J Plant Ecol ›› 2021, Vol. 14 ›› Issue (4): 662-672 .DOI: 10.1093/jpe/rtab019

• Research Articles • Previous Articles     Next Articles

Differences in seed dormancy and germination in amphicarpic legumes: manifold bet-hedging in space and time

Ricardo Sánchez-Martín1,*, José Maria Gómez2, Pierre-Olivier Cheptou3 and Rafael Rubio de Casas4,*   

  1. 1 Departamento Ecología Vegetal, Centro de Investigaciones sobre Desertificación (CIDE-CSIC-UV-GV), Carretera de Moncada-Náquera Km 4,5, 46113 Moncada, Valencia, Spain, 2 Departamento de Ecología Funcional y Evolutiva, Estación Experimental de Zonas Áridas, EEZA-CSIC, Ctra. de Sacramento s/n, La Cañada de San Urbano, 04120 Almería, Spain, 3 Centre d’Ecologie Fonctionnelle et Evolutive (CEFE), CEFE UMR 5175, CNRS, Universite de Montpellier, Universite Paul-Valery, 7 Montpellier, EPHE, 1919 route de Mende, 34293 Montpellier Cedex 05, France, 4 Departamento de Ecología, Universidad de Granada, Avda. de Fuentenueva s/n, 18071 Granada, Spain

    *Corresponding author. E-mail: ricardo.sanchez@uv.es (R.S.-M.); rubiodecasas@ugr.es (R.R.C.)
  • Received:2019-12-19 Revised:2020-04-07 Accepted:2021-02-06 Online:2021-03-08 Published:2021-08-01

Abstract:

Aims

Dispersal through space or time via dormancy is one of the primary processes whereby organisms can influence the environment they experience. In plants, strong evolutionary correlations are expected between the two kinds of dispersal because both are performed by the seeds and play comparable adaptive roles. In this paper, we investigated these evolutionary correlations using amphicarpic plants, which simultaneously produce aerial seeds with high spatial dispersal propensity and subterranean seeds that do not disperse.

Methods

We investigated the variation in dormancy and germination in aerial and subterranean seeds of two amphicarpic legumes (Vicia amphicarpa L. and Lathyrus amphicarpos L.) and two closely related homocarpic taxa (Vicia sativa L. and Lathyrus cicera L.) by estimating germination percentages following different combinations of dormancy breaking treatments (i.e. dry after-ripening, cold stratification and physical scarification).

Important Findings

Our results showed complex interactions between spatial and temporal dispersal. Right after dispersal, aerial seeds were more dormant than their subterranean counterparts, but this trend reversed with after-ripening, as seeds developed physical dormancy. Seeds of homocarpic plants germinated at higher percentages than those of their amphicarpic congeners and lost dormancy homogeneously with after-ripening. Conversely, amphicarpic seeds exhibited varied dormancy strategies modulated by both physiological and physical dormancy. These are expected to increase variation in emergence timing, providing multiple levels of diversifying bet-hedging. This strategy might be adaptive under highly unpredictable conditions by enabling plants to rely on historically favorable sites in good seasons without preventing spatial and temporal migration.

Key words: amphicarpy dormancy/colonization trade-off, amphicarpic legumes, environmental heterogeneity, seed dormancy and germination, Mediterranean environments

摘要:
两型结实豆科植物种子休眠和萌发的差异:空间和时间上多样性的两头下注策略
通过休眠而实现的在空间或时间上的传播是生物体对它们所经历的环境施加影响的主要过程之一。在植物中,由于这两种传播都是通过种子进行的,而且两者在适应性方面发挥的作用也是类似的,因此预测它们之间存在较强的进化相关性。在本研究中,我们使用了两型结实的植株来研究这些进化相关性,这类植株能同时产生具有高度空间传播力的种子以及不会传播的地下种子。我们对经不同组合的休眠过程破坏处理(即干燥后熟、冷积层和物理划伤)后的种子的萌发百分比进行了评估,以研究两种两型结实豆科植物——野豌豆(Vicia amphicarpa L.)和山黧豆(Lathyrus amphicarpos L.),以及同它们亲缘关系很近的两种单型结实类群——救荒野豌豆(Vicia sativa L.)和红山黧豆(Lathyrus cicera L.)的飞播种子和地下种子在休眠和萌发方面的变化情况。研究结果表明,空间传播和时间传播之间存在着复杂的相互作用。在刚完成传播时,空播种子比地下种子更具休眠性,但当种子经后熟处理而开始物理休眠时,这种趋势也随之逆转。单型结实植株种子的萌发百分比高于其两型结实的同属植株,并在后熟处理后都同样失去了休眠性。相反,两型结实植株的种子则表现出同时受生理休眠和物理休眠调节的不同休眠性策略,预计这可能使出苗时间发生变化,从而提供了多层次多样化的两头下注策略(bet-hedging)。这一策略能够使植株依赖于丰产季中的历史有利区域而不阻碍空间和时间上的迁移,从而有可能在不可预测性很高的条件下具有适应性。

关键词: 两型结实细胞休眠/定殖权衡, 两型结实豆科植物, 环境异质性, 种子休眠和萌发, 地中海环境