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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 scutellum labeled with TUNEL and DAPI to illustrate nuclear and morphological alterations following naturally aged (NA) or accelerated ageing (AA) treatments. Aged wheat seeds were embedded in paraffin. The scutellum sections 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 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. White arrows indicated normal well stained round nuclei; white arrow heads, longer nuclei; red arrow heads, cell or cell layers devoid of nuclei; red arrow, cells or cell layers with altered morphology; SE, scutellum epthelium; and SP, scutellum paranchyma. Scale bar represents 50 μm.
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Figure 1: Wheat scutellum labeled with TUNEL and DAPI to illustrate nuclear and morphological alterations following naturally aged (NA) or accelerated ageing (AA) treatments. Aged wheat seeds were embedded in paraffin. The scutellum sections 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 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. White arrows indicated normal well stained round nuclei; white arrow heads, longer nuclei; red arrow heads, cell or cell layers devoid of nuclei; red arrow, cells or cell layers with altered morphology; SE, scutellum epthelium; and SP, scutellum paranchyma. Scale bar represents 50 μm.

Mentions: We generated a total of 2,006 sections from 111 wheat seeds representing NA or AA aging treatments and different levels of germination and produced 758 micrographs (Table 1). Examining these micrographs revealed considerable changes in scutellum, but not aleurone, of naturally aged and AA wheat seeds. The following patterns of changes in scutellum were obtained through a summary of detailed inspection on all related micrographs for each aging treatment and illustrated in Figure 1.


The Associative Changes in Scutellum Nuclear Content and Morphology with Viability Loss of Naturally Aged and Accelerated Aging Wheat ( Triticum aestivum ) Seeds
Wheat scutellum labeled with TUNEL and DAPI to illustrate nuclear and morphological alterations following naturally aged (NA) or accelerated ageing (AA) treatments. Aged wheat seeds were embedded in paraffin. The scutellum sections 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 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. White arrows indicated normal well stained round nuclei; white arrow heads, longer nuclei; red arrow heads, cell or cell layers devoid of nuclei; red arrow, cells or cell layers with altered morphology; SE, scutellum epthelium; and SP, scutellum paranchyma. Scale bar represents 50 μm.
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC5037135&req=5

Figure 1: Wheat scutellum labeled with TUNEL and DAPI to illustrate nuclear and morphological alterations following naturally aged (NA) or accelerated ageing (AA) treatments. Aged wheat seeds were embedded in paraffin. The scutellum sections 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 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. White arrows indicated normal well stained round nuclei; white arrow heads, longer nuclei; red arrow heads, cell or cell layers devoid of nuclei; red arrow, cells or cell layers with altered morphology; SE, scutellum epthelium; and SP, scutellum paranchyma. Scale bar represents 50 μm.
Mentions: We generated a total of 2,006 sections from 111 wheat seeds representing NA or AA aging treatments and different levels of germination and produced 758 micrographs (Table 1). Examining these micrographs revealed considerable changes in scutellum, but not aleurone, of naturally aged and AA wheat seeds. The following patterns of changes in scutellum were obtained through a summary of detailed inspection on all related micrographs for each aging treatment and illustrated in Figure 1.

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.