Vernalization of Oriental hybrid lily 'Sorbonne': changes in physiology metabolic activity and molecular mechanism.

Oriental hybrid lily 'Sorbonne' was used to investigate molecular changes during the storage at 4 °C for dormancy-release besides physiology metabolic activity observations. In physiological mechanism, endogenous abscisic acid (ABA) concentration level of lily bulbs decreased as the cold preservation time increased, and it kept at a stable level after being preserved for 35 days. The level of soluble sugars concentrations also changed during the cold preservation time, and it increased as the cold preservation time raised to 49 days then decreased afterward. On molecule level, a new transcriptome providing comprehensive sequence profiling data of variation during dormancy-release in lily was constructed. 34,367 unigenes expressed differentially between the control and the treatment was analyzed. 14 genes including 8 MADS-box family genes, 4 genes related to plant hormone, and 2 DNA methylation genes were selected to identify the levels of their expression by qRT-PCR. Our results show that the decrease of ABA level during cold storage, as well as changes in plant hormone genes was correlated with dormancy-release; MADS-box family genes VRN2, FLC, FT, SOC1 a, as well as LFY, MIKC and ARF, MYB transcription factor were included in lily floral induction and DNA methylation was correlated to lily vernalization under low temperature. According to the results of the present studies, we predicted that plant hormone pathway, energy metabolic pathway, vernalization pathway, and DNA methylation played important roles during vernalization; these data provided the foundation for future studies of vernalization to induce flowering of lily.