Perspectives on embryo maturation and seed quality in a global climate change scenario.

Global climate change has already brought noticeable alterations to multiple regions of our planet. Several important steps of plant growth and development, such as embryogenesis, can be affected by environmental changes. For instance, these changes would affect how stored nutrients are used during early stages of seed germination as it transitions from a heterotrophic to autotrophic metabolism, a critical period for the seedling's survival. In this perspective, we provide a brief description of relevant processes that occur during embryo maturation and account for nutrient accumulation, which are sensitive to environmental change. As examples of the effects associated with climate change are increased CO2 levels and changes in temperature. During seed development, most of the nutrients stored in the seed are accumulated during the seed maturation stage. These nutrients include, depending on the plant species, carbohydrates, lipids and proteins. Regarding micronutrients, it has also been established that iron, a key micronutrient for various electron transfer processes in plant cells, accumulates during embryo maturation. Several articles have been published indicating that climate change can affect the quality of the seed, in terms of total nutritional content, but also, it may affect seed production. Here we discuss the potential effects of temperature and CO2 increase from an embryo autonomous point of view, in an attempt to separate the maternal effects from embryonic effects.

Using an embryo specific promoter to modify iron distribution pattern in Arabidopsis.

Iron is an essential micronutrient for life. During the development of the seed, iron accumulates during embryo maturation. In Arabidopsis thaliana, iron mainly accumulates in the vacuoles of only one cell type, the cell layer that surrounds provasculature in hypocotyl and cotyledons. Iron accumulation pattern in Arabidopsis is an exception in plant phylogeny, most part of the dicot embryos accumulate iron in several cell layers including cortex and, in some cases, even in protodermis. It remains unknown how does iron reach the internal cell layers of the embryo, and in particular, the molecular mechanisms responsible of this process. Here, we use transgenic approaches to modify the iron accumulation pattern in an Arabidopsis model. Using the SDH2-3 embryo-specific promoter, we were able to express VIT1 ectopically in both a wild type background and a mutant vit1 background lacking expression of this vacuolar iron transporter. These manipulations modify the iron distribution pattern in Arabidopsis from one cell layer to several cell layers, including protodermis, cortex cells, and the endodermis. Interestingly, total seed iron content was not modified compared with the wild type, suggesting that iron distribution in embryos is not involved in the control of the total iron amount accumulated in seeds. This experimental model can be used to study the processes involved in iron distribution patterning during embryo maturation and its evolution in dicot plants.