Structural aspects and trends in the evolution of recalcitrant seeds in dicotyledons

1994 ◽  
Vol 4 (2) ◽  
pp. 225-239 ◽  
Author(s):  
I. von Teichman ◽  
A. E. van Wyk
Keyword(s):  
Seed Viability ◽  
Endosperm Development ◽  
Functional Adaptation ◽  
Evolutionary Status ◽  
Character State ◽  
Recalcitrant Seeds ◽  
Recalcitrant Seed ◽  
Ancestral Character State ◽  
Storage Reserve ◽  
Orthodox Seeds

AbstractThis review focuses on the possible evolutionary status and functional significance of recalcitrance and certain associated ovule/seed characters, within the framework of modern systems of angiosperm classification. The presence of recalcitrant seed viability in 45 dicotyledonous families is significantly associated with bitegmic and crassinucellate ovules and with nuclear endosperm development, all considered ancestral (plesiomorphic) character states of the ovule; as well as with greater seed size, woody habit and tropical habitat, also regarded as ancestral character states in the dicotyledons. In many species with recalcitrant seeds, the predominant storage reserve is carbohydrate. Recalcitrance is significantly associated with the exalbuminous type of reserve storage. It is proposed that in large recalcitrant seeds, the transfer of the main storage function from endosperm to embryo was probably an early development. In many species with recalcitrance, the ovules/seeds are characterized by extensive vascularization of the integument(s)/seed coat or by a pachychalaza. Pachychalazy is proposed to be a significant functional adaptation for a more efficient transfer of nutrients to the embryo/seed. Recalcitrance and some of the other character states proposed to be plesiomorphic in dicotyledons are also present in some gymnosperms, including presumed sister groups of the dicotyledons. In relatively advanced dicotyledonous families, mostly with orthodox seeds, recalcitrance probably persisted only in isolated relict members. Determination of character polarity is particularly problematic at lower taxonomic levels, because there is always the possibility that, in some taxa, a character state such as recalcitrance may have arisen secondarily as a reversal. Available evidence supports our view that seed recalcitrance can be regarded as a relatively ancestral character state in dicotyledons.

scholarly journals A new approach towards the so-called recalcitrant seeds

2018 ◽  
Vol 40 (3) ◽  
pp. 221-236 ◽  
Author(s):  
Claudio José Barbedo
Keyword(s):  
Plant Conservation ◽  
Point Of View ◽  
Recalcitrant Seeds ◽  
New Approach ◽  
Recalcitrant Seed ◽  
Seed Conservation ◽  
Conservation Technology ◽  
Orthodox Seeds ◽  
Standard Life ◽  
Life Behavior

ABSTRACT: Water is essential, irreplaceable, and indispensable for any kind of carbon-based-life metabolic activity. Water-dependent living beings are the expected pattern in nature. However, some organisms can survive for some time at a minimum water content, such as seeds of some species (orthodox seeds). Nevertheless, the expected standard life behavior is found in seeds of another group of species, the so-called recalcitrant seeds, which are sensitive to desiccation. A huge range of different behaviors can be found between these two groups, leading authors to consider that orthodoxy and recalcitrance is not an all-or-nothing situation. Notwithstanding, we are still too far from understanding the differences and similarities between all these kinds of seeds and this has been a serious barrier to the development of plant conservation technologies. A new approach to understanding the differences between these seeds is presented here based on seed maturation, environmental influences, and evolution. From this point of view, all kinds of seed behavior are contemplated and, consequently, some new perspectives are considered for the recalcitrant seed conservation technology, the most intensely desired technology nowadays in this area.

