Abscisic acid affects the floret numbers of inflorescence by regulating indole-3-acetic acid transport and accumulation in Lavandula angustifolia

Abstract

Lavender flower essential oil had been used for a variety of therapeutic and cosmetic purposes. Previous studies mainly focused on essential oil composition and extraction methods, ignoring the factors that affected the production of essential oils, such as the floret number. This study aims to get a deep insight into the mechanism of floret number differences. Hormone analysis showed that there was a positive correlation between abscisic acid (ABA) content and the number of florets, while indole-3-acetic acid (IAA) was negatively correlated with floret numbers. RNA-Seq results showed that 1 035 differentially expressed genes (DEG) can be identified, of which 19 genes were significantly enriched in the carotenoid biosynthesis pathway. Common network analysis showed that the expression of the key genes of ABA pathway metabolism was negatively related to the DEG of IAA, especial IAA18. Exogenous IAA significantly inhibited the number of lavender florets and affected the expression of ABA metabolism genes. The results might be useful for a better understanding of the molecular mechanism of floret number differences.