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The Associative Changes in Scutellum Nuclear Content and Morphology with Viability Loss of Naturally Aged and Accelerated Aging Wheat ( Triticum aestivum ) Seeds

View Article: PubMed Central - PubMed

ABSTRACT

Timely prediction of seed viability loss over long-term storage represents a challenge in management and conservation of ex situ plant genetic resources. However, little attention has been paid to study the process of seed deterioration and seed aging signals under storage. An attempt was made here to investigate morphological and molecular changes in the scutellum and aleurone sections of naturally or artificially aged wheat seeds using TUNEL assay and DAPI staining. Twelve wheat genotypes or samples exposed to natural ageing (NA) or accelerated ageing (AA) were assayed and these samples had germination rates ranging from 11 to 93%. The assayed samples showed substantial changes in scutellum, but not aleurone. The nuclei observed in the majority of the scutellum cells of the NA seed samples of lower germination rates were longer in size and less visible, while the scutellum cell morphology or arrangement remained unchanged. In contrast, longer AA treatments resulted in the loss of scutellum cell structure, collapse of cell layers, and disappearance of honey comb arrangements. These nuclei and structural changes were consistent with the DNA assessments of nuclear alternations for the selected wheat samples. Interestingly, the sample seed germination loss was found to be associated with the reductions in the scutellum nuclear content and with the increases in the scutellum nuclei length to width ratio. These findings are significant for understanding the process of wheat seed deterioration and are also useful for searching for sensitive seed aging signals for developing tools to monitor seed viability under storage.

No MeSH data available.


Wheat aleurone labeled with TUNEL and DAPI to illustrate nuclear and morphological alterations following NA or AA treatments. Aged wheat seeds were embedded in paraffin. The endosperm sections containing aleurone cell layers were assayed with TUNEL and DAPI staining, and visualized under a fluorescence microscope. Each section has a sample label from (A–L) and its germination rate, and/or is highlighted with narrows. Specifically, (A), CN2707-1996; (B), CN2767-1996; (C), CN44514-1997; (D), CN44426-1996; (E), CN42511-1995; (F), CN43693-1994; (G), AC Barrie-2012; (H), AC Superb-2013; (I), AC Barrie-AA 44h@43°C; (J), AC Superb-AA 48h@43°C; (K), AC Barrie-AA 72h@43°C; and (L), AC Superb-AA 96 h @41°C. Red arrows indicate cells or cell layers with altered morphology. Scale bar represents 50 μm.
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Figure 2: Wheat aleurone labeled with TUNEL and DAPI to illustrate nuclear and morphological alterations following NA or AA treatments. Aged wheat seeds were embedded in paraffin. The endosperm sections containing aleurone cell layers were assayed with TUNEL and DAPI staining, and visualized under a fluorescence microscope. Each section has a sample label from (A–L) and its germination rate, and/or is highlighted with narrows. Specifically, (A), CN2707-1996; (B), CN2767-1996; (C), CN44514-1997; (D), CN44426-1996; (E), CN42511-1995; (F), CN43693-1994; (G), AC Barrie-2012; (H), AC Superb-2013; (I), AC Barrie-AA 44h@43°C; (J), AC Superb-AA 48h@43°C; (K), AC Barrie-AA 72h@43°C; and (L), AC Superb-AA 96 h @41°C. Red arrows indicate cells or cell layers with altered morphology. Scale bar represents 50 μm.

Mentions: Interestingly, there were no significant changes detected in the layer cells, morphology and nuclear content of aleurone among different NA and AA genotypes or samples (Figure 2). However, longer AA treatments seemed to result in the loss of cellular integrity and the broken cell layers (Figures 2I,J) and such damage was intensified with an increased AA duration (Figures 2K,L). Also, the damage in aleurone from AA treatment was dependent on genotype background. For example, the AA sample (‘AC Barrie’, 72h@43°C) displayed more cell disruption than the AA sample (‘AC Superb,’ 96h@41°C), as the latter possessed more intact cells and cell layers. In contrast to the NA genotypes with variable germination rates, such damage in the aleurone cells morphology was not visible (Figures 2C–F).