Seed development in relation to desiccation tolerance: A comparison between desiccation-sensitive (recalcitrant) seeds of Avicennia marina and desiccation-tolerant types

1993 ◽  
Vol 3 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Jill M. Farrant ◽  
N. W. Pammenter ◽  
Patricia Berjak
Keyword(s):  
Seed Development ◽  
Seedling Establishment ◽  
Soluble Sugars ◽  
Avicennia Marina ◽  
Sensu Stricto ◽  
Starch Accumulation ◽  
Recalcitrant Seeds ◽  
Recalcitrant Seed ◽  
Orthodox Seeds

AbstractDevelopment of the highly desiccation-sensitive (recalcitrant) seeds of primarily one species, Avicennia marina, is reviewed and compared with the ontogeny of desiccation-tolerant (orthodox) seeds. A. marina seeds undergo no maturation drying and remain metabolically active throughout development, which grades almost imperceptibly into germination. While PGR control of histodifferentiation is essentially similar to that characterizing desiccation-tolerant seeds, the phase of growth and reserve deposition is characterized by exceedingly high cytokinin levels which, it is proposed, promote a sink for assimilate import. While some starch accumulation does occur, the predominant reserves are soluble sugars which are readily available for the immediate onset of seedling establishment upon shedding. ABA levels are negligible in the embryo tissues during seed maturation, but increase in the pericarp, which imposes a constraint upon germination until these outer coverings are sloughed or otherwise removed. The pattern of proteins synthesized remains qualitatively similar throughout seed development in A. marina, and no LEA proteins are produced. This suggests both that seedling establishment is independent of maturation proteins and that the absence of LEAs and desiccation sensitivity might be causally related. The study on A. marina reveals that for this recalcitrant seed-type, germination per se cannot be defined: rather, it is considered as the continuation of development temporarily constrained by the pericarp ABA levels. This leads to a reexamination of the role of rehydration as key event sensu stricto, in the germination processes in desiccation-tolerant (orthodox) seeds.

scholarly journals Differential Influx of Natural Plant Growth Regulators during Embryogeny in the Recalcitrant Seeds of Syzygium cumini (L) Skeels

2022 ◽  
Author(s):  
Parvathy S. Nair ◽  
K.G. Ajith Kumar ◽  
G.P. Gayatri ◽  
Ajayakumar .
Keyword(s):  
Plant Growth ◽  
Plant Growth Regulators ◽  
Growth Regulators ◽  
Defense Mechanism ◽  
Syzygium Cumini ◽  
Recalcitrant Seeds ◽  
Recalcitrant Seed ◽  
Embryonic Tissues ◽  
Orthodox Seeds ◽  
High Level

Background: The hormonal up-regulation and down-regulation in recalcitrant seeds, on the other hand, has received little research. We tested fou plant growth regulators from distinct families of phytohormones at the same time to better understand their differential input from maternal tissues to growing Syzygium cumini seeds. Methods: During April-June 2020, seeds were collected in their native habitats in the Western Ghats. Seeds were chosen at random from each treatment. The embryonic tissues of seeds were chopped up and frozen for LC-MS/MS hormonal profiling. Result: Except for ABA, the dynamics of key plant hormones in this recalcitrant seed were identical to that of desiccation-tolerant orthodox seeds. When compared to other conventional seeds, SA was shown to accumulate at an unusually high level in mature embryonic tissues, demonstrating the highly hydrated seed’s defense mechanism against fungal attack following seed shedding.

Evolutionary and ecological aspects of recalcitrant seed biology

2000 ◽  
Vol 10 (3) ◽  
pp. 301-306 ◽  
Author(s):  
N.W. Pammenter ◽  
Patricia Berjak
Keyword(s):  
Soil Seed Bank ◽  
Evolutionary Status ◽  
Recalcitrant Seeds ◽  
Recalcitrant Seed ◽  
Seed Biology ◽  
Seedling Bank ◽  
Short Life Span ◽  
Ecological Aspects ◽  
Wide Range ◽  
Regeneration Ecology

