Structural changes in the micropylar region and overcoming dormancy in Cerrado palms seeds

Mazzottini-dos-Santos, Hellen Cássia; Ribeiro, Leonardo Monteiro; Oliveira, Denise María Trombert

doi:10.1007/s00468-018-1723-y

Cited by 14 publications

(16 citation statements)

References 35 publications

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“…The haustorium has a critical metabolic role since it interfaces the endosperm, which contains reserves that are digested and remobilized to sustain seedling development. That is, the haustorium plays multiple roles [ 4 , 9 , 10 ]: ( i ) induces enzymatic activities in the endosperm to allow remobilization; ( ii ) synthesizes digestion enzymes; ( iii ) transfers metabolites from the digestion zone to the seedling; ( iv ) involves specific metabolic pathways to coordinate post-germination events. The haustorium increases in size up to c. 90 days and its metabolic degradation starts at about 160 days [ 11 ].…”

Section: Setting the Scene: Specific Germination Stagesmentioning

confidence: 99%

“…Oil palm seed reserve carbohydrates are mostly in the form of insoluble (galacto) mannanes, which have been shown by 13 C-NMR spectroscopy to be mostly made of linear mannans with a small proportion (less than 20%) of galactomannans [ 21 ]. These polymers are accumulated in cell walls and thus their degradation may participate in endosperm cellular thinning to favor cotyledonary petiole emergence, as suggested in macaw palm [ 10 ]. Galactomannans hydrolysis (via β-endomannanase activity) has been shown in situ by histochemistry endosperm, but not in the haustorium in macaw palm [ 9 ], suggesting that β-endomannanases are neither produced nor secreted by the haustorium epidermis, but are synthesized by the endosperm itself.…”

Section: Non-lipid Reserve Remobilizationmentioning

confidence: 99%

“…Cell wall carbohydrate degradation probably also involves—like in other crops [ 22 ]—some other enzymatic activities, such as galacturonases, glucanases, cellulases, expansins, etc., in particular to facilitate the cotyledonary petiole emergence. In fact, in palm species other than oil palm, the degradation of pectins in the micropylar region (beneath the germination pore, Figure 3 ) has been demonstrated [ 10 ].…”

Section: Non-lipid Reserve Remobilizationmentioning

confidence: 99%

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Seed Germination in Oil Palm (Elaeis guineensis Jacq.): A Review of Metabolic Pathways and Control Mechanisms

Cui

Lamade

Tcherkez

2020

IJMS

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Oil palm is an oil-producing crop of major importance at the global scale. Oil palm mesocarp lipids are used for myriads industrial applications, and market demand has been growing for decades. In addition, oil palm seeds are oleaginous, and the oil extracted therefrom can be used for several purposes, from food to cosmetics. As such, there is a huge need in oil palm seeds to maintain the global cohort of more than 2 billion trees. However, oil palm seed germination is a rather difficult process, not only to break dormancy, but also because it is long and often reaches lower-than-expected germination rates. Surprisingly, despite the crucial importance of germination for oil palm plantation management, our knowledge is still rather limited, in particular about germinating oil palm seed metabolism. The present review incorporates different pieces of information that have been obtained in the past few years, in oil palm and in other palm species, in order to provide an overview of germination metabolism and its control. Further insights can also be gained from other oleaginous model plants, such as Arabidopsis or canola, however, palm seeds have peculiarities that must be accounted for, to gain a better understanding of germinating seed metabolism.

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Section: Setting the Scene: Specific Germination Stagesmentioning

confidence: 99%

Section: Non-lipid Reserve Remobilizationmentioning

confidence: 99%

Section: Non-lipid Reserve Remobilizationmentioning

confidence: 99%

See 1 more Smart Citation

Seed Germination in Oil Palm (Elaeis guineensis Jacq.): A Review of Metabolic Pathways and Control Mechanisms

