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4. Drawings of some stages of seed development in Adesmia bicolor. . A mature embryo sac showing the egg apparatus (ea), polar nuclei (pn) and the aligned antipodals (an). . The zygote (z) is implanted over the synergid remnants (sy). The primary endosperm nucleus (en) is also observed. . The micropylar half of a developing seed showing an advanced proembryo (pe), the former ovular outer integument (oi), the micropyle (m), the remaining ventral nucellar projection (nu) and the nucellar endothelial epidermis (ed). The nuclear endosperm (ne) develops a free-nuclear micropylar haustorium (mh) which contacts some protrusive cells of the carpellary wall (cw). . Longitudinal section of mature seed. The inflexed embryo shows a cotyledon (ct), two of the three cotyledonary central veins (cv), a marginal one (v), the radicle (ra) and the rudimentary gemule (gm). The testa with an epidermal palisade layer of macrosclereids (pms) and hypodermal hourglass cells (hg), the tegumentary parenchyma (pa), scarce remnants of the cellular endosperm (ce), tracheid bar (tb), vascular bundle (vb), lens (le), astrosclereids (as) and funicle (fu) can be seen. Scale bars: Figs 1, 2, 20 µm; , 50 µm; , 200 µm.
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Seed ontogeny of Adesmia bicolor and Adesmia latifolia was analysed using light microscopy and standard histological techniques. Fertilization was porogamic. Linear proembryonal tetrads were observed in A. bicolor. The robust elongated suspensors possessed specialized basal cells. The nucellar epidermis became endothelial. The free-nuclear endosper...
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... robust, long and differentiated suspensor, sharply distinct from the globular embryo proper, was Fig. 2. The zygote (z) is implanted over the synergid remnants (sy). The primary endosperm nucleus (en) is also observed. Fig. 3. The micropylar half of a developing seed showing an advanced proembryo (pe), the former ovular outer integument (oi), the micropyle (m), the remaining ventral nucellar projection (nu) and the nucellar endothelial epidermis (ed). The nuclear endosperm (ne) develops a free-nuclear micropylar haus- torium (mh) which contacts some protrusive cells of the carpellary wall (cw). Fig. 4. Longitudinal section of mature seed. The inflexed embryo shows a cotyledon (ct), two of the three cotyledonary central veins (cv), a marginal one (v), the radicle (ra) and the rudimentary gemule (gm). The testa with an epidermal palisade layer of macrosclereids (pms) and hypodermal hourglass cells (hg), the tegumen- tary parenchyma (pa), scarce remnants of the cellular endosperm (ce), tracheid bar (tb), vascular bundle (vb), lens (le), astrosclereids (as) and funicle (fu) can be seen. in A. bicolor (Figs 17, 18, 24) and A. latifolia. The hyaline vacuolated suspensorial cells ( Figs 7, 13) were moderately larger than the embryonal cells ( Figs 7, 13, 17, 18). The basal suspensor cells were specialized in both species. However, although two terminal falcate cells were present in A. bicolor (Fig. 13), similar to A. securigerifolia (Izaguirre et al., 1994), one or two terminally elongated cells were observed in A. latifolia (Figs 7, 9). Such suspensors persist until late embryogeny ( Figs 16, 27, 28) and disintegrate during the growth of the hypocotyl and radicle. Suspensors show great variation in Papilion- oideae (Prakash, 1987). Some non-correlative ten- dency of derived papilionoid herbaceous groups to more elaborated suspensors has been reported by Lersten (1983). In Adesmia, they have a significant similarity to the suspensors of Sophora flavescens Ait. (Sophoreae) and many Phaseoleae (Lersten, 1983), such as Vigna catjang Walp. (Anantaswamy Rau, 1951a), Phaseolus trilobus Ait. (Anantaswamy Rau, 1953) and Phaseolus multiflorus Willd. (Lersten, 1983). However, only filamentous suspensors are present in Phaseolus aconitifolius Jacq. (Deshpande & Bhasin, 1974), revealing interspecific variation of suspensors in Phaseoleae. Hedysarum coronarium L. (Hedysareae) and Melilotus officinalis Lam. (Trifo- lieae Endl.) have suspensors similar to those of Adesmia ( Lersten, 1983). Notable similarities were also found between Adesmia suspensors and elon- gated suspensors with a specialized spheroid basal cell of Stylosanthes montevidensis Vogel and Stylosan- thes leiocarpa Vogel (Aeschynomeneae Benth. & Hook.f.) (Izaguirre, Mérola & Beyhaut, 1998), but only filamentous suspensors appear in Stylosanthes mucronata Willd. (Lersten, 1983). Other members of Aeschynomeneae, such as Arachis and Aeschynomene, have much smaller suspensors. Many other papilion- oid taxa have much more elaborated suspensors, such as the large spheroid suspensors of Cytisus laburnum L. and the evaginated haustorial type of Crotalaria striata DC. (Anantaswamy Rau, 1953;Lersten, ...
