ABSTRACT: The timing of flower opening is essential for pollination and thus seed production. Despite flower opening has been a long lasting topic for plant biologists, the underling molecular mechansim remains elusive. Here we used a unique cucumber line â6457â that spontaneously produces super ovary with delayed corolla opening as material, and explored the physiological, cytological, nutritional and transcriptomic reasons for the delayed corolla opening in super ovary. Our data showed that cell division and cell expansion persisited for a longer period of time in the super ovary, especially during the green yellow bud stage and yellow bud stage. Similarly, RNA-seq analyses showed that RNA and protein synthesis related genes were upregulated during these two stages, which may account for the decreased nitrogen and phosphrate content in the super ovary. Further, activation of transcription factors were delayed in the green yellow bud stage, while signalling kinases related genes were upregulated in the yellow bud stage in the super ovary. Photosynthesis related genes were also significantly activated in the super ovary, which corresponds to the increased soluble suble content. Phytohoromones such as cytokinins and gibberllins were elevated in the super ovary. Consistently, cytokinins and gibberllins related genes showed significantly enhanced expression. Therefore, both developmental and nutritional factors regulate the timing of female flower opening in cucumber, and provide a valuable foundation for dissecting the underling regulatory pathways of flower opening in planta. The normal ovary blooms at 4-5 days after labeling (when the ovary is visible) (DAL), with the majority blooms at 5 DAL, while the anthesis of super ovary occurs at 8-9 DALs, with most super ovaries blooms at 9 DAL.In the normal ovary, corolla at 1 DAL (N1), 3 DAL (N3), 4 DAL (N4), and 5 DAL (N5) is the typical stage for green bud, green yellow bud, yellow bud, and flowering, respectively, whereas in the super ovary, corolla at 1 DAL (S1) is the green bud, corolla at 3, 4 and 5 DAL (S3, S4, S5) is the green yellow bud, corolla at 7 and 8 DAL (S7, S8) is the yellow bud, and corolla at 9 DAL (S9) is the typical flowering stage.Transcriptome profiling of 11 stages include N1,N3,N4,N5,S1,S3,S4,S5,S7,S8 and S9 were performed, and each stage had 3 biological replicates.
