Dynamic Responses of Antioxidant and Glyoxalase Systems to Seed Aging Based on Full-Length Transcriptome in Oat (Avena sativa L.)

Abstract

Seed aging is a major challenge for food security, agronomic production, and germplasm conservation, and reactive oxygen species (ROS) and methylglyoxal (MG) are highly involved in the aging process. However, the regulatory mechanisms controlling the abundance of ROS and MG are not well characterized. To characterize dynamic response of antioxidant and glyoxalase systems during seed aging, oat (Avena sativa L.) aged seeds with a range of germination percentages were used to explore physiological parameters, biochemical parameters and relevant gene expression. A reference transcriptome based on PacBio sequencing generated 67,184 non-redundant full-length transcripts, with 59,050 annotated. Subsequently, eleven seed samples were used to investigate the dynamic response of respiration, ROS and MG accumulation, antioxidant enzymes and glyoxalase activity, and associated genes expression. The 48 indicators with high correlation coefficients were divided into six major response patterns, and were used for placing eleven seed samples into four groups, i.e., non-aged (Group N), higher vigor (Group H), medium vigor (Group M), and lower vigor (Group L). Finally, we proposed a putative model for aging response and self-detoxification mechanisms based on the four groups representing different aging levels. In addition, the outcomes of the study suggested the dysfunction of antioxidant and glyoxalase system, and the accumulation of ROS and MG definitely contribute to oat seed aging.

Genome-Wide Analysis and Expression Profiling of Glutathione Reductase Gene Family in Oat (Avena sativa) Indicate Their Responses to Abiotic Stress during Seed Imbibition

“…It is indispensable for the earliest metabolic events during seed germination and maintenance of seed vigor [ 14 ]. The level of GSH was suggested to be a promising indicator for seed germination and seedling growth, and was correlated with seed longevity [ 33 , 34 ]. GR is considered to be a crucial enzyme that works on the catalytic reduction of GSSG to the reduced GSH form, thereby involving in plant stress resistance, seed vigor maintenance, growth, and development.…”

“…The deletion of chloroplast specific GR2 leads to the embryo lethality, while lack of mitochondrial GR2 leads to a partially oxidized glutathione pool and decreased seed ageing resistance of Arabidopsis [ 14 , 21 ]. In addition, our previous study found that the expression of GR1 in aged A. sativa seed embryos (aged from 24 d to 42 d) decreased by 50%–70% compared with the control after imbibition for 24 h and that GR2 levels decreased significantly in minorly and moderately aged seeds, but were raised significantly in severely aged seeds [ 33 ]. In present study, the expression of AsGR2-C2 and AsGR2-D decreased significantly in dry seeds after ageing treatment, but they increased rapidly in the early stage of imbibition.…”

“…For control, cold treatment and ageing treatment, seeds were imbibed in distilled water. Seed ageing treatment were according to Xia et al [ 13 ], and seeds ageing time was according to our previous investigation [ 33 ]. Cold treatment was carried out at 10 °C, while control and other treatments were imbibed at 20 °C in the plant growth incubator under 16 h dark and 8 h light cycle.…”

Germination of aged oat seeds associated with changes in antioxidant enzyme activity and storage compounds mobilization

“…The mechanisms of the aging or deterioration of oat seeds have been investigated, including changes in antioxidants and gene expression (Kong et al, 2015), as well as mitochondrial structure (Xia et al, 2015). Tricarboxylic acid (TCA) cycle (Chen et al, 2016) and AsA‐GSH cycle are affected due to activity of various enzymes, such as APX, DHAR, MDHAR, and so forth, in medium vigor seeds after aging (Cheng et al, 2020; Sun et al, 2022). The MDA content, CAT and APX activity were maximized in oat seeds after 32 days of artificially accelerated aging, affecting pathways such as the TCA cycle in mitochondria (Cheng et al, 2020).…”

Genome-wide analysis and expression profiling of glyoxalase gene families in oat (Avena sativa) indicate their responses to abiotic stress during seed germination

“…Therefore, the identification and expression analysis of these genes at the whole-genome level will help to rapidly advance stress-resistant breeding and seed vigor improvement in oat. In our previous research, we discovered a close association between the GSH-dependent glyoxalases and the AsA-GSH cycle with oat seed vigor, where GSH content serves as a potential marker for seed germination percentage ( Sun et al., 2022b ). We also conducted a genome-wide identification of the glutathione reductase ( GR ) genes involved in the AsA-GSH cycle and analyzed its expression pattern during seed germination under stress conditions ( Sun et al., 2022a ).…”