Epigenetic reprogramming and non-cell autonomous communication as mechanisms of seed formation
Final Report Abstract
The seeds of flowering plants are composed of three main structures: the embryo, which will form a new plant; the endosperm, which functions as a nourishing tissue; and the seed coat, which protects the embryo and the endosperm. The development of these three structures only happens after fertilization by the paternal pollen. Moreover, embryo, endosperm and seed coat must communicate with each other for seed development to be successful. In particular, the communication between the endosperm and the seed coat is determinant for the final size of the seed. In this project we discovered that plant hormones, called brassinosteroids (BRs), are critical for seed development. First, BRs are necessary for seed coat formation: without these hormones the seed coat grows less than normal. We propose that this is because BRs are necessary for the activation of genes required for seed coat growth, which are shut down before fertilization by an epigenetic mechanism: a chemical modification of the DNA, which must be erased for those genes to become active. Moreover, we discovered that seeds lacking BRs also make endosperms that are smaller than normal. We believe this is because the poorly developed seed coat does not allow the endosperm to grow to its normal size. Therefore, we propose that the endosperm and the seed coat can “sense” each other’s physical presence and adjust their growth accordingly. These observations can have important implications for plant breeding: seed endosperm is not just important for the nourishment of the plant embryo but is also a major part of our diet. Cereal grains are mostly composed of endosperm and are a staple food for most of the world population. Therefore, understanding the mechanisms that control the growth of the endosperm can have an obvious agronomical interest. Given that BRs play a role in determining how much seeds can grow, the manipulation of this hormone can therefore be a promising strategy to optimize crop production and contributing to food security.
Publications
-
BRI1-mediated removal of seed coat H3K27me3 marks is a brassinosteroid-independent process.
Pankaj, Rishabh; Lima, Rita B.; Luo, Guan-Yu; Ehlert, Sinah; del Toro-de León, Gerardo; Bente, Heinrich; Finger, Pascal; Sato, Hikaru & Figueiredo, Duarte D.
-
Seed coat-derived brassinosteroids non-cell autonomously regulate endosperm development.
Lima, Rita B.; Pankaj, Rishabh; Ehlert, Sinah; Finger, Pascal; Fröhlich, Anja; Bayle, Vincent; Landrein, Benoit; Sampathkumar, Arun & Figueiredo, Duarte D.