AbstractThere is a substantial literature on the basic physiology and response to desiccation of recalcitrant seeds, but little is known about their ecology and even less of their evolutionary status. It is difficult to assess the response of early land plants to dehydration, but it is likely that desiccation tolerance in vegetative tissue arose concomitantly with the invasion of the land. Similarly, from the fossil record it is not possible to assess the desiccation response of early seeds, and furthermore, it is difficult to see phylogenetic relationships among species producing recalcitrant seeds. A consideration of the available evidence, however, suggests that the first seeds were desiccation-sensitive, but tolerance evolved early and probably a number of times, independently. The desiccation sensitivity and short life span (generally shorter than the interval between flowering) of recalcitrant seeds have implications in terms of regeneration ecology. A long-term soil seed bank as such does not exist; rather the seeds germinate and form a seedling bank. However, there is a wide range in post-shedding physiology among recalcitrant seed species, and although species producing recalcitrant seeds are common in the humid tropics, they do occur in habitats with more marked seasonal variation. Here regeneration strategies may be more specialized.

scholarly journals GA/ABA Antagonism in the Physiology of Seed Germination in the Recalcitrant and Vulnerable Tree- Vateria indica L.

2021 ◽  
Author(s):  
G.P. Gayatri ◽  
K.G. Ajith Kumar ◽  
Parvathy S. Nair ◽  
M. Somasekharan Pillai
Keyword(s):  
Seed Germination ◽  
Recalcitrant Seeds ◽  
Tropical Plants ◽  
Recalcitrant Seed ◽  
Retarding Effect ◽  
Western Ghats Of India ◽  
Orthodox Seeds ◽  
Almost All ◽  
Germination And Growth ◽  
Working Out

Background: Seed recalcitrance is a major problem associated with many tropical plants, limiting their natural regeneration. Vateria indica L. is a vulnerable and endemic tree species in South-Western Ghats of India, which is also recalcitrant. ABA and gibberellins are the most important plant hormones required for seed germination. It is the balance between ABA and GA which is responsible for desiccation tolerance in orthodox seeds. Exogenous hormones pretreatment has been also reported to influence seed germination. But such studies had been sparsely done in the case of recalcitrant seeds. This study aims to find out whether GA/ABA antagonism in recalcitrant plants is operating in the same way, like that in the orthodox seeds.Methods: The effect of the exogenous pre-soaking application of phytohormones viz. GA3 and ABA individually as well as their combinations on seed germination and growth of Vateria indica L. were carried out in the present work. The seeds were collected from April to July 2018 and the experiment was designed at Post Graduate and Research Department of Botany, Government College for Women, Thiruvananthapuram. When different concentrations of each phytohormone were externally given to the seeds, ABA reduced the germination and growth in almost all the concentrations. But GA3 gave better results. When combinations of GA3 and ABA were used, germination was poor in the sample where ABA was more than GA3, But in samples with same concentrations of both the hormones and with more GA3 gave better results. Result: This study clearly showed that GA3 when given externally along with ABA, might have affected the endogenous ABA in this recalcitrant seed and suppressed its retarding effect. Thus ABA/GA antagonism is working out, here, in the same way as in orthodox seeds. Since the germination of recalcitrant seeds is a less investigated area, the present study will form a basis and a lot more for further such studies.

Mitotic Activity Dynamics in Recalcitrant Seeds Acer sachharinum during Maturation and Germination

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 479c-479
Author(s):  
L. Kozeko ◽  
V. Troyan ◽  
L. Musatenko
Keyword(s):  
Cell Division ◽  
Mitotic Activity ◽  
Quiescent State ◽  
Activity Levels ◽  
Recalcitrant Seeds ◽  
Mature Embryos ◽  
Before And After ◽  
Orthodox Seeds ◽  
Mature Seeds ◽  
Activity Dynamics

