Waterworth Wanda M, Bray Clifford M, West Christopher E
University of Leeds, Leeds, United Kingdom.
The University of Manchester, Manchester, United Kingdom.
Front Plant Sci. 2019 May 31;10:706. doi: 10.3389/fpls.2019.00706. eCollection 2019.
Successful germination represents a crucial developmental transition in the plant lifecycle and is important both for crop yields and plant survival in natural ecosystems. However, germination potential decreases during storage and seed longevity is a key determinant of crop production. Decline in germination vigor is initially manifest as an increasing delay to radicle emergence and the completion of germination and eventually culminating in loss of seed viability. The molecular mechanisms that determine seed germination vigor and viability remain obscure, although deterioration in seed quality is associated with the accumulation of damage to cellular structures and macromolecules including lipids, protein, and nucleic acids. In desiccation tolerant seeds, desiccation/rehydration cycles and prolonged periods in the dry quiescent state are associated with remarkable levels of stress to the embryo genome which can result in mutagenesis of the genetic material, inhibition of transcription and replication and delayed growth and development. An increasing number of studies are revealing DNA damage accumulated in the embryo genome, and the repair capacity of the seed to reverse this damage, as major factors that determine seed vigor and viability. Recent findings are now establishing important roles for the DNA damage response in regulating germination, imposing a delay to germination in aged seed to minimize the deleterious consequences of DNA damage accumulated in the dry quiescent state. Understanding the mechanistic basis of seed longevity will underpin the directed improvement of crop varieties and support preservation of plant genetic resources in seed banks.
成功萌发是植物生命周期中一个关键的发育转变，对作物产量和自然生态系统中的植物存活都很重要。然而，种子在储存期间萌发潜力会下降，种子寿命是作物生产的关键决定因素。萌发活力的下降最初表现为胚根出现和萌发完成的延迟增加，最终导致种子活力丧失。尽管种子质量的下降与细胞结构和包括脂质、蛋白质和核酸在内的大分子的损伤积累有关，但决定种子萌发活力和活力的分子机制仍不清楚。在耐干燥种子中，干燥/再水化循环以及在干燥静止状态下的长时间停留会给胚基因组带来显著水平的压力，这可能导致遗传物质的诱变、转录和复制的抑制以及生长和发育的延迟。越来越多的研究表明，胚基因组中积累的DNA损伤以及种子逆转这种损伤的修复能力是决定种子活力和活力的主要因素。最近的研究结果表明，DNA损伤反应在调节萌发过程中起着重要作用，会使老化种子的萌发延迟，以尽量减少在干燥静止状态下积累的DNA损伤的有害后果。了解种子寿命的机制基础将为作物品种的定向改良提供支持，并有助于种子库中植物遗传资源的保存。