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... mature ovules and developing seeds of A. bicolor and A. latifolia, the funicular axis is oriented at 90° to the chalaza-micropyle axis (Fig. 26). The embryo sac is incurved (Fig. 1). A conspicuous ventral nucellar projection is also present (Figs 3, 24, 26). Thus, the seed derives from an ana-campylotropous ovule. However, the ovular type has been mentioned as campylotropous in A. securigerifolia (Izaguirre et al., 1994) and as hemianatropous in A. latifolia (Moço, 2002;Moço & Mariath, 2004). The outer integument is more developed than the inner, which disappears just after fertilization, turning the former zig-zag micropyle into a just-curved exostome (Figs 3, 6, 11, 12). The ana-campylotropous ovular type has been reported for Papilionoideae (Kopooshian & Isely, 1966), although ovules are mainly campylotropous in this subfamily (Corner, 1951;Dnyansagar, 1951;Prakash, 1987). Moço (2002) has found many simi- larities in ovular morphology in Adesmieae and Zornia ...
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... the globular embryo stage, an elongated and incurved sac-like nuclear endosperm haustorium ( Figs 24, 26) was observed in A. bicolor and A. lati- folia. It contacted laterally the tegumentary paren- chyma of the funicular side of the seed ( Figs 8, 14, 20, 21, 24, 26), as in A. securigerifolia (Izaguirre et al., 1994). In the literature on endosperm development in Papilionoideae (Anantaswamy Rau, 1951bRau, , 1953Johri & Garg, 1959;Prakash, 1987;Johri et al., 1992;Ashrafunnissa & Pullaiah, 1997), it has been men- Part of the nuclear endosperm (ne) protrudes towards the micropyle and forms a free-nuclear micropylar haustorium (mh), which advances along the exostome towards the carpel wall (cw). The outer ovular integument (oi), endothelial nucellar layer (ed) and lens (le) are also indicated. Fig. 7. The basis of a developed suspensor (su) showing the elongated basal cell (bc). The nucellar endosperm (ne) and nucellar endothelial layer (ed) are also shown, as is the tegumentary parenchyma (pa) with the epidermal palisade layer of macrosclereids (pms). Fig. 8. Detail of the ventral region of a seed during advanced embryo development. The nuclear endosperm haustorium (he) is attached to the tegumentary paren- chyma (pa) and the nucellar endothelial epidermis (ed). The cellular endosperm (ce) with its cellular membrane-like layer (cm) can be seen. Hylar astrosclereids (as) and part of a cotyledon (ct) are also shown. Fig. 9. The funicular zone of an advanced stage of the seed. The funicle (fu) with the counter palisade layer of funicular macrosclereids (fms) is shown. Hylar macrosclereids (hms), tracheid bar (tb), astrosclereids (as), tegumentary parenchyma (pa) and degenerating nucellar endothelial layer (ed) are also indicated, as is the cellular endosperm (ce). Fig. 10. Detail of the seed cover showing the palisade layer of macrosclereids (pms), hourglass layer (hg), tegumentary parenchyma (pa) and the cellular endosperm (ce). Scale bars: Figs 5, 7-9, 50 mm; Figs 6, 10, 25 mm. tioned that nuclear endosperm haustoria reach ter- minally the surrounding tissues in the chalaza region. Only Rothia trifoliata DC. (Anantaswamy Rau, 1951c) shows a lateral haustorium similar to that of Adesmia, whereas, in Indigofera trita L.f. (Anan- taswamy Rau, 1953), it derives from an amphitropous curvature during advanced seed development. Conse- quently, the lateral free-nuclear endosperm hausto- Fig. 11. The micropylar region of a very young seed showing the proembryo (pe) and the free-nuclear endosperm (ne) protruding towards the micropyle (m) and forming the micropylar haustorium (mh). The ovular outer integument (oi) and the carpel wall (cw) with many protrusive cells can also be seen. Fig. 12. Detail of the free-nuclear