In orthodox seeds the cell division within the embryo meristems arrests during maturation at embryo moisture content (MC) 65% to 47%, and the maturation completion and transition of seeds to quiescent state occurs at MC about 10%. The arrest of cycling happens asynchronously in different meristematic tissues during desiccation: first in shoot and then in root. The aim of this work was to define a mitotic activity dynamics in recalcitrant seeds with the high MC at maturation end and the absence of quiescent state characteristic of it. The object was seeds of Acer saccharinum, using widely for planting of greenery in Kiev city. The mitotic activity was determined in 0.5 mm of the embryo root pole (RP) and 0.5 mm of the shoot pole with embryo leaves (SP). The A. sachharinum seeds completed them maturation at MC 53% (FW basis). During maturation the mitotic index (MI) in RP decreased from 3.2% in immature seeds (at embryos MC 80%) to 0 in mature seeds and in SP–from 5.4% to 3.3%, respectively. Cell division in SP arrested by dehydration of mature embryos to MC 46% by PEG 6000 (30%). The seeds lost viability by desiccation to MC 34%. The mature seeds were able to germinate immediately after abscission. During seed germination the cell division reactived in RP and increased in SP already before root protrusion. In plantlets 10–15 mm long the MI increased to 8% in RP and 12% in SP. Thus, the strategy of immediate germination of recalcitrant A. sachharinum seeds includes a preservation of cell division in SP of mature embryos, in contrast with orthodox seeds, and high mitotic activity levels in meristems of germinating embryos before and after root protrusion.

scholarly journals Desiccation Tolerance as the Basis of Long-Term Seed Viability

2020 ◽  
Vol 22 (1) ◽  
pp. 101
Author(s):  
Galina Smolikova ◽  
Tatiana Leonova ◽  
Natalia Vashurina ◽  
Andrej Frolov ◽  
Sergei Medvedev
Keyword(s):  
Desiccation Tolerance ◽  
Vascular Plants ◽  
Molecular Mechanisms ◽  
Regulation Of Gene Expression ◽  
Seed Viability ◽  
Late Embryogenesis Abundant ◽  
Maturation Stage ◽  
Terrestrial Plants ◽  
Complex Anatomy ◽  
Orthodox Seeds

Desiccation tolerance appeared as the key adaptation feature of photoautotrophic organisms for survival in terrestrial habitats. During the further evolution, vascular plants developed complex anatomy structures and molecular mechanisms to maintain the hydrated state of cell environment and sustain dehydration. However, the role of the genes encoding the mechanisms behind this adaptive feature of terrestrial plants changed with their evolution. Thus, in higher vascular plants it is restricted to protection of spores, seeds and pollen from dehydration, whereas the mature vegetative stages became sensitive to desiccation. During maturation, orthodox seeds lose up to 95% of water and successfully enter dormancy. This feature allows seeds maintaining their viability even under strongly fluctuating environmental conditions. The mechanisms behind the desiccation tolerance are activated at the late seed maturation stage and are associated with the accumulation of late embryogenesis abundant (LEA) proteins, small heat shock proteins (sHSP), non-reducing oligosaccharides, and antioxidants of different chemical nature. The main regulators of maturation and desiccation tolerance are abscisic acid and protein DOG1, which control the network of transcription factors, represented by LEC1, LEC2, FUS3, ABI3, ABI5, AGL67, PLATZ1, PLATZ2. This network is complemented by epigenetic regulation of gene expression via methylation of DNA, post-translational modifications of histones and chromatin remodeling. These fine regulatory mechanisms allow orthodox seeds maintaining desiccation tolerance during the whole period of germination up to the stage of radicle protrusion. This time point, in which seeds lose desiccation tolerance, is critical for the whole process of seed development.

scholarly journals Exploring and Reconstructing Ancestral Anatomies using Ontology-Informed Approaches

2019 ◽  
Vol 3 ◽  
Author(s):  
Sergei Tarasov ◽  
Istvan Miko ◽  
Matthew Yoder ◽  
Josef Uyeda
Keyword(s):  
Phylogenetic Trees ◽  
Character State ◽  
Ancestral Reconstruction ◽  
Anatomy Ontology ◽  
Insect Order ◽  
Ancestral Character State ◽  
Body Regions ◽  
Individual Traits ◽  
History Of ◽  
Complex Characters

