Department of Plant Biology, Ecology, and Evolution, Oklahoma State University, 421 Physical Sciences, Stillwater, OK, USA.
Department of Integrative Biology, Michigan State University, 288 Farm Lane, East Lansing, MI, USA.
Ann Bot. 2022 Jul 18;129(7):817-830. doi: 10.1093/aob/mcac045.
Seed mucilage is a common and highly diverse trait shared among thousands of angiosperm species. While it has long been recognized that mucilage allows seeds to anchor to substrates (antitelechory), resisting abiotic and biotic dislodgement, we still lack a mechanistic understanding of this process.
We propose a mechanistic model of how mucilage affects substrate anchorage and fluid resistance, ultimately contributing to dislodgement resistance. To test this model, we subjected mucilaginous seeds of 52 species, varying in eight measured seed traits, to 7 d of continuous water flow at a range of dislodgement potentials.
Supporting our model, mucilage mass increased the force necessary to dislodge both dry and wet seeds; our measurement of the dislodgement force of dry mucilage explained time to dislodgement well. The effect size was remarkably large; increasing the standardized mucilage mass by 1 s.d. resulted in a 280-fold increase in the time to dislodgement. Fluid resistance was largely dependent on the speed of water flow and the seed's modified drag coefficient, but not seed traits. Neither mucilage expansion speed nor mucilage decay rate explained dislodgement potential well.
Our results suggest that the degree of anchorage to a substrate, measured with a simple dislodgement force assay, is highly predictive of mucilaginous seed retention in highly erosive environments. In contrast, we found that other seed and mucilage traits are of lesser importance to anchorage.
种子粘液是一种在成千上万种被子植物中普遍存在且高度多样化的特征。虽然人们早就认识到粘液可以使种子附着在基质上（抗转移），从而抵抗非生物和生物的位移，但我们仍然缺乏对这一过程的机制理解。
我们提出了一个粘液如何影响基质附着和流体阻力的机制模型，最终有助于抵抗位移。为了验证这个模型，我们对 52 个物种的粘液种子进行了 7 天的连续水流实验，水流速度范围涵盖了不同的位移潜力。
支持我们的模型，粘液质量增加了干燥和湿润种子的位移所需的力；我们对干燥粘液的位移力的测量很好地解释了位移时间。效应大小非常大；标准化粘液质量增加 1 个标准差，导致位移时间增加了 280 倍。流体阻力主要取决于水流速度和种子的修正阻力系数，而与种子特征无关。粘液膨胀速度和粘液衰减率都不能很好地解释位移潜力。
我们的结果表明，用简单的位移力测定法测量的与基质的附着程度，对粘液种子在高度侵蚀环境中的保留能力具有高度预测性。相比之下，我们发现其他种子和粘液特征对附着的重要性较小。
