scholarly journals Tannic cell walls form a continuous apoplastic barrier sustaining Arabidopsis seed coat biophysical properties

2020 ◽  
Author(s):  
Lara Demonsais ◽  
Anne Utz-Pugin ◽  
Sylvain Loubéry ◽  
Luis Lopez-Molina
Keyword(s):  
Seed Coat ◽  
Cell Walls ◽  
Seed Viability ◽  
Mechanical Damage ◽  
Building Blocks ◽  
Land Plant ◽  
Plant Evolution ◽  
Arabidopsis Seed ◽  
Flavonoid Synthesis ◽  
Physiological Properties

ABSTRACTSeeds are a late land plant evolution innovation that promoted the striking spread and diversity of angiosperms. The seed coat is a specialized dead tissue protecting the plant embryo from mechanical damage. In many species, including Arabidopsis thaliana, the seed coat also achieves a remarkable balancing act: it limits oxygen uptake, avoiding premature embryo oxidative damage, but not entirely so as to enable seed dormancy release. The seed coat biophysical features implementing the striking physiological properties of the seed remain poorly understood. Tannins, a type of flavonoids, are antioxidants known to accumulate in the Arabidopsis seed coat and transparent testa (tt) mutant seeds, deficient in flavonoid synthesis, exhibit low dormancy and viability. However, their precise contribution to seed coat architecture and biophysics remains evasive. A seed coat cuticle, covering the endosperm outer surface was, intriguingly, previously shown to be more permeable in tt mutants deficient not in cuticular component synthesis, but rather in flavonoid synthesis. Investigating the role of flavonoids in cuticle permeability led us to identify cell walls, originating from the seed coat inner integument 1 cells, impregnated with tannins. We found that tannic cell walls are tightly associated with the cuticle, forming two fused layers that regulate endosperm permeability. In addition, we show that tannic cell walls are prominent building blocks of the seed coat, constituting a continuous barrier around the seed living tissues. Altogether our findings reveal the existence of tannic cell walls as a previously unrecognized biological barrier sustaining the seed’s key physiological properties.One sentence summaryThe seed coat is largely composed of plant cell walls impregnated with tannins, forming a thick and continuous protective barrier surrounding the embryo promoting seed viability and dormancy.

scholarly journals The catalytic core of DEMETER guides active DNA demethylation in Arabidopsis

2019 ◽  
Vol 116 (35) ◽  
pp. 17563-17571 ◽  
Author(s):  
Changqing Zhang ◽  
Yu-Hung Hung ◽  
Hyun Jung Rim ◽  
Dapeng Zhang ◽  
Jennifer M. Frost ◽  
...  
Keyword(s):  
Domain Architecture ◽  
Seed Viability ◽  
Land Plant ◽  
Dna Demethylation ◽  
Plant Evolution ◽  
Dna Glycosylase ◽  
Catalytic Core ◽  
Active Dna Demethylation ◽  
N Terminus

The Arabidopsis DEMETER (DME) DNA glycosylase demethylates the maternal genome in the central cell prior to fertilization and is essential for seed viability. DME preferentially targets small transposons that flank coding genes, influencing their expression and initiating plant gene imprinting. DME also targets intergenic and heterochromatic regions, but how it is recruited to these differing chromatin landscapes is unknown. The C-terminal half of DME consists of 3 conserved regions required for catalysis in vitro. We show that this catalytic core guides active demethylation at endogenous targets, rescuing dme developmental and genomic hypermethylation phenotypes. However, without the N terminus, heterochromatin demethylation is significantly impeded, and abundant CG-methylated genic sequences are ectopically demethylated. Comparative analysis revealed that the conserved DME N-terminal domains are present only in flowering plants, whereas the domain architecture of DME-like proteins in nonvascular plants mainly resembles the catalytic core, suggesting that it might represent the ancestral form of the 5mC DNA glycosylase found in plant lineages. We propose a bipartite model for DME protein action and suggest that the DME N terminus was acquired late during land plant evolution to improve specificity and facilitate demethylation at heterochromatin targets.

scholarly journals Mechanical damage caused by the use of grain carts for transport during soybean seed harvest

2018 ◽  
Vol 40 (4) ◽  
pp. 422-427
Author(s):  
Rodrigo Albaneze ◽  
Francisco Amaral Villela ◽  
Jean Carlo Possenti ◽  
Karina Guollo ◽  
Ivan Carlos Riedo
Keyword(s):  
Moisture Content ◽  
Seed Production ◽  
Seed Coat ◽  
Seed Viability ◽  
Mechanical Damage ◽  
Soybean Seed ◽  
Soybean Seeds ◽  
High Quality ◽  
Moisture Contents ◽  
Seed Harvest

