Genetic regulation and functional relevance of maize starchy endosperm programmed cell death

Around 60% of our daily diet is directly derived from cereal grains. In the grain, most nutrients are stored in a highly specialized reserve tissue called the starchy endosperm (SE).

SE development ends by the execution of a controlled cell death program (PCD), which leaves the nutrient-filled cell corpses largely intact.

PCD has been proposed to be crucial for storage compound preservation, but despite this potential importance, surprisingly little is known on the genetic regulation of SE PCD.

In this project, I hypothesise that cereal SE PCD is controlled by a gene regulatory network that I propose to investigate in maize (Zea mays).

To this end, I will combine the extensive knowledge I acquired during my PhD on maize kernel development with the well-documented expertise of the host lab in plant PCD analysis.

I will first determine the spatio-temporal pattern of SE PCD under the growth conditions of the host institute and characterise its subcellular features in detail by ultrastructural analyses.

As SE PCD is not executed homogenously in time and space, I propose to perform then a single-nucleus RNA-seq combined with a spatial transcriptomics approach on dissected endosperm tissue in order to obtain transcriptome profiles and developmental trajectories with single-cell resolution.

Based on their expression profiles, I will finally select up to 20 PCD-associated candidate transcription factors and screen them for gain-of-function PCD phenotypes in transient expression systems. Promising candidates will be functionally analysed in maize SE via gain- and loss-of-function approaches.

In the resulting maize lines, I will investigate the changes in PCD progression and use them to assess the physiological relevance of a correct PCD execution in the SE.

In sum, this project will generate the first functional insights on the gene regulatory networks of cereal SE PCD and will provide new leads for future agronomic applications.