Developmental analyses reveal early arrests of the spore-bearing parts of reproductive organs in unisexual flowers of cucumber (Cucumis sativus L.).
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.
PKU-Yale Joint Research Center of Agricultural and Plant Molecular Biology, National Key Laboratory of Protein Engineering and Plant Gene Engineering, College of Life Sciences, Peking University, 100871 Beijing, China.
Su-Lan
SL
Bai
Yi-Ben
YB
Peng
Ji-Xin
JX
Cui
Hai-Tao
HT
Gu
Li-Yun
LY
Xu
Yi-Qin
YQ
Li
Zhi-Hong
ZH
Xu
Shu-Nong
SN
Bai
D018553:Cucumis sativus / Q000235:genetics / Q000254:growth & development* / Q000648:ultrastructure; D035264:Flowers / Q000254:growth & development* / Q000378:metabolism / Q000648:ultrastructure; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D026161:MADS Domain Proteins / Q000096:biosynthesis / Q000235:genetics; D010940:Plant Proteins / Q000096:biosynthesis / Q000235:genetics
C111450:CUM protein, Cucumis sativus; D026161:MADS Domain Proteins; D010940:Plant Proteins