In flowering plants, cell–cell communication plays a key role in reproductive success, as both pollination and fertilization require pathways that regulate interactions between many different cell types. Some of the most critical of these interactions are those between the pollen tube (
The model pennate diatom
Proteomics data are available via ProteomeXchange with identifier PXD021172.
The marine diatom
- NSF-PAR ID:
- 10387837
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Plant Direct
- Volume:
- 6
- Issue:
- 12
- ISSN:
- 2475-4455
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Summary PT ) and the embryo sac, which ensure the delivery of sperm cells required for double fertilization. Synergid cells function to attract thePT through secretion of small peptides and inPT reception via membrane‐bound proteins associated with the endomembrane system and the cell surface. While many synergid‐expressed components regulatingPT attraction and reception have been identified, few tools exist to study the localization of membrane‐bound proteins and the components of the endomembrane system in this cell type. In this study, we describe the localization and distribution of seven fluorescent markers that labelled components of the secretory pathway in synergid cells ofArabidopsis thaliana . These markers were used in co‐localization experiments to investigate the subcellular distribution of the twoPT reception componentsLORELEI , aGPI ‐anchored surface protein, andNORTIA , aMILDEW RESISTANCE LOCUS O protein, both found within the endomembrane system of the synergid cell. These secretory markers are useful tools for both reproductive and cell biologists, enabling the analysis of membrane‐associated trafficking within a haploid cell actively involved in polar transport. -
Summary The mitochondrial and chloroplast
mRNA s of the majority of land plants are modified through cytidine to uridine (C‐to‐U)RNA editing. Previously, forward and reverse genetic screens demonstrated a requirement for pentatricopeptide repeat (PPR ) proteins forRNA editing. Moreover, chloroplast editing factorsOZ 1,RIP 2,RIP 9 andORRM 1 were identified in co‐immunoprecipitation (co‐IP) experiments, albeit the minimal complex sufficient for editing activity was never deduced. The current study focuses on isolated, intact complexes that are capable of editing distinct sites. Peak editing activity for four sites was discovered in size‐exclusion chromatography (SEC) fractions ≥ 670 kDa, while fractions estimated to be approximately 413 kDa exhibited the greatest ability to convert a substrate containing the editing siterps14 C80.RNA content peaked in the ≥ 670 kDa fraction. Treatment of active chloroplast extracts withRN ase A abolished the relationship of editing activity with high‐MW fractions, suggesting a structuralRNA component in native complexes. By immunoblotting,RIP 9,OTP 86,OZ 1 andORRM 1 were shown to be present in active gel filtration fractions, thoughOZ 1 andORRM 1 were mainly found in low‐MW inactive fractions. Active editing factor complexes were affinity‐purified using anti‐RIP 9 antibodies, and orthologs to putativeArabidopsis thaliana RNA editing factorPPR proteins,RIP 2,RIP 9,RIP 1,OZ 1,ORRM 1 andISE 2 were identified via mass spectrometry. Western blots from co‐IP studies revealed the mutual association ofOTP 86 andOZ 1 with nativeRIP 9 complexes. Thus,RIP 9 complexes were discovered to be highly associated with C‐to‐URNA editing activity and other editing factors indicative of their critical role in vascular plant editosomes. -
Premise of the Study Polyploidy has been long recognized as an important force in plant evolution. Previous studies had suggested widespread occurrence of polyploidy and the allopolyploid origin of several species in the diverse neotropical genus
Lachemilla (Rosaceae). Nonetheless, this evidence has relied mostly on patterns of cytonuclear discordance, and direct evidence from nuclear allelic markers is still needed.Methods Here we used
PCR target enrichment in combination with high throughput sequencing to obtain multiple copies of the nuclear ribosomal (nr)DNA cistron and 45 regions of the plastid genome (cpDNA ) from 219 accessions representing 48 species ofLachemilla and to explore the allopolyploid origin of species in this group.Key Results We were able to identify multiple nr
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DNA cistron to detect allopolyploidy when concerted evolution of this region is not complete. Additionally, with a robust chloroplast phylogeny in place, the direction of hybridization events can be established, and multiple, independent origins of allopolyploid species can be identified. -
Summary Euonymus alatus diacylglycerol acetyltransferase (Ea DA cT) catalyzes the transfer of an acetyl group from acetyl‐CoA to thesn ‐3 position of diacylglycerol to form 3‐acetyl‐1,2‐diacyl‐sn ‐glycerol (acetyl‐TAG ).Ea DA cT belongs to a small, plant‐specific subfamily of the membrane bound O‐acyltransferases (MBOAT ) that acylate different lipid substrates. Sucrose gradient density centrifugation revealed thatEa DA cT colocalizes to the same fractions as an endoplasmic reticulum (ER )‐specific marker. By mapping the membrane topology ofEa DA cT, we obtained an experimentally determined topology model for a plantMBOAT . TheEa DA cT model contains four transmembrane domains (TMD s), with both the N‐ and C‐termini orientated toward the lumen of theER . In addition, there is a large cytoplasmic loop between the first and secondTMD s, with theMBOAT signature region of the protein embedded in the thirdTMD close to the interface between the membrane and the cytoplasm. During topology mapping, we discovered two cysteine residues (C187 and C293) located on opposite sides of the membrane that are important for enzyme activity. In order to identify additional amino acid residues important for acetyltransferase activity, we isolated and characterized acetyltransferases from other acetyl‐TAG ‐producing plants. Among them, the acetyltransferase fromEuonymus fortunei possessed the highest activityin vivo andin vitro . Mutagenesis of conserved amino acids revealed that S253, H257, D258 and V263 are essential forEa DA cT activity. Alteration of residues unique to the acetyltransferases did not alter the unique acyl donor specificity ofEa DA cT, suggesting that multiple amino acids are important for substrate recognition. -
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