Minimal assay detects population-level senescence in the aquatic plant Lemna minor

AbstractAt the population level, senescence occurs when older individuals have an increased risk of death and reduced reproduction compared to younger individuals. We investigated senescence in the aquatic plant Lemna minor (common duckweed), an important species for plant senescence research. Our objectives were to (1) confirm or refute the presence of population-level senescence in this model species; (2) develop a minimal assay of senescence requiring only once-weekly data collection; and (3) test whether there were appreciable differences in senescence in plants grown in glass compared to polystyrene petri dishes, with an aim to reducing single-use plastic waste and long-term research materials costs. We found that weekly survival arced downward with age when viewed on a semi-log plot, and weekly production of descendants decreased with age, with both findings indicating population-level senescence that matched previous work using more frequent data-collection (per Objectives 1 and 2). Additionally, we found no noteworthy differences in senescence between plants grown in glass versus polystyrene petri dishes (per Objective 3). The use of weekly data collection could liberate personnel resources for other research-group functions, and could make the Lemna system suitable for senescence- or demography-education exercises. The use of glass dishes could reduce lab waste and expense.

摘要
在种群水平上，衰老（senescence）指相较于年轻个体，年长个体的死亡风险升高、繁殖能力下降的现象。本研究以水生植物小浮萍（Lemna minor，common duckweed）为研究对象，该物种是植物衰老研究的重要模式物种。本研究的核心目标包括三项：（1）验证该模式物种是否存在种群水平的衰老现象；（2）开发仅需每周开展一次数据采集的简化衰老检测方法；（3）对比玻璃培养皿与聚苯乙烯培养皿培育的植株在衰老程度上是否存在明显差异，以期减少一次性塑料废弃物产生并降低长期科研耗材成本。
研究结果显示：在半对数坐标图中，植株每周存活率随龄期增长呈向下弧形趋势，且每周后代产生量随龄期增长逐渐降低；上述两项结果均表明该物种存在种群水平的衰老现象，与此前采用高频数据采集方式得到的研究结论相符（对应目标1与目标2）。此外，本研究未发现两种培养皿培育的植株在衰老程度上存在值得关注的差异（对应目标3）。
采用每周一次的数据采集方案，可将科研人员从数据收集环节解放出来，投入其他课题组工作，同时也使小浮萍研究体系适用于衰老或种群统计学相关的教学实践活动。使用玻璃培养皿则可降低实验室废弃物产生与科研开支。