Prieu Charlotte, Matamoro-Vidal Alexis, Raquin Christian, Dobritsa Anna, Mercier Raphaël, Gouyon Pierre-Henri, Albert Béatrice
Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, 91405 Orsay cedex, France CNRS, Orsay F-91405, France Institut de Systématique, Évolution, Biodiversité, ISYEB-UMR 7205 - CNRS, MNHN, UPMC, EPHE, Muséum national d'Histoire naturelle, Sorbonne Universités, 57 rue Cuvier, CP39, F-75005, Paris, France
Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, 91405 Orsay cedex, France CNRS, Orsay F-91405, France Institut de Systématique, Évolution, Biodiversité, ISYEB-UMR 7205 - CNRS, MNHN, UPMC, EPHE, Muséum national d'Histoire naturelle, Sorbonne Universités, 57 rue Cuvier, CP39, F-75005, Paris, France.
Am J Bot. 2016 Mar;103(3):452-9. doi: 10.3732/ajb.1500301. Epub 2016 Mar 9.
Pollen grains are subject to intense dehydration before dispersal. They rehydrate after landing on a stigma or when placed in humid environment by absorbing water from the stigma or surroundings. Resulting fluctuations in water content cause pollen grains to undergo significant changes in volume. Thus, morphological or structural adaptations might exist to help pollen adjust to sudden volume changes, though little is known about the correlation between pollen morphology and its ability to accommodate volume changes. We studied the effect of one morphological feature of pollen grains, the aperture number, on pollen wall resistance to water inflow in Arabidopsis thaliana.
We used three Arabidopsis thaliana mutants that differ in the number of apertures in their pollen (zero, four, or a mix of four to eight, respectively) and the wild type with pollen with three apertures. We tested pollen survival in solutions with various mannitol concentrations.
The number of intact pollen grains increased with increasing mannitol concentration for all pollen morphs tested. At a given mannitol concentration, however, an increase in aperture number was associated with an increase in pollen breakage.
Aperture patterns, i.e., number, shape, and position, influence the capacity to accommodate volume variations in pollen grains. When subjected to water inflow, pollen grains with few apertures survive better than pollen with many apertures. Trade-offs between survival and germination are likely to be involved in the evolution of pollen morphology.
花粉粒在散播前会经历强烈脱水。落在柱头上或置于潮湿环境中时，它们通过从柱头或周围环境吸收水分而重新水化。由此导致的含水量波动会使花粉粒体积发生显著变化。因此，可能存在形态或结构上的适应性变化来帮助花粉适应体积的突然变化，尽管关于花粉形态与其容纳体积变化能力之间的相关性知之甚少。我们研究了拟南芥花粉粒的一个形态特征——萌发孔数量，对花粉壁阻止水分流入的影响。
我们使用了三种拟南芥突变体，它们花粉的萌发孔数量各不相同（分别为零个、四个，或四个到八个的混合），以及野生型，其花粉有三个萌发孔。我们测试了花粉在不同甘露醇浓度溶液中的存活率。
对于所有测试的花粉形态，完整花粉粒的数量随甘露醇浓度的增加而增加。然而，在给定的甘露醇浓度下，萌发孔数量的增加与花粉破裂的增加相关。
萌发孔模式，即数量、形状和位置，会影响花粉粒容纳体积变化的能力。当受到水分流入时，萌发孔少的花粉粒比萌发孔多的花粉粒存活得更好。存活与萌发之间的权衡可能参与了花粉形态的进化。