Abstract: Mechanical damage constitutes one of the factors limiting production of high quality soybean seeds. The aim of this study was to evaluate the effects on seed viability and mechanical damage caused to soybean seeds when using a grain cart, together with an auger unloading system, as a means of transporting grain from the combine to the truck. Seed samples were collected in two seed production fields in the region of Abelardo Luz, SC, Brazil, at three different times (10:00, 12:30, and 16:00) and from three places (in the combine grain tank, in the grain wagon, and in the truck). The percentages of broken seeds, moisture content, mechanical damage to the seed coat, and germination were evaluated. The use of auxiliary grain cart equipment contributed to an increase in breakage and mechanical injury in seeds, worsening seed viability. Seeds collected at lower moisture contents had higher breakage and higher rates of mechanical damage.

scholarly journals Identification of tannic cell walls at the outer surface of the endosperm upon Arabidopsis seed coat rupture

2020 ◽  
Vol 104 (3) ◽  
pp. 567-580 ◽  
Author(s):  
Lara Demonsais ◽  
Anne Utz‐Pugin ◽  
Sylvain Loubéry ◽  
Luis Lopez‐Molina
Keyword(s):  
Seed Coat ◽  
Outer Surface ◽  
Cell Walls ◽  
Arabidopsis Seed

scholarly journals Starting to Gel: How Arabidopsis Seed Coat Epidermal Cells Produce Specialized Secondary Cell Walls

2015 ◽  
Vol 16 (2) ◽  
pp. 3452-3473 ◽  
Author(s):  
Cătălin Voiniciuc ◽  
Bo Yang ◽  
Maximilian Schmidt ◽  
Markus Günl ◽  
Björn Usadel
Keyword(s):  
Seed Coat ◽  
Cell Walls ◽  
Epidermal Cells ◽  
Arabidopsis Seed ◽  
Secondary Cell Walls

KNAT7 regulates xylan biosynthesis in Arabidopsis seed-coat mucilage

2020 ◽  
Vol 71 (14) ◽  
pp. 4125-4139
Author(s):  
Yiping Wang ◽  
Yan Xu ◽  
Shengqiang Pei ◽  
Mingmin Lu ◽  
Yingzhen Kong ◽  
...  
Keyword(s):  
Plant Cell ◽  
Seed Coat ◽  
Cell Walls ◽  
Wall Structure ◽  
Plant Cell Walls ◽  
Arabidopsis Seed ◽  
Ideal System ◽  
Xylan Biosynthesis ◽  
Seed Coat Mucilage ◽  
Seed Mucilage

Abstract As a major hemicellulose component of plant cell walls, xylans play a determining role in maintaining the wall structure. However, the mechanisms of transcriptional regulation of xylan biosynthesis remain largely unknown. Arabidopsis seed mucilage represents an ideal system for studying polysaccharide biosynthesis and modifications of plant cell walls. Here, we identify KNOTTED ARABIDOPSIS THALIANA 7 (KNAT7) as a positive transcriptional regulator of xylan biosynthesis in seed mucilage. The xylan content was significantly reduced in the mucilage of the knat7-3 mutant and this was accompanied by significantly reduced expression of the xylan biosynthesis-related genes IRREGULAR XYLEM 14 (IRX14) and MUCILAGE MODIFIED 5/MUCILAGE-RELATED 21 (MUM5/MUCI21). Electrophoretic mobility shift assays, yeast one-hybrid assays, and chromatin immunoprecipitation with quantitative PCR verified the direct binding of KNAT7 to the KNOTTED1 (KN1) binding site [KBS,TGACAG(G/C)T] in the promoters of IRX7, IRX14, and MUM5/MUCI21 in vitro, in vivo, and in planta. Furthermore, KNAT7 directly activated the expression of IRX14 and MUM5/MUCI21 in transactivation assays in mesophyll protoplasts, and overexpression of IRX14 or MUM5/MUCI21 in knat7-3 partially rescued the defects in mucilage adherence. Taken together, our results indicate that KNAT7 positively regulates xylan biosynthesis in seed-coat mucilage via direct activation of the expression of IRX14 and MUM5/MUCI21.

scholarly journals The Catalytic Core of DEMETER Guides Active DNA Demethylation in Arabidopsis

2019 ◽  
Author(s):  
Changqing Zhang ◽  
Yu-Hung Hung ◽  
Xiang-Qian Zhang ◽  
Dapeng Zhang ◽  
Jennifer M. Frost ◽  
...  
Keyword(s):  
Domain Architecture ◽  
Seed Viability ◽  
Land Plant ◽  
Dna Demethylation ◽  
Plant Evolution ◽  
Dna Glycosylase ◽  
Catalytic Core ◽  
Active Dna Demethylation ◽  
N Terminus