micropylar haustorium (mh) connected to the carpel wall (cw). The outer ovular integument (oi) and micropyle (m) are also shown. Fig. 13. The basis of a developed suspensor (su) showing the falcate paired basal cells (bc). The nuclear endosperm (ne) and nucellar endothelial layer (ed) are also shown. The tegumentary parenchyma (pa) with an epidermal palisade layer of macrosclereids (pms) and the micropyle (m) are also indicated. Fig. 14. Detail of the ventral region of a seed at an advanced stage. The nuclear endosperm haustorium (he) is attached to the tegumentary parenchyma (pa) and the nucellar endothelial epidermis (ed). The nucellus (nu) is also shown. Fig. 15. The funicular zone of an advanced seed. The funicle (fu) with a differentiating counter palisade layer of funicular macrosclereids (fms) can be seen. Hylar macrosclereids (hms), tracheid bar (tb), astrosclereids (as), tegumentary parenchyma (pa) and chalazal vascular bundle (vb) are also shown. Fig. 16. Detail of the seed coat showing the palisade layer of macrosclereids (pms), hourglass layer (hg), tegumentary parenchyma (pa) and suspensor (su). Scale bars: Figs 11, 13-15, 50 mm; Figs 12, 16, 25 mm. rium of Adesmia is a peculiar case in Papilionoideae. In both investigated Adesmia species, this hausto- rium remains laterally connected to the tegumentary parenchyma until late seed stages. In A. securigeri- folia, it separates from the integument during advanced seed development (Izaguirre et al., ...
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... formation in the endosperm of A. bicolor and A. latifolia commences shortly after the cordiform embryonal stage, from the micropylar region towards the chalaza. Gradually, the micropylar half of the endosperm becomes cellular, forming a peripheral endosperm proper ( Figs 8, 20, 27), whereas the coeno- cytic chalazal half remains laterally haustorial. A slight membrane-like layer of the cellular endosperm (Fig. 8) separates the two endospermic zones. A similar layer has been mentioned as a unique feature in Phaseolus lunatus L. (Sterling, 1955). However, a membrane-like layer has also been illustrated for Trigonella foenum-graecum L. (Trifolieae) by Anan- taswamy Rau (1953). The partial cellularization of the endosperm from the micropyle, associated with a per- sistent free-nuclear chalazal haustorium in Adesmia, has also been described as widespread in various Papilionoideae, such as in most investigated Phaseoleae (Dolichos lablab L., some species of Glycine Willd., Phaseolus L., Rhynchosia Lour., Ter- amnus P.Browne and Vigna Savi), Galegeae Bronn in Dumortier (Alysicarpus Neck. ex Desv., Tephrosia Pers.), Sophoreae (Castanospermum A.Cunn. ex Hook.), Vicieae (Abrus Adans.) and some Aeschynome- neae (Aeschynomene) (Anantaswamy Rau, 1951b, 1953Johri & Garg, 1959;Deshpande & Bhasin, 1974;Johri et al., 1992;Ashrafunnissa & Pullaiah, 1997). In a few cases, no cellular endosperm is formed, for example in Stylosanthes Sw. (Aeschynomeneae) (Dnyansagar, 1951;Izaguirre et al., 1998), whereas endosperm cellularization is almost complete in many other legumes: Dalbergia sissoo Roxb. and Pongamia glabra Vent. (Dalbergiae), many Crotalaria species (Genisteae), Glycine max Merr. (Phaseoleae), Zornia diphylla (L.) Pers. (Aeschynomeneae) and Millettia ovalifolia Kurz. (Galegeae) (Anantaswamy Rau, 1953; bicolor showing the globular embryo (ge) and suspensor (su). The active free-nuclear endosperm (ne) produces a lateral haustorium (he) at the funicular side. The chalaza (cha), nucellus (nu) and endothelial layer (ed), tegumentary parenchyma (pa), funicle (fu) and hylar region (hr) and the palisade layer of macrosclereids (pms) with the lens (le), can be seen. Fig. 25. Proembryonal tetrad (pet) of A. bicolor with pollen tube (pt) and synergid remnants (sy). Fig. 26. Young seed of A. latifolia