Flowering Stage and Daytime Affect Scent Emission of Malus ioensis "Prairie Rose".

Junjun Fan,Fuliang Cao,Guibin Wang,Donglin Zhang,Wangxiang Zhang

doi:10.3390/molecules24132356

Junjun Fan, Fuliang Cao + Show 3 more

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https://doi.org/10.3390/molecules24132356

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Abstract

Flowering crabapple is an important ornamental flower. It is vital to understand the floral scent properties and the associated release dynamics for carrying out fragrant flower breeding or floral regulation of crabapple. Static headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry was used to detect the volatile compounds in Malus ioensis “Prairie Rose” flowers at different flowering stages and at different day-night time. The results showed that methylheptenone, phenylethanol, geranylacetone, 2-(4-methoxyphenyl)ethanol, α-cedrene were the major compounds in M. ioensis “Prairie Rose”, but the compounds released during different stages and different day-night time were significantly different (P < 0.0001). A total of 25 volatile compounds were identified from the four flowering stages. The floral scents in the initial and flowering stages were the most similar (dissimilarity 0.21). The main compounds in these two stages were geranylacetone and methylheptenone, and the contents of geranylacetone and phenylethanol were positively correlated with the flowering stages. From the bud stage to the end of flowering, the total amount of volatile compounds released showed an initial increase followed by a decrease and the amounts of compounds released during the initial flowering stage were the highest. The aliphatic and benzenoids content was significant higher in the daytime than at night. A total of 15 compounds were detected in the five time periods. Methylheptenone and phenylethanol were particularly released in the 10:00–12:00 and 15:00–17:00 time periods. There were only three common compounds among the five time periods and the types of flower volatiles released during the daytime were obviously higher than those released at night. From the nocturnal to diurnal, the amount of flower volatiles released first increased, then decreased, and the release reached a peak between 10 am and 12 noon, which was consistent with the pollination biological characteristics of Malus flowers. Our findings are important for understanding the mechanism of insect visits to crabapple and the regulation of crabapple flower scent.

Highlights

Floral scent compounds are secondary metabolites released by plant flowers
Our findings are important for understanding the mechanism of insect visits to crabapple and the regulation of crabapple flower scent
A total of 25 volatile compounds were identified from the four flowering stages of M. ioensis

Summary

Introduction

Floral scent compounds are secondary metabolites released by plant flowers. These are mainly volatile compounds with low molecular weight (generally less than 300 Dalton), such as terpenoids, benzenes/phenylpropanoids, aliphthics, and some nitrogen- and sulfur-containing compounds [1]. The floral scent is an important expression signal for plants to induce insect pollination, as well as an important quality indicator for evaluating ornamental plants and cut flowers [2]. Studies had shown that floral scent had a greater influence on consumers than flower color and shape [3]. Most of the common flower-breeding goals are concentrated on flower shape, flower color, and flowering time, with the result that flowers are not bred for fragrance [4], and many cultivated flowers have gradually lost their aroma [5].

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