Ancestral character state reconstruction has been long used to gain insight into the evolution of individual traits in organisms. However, organismal anatomies (= entire phenotypes) are not merely ensembles of individual traits, rather they are complex systems where traits interact with each other due to anatomical dependencies (when one trait depends on the presence of another trait) and developmental constraints. Comparative phylogenetics has been largely lacking a method for reconstructing the evolution of entire organismal anatomies or organismal body regions. Herein, we present a new approach named PARAMO (Phylogenetic Ancestral Reconstruction of Anatomy by Mapping Ontologies, Tarasov and Uyeda 2019) that takes into account anatomical dependencies and uses stochastic maps (i.e., phylogenetic trees with an instance of mapped evolutionary history of characters, Huelsenbeck et al. 2003) along with anatomy ontologies to reconstruct organismal anatomies. Our approach treats the entire phenotype or its component body regions as single complex characters and allows exploring and comparing phenotypic evolution at different levels of anatomical hierarchy. These complex characters are constructed by ontology-informed amalgamation of elementary characters (i.e., those coded in character matrix) using stochastic maps. In our approach, characters are linked with the terms from an anatomy ontology, which allows viewing them not just as an ensemble of character state tokens but as entities that have their own biological meaning provided by the ontology. This ontology-informed framework provides new opportunities for tracking phenotypic radiations and anatomical evolution of organisms, which we explore using a large dataset for the insect order Hymenoptera (sawflies, wasps, ants and bees).

A review of recalcitrant seed physiology in relation to desiccation-tolerance mechanisms

1999 ◽  
Vol 9 (1) ◽  
pp. 13-37 ◽  
Author(s):  
N. W. Pammenter ◽  
Patricia Berjak
Keyword(s):  
Desiccation Tolerance ◽  
Mechanical Damage ◽  
Antioxidant Systems ◽  
Intermediate Water ◽  
Variable Response ◽  
Embryonic Axes ◽  
Efficient Operation ◽  
Recalcitrant Seed ◽  
Orthodox Seeds ◽  
Water Contents

AbstractA suite of mechanisms or processes that together have been implicated in the acquisition and maintenance of desiccation tolerance in orthodox seeds is discussed in the context of the behaviour of desiccation-sensitive seeds, and where appropriate, parallels are drawn with the situation in vegetative plant tissues that tolerate dehydration. Factors included are: physical characteristics of cells and intracellular constituents; insoluble reserve accumulation; intracellular de-differentiation; metabolic ‘switching off’; presence, and efficient operation, of antioxidant systems; accumulation of putatively protective substances including LEAs, sucrose and other oligosaccharides, as well as amphipathic molecules; the presence and role of oleosins; and the presence and operation of repair systems during rehydration. The variable response to dehydration shown by desiccation-sensitive seeds is considered in terms of the absence or incomplete expression of this suite of mechanisms or processes.Three categories of damage are envisaged: (i) reduction in cell volume which can lead to mechanical damage; (ii) aqueous-based degradative processes, probably consequent upon deranged metabolism at intermediate water contents. This is termed ‘metabolism-induced damage’ and its extent will depend upon the metabolic rate and the rate of dehydration; and (iii) the removal of water intimately associated with macromolecular surfaces leading to denaturation: this is referred to as desiccation damagesensu stricto. The effects of drying rate and the maturity status of seeds are considered in relation to the responses to dehydration, leading to the conclusion that the concept of critical water contents on a species basis is inappropriate. Viewing seed postharvest physiology in terms of a continuum of behaviour is considered to be more realistic than attempting precise categorization.Rapid dehydration of excised embryonic axes (or other explants) from desiccation-sensitive seeds permits retention of viability (in the short term) to water contents approaching the level of non-freezable water. This opens up the possibility of long-term conservation, by cryopreservation techniques, of the genetic resources of species producing non-orthodox seeds.

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