The Petunia CHANEL Gene is a ZEITLUPE Ortholog Coordinating Growth and Scent Profiles

Abstract

The floral perianth, comprising sepals and petals, conceals the sexual organs and attracts pollinators. The coordination of growth and scent emission is not fully understood. We have analyzed the effect of knocking down <i>CHANEL</i> (<i>PhCHL</i>), the <i>ZEITLUPE</i> ortholog in petunia (<i>PhCHL</i>) by hairpin RNAs. Plants with low <i>PhCHL</i> mRNA had overall decreased size. Growth evaluation using time lapse image analysis showed that early leaf movement was not affected by <i>RNAi:PhCHL</i>, but flower angle movement was modified, moving earlier during the day in knockdown plants than in wild types. Despite differences in stem length, growth rate was not significantly affected by loss of <i>PhCHL</i>. In contrast, petal growth displayed lower growth rate in <i>RNAi:PhCHL</i>. Decreased levels of <i>PhCHL</i> caused strongly modified scent profiles, including changes in composition and timing of emission resulting in volatile profiles highly divergent from the wild type. Our results show a role of <i>PhCHL</i> in controlling growth and development of vegetative and reproductive organs in petunia. The different effects of <i>PhCHL</i> on organ development indicate an organ-specific interpretation of the down regulation of <i>PhCHL</i>. Through the control of both timing and quantitative volatile emissions, <i>PhCHL</i> appears to be a major coordinator of scent profiles.