during stage of proembryo (pe), showing initial haustorium (he) of the nuclear endosperm (ne), nucellus (nu) with endothelial layer (ed) and differen- tiating lens (le). Fig. 27. Seed of A. bicolor at advanced cotyledon (ct) development, showing radicle (ra) and sus- pensor (su). The nuclear endosperm haustorium (he) is now inactive at the funicular side, whereas the cellular endosperm (ce) fills a considerable part of the seed cavity. The nucellus is mostly reabsorbed, whereas its endothelial layer (ed) is degenerating in the ventral seed side. The seed histology is now very differentiated: epidermal palisade layer of macrosclereids (pms), hourglass layer (hg), tegu- mentary parenchyma (pa), tracheid bar (tb) and hylar astrosclereids (as) can be seen, as can the funicle (fu). Fig. 28. An advanced seed of A. bicolor showing the suspen- sor (su), embryo with differentiated radicle (ra) and cotyle- dons (ct), degenerating endothelial layer (ed), palisade layer of macrosclereids (pms), hourglass layer (hg), funicle (fu), tracheid bar (tb), tegumentary parenchyma (pa) and scarce remnants of cellular endosperm (ce). Scale bars: Fig. 24, 150 mm; Fig. 25, 50 mm; Fig. 26, 70 mm; Figs 27, 28, 100 mm. Johri & Garg, 1959;Pal, 1960;Prakash & Chan, 1976). During cotyledon growth in A. bicolor and A. latifolia, the moderately massive endospermic tissue distributes itself around the embryo (Fig. 27). The free-nuclear haustoria persist at the funicular side in both Adesmia species (Figs 20, 21, 27), until disinte- gration during late embryogenesis, as in many other legumes of diverse tribes, for example Glycine jav- anica L., Phaseolus trilobus Ait., Dolichos lablab L. (Anantaswamy Rau, 1953), Millettia ovalifolia L. (Pal, 1960) and Alysicarpus bupleurifolius DC. (Ashrafunnissa & Pullaiah, 1997). Seeds of A. bicolor at advanced cotyledon development show an advanced histological differentiation, and nuclear endosperm haustoria remain inactive at the funicular side, whereas cellular endosperm fills a considerable part of the seed cavity (Fig. 27). Only a few remnants of cellular endosperm (Figs 4, 10, 21, 28) are present close to seed maturity in A. bicolor and A. latifolia. Papilionoid seeds are exalbuminous, containing only traces of endospermic tissue (Corner, 1951;Johri & Garg, 1959;Prakash, 1987), or are albuminous, as in Crotalaria, Indigofera (Corner, 1951) and Astragalus L. (Maldonado, ...
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... chalazal barrier tissue, or hypostase, has been described in mature ovules of A. latifolia (Moço, 2002). However, this structure could not be distin- guished in either developing seeds of A. bicolor and A. latifolia (present study) or A. securigerifolia (Izaguirre et al., 1994). The hypostase acts as a barrier against chalazal nuclear endosperm haustoria in developing seeds (Anantaswamy Rau, 1951b, 1953Bouman, 1984). Since the active zone of the nuclear endosperm haustoria is lateral (Figs 24, 26) rather than chalazal in the Adesmia species studied, the hypostase, as described by Moço (2002) in developed ovules of A. latifolia, may become non-functional and atrophy during early seed ...
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... nucellus is slowly reabsorbed from the micro- pyle to the chalaza, where it persists until advanced embryogeny (Fig. 24). The massive ventral nucellar projection (Figs 3, 14, 24, 26) also remains until cel- lular endosperm development, as in A. securigerifolia (Izaguirre et al., 1994). Such a long nucellar persis- tence in the chalaza has also been observed in numerous Papilionoideae, for example species of Glycine Willd., Clitoria L. and Pongamia Adans. (Anantaswamy Rau, 1951b), Sesbania Scop. and Zornia J.F. Gmel. (Anantaswamy Rau, 1953), Pha- seolus L. (Sterling, 1955) and Millettia Wight & Arn. (Pal, ...