The Associative Changes in Scutellum Nuclear Content and Morphology with Viability Loss of Naturally Aged and Accelerated Aging Wheat ( Triticum aestivum ) Seeds
Wheat aleurone labeled with TUNEL and DAPI to illustrate nuclear and morphological alterations following NA or AA treatments. Aged wheat seeds were embedded in paraffin. The endosperm sections containing aleurone cell layers were assayed with TUNEL and DAPI staining, and visualized under a fluorescence microscope. Each section has a sample label from (A–L) and its germination rate, and/or is highlighted with narrows. Specifically, (A), CN2707-1996; (B), CN2767-1996; (C), CN44514-1997; (D), CN44426-1996; (E), CN42511-1995; (F), CN43693-1994; (G), AC Barrie-2012; (H), AC Superb-2013; (I), AC Barrie-AA 44h@43°C; (J), AC Superb-AA 48h@43°C; (K), AC Barrie-AA 72h@43°C; and (L), AC Superb-AA 96 h @41°C. Red arrows indicate cells or cell layers with altered morphology. Scale bar represents 50 μm.
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Figure 2: Wheat aleurone labeled with TUNEL and DAPI to illustrate nuclear and morphological alterations following NA or AA treatments. Aged wheat seeds were embedded in paraffin. The endosperm sections containing aleurone cell layers were assayed with TUNEL and DAPI staining, and visualized under a fluorescence microscope. Each section has a sample label from (A–L) and its germination rate, and/or is highlighted with narrows. Specifically, (A), CN2707-1996; (B), CN2767-1996; (C), CN44514-1997; (D), CN44426-1996; (E), CN42511-1995; (F), CN43693-1994; (G), AC Barrie-2012; (H), AC Superb-2013; (I), AC Barrie-AA 44h@43°C; (J), AC Superb-AA 48h@43°C; (K), AC Barrie-AA 72h@43°C; and (L), AC Superb-AA 96 h @41°C. Red arrows indicate cells or cell layers with altered morphology. Scale bar represents 50 μm.
Mentions: Interestingly, there were no significant changes detected in the layer cells, morphology and nuclear content of aleurone among different NA and AA genotypes or samples (Figure 2). However, longer AA treatments seemed to result in the loss of cellular integrity and the broken cell layers (Figures 2I,J) and such damage was intensified with an increased AA duration (Figures 2K,L). Also, the damage in aleurone from AA treatment was dependent on genotype background. For example, the AA sample (‘AC Barrie’, 72h@43°C) displayed more cell disruption than the AA sample (‘AC Superb,’ 96h@41°C), as the latter possessed more intact cells and cell layers. In contrast to the NA genotypes with variable germination rates, such damage in the aleurone cells morphology was not visible (Figures 2C–F).

View Article: PubMed Central - PubMed

ABSTRACT

Timely prediction of seed viability loss over long-term storage represents a challenge in management and conservation of ex situ plant genetic resources. However, little attention has been paid to study the process of seed deterioration and seed aging signals under storage. An attempt was made here to investigate morphological and molecular changes in the scutellum and aleurone sections of naturally or artificially aged wheat seeds using TUNEL assay and DAPI staining. Twelve wheat genotypes or samples exposed to natural ageing (NA) or accelerated ageing (AA) were assayed and these samples had germination rates ranging from 11 to 93%. The assayed samples showed substantial changes in scutellum, but not aleurone. The nuclei observed in the majority of the scutellum cells of the NA seed samples of lower germination rates were longer in size and less visible, while the scutellum cell morphology or arrangement remained unchanged. In contrast, longer AA treatments resulted in the loss of scutellum cell structure, collapse of cell layers, and disappearance of honey comb arrangements. These nuclei and structural changes were consistent with the DNA assessments of nuclear alternations for the selected wheat samples. Interestingly, the sample seed germination loss was found to be associated with the reductions in the scutellum nuclear content and with the increases in the scutellum nuclei length to width ratio. These findings are significant for understanding the process of wheat seed deterioration and are also useful for searching for sensitive seed aging signals for developing tools to monitor seed viability under storage.

No MeSH data available.