Cui

Lamade

Tcherkez

2020

IJMS

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“…The embryo of palms is immersed in the endosperm and located near the seed coat, separated from it only by the few layers of the micropylar endosperm (for more details, see Fig. 1 of Mazzottini-dos-Santos et al 2018). This embryo is linear and with two distinct regions: the proximal region, adjacent to the micropylar endosperm, which corresponds to the cotyledonary petiole where the microscopic embryo axis is inserted, and the distal region, towards the middle of the seed, which is the cotyledonary blade, called haustorium in palm embryos (DeMason and Thomson 1981;Sekhar and DeMason 1988;Moura et al 2010;Baskin and Baskin 2014;Mazzottini-dos-Santos et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Ultrastructural aspects of metabolic pathways and translocation routes during mobilization of seed reserves in Acrocomia aculeata (Arecaceae)

Mazzottini-dos-Santos

Ribeiro

Oliveira

et al. 2020

Braz. J. Bot

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Seeds of several palms are reserve-rich, and have a complex and poorly understood mobilization. The massive endosperm and embryo of Acrocomia aculeata Lodd. ex Mart. possess large amounts of proteins, polysaccharides, and lipids. We evaluated cell features related to reserve mobilization during germination and initial development of seedlings of A. aculeata. Samples of the haustorium (the cotyledonary blade) at different developmental stages and of the entire digestion zone of the endosperm were processed by standard methods for ultrastructural evaluation. The haustorium reserve mobilization begins when germination starts, and proteins are the first to be metabolized, followed by polysaccharides and lipids. Haustorial cells present lipid bodies associated with glyoxysomes and protein vacuoles, which are involved in lipid mobilization. The digestion zone of the endosperm comprises cell layers adjacent to the haustorium, in which reserve mobilization begins after the protrusion of the cotyledonary petiole. The endosperm reserve mobilization is similar to observed in the haustorium, firstly proteins, polysaccharides, and lipids in the end. The abundant carbohydrates in the cell walls of endosperm are hydrolyzed, and the cells lose integrity, while digestion products accumulate around the haustorium. The sinuosities observed in the plasma membrane and the organelles predominating in the epidermal cells of the haustorium are consistent with absorption and transitory storage of reserves, and there is no evidence of the secretion of enzymes that can act in the mobilization of endosperm reserves. Therefore, the endosperm has a storage and self-degradation function, and the products of hydrolysis are transported towards the haustorium via the apoplastic route.

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“…However, many recent studies still conclude that palm diaspores have physiological dormancy or use terms such as embryonic dormancy (Nazário et al 2017), physiological and physical dormancy (Medeiros et al 2015), and even in some cases the seeds are reported to be dormant due to constraint resulting from the operculum (Moura et al 2019). Further, there is disagreement as to whether morphological dormancy should be considered as a form of dormancy or be reclassified as an absence of actual dormancy (Mazzottini-dos-Santos et al 2018;Visscher et al 2020). The purpose of this opinion paper is to show, with some recent examples, that dormancy class in Arecaceae species is still entirely misrepresented or misinterpreted.…”

mentioning

confidence: 99%

Defining correct dormancy class matters: morphological and morphophysiological dormancy in Arecaceae

Jaganathan

2020

Annals of Forest Science

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& Key message Dormancy in Arecaceae diaspores is due to underdeveloped embryos, therefore, morphological dormancy or morphophysiological dormancy. Consequently, claims such as external seed structures inhibit germination, embryos are fully developed at maturity, and underdeveloped embryo is not a form of dormancy are rejected, because embryo size of the diaspore at the time of dispersal was not taken into consideration. The re-classification proposal for moving morphological dormancy into non-dormancy is also discouraged. This is owing to the fact that when both morphological dormancy and non-dormant seeds are placed under conditions suitable for germination, those with morphological dormancy do not germinate immediately due to time needed for growth of the embryo, whereas non-dormant seeds can germinate quickly. The implications of correctly defining dormancy class are important, for researchers working with seeds at various levels from forestry to molecular biology.

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Structural changes in the micropylar region and overcoming dormancy in Cerrado palms seeds

Cited by 14 publications

References 35 publications

Seed Germination in Oil Palm (Elaeis guineensis Jacq.): A Review of Metabolic Pathways and Control Mechanisms

Seed Germination in Oil Palm (Elaeis guineensis Jacq.): A Review of Metabolic Pathways and Control Mechanisms

Ultrastructural aspects of metabolic pathways and translocation routes during mobilization of seed reserves in Acrocomia aculeata (Arecaceae)

Defining correct dormancy class matters: morphological and morphophysiological dormancy in Arecaceae

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