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... nucellus is slowly reabsorbed from the micro- pyle to the chalaza, where it persists until advanced embryogeny (Fig. 24). The massive ventral nucellar projection (Figs 3, 14, 24, 26) also remains until cel- lular endosperm development, as in A. securigerifolia (Izaguirre et al., 1994). Such a long nucellar persis- tence in the chalaza has also been observed in numerous Papilionoideae, for example species of Glycine Willd., Clitoria L. and Pongamia Adans. (Anantaswamy Rau, 1951b), Sesbania Scop. and Zornia J.F. Gmel. (Anantaswamy Rau, 1953), Pha- seolus L. (Sterling, 1955) and Millettia Wight & Arn. (Pal, ...
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... the subhylar tracheid bar (Figs 4, 9, 21, 27, 28) is located lateral to the chalazal vascular bundle (Fig. 15), it conforms to the widespread pattern in Papilionoideae (Lersten, 1982). The tracheids are sca- lariform in A. latifolia (Fig. 22) and reticulate in A. bicolor (Fig. 23). Non-vestured tracheids have been reported at scanning electron microscopic level for A. smithiae (Lersten, ...
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... research in both Adesmia species shows a funicular counter palisade layer (Corner, 1951). In A. latifolia, the aril is absent (Figs 4, 9, 15, 21, 24, 27, 28). A subhylar cap of astrosclereids is present along the ventral side of developed seeds, subjacent to the conspicuous lens in both species. In A. bicolor, such astrosclereids form a massive tissue (Figs 4, 15), whereas, in A. latifolia, they are longer armed ( Figs 9, 20), resulting in prominent intercellular spaces. According to the seed ecological correlation between lens and subjacent tissues (Van Staden, Manning & Kelly, 1989), the sclerenchyma with intercellular spaces beyond the lens in A. latifolia may be related to wetland habitats, whereas the massive scleren- chyma of A. bicolor may reflect lower soil water ...
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Seed coat development of Harpagophytum procumbens (Devil's Claw) and the possible role of the mature seed coat in seed dormancy were studied by light microscopy (LM), transmission electron microscopy (TEM) and environmental scanning electron microscopy (ESEM). Very young ovules of H. procumbens have a single thick integument consisting of densely p...
Citations
... Therefore, there is a wide range of literature examining their evolution, ecology, physiology and anatomy (e.g. Baskin et al., 2000;Fenner, 2000;Baskin and Baskin, 2001;Rodriguez-Pontes, 2008;Graeber et al., 2011;Morris et al., 2011). Seeds can be dispersed with various kinds of additional tissue, usually represented by the pericarp, which is formed from the ovary. ...
... For example, in the Apiaceae family one usually finds diaspores with thin, single-layered seed coats coalesced with a thicker pericarp, with ribs and secretory oil ducts (Petri, 1979;Tămaș, 2004;Calvino et al., 2008;Bercu and Broasca, 2012;Lobiuc et al., 2012). In the Fabaceae, the diaspores are seeds with thick seed coats consisting of palisade sclerenchyma, brachysclereids and some live nutritious tissues (Tămaș, 2004;Rodriguez-Pontes, 2008). Phylogeny can also predict the morphology and size of the diaspores. ...
Anatomical and morphological seed traits are of great ecological importance and are a main subject of, for example, seed bank or endozoochory studies. However, we observed a lack of information about the relationship between seed anatomy and seed morphology and its ecological implications. To fill this gap, we linked the anatomical features of diaspore coverings to morphological characteristics of free seeds and one-seeded fruits. We predicted that: (1) the thickness and anatomical complexity of seed coat and pericarp are related to diaspore size and shape; and (2) the presence or absence of the pericarp may influence seed-coat thickness and anatomy. In our study we investigated diaspores of 39 central-eastern European herbaceous species and recorded the thickness and anatomical complexity of their seed coverings, and we determined diaspore mass and shape. Our results indicate that diaspore mass is positively related to covering thickness, lignification degree and anatomical complexity. This might be the case because bigger diaspores tend to remain on the soil surface and are more exposed to predation risk and environmental threat than smaller diaspores. Furthermore, more round-shaped diaspores had disproportionately thicker and more lignified coverings than long or flat ones, probably because round-shaped diaspores much more frequently form seed banks and therefore persist for a long time in the soil. We also found that free seeds as diaspores have a thicker and more lignified seed coat than seeds enclosed in fruits. In one-seeded fruits, the pericarp ‘takes the protective role’, it is thick, and the seed coat is poorly developed.
