality, germination, and storage as needed for different uses.



2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Jennifer Doucet ◽  
Hyun Kyung Lee ◽  
Nethangi Udugama ◽  
Jianfeng Xu ◽  
Baoxiu Qi ◽  
...  

Abstract Background In the Brassicaceae, the early stages of compatible pollen-stigma interactions are tightly controlled with early checkpoints regulating pollen adhesion, hydration and germination, and pollen tube entry into the stigmatic surface. However, the early signalling events in the stigma which trigger these compatible interactions remain unknown. Results A set of stigma-expressed pseudokinase genes, termed BRASSIKINs (BKNs), were identified and found to be present in only core Brassicaceae genomes. In Arabidopsis thaliana Col-0, BKN1 displayed stigma-specific expression while the BKN2 gene was expressed in other tissues as well. CRISPR deletion mutations were generated for the two tandemly linked BKNs, and very mild hydration defects were observed for wild-type Col-0 pollen when placed on the bkn1/2 mutant stigmas. In further analyses, the predominant transcript for the stigma-specific BKN1 was found to have a premature stop codon in the Col-0 ecotype, but a survey of the 1001 Arabidopsis genomes uncovered three ecotypes that encoded a full-length BKN1 protein. Furthermore, phylogenetic analyses identified intact BKN1 orthologues in the closely related outcrossing Arabidopsis species, A. lyrata and A. halleri. Finally, the BKN pseudokinases were found to be plasma-membrane localized through the dual lipid modification of myristoylation and palmitoylation, and this localization would be consistent with a role in signaling complexes. Conclusion In this study, we have characterized the novel Brassicaceae-specific family of BKN pseudokinase genes, and examined the function of BKN1 and BKN2 in the context of pollen-stigma interactions in A. thaliana Col-0. Additionally, premature stop codons were identified in the predicted stigma specific BKN1 gene in a number of the 1001 A. thaliana ecotype genomes, and this was in contrast to the out-crossing Arabidopsis species which carried intact copies of BKN1. Thus, understanding the function of BKN1 in other Brassicaceae species will be a key direction for future studies.



AoB Plants ◽  
2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Damien Poulain ◽  
Lucy Botran ◽  
Helen M North ◽  
Marie-Christine Ralet

Abstract Arabidopsis thaliana (Arabidopsis) seeds are myxospermous and release two layers of mucilage on imbibition. The outer layer can be extracted with water facilitating the analysis of its major constituent, polysaccharides. The composition and properties of outer mucilage have been determined for 306 natural accessions and six control genotypes to generate a data set comprising six traits measured in four biological replicates for each. Future exploitation of this data is possible in a range of analyses and should yield information concerning genetic diversity, underlying genetic factors and the biological function of mucilage as an adaptive trait.



1991 ◽  
Vol 69 (11) ◽  
pp. 2448-2454 ◽  
Author(s):  
S. P. Vander Kloet

Self pollen of Vaccinium corymbosum germinates as well as outcross (compatible) pollen from the same population and more rapidly than compatible pollen from more distant populations. When a mixture of self and compatible pollen, either from the same or incontiguous populations, is applied to the stigma, the time required for berry ripening is significantly reduced compared with compatible pollen alone, although seed set also decreases significantly. Adding compatible pollen from different pollen donors significantly increased seed set but also increased the time for berry maturation by 5 days. Self pollen in conjunction with compatible pollen resulted in a 50% loss of viable seed production and an 8% gain in berry maturation time. Self-pollination resulted in embryo abortion in V. corymbosum. Key words: pollination, Vaccinium, seed set, outcrossing.



1984 ◽  
Vol 62 (6) ◽  
pp. 1298-1303 ◽  
Author(s):  
Joel S. Shore ◽  
Spencer C. H. Barrett

Controlled pollination experiments were performed on the self-incompatible distylous herb Turnera ulmifolia L. to investigate the effects of pollination intensity and large amounts of incompatible pollen on seed set. In the first experiment, known numbers of compatible pollen grains ranging from 1 to 100 were applied to stigmas of the floral morphs. In both morphs, increasing amounts of pollen generally resulted in increased levels of seed set, although considerable variance was observed at all pollination intensities. Approximately two to seven pollen grains are required to produce a single seed and more than 95 grains are required to achieve maximum seed set in T. ulmifolia. Regression analysis of the seed set data failed to detect a difference in the response of the floral morphs to pollination intensity. In the second experiment, known proportions of compatible and incompatible pollen were applied to stigmas at various time intervals. Most treatments involving mixtures of compatible and incompatible pollen had no significant effect on seed set when compared with the controls. Clogging was only observed in the long-styled morph when one anther of compatible pollen was applied to stigmas 1.5 and 3.0 h after pollination with five anthers of incompatible pollen. The clogging of stigmas by incompatible pollen seems unlikely to have played a major role in the evolution and maintenance of distyly in Turnera ulmifolia.



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