Developmental analyses reveal early arrests of the spore-bearing parts of reproductive organs in unisexual flowers of cucumber (Cucumis sativus L.)

• Published in: Planta Vol. 220; no. 2; pp. 230 - 240
• Main Authors: Bai, S.L, Peng, Y.B, Cui, J.X, Gu, H.T, Xu, L.Y, Li, Y.Q, Xu, Z.H, Bai, S.N
• Format: Journal Article
• Language: English
• Published: Berlin Springer-Verlag 01-12-2004; Springer; Springer Nature B.V
• Subjects: Agronomy. Soil science and plant productions; Anthers; Biological and medical sciences; Carpels; Cucumbers; Cucumis sativus; Cucumis sativus - genetics; Cucumis sativus - growth & development; Cucumis sativus - ultrastructure; Developmental biology; DNA damage; Economic plant physiology; Female flowers; Females; Flower stigma; flowering; Flowering, floral biology, reproduction patterns; Flowers; Flowers & plants; Flowers - growth & development; Flowers - metabolism; Flowers - ultrastructure; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Developmental; Gene Expression Regulation, Plant; Growth and development; MADS Domain Proteins - biosynthesis; MADS Domain Proteins - genetics; Male flowers; morphogenesis; Nectaries; plant morphology; plant physiology; Plant Proteins - biosynthesis; Plant Proteins - genetics; plant reproduction; Stamens; ultrastructure; vegetable crops; Anther; Cucumis; Flower; Stamen; Cucurbitaceae; Unisexual flower development; Cucumis sativus; Gene expression; Meristem; Spores; CUM1 gene expression; Gene; Dicotyledones; Angiospermae; Development; Spermatophyta
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s00425-004-1342-2

To understand the regulatory mechanisms governing unisexual flower development in cucumber, we conducted a systematic morphogenetic analysis of male and female flower development, examined the dynamic changes in expression of the C-class floral organ identity gene CUM1, and assessed the extent of DNA damage in inappropriate carpels of male flowers. Accordingly, based on the occurrence of distinct morphological events, we divided the floral development into 12 stages ranging from floral meristem initiation to anthesis. As a result of our investigation we found that the arrest of stamen development in female flowers, which occurs just after the differentiation between the anther and filament, is mainly restricted to the primordial anther, and that it is coincident with down-regulation of CUM1 gene expression. In contrast, the arrest of carpel development in the male flowers occurs prior to the differentiation between the stigma and ovary, given that no indication of ovary differentiation was observed even though CUM1 gene expression remained detectable throughout the development of the stigma-like structures. Although the male and female reproductive organs have distinctive characteristics in terms of organ differentiation, there are two common features regarding organ arrest. The first is that the arrest of the inappropriate organ does not affect the entirety of the organ uniformly but occurs only in portions of the organs. The second feature is that all the arrested portions in both reproductive organs are spore-bearing parts.