... Embryological studies in Papilionoideae (Ashrafunnisa and Pullalah 1999;Riahi et al. 2003;Faigo´n-Soverna et al. 2003;Moço and Mariath 2003;Zulkarnain 2005;Galati et al. 2006;Rezanejad 2007;Rodriguez-Pontes 2008;Riahi and Zarre 2009;Salinas-Gamboa et al. 2016) and a few embryological studies in Onobrychis (Chehregani et al. 2011;Ghassempour and Majd 2012) have provided useful characters in embryogenesis and classification. Therefore, in this study we investigate detailed embryological processes in O. persica using bright field, polarizing and fluorescence microscopy and compare them with some spices in this genus. ...
... In O. persica the mature embryo-sac has a Polygonum type of development that is common in this family (Riahi et al. 2003;Moço and Mariath 2003;Galati et al. 2006;Rezanejad 2007;Rodriguez-Pontes 2008;Bakar Büyükkartal 2009). This type is the most common in angiosperms and is considered as the primitive embryological character (Liu et al. 2003). ...
... It is a remarkable finding that we have observed two seeds in legume of O. persica. The outer integument with several cell layers is common in Fabaceae (Galati et al. 2006;Rodriguez-Pontes 2008;Vardar 2013). In O. persica, the outer integument has four or five layers, but in Astragalus cemerinus, A. ruscifolius and Swainsona formosa the outer integument is two or three cell layers thick (Zulkarnain 2005;Riahi and Zarre 2009). ...
Developmental aspects of anther, pollen grains, ovule, embryo and seed has described in Onobrychis persica Sirj. and Rech.f. (Fabaceae) under bright field, polarizing and fluorescence microscopy. Anther development starts when the flowers are very small. The anther is tetrasporangiate, and its wall development follows the dicotyledonous type and consists of four layers: epidermis, endothecium, middle layer and a secretory tapetum. Cytokinesis is simultaneous and arrangement of microspores is tetrahedral and tetragonal. Fibrous thickenings are developed in the endothecium when shed. Ellipsoidal tricolpate pollen grains are two-celled when anthers dehisce. The young hemianatropous ovule changes to a anatropous, crassinucellar and bitegumic mature one with zigzag micropyle. Meiosis of megasporocytes results in a T-shaped tetrad. The chalazal megaspore develops into an eight-nucleate embryo sac with the pattern of Polygonum type. The polar nuclei remain separated before fertilization. After cellularization of endosperm, peripheral cells show dense lipid content. The axial embryo shows fleshy cotyledons, which accumulate lipid and starch. The inner integument differentiates into an endothelium and largely vanishes during development while the outer one produces several layers and establishes the typical seed coat structure: macrosclereid cells, osteosclereids and parenchyma cells. Different compounds, such as starch and lipid content were demonstrated with special staining in the tissues. The systematic significance of the embryological characters is discussed in O. persica.
... Moreover, although the suspensors in some leguminous species (e.g., four Astragalus L. species, and Vicia faba L.) degenerate after initiation of the cotyledons as in most fl owering plants ( Johansson and Walles, 1993 ;Wredle et al., 2001 ;Riahi et al., 2003 ;Riahi and Zarre, 2009 ), in others (e.g., eight Crotalaria L. species and two Adesmia DC. species), the suspensor persists until later in seed development ( Rau, 1950 ;Rodriguez-Pontes, 2008 ). Therefore, differences in the timing of the PCD of the suspensors may also occur in Leguminosae, and in cases in which the suspensor degenerates in the earlier stages of seed development, it remains unclear how the embryos absorb nutrients. ...
Premise of the study:
In angiosperm seeds, the developing embryo acquires nutrients via a suspensor that typically undergoes programmed cell death (PCD) at the early cotyledon stage. However, in Leguminosae (the third largest angiosperm family), the suspensors can disappear at the heart-shaped stage (i.e., prior to the cotyledon stage) or still persist at the cotyledon stage. Here, in a comprehensive survey of legume suspensors and embryos, the variation and the evolutionary direction of timing of suspensor PCD in Leguminosae were characterized, and systematic implications were evaluated.
Methods:
Suspensor development and morphology for 66 leguminous species from 49 genera, 21 tribes, and 3 subfamilies were comparatively studied using standard paraffin sectioning and light microscopy.
