In the species of the Cucurbitaceae family, the occurrence of separate male and female flowers in the same plant (monoecy) is controlled by an ethylene biosynthesis ACS gene, which specifically suppresses the development of stamen in the female flower. In watermelon, a mutation of loss of function in CitACS4 promotes the conversion of female into hermaphrodite flowers, and of monoecious into andromonoecious plants. We have studied whether the ethylene produced by CitACS4 enzyme could also be involved in other ethylene-regulated traits, including pistillate flowering transition and the number of female flowers per plant, the development of floral organs other than stamens, as well as fruit and seed set, and fruit development. A linkage analysis approach was performed in three independent F2 populations segregating for the two alleles of the gene (M, monoecious; m, andromonoecious), and the different traits under study. The CitACS4m allele not only cosegregated with andromonoecy, but also with earlier pistillate transition, an increased number of pistillate flowers per plant, and a slower growth and maturation of petals and carpels, which delayed anthesis time in hermaphrodite flowers. The m allele was also found to be linked to a reduced fruit set, which was not caused by a deficiency in pollination or fertilization. The gene also affected the longitudinal and transverse growth rates of the ovary and fruit, which means that fruits from andromonoecious plants (mm) were rounder than those from monoecious (MM) ones. Taken together, these data indicate that the locus defined by the ethylene biosynthesis and sex-determining gene CitACS4 acts as a pleiotropic regulator of the complete development of the pistillate flower and the earlier development of the fruit.

中文翻译：

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性别决定基因CitACS4是西瓜（Citrullus lanatus）的花和果实发育的多效调节剂。

在葫芦科（Cucurbitaceae）科的物种中，同一植物中的雄花和雌花的发生（单生）受乙烯生物合成ACS基因的控制，该基因特异性地抑制雌花中雄蕊的发育。在西瓜中，CitACS4中功能丧失的突变促进雌性转化为雌雄同体的花朵，并将雌雄同体的植物转化为雄雄同体的植物。我们研究了CitACS4酶产生的乙烯是否也可能参与其他乙烯调节的性状，包括雌蕊开花过渡和每株雌花的数量，雄蕊以外的花器官的发育以及果实和种子的结实。和水果的发育。在三个独立的F2种群中进行了连锁分析，这些种群针对该基因的两个等位基因（M，单性，m和雄性单性）以及所研究的不同性状进行了分离。该CitACS4m等位基因不仅与雄性单株共分离，而且与较早的雌蕊过渡共分离，每株雌蕊花的数量增加，花瓣和心皮的生长和成熟较慢，这延迟了雌雄同体花的开花时间。还发现该m等位基因与减少的坐果有关，这不是由于授粉或受精不足引起的。该基因还影响卵巢和果实的纵向和横向生长速率，这意味着雄性单性植物的果实（mm）比雌性（MM）的果实更圆。综上所述，这些数据表明由乙烯生物合成和性别决定基因CitACS4定义的基因座 充当多效调节剂，调节雌蕊花的完整发育和果实的早期发育。