Integrated dominance mechanisms regulate reproductive architecture in Arabidopsis thaliana and Brassica napus

The production of seed in flowering plants is complicated by the need to first invest in reproductive shoots, inflorescences, flowers and fruit. Furthermore, in many species, it will be months between plants generating flowers and setting seed. How can plants therefore produce an optimal seed-set relative to environmental resources when the ‘reproductive architecture’ that supports seed-set needs to be elaborated so far in advance? Here, we address this question by investigating the spatio-temporal control of reproductive architecture in Arabidopsis (Arabidopsis thaliana) and Brassica napus. We show that resource- and resource-related signals such as substrate volume play a key role in determining the scale of reproductive effort, and that this is reflected in the earliest events in reproductive development, which broadly predicts the subsequent reproductive effort. We show that a series of negative feedbacks both within and between developmental stages prevent plants from over-committing to early stages of development. These feedbacks create a highly plastic, homeostatic system in which additional organs can be produced in the case of reproductive failure elsewhere in the system. We propose that these feedbacks represent an ‘integrated dominance’ mechanism that allows resource use to be correctly sequenced between developmental stages to optimise seed set.