Periodic Reporting for period 1 - END-osperm (Genetic regulation and functional relevance of maize starchy endosperm programmed cell death)
Período documentado: 2022-09-01 hasta 2024-08-31
The starchy endosperm in cereals serves as the primary storage tissue in the grain, constituting approximately 60% of the human diet. A comprehensive understanding of endosperm development is essential for enhancing grain quality and yield, under normal and fluctuating environmental conditions. This is a critical challenge given the escalating demands resulting from global population growth and heightened agricultural risks due to climate change.
The final phase of starchy endosperm development involves programmed cell death. During this process, the central starchy endosperm undergoes a conservative cell death, preserving the nutrient-filled cell remains. The objective of the project was to unravel the genetic regulation of starchy endosperm cell death in the model species maize.
Our findings revealed that starchy endosperm cell death also encompasses another type of cell death, leading to the specific elimination of cells surrounding the embryo. This process is essential for optimal embryo expansion. A comparative analysis of the two types of cell death occurring in the starchy endosperm—namely, the conservative cell death in the central starchy endosperm and the specific elimination of cells around the embryo—highlighted distinct cyto-morphological features and the requirement for different genetic regulators.
Specifically, the kil1 kil2 signaling pathway was identified as the genetic regulator for starchy endosperm elimination around the embryo, while other genetic regulators may play a role in the conserved cell death of the central starchy endosperm. In summary, these results offer new insights into the regulation of starchy endosperm cell death and present novel avenues for optimizing grain quality through the manipulation of cell death processes.
The final phase of starchy endosperm development involves programmed cell death. During this process, the central starchy endosperm undergoes a conservative cell death, preserving the nutrient-filled cell remains. The objective of the project was to unravel the genetic regulation of starchy endosperm cell death in the model species maize.
Our findings revealed that starchy endosperm cell death also encompasses another type of cell death, leading to the specific elimination of cells surrounding the embryo. This process is essential for optimal embryo expansion. A comparative analysis of the two types of cell death occurring in the starchy endosperm—namely, the conservative cell death in the central starchy endosperm and the specific elimination of cells around the embryo—highlighted distinct cyto-morphological features and the requirement for different genetic regulators.
Specifically, the kil1 kil2 signaling pathway was identified as the genetic regulator for starchy endosperm elimination around the embryo, while other genetic regulators may play a role in the conserved cell death of the central starchy endosperm. In summary, these results offer new insights into the regulation of starchy endosperm cell death and present novel avenues for optimizing grain quality through the manipulation of cell death processes.
Firstly, we analyzed the cytomorphological features of starchy endosperm cell death. We showed that a different cell death processes from the one happening in the center of the starchy endosperm takes place in the endosperm adjacent to the embryo, leading to cell elimination. The execution of these two cell death processes proved to be entirely different, suggesting the involvement of different regulators.
To analyze the differences in gene networks activated during these two starchy endosperm cell death processes, we subsequently conducted a novel transcriptomic approach. This allowed us to generate an atlas of endosperm single nucleus RNA-seq during the filling stage when both cell death processes are active. Interestingly, we observed that the classical regulators of plant cell death were expressed in the endosperm adjacent to the embryo but not in the central starchy endosperm.
Following a screening of numerous potential candidates for starchy endosperm cell death regulation, we ultimately identified two candidates capable of inducing ectopic cell death when overexpressed. Upon inhibiting them in the starchy endosperm, we observed impaired endosperm elimination around the embryo, resulting in smaller embryos. Importantly, this effect was not observed in central starchy endosperm cell death, indicating the involvement of potentially distinct regulators.
In summary, our study reveals the occurrence of two distinct cell death processes in the starchy endosperm of maize: the conservative cell death of the central starchy endosperm and cell elimination in the starchy endosperm adjacent to the embryo. These processes are likely regulated by different gene networks, and for the latter, we have already identified two regulators.
Currently, we are in the process of writing an article summarizing the obtained results, with the intention of publishing it within next months in a high-quality, peer-reviewed journal. We also plan to disseminate the results through conferences such as the Cell Biology of Plants, and beyond from the SCBF. Additionally, the results will be shared on my X account @NicolasMDoll after publication. In parallel, we are currently writing a review on endosperm cell death in angiosperms that will be submitted to the Journal of Experimental Botany next week.
To analyze the differences in gene networks activated during these two starchy endosperm cell death processes, we subsequently conducted a novel transcriptomic approach. This allowed us to generate an atlas of endosperm single nucleus RNA-seq during the filling stage when both cell death processes are active. Interestingly, we observed that the classical regulators of plant cell death were expressed in the endosperm adjacent to the embryo but not in the central starchy endosperm.
Following a screening of numerous potential candidates for starchy endosperm cell death regulation, we ultimately identified two candidates capable of inducing ectopic cell death when overexpressed. Upon inhibiting them in the starchy endosperm, we observed impaired endosperm elimination around the embryo, resulting in smaller embryos. Importantly, this effect was not observed in central starchy endosperm cell death, indicating the involvement of potentially distinct regulators.
In summary, our study reveals the occurrence of two distinct cell death processes in the starchy endosperm of maize: the conservative cell death of the central starchy endosperm and cell elimination in the starchy endosperm adjacent to the embryo. These processes are likely regulated by different gene networks, and for the latter, we have already identified two regulators.
Currently, we are in the process of writing an article summarizing the obtained results, with the intention of publishing it within next months in a high-quality, peer-reviewed journal. We also plan to disseminate the results through conferences such as the Cell Biology of Plants, and beyond from the SCBF. Additionally, the results will be shared on my X account @NicolasMDoll after publication. In parallel, we are currently writing a review on endosperm cell death in angiosperms that will be submitted to the Journal of Experimental Botany next week.
Our findings present a comprehensive description of starchy endosperm cell death with unprecedented resolution, encompassing both cyto-morphological and transcriptomic aspects. Notably, we have identified genetic regulators responsible for starchy endosperm cell elimination, marking the first such identification to our knowledge. These results not only offer novel insights into the regulation of starchy endosperm cell death but also lay the foundation for potential optimization of maize grain nutritive quality.
The impact of blocking starchy endosperm cell elimination is significant, particularly in altering the final ratio between embryo and endosperm in mature grains. Given that embryos and endosperms store distinct types of nutrients, a modification in the embryo/endosperm ratio translates into a change in the overall composition of the grain. This alteration represents a promising target for future improvements in cereal grain quality, opening avenues for enhancing the nutritional profile of maize grains.
The impact of blocking starchy endosperm cell elimination is significant, particularly in altering the final ratio between embryo and endosperm in mature grains. Given that embryos and endosperms store distinct types of nutrients, a modification in the embryo/endosperm ratio translates into a change in the overall composition of the grain. This alteration represents a promising target for future improvements in cereal grain quality, opening avenues for enhancing the nutritional profile of maize grains.