图3. 调控玉米花器官发育和小花性别决定的基因
a：玉米花器官发育“ABCDE”模型调控基因。不同色块代表不同类型的花器官调控基因,下方标注代表不同花器官及其对应轮数。A类基因决定第一轮内稃和外稃的形成,第二轮和第三轮浆片和雄蕊的形成分别由A+B和B+C基因调控,第四轮心皮发育则由C类基因单独调控。D类基因主要在胚珠发育中起作用,E类基因则参与所有的花器官发育调控。b：小花性别决定基因调控网络。 表示正调控。 表示负调控

Fig. 3. Genes regulating maize floral organs development and floret sex determination
a: The “ABCDE model” of floral organ identity. Different color blocks show different types of floral organ regulatory genes, and the label shows floral organ developed in the whorl. A-type genes determine the identity of palea and lemma. Lodicule and stamen are regulated by A+B and B+C, respectively. Carpel identity is regulated by the C-type genes. D-type genes act in ovule development, and the E-type genes involve in the regulation of development of all floral whirls. b: Floret sex determination genes regulatory network. : Positive regulation. : Negative regulation