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

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.

Suppression of LOX activity enhanced seed vigour and longevity of tobacco (Nicotiana tabacum L.) seeds during storage

“…ROS generated by respiration contributed to aging which in turn lead to the accumulation of H 2 O 2 in seed cell cytoplasm ( Kibinza et al , 2011 ). Excessive ROS caused lipid peroxidation through LOX, resulting in MDA damaged cell membranes, to further accelerate the seed deterioration ( Ahmed et al , 2016 ; Shimizu et al , 2006 ; Sharma et al , 2012 ), which was consistent with our study. H 2 O 2 and MDA content, and LOX activity kept a similarly upward tendency in RT/C (Figs 3 and 4 , Supplementary Figs S3 and S5 ).…”

“…Seed aging, in part, still followed the ‘free radical theory’ which posited that damage caused by the accumulation of free radicals was the underlying mechanism in the organism aging ( Harman, 1993 ; Kibinza et al , 2011 ). Numerous studies reported the importance of reactive oxygen species (ROS) in seed aging ( Kibinza et al , 2006 ; Chen et al , 2013 ; Ahmed et al , 2016 ). Hydrogen peroxide (H 2 O 2 ), one of ROS, at proper concentration was conducive to seed dormancy-broken and germination enhancement, however, the over-accumulation of H 2 O 2 easily caused cell injury ( Kumar et al , 2015 ).…”

Genetic Modification for Improving Seed Vigor Is Transitioning from Model Plants to Crop Plants

“…Proteomics analysis displays a similar proteome characterization between artificial and natural aged Arabidopsis seed (Rajjou et al, 2008). However, a recent study reported substantial differences in scutellum nuclear content and morphology between the viability loss of accelerated and naturally aged wheat seed (Ahmed et al, 2016). Numerous studies have been performed on the process of seed deterioration in various plant species (e.g., Catusse et al, 2008, 2011; Galpaz and Reymond, 2010; Han et al, 2014; Nagel et al, 2014).…”

Biology of Seed Vigor in the Light of -omics Tools

“…With the advent of -omics methodologies, a significant in-depth understanding of regulatory mechanisms signaling seed deterioration and invigoration has been gained and applies to crops [37,34]. Changes in specific sequences of highly polymorphic genetic markers in aging rice [38], tomatoes [39] and wheat seeds [40] provide hints of molecular hints on genetic influences behind seed aging.…”

“…From these QTL regions identified in the brief review above, putative candidate genes associated with many seed vigor traits in the hotspot QTL regions have been published for crops like Advances in Seed Biologywheat [35], maize [38] and rice [40]. Besides, Carrera et al [54] used gene expression profiling -omics method to produce a list of candidate genes that signify seed germination which was used to produce TAGGIT, a spreadsheet based seed specific gene ontology that describes the seed germination signature.…”