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Evolution and ecology of fast seed germination in the Chenopodiaceae/Amaranthaceae alliance

藜科/苋科联盟种子快速发芽的进化和生态学

基本信息

批准号：
243069004
负责人：
Professorin Dr. Gudrun Kadereit, since 9/2013
金额：
--
依托单位：
Bereich Systematik, Biodiversität & Evolution der Pflanzen
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2013
资助国家：
德国
起止时间：
2012-12-31 至 2015-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/243069004?language=en
关键词：
Evolution ecology fast seed germination

项目摘要

Seed germination and seedling growth are the most vulnerable and stressful phases in a plants life-cycle. This is especially the case in harsh, unpredictable and dynamic habitats where only short spells of favorable conditions allow for successful seedling establishment. Increasing germination speed and seedling growth is a possible solution to this problem because it reduces seedling mortality. The ability to germinate fast (i.e. within one or a few days) requires a number of seed ecological and morphological adaptations, e.g. non-dormancy and a completely developed embryo. The Amaranthaceae/Chenopodiaceae (A/C) alliance contains a high number of fast germinating species. Furthermore the fastest germinators in flowering plants have been recorded from Chenopodiaceae with spirally-coiled embryos. Interestingly a high proportion of fast germinating species in the A/C alliance are C4 plants and heterospermic. The goal of this project is to investigate the evolution and adaptive nature of fast seed germination in the A/C complex as a whole and in Atriplex as a species-rich genus with highly diverse seed traits. We will reconstruct ancestral characters states to trace the evolution of seed traits and we will search for correlated evolution of germination speed, seed characters, vegetative plant traits and habitat conditions on the basis of molecular phylogenies. The major hypotheses we will test are: 1. Fast germination is an adaptation to stressful habitat conditions. 2. Species in stressful habitats have evolved specific seed morphological traits enabling fast germination. 3. Short-lived species and pioneer species benefit more from fast germination than long-lived species. 4. Trade-offs exist between bet-hedging mechanisms such as seed dimorphism, seed mass, seed dormancy and seed dispersal. 5. Higher germination speed co-evolved with C4 photosynthesis and the latter enables for faster seedling growth and establishment.

种子萌发和幼苗生长是植物生活史中最脆弱和最受胁迫的阶段。尤其是在恶劣、不可预测和动态的生境中，只有短暂的有利条件才能成功地建立幼苗。提高种子萌发速度和幼苗生长速度是解决这一问题的可能办法，因为它可以降低幼苗死亡率。快速萌发的能力(即在一天或几天内)需要许多种子生态和形态适应，例如非休眠和完全发育的胚胎。苋科/藜科(A/C)联盟包含大量快速萌发的物种。此外，在开花植物中记录到的最快的萌发子是从藜科中记录的，具有螺旋卷曲的胚胎。有趣的是，在A/C联盟中，快速萌发的物种中有很高比例是C4植物和异种植物。该项目的目的是研究种子快速萌发在整个A/C复合体中的进化和适应性质，以及作为一个物种丰富的具有高度多样性的种子特征的滨藜属。我们将重建祖先性状状态以追踪种子性状的进化，并将在分子系统学的基础上寻找种子萌发速度、种子性状、营养植物性状和生境条件的相关进化。我们将检验的主要假设是：1.快速萌发是对紧张的栖息地条件的适应。2.在紧张的生境中，物种进化出特定的种子形态特征，使其能够快速萌发。3.短命物种和先锋物种比长寿物种更能从快速萌发中获益。4.种子二形性、种子质量、种子休眠和种子扩散等较好的对冲机制之间存在权衡。5.较高的萌发速度与C4光合作用共同进化，C4光合作用使幼苗生长和建成更快。