AbstractThe Arabidopsis DEMETER (DME) DNA glycosylase demethylates the maternal genome in the central cell prior to fertilization, and is essential for seed viability. DME preferentially targets small transposons that flank coding genes, influencing their expression and initiating plant gene imprinting. DME also targets intergenic and heterochromatic regions, and how it is recruited to these differing chromatin landscapes is unknown. The C-terminal DME catalytic core consists of three conserved regions required for catalysis in vitro. We show that the catalytic core of DME guides active demethylation at endogenous targets, rescuing the developmental and genomic hypermethylation phenotypes of DME mutants. However, without the N-terminus, heterochromatin demethylation is significantly impeded, and abundant CG-methylated genic sequences are ectopically demethylated. We used comparative analysis to reveal that the conserved DME N-terminal domains are only present in the flowering plants, whereas the domain architecture of DME-like proteins in non-vascular plants mainly resembles the catalytic core, suggesting that it might represent the ancestral form of the 5mC DNA glycosylase found in all plant lineages. We propose a bipartite model for DME protein action and suggest that the DME N-terminus was acquired late during land plant evolution to improve specificity and facilitate demethylation at heterochromatin targets.

Morphological peculiarities of seeds of some species of the genus Epipactis Zinn. (Orchidaceae Juss.) of Ukrainian flora

2019 ◽  
Vol 11 (1) ◽  
pp. 93-100
Author(s):  
T Ljubka ◽  
O Tsarenko ◽  
I Tymchenko
Keyword(s):  
Seed Coat ◽  
Cell Walls ◽  
Morphological Study ◽  
Population Level ◽  
Intercellular Spaces ◽  
Different Populations ◽  
Periclinal Walls ◽  
High Degree ◽  
Shape And Size ◽  
Generative Organs

The investigation of macro- and micromorphological peculiarities of seeds of four species of genus Epipactis (Orchidaceae) of Ukrainian flora were carried out. The genus Epipactis is difficult in the in in taxonomic terms and for its representatives are characterized by polymorphism of morphological features of vegetative and generative organs of plants and ability of species to hybridize. The aim of the research was to perform a comparative morphological study of seeds of E. helleborine, E. albensis, E. palustris, E. purpurata and to determine carpological features that could more accurately identify species at the stage of fruiting. A high degree of variation in the shape of the seeds in different populations within the species and overlap of most quantitative carpological characteristics of studied species are noted. There were no significant differences in micromorphological features of the structure of the testa at species or population level. The reticulate surface of the testa is characteristic of all species, the cells of testa are mostly elongated, penta-hexagonal, individual cells almost isodiametric-pentagonal. From the micropillary to the chalasal end, a noticeable change in the shape and size of the seed coat cells is not observed. There are no intercellular spaces, the anticlinal walls of adjacent cells are intergrown and the boundaries between them become invisible. The outer periclinal walls have a single, mainly longitudinal thin ribbed thickenings. Anticlinal cell walls are thick, dense, smooth. The longitudinal Anticlinal walls are almost straight, transverse - straight or sometimes curved in some cells. Epicuticular deposits on the periclinal walls are absent. It is concluded that the use of macro and micromorphological characteristics of seeds of these species for clearer diagnosis at the stage of fruiting is low informative.

scholarly journals From tree to architecture: how functional morphology of arborescence connects plant biology, evolution and physics

2021 ◽  
Author(s):  
Anita Roth-Nebelsick ◽  
Tatiana Miranda ◽  
Martin Ebner ◽  
Wilfried Konrad ◽  
Christopher Traiser
Keyword(s):  
Land Plant ◽  
Plant Evolution ◽  
Ecological Niches ◽  
Long Distance ◽  
Ongoing Research ◽  
Long Distance Transport ◽  
Theoretical Approaches ◽  
Trade Offs ◽  
Interfacial Physics ◽  
Plant Water Transport

AbstractTrees are the fundamental element of forest ecosystems, made possible by their mechanical qualities and their highly sophisticated conductive tissues. The evolution of trees, and thereby the evolution of forests, were ecologically transformative and affected climate and biogeochemical cycles fundamentally. Trees also offer a substantial amount of ecological niches for other organisms, such as epiphytes, creating a vast amount of habitats. During land plant evolution, a variety of different tree constructions evolved and their constructional principles are a subject of ongoing research. Understanding the “natural construction” of trees benefits strongly from methods and approaches from physics and engineering. Plant water transport is a good example for the ongoing demand for interdisciplinary efforts to unravel form-function relationships on vastly differing scales. Identification of the unique mechanism of water long-distance transport requires a solid basis of interfacial physics and thermodynamics. Studying tree functions by using theoretical approaches is, however, not a one-sided affair: The complex interrelationships between traits, functionality, trade-offs and phylogeny inspire engineers, physicists and architects until today.

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