Temperature effects on pollen performance and their consequences for seed reproduction in wild plants

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The close link between the environment and success of plant sexual reproduction has been known for a long time. Yet, it has received increased interest over last two decades, due to the potential negative consequences of climate change on seed crops, namely short-term crop failure and long-term reduction in seed yields. Numerous studies provide evidence that this climate change-induced variation in seed quality and quantity inevitably leads to alternations in plant biology, ecology and distribution. When looking at the different stages of seed production, pollen has been shown to be the most temperature sensitive and thus the most limiting part of plant sexual reproduction. Under temperature stress, plants always tend to produce less pollen of lower quality, due to the direct exposure of small, haploid, unprotected male gametophytes to the hostile environment. In order to cope with this stress, plants have developed several strategies at different levels of their organization showing plasticity in their reproductive response to ensure fertilization. However, due to multiple knowledge gaps (e.g. strong dominance of biochemical and physiological studies, strong focus on crop and model plant species), we are still uncertain of how plastic the male gametophyte performance is in response to given thermal conditions and to what extent this plasticity allows plants to adjust seed production to a changing environment, especially in wild plants. Here we propose to examine in detail the temperature effects on pollen performance (PP; expressly in total ten functional traits of the male gametophyte that influence its ability to achieve successful fertilization) at the individual, intraspecific, and interspecific levels, and evaluate their potential importance for the success of plant seed regeneration in wild (i.e. non-cultivated, non-model) species. The specific aims are to: 1) estimate the plasticity of individual plant PP with regards to interannual variation in weather conditions, 2) evaluate the level of intraspecific variability in PP in wild plant populations, 3) assess the adaptability of PP to high-temperature stress at population and species levels and 4) determine the upper thermal limits of PP and estimate its variation along climatic gradients.The project results will progress ecology by increasing understanding on how temperature affects pollen performance at different levels and its susceptibility to high-temperature stress, which will increase as climate change goes on.