[en] Flowering in temperate maize occurs largely autonomously after the plant has accumulated a given amount of vegetative growth. Mutants affected in leaf initiation rate or in phyllotaxy however indicate that total leaf number can vary independently of flowering time, e.g. in relation with cytokinin signalling. By contrast, heterochronic mutants in which juvenile-to-adult and/or adult vegetative-to-reproductive phase changes are abnormal aided in the identification of key regulators of endogenous developmental timing in maize. These regulators include gibberellins and micro-RNAs, such as miR156 and miR172, which have been identified more recently.
Progress towards unravelling the maize flowering time genetic network is also emerging from comparison with other species. Although maize expansion beyond domestication centres implied reduction in photoperiod sensitivity, molecular genetic studies indicated conservation of genes which, in Arabidopsis or rice, act in a signalling cascade whereby flowering is controlled by photoperiod. Several gene sequences are now available to assess functionality of such a pathway in maize and evaluate its contribution to flowering time control.
