Cloning and Expression of Omission of Second Division-like Genes from Carnation

The omission of second division gene ( OSD1 ) gene plays a fundamental role in meiosis and is associated with 2n gamete formation in Arabidopsis thaliana . The objective of this work was to unravel the mechanisms leading to 2n pollen production, and isolate and analyze the expression patterns of OSD-like ( OSDL ) genes in carnation ( Dianthus caryophyllus ). We found an absence of the second meiotic division caused the formation of 2n pollen. Three homoeologous genes were cloned and labeled as OSDLa , OSDLb , and OSDLc in a diploid carnation. The cDNAs were 1180 bp for OSDLa , 1288 bp for OSDLb , and 971 bp for OSDLc . A strong similarity was found between the amino sequences of OSDLb and OSDLc . An evident feature of OSDL s proteins is the presence of D-box and MR-tail domains; however, the GxEN/KEN-box domain, which is distinct among the other plant proteins was absent. Quantitative real time polymerase chain reaction (qRT-PCR) analysis showed that OSDL genes maintain continuous expression in buds and other tissues. OSDLa has the highest expression in buds of 1.1–1.2 cm long (stage 2), and OSDLb has a high level of expression in buds of 0.9–1.0 cm long (stage 1) and stage 2 buds and ovary tissues in three carnation cultivars. The expression level of OSDLc was highest in ovaries. These expression patterns strongly suggest that OSDLs in carnation involve male meiosis and ovary development. These findings can have potential applications in fundamental polyploidization research and plant breeding programs in carnation.