Temperature change shortens maturation time in Lilium with evidence for molecular mechanisms

Abstract

Lilium bulbs take at least 3 years to grow to commercial size; thus, finding ways to shorten the time to maturation would greatly reduce the cost of cultivation. Here, we used bulbs of Lilium OT “Robina” to test a short period of lowered temperature as a means to induce phase transition. The suitable temperature treatment to induce phase transition was 15 °C for 4 weeks. In this treatment, the main stem grew out, which shortened the growth cycle by at least 1 year compared with bulbs grown using standard temperatures. Moreover, we found potential molecular mechanisms to explain the induced phase transition. Using transcriptome sequencing, we found 373 differentially expressed genes, of which 172 were upregulated and 201 were downregulated. Many of the differentially expressed genes were involved in key regulatory pathways. The expression patterns of two key genes SPL9 and SPL15 were examined by quantitative real-time polymerase chain reaction. The results indicated that SPL9 and SPL15 played important roles in the age and phase transition of Lilium. This study provides a method for reducing the maturation time of Lilium bulbs and provides potential target genes that future researchers and breeding programs can pursue.