Engineering pollen-independent seed and fruit production in crops

Seed development in most flowering plants is coupled to fertilization, which leads to the formation of two structures: the embryo, which forms the next generation; and the nourishing endosperm. Some plant species, however, can produce seeds without fertilization. This phenomenon is called apomixis and, although relatively infrequent, it occurs in several plant families.

This type of asexual reproduction via seeds is highly desirable in agriculture: first, it would allow the fixation of hybrid vigour, by producing clonal progeny; second, it would allow seed and fruit production without pollen.

This is particularly relevant when pollination is limited, for example under heat stress, to which pollen is extremely sensitive. In fact, due to global warming pollen failure is expected to significantly contribute to crop yield losses. Unfortunately, no major crops can do apomixis and its introduction via classical breeding is not possible.

The engineering of apomictic traits into crops has thus seen limited success until recently: novel advances now allow the production of clonal progeny in rice and maize. However, these clonal systems are not pollen independent. Full apomixis requires engineering of three traits: apomeiosis, parthenogenesis, and autonomous endosperm.

And while the first two can now be engineered to some degree, the latter is still a major challenge and, without it, a truly pollen-independent system is not possible. Thus, in this project I aim to uncover the mechanisms required for autonomous endosperm formation. For this we will resort to naturally occurring apomicts for gene discovery: dandelion and rockcress.

We will then engineer the determinants of autonomous endosperm in tomato, which is the most important vegetable crop worldwide, and whose pollen is extremely sensitive to heat.

With this, I aim to unlock the final puzzle piece for pollen-independent seed and fruit production, which would allow the deployment of full apomixis in agricultural systems.