Key results:
Three patterns of suspensor PCD were observed at the early cotyledon stage. (A) The suspensor persisted. (B) The suspensor separated from the wall of the embryo sac and persisted as a vestige at the radicle apex. (C) The suspensor disappeared completely, and the absorption of nutrients by embryo was carried out via a "contact zone" between the embryo and the endosperm. Pattern C of early suspensor PCD was found only in the tribe Fabeae. An ancestral character reconstruction revealed that the long-lived suspensors of pattern A represented a plesiomorphic condition in Leguminosae and that the suspensors of pattern C evolved only once in the common ancestor of Fabeae.
Conclusions:
In Leguminosae, short-lived suspensors have thus evolved multiple times from long-lived suspensors. It remains largely unknown, however, how the embryo acquires nutrients after the early suspensor PCD.
... Em corte transversal, notou-se que todos os traqueóides apresentaram um arranjo vertical (Figura 1E). Esse padrão foi registrado nas outras espécies de Adesmia (A. securigerifolia, A. bicolor e A. latifolia) estudadas quanto a esse aspecto (Izaguirre et al., 1994;Rodriguez-Pontes, 2008) e é considerado o mais comum registrado entre as Faboideae (Lersten, 1982). Segundo Rodriguez-Pontes (2008), estes traqueóides, em A. latifolia, apresentam ornamentação de parede do tipo escalariforme, porém com contornos mais achatados e, em A. bicolor, são do tipo reticulado. ...
... Esse padrão foi registrado nas outras espécies de Adesmia (A. securigerifolia, A. bicolor e A. latifolia) estudadas quanto a esse aspecto (Izaguirre et al., 1994;Rodriguez-Pontes, 2008) e é considerado o mais comum registrado entre as Faboideae (Lersten, 1982). Segundo Rodriguez-Pontes (2008), estes traqueóides, em A. latifolia, apresentam ornamentação de parede do tipo escalariforme, porém com contornos mais achatados e, em A. bicolor, são do tipo reticulado. Em A. tristis, essas células apresentam espessamento de parede do tipo escalariforme com contorno circular à elíptico com ocorrência de anastomose em algumas áreas (Figura 1F). ...
... Essa morfologia encontrada em A. tristis, se encaixa em uma categoria intermediária (forma 3), descrita por Smith (1983), pois cotilédones foliares pertencem à forma 1 e, os de reserva, à forma 2. Smith (1983) registrou as três formas descritas na tribo Dalbergieae, considerando o cotilédone de A. muricata como foliar. O mesofilo do cotilédone de A. tristis é irrigado por três feixes procambiais centrais (Figura 2F), padrão também descrito em A. bicolor e A. latifolia (Rodriguez-Pontes, 2008), e mais comum entre as Fabaceae (Smith, 1981). Fica implícito neste estudo que, pequenas diferenças na estrutura da testa e do hilo, nas sementes das espécies do gênero Adesmia, imprimem características de adaptabilidade da espécie ao meio quanto a umidade predominante no local. ...
Adesmia tristis is a species endemic to South Brazil and very promising as forage in high altitude pastures with soils rich in aluminium and low in phosphorus. The objective of this study was to analyze seed morphology and anatomy to understand dormancy in these diaspores. The seeds were harvested in the São Fransisco de Paula region, RS, Brazil, between December 2007 - January 2008, and this material used to study seed sections. It was found that this species has tegument dormancy due to the impermeability of the macrosclereid and osteosclereid layers of the testa. The hilum structure follows the general pattern in Fabaceae, the tracheid arrangement is vertical, the astroesclereids form large intercelluar spaces, increasing seed adaptation to variations in environmental moisture.
The embryo development of Mimosa pudica and the seedling development of Acacia farnesiana, Albizzia julibrissin, Leucaena glauca and Mimosa pudica were studied by wax method in this paper. The results showed that M. pudica has a suspensor composed of about ten cells which degenerate and integrate into the embryo proper during the cotyledons development. The coleorhiza in M. pudica is from the residual suspensor cells and the cells produced by periclinal and anticlinal divisions of the meristematic cells in the embryo development. The coleorhiza in the four studied taxa is broken by the elongation of the primary root, withdraws and finally falls off during the seedling development.
