Ca2+ signal contributing to the synthesis and emission of monoterpenes regulated by light intensity in Lilium ‘siberia’

Abstract

The floral scent is an important part of plant volatile compounds, and is influenced by environmental factors. The emission of monoterpenes of Lilium ‘siberia’ is regulated by light intensity, but the mechanism is large unknown. In this study, the expression of Li-mTPS, a monoterpene synthase gene in the tepals of Lilium ‘siberia’, and net Ca2+ flux were investigated after exposure to different levels of light intensity (0, 100, 300, 600, 1000, and 1500 μmol m−2 s−1). Moreover the effect of LaCl3 and ethylene glycol-bis-(2-aminoethylether)-N,N,N′,N′-tetraacetic acid (EGTA) on the Li-mTPS expression, monoterpene emission, and net Ca2+ flux were examined at 600 μmol m−2 s−1. The results showed that along with the enhancement of light intensity, the expression level of Li-mTPS increased gradually, and the net Ca2+ influx was also enhanced showing a similar pattern. It was found that LaCl3 and EGTA effectively inhibited the increase in expression of Li-mTPS and the net Ca2+ influx induced by light treatment. Moreover, the release amounts of monoterpenes decreased significantly after treatment with LaCl3 and EGTA. So it can be concluded that Ca2+ signal contributed to the biosynthesis and emission of monoterpenes regulated by light intensity in Lilium ‘siberia’ tepals. The increased light intensity firstly triggered the Ca2+ influx to cytoplasm, and then the gene expression of monoterpene synthases downstream was activated to regulate the biosynthesis and emission of monoterpenes. But in the signaling pathway other mechanisms were thought to be involved in the emission of monoterpenes regulated by light intensity, which need to be investigated in future research.