# Analysis of Floral Scent Component of Three Iris Species at Different Stages
## 1 Introduction  
Floral fragrances are mainly composed of small-molecule volatile compounds, which can be extracted, collected, or biosynthesized, and are widely used in various fields, such as daily chemicals, medicine, food, and others [1]. Floral fragrances are crucial characteristics of plants, having several important functions. Plants release volatile components through flower organs to attract insects for pollination and fruit development. Additionally, floral fragrances aid in the defense of plants by attracting natural enemies and deterring potential damage. Moreover, floral fragrances enhance the ornamental value of plants. As people's understanding continues to deepen and the application of flower fragrances keeps being promoted, breeding fragrant flowers has become an important direction in flower cultivation. To date, more than 1700 natural aroma substances have been discovered and identified in plants. Although thousands of plant floral aroma compounds have been identified, only 12 are found in more than 50% of seed plant families, such as limonene (71%), (E)-Ocimene(71%), Myrcene (70%), and so on [2]. Observing many studied plants, it is evident that there are usually between 20 and 60 kinds of floral fragrance substances [3]. During the entire flowering process, the flower itself regulates the synthesis and volatilization of volatile components. Different plants share similar regulatory mechanisms. Generally, in the early stage of flowering, the volatilization of floral aroma components gradually increases, reaching its peak when flowers are ready for pollination [4]. In a study on the floral fragrance of the German bearded Iris [5], 219 species in 10 categories are identified, including 42 terpen, 19 alkanes, 11 aromatic compounds, 52 esters, 41 alcohols, 17 ketones, 21 aldehydes, 9 acids, and 4 phenols. The volatile components of different species and cultivars show significant variations. Furthermore, it should be noted that, during the flowering process, there is a certain time lag between the peak expression of the gene encoding the floral aroma synthase and the volatilization of the corresponding floral aroma components, sometimes even lasting 1 to 2 days [6;7]. These findings also indicate that the expression of structural genes that are responsible for producing floral aroma substances ultimately affects the volatilization of floral aroma compounds. There are approximately 260 to 300 species of Iris plants worldwide, mainly distributed in the temperate regions of the northern hemisphere [8]. However, in my country's north-west region, there are 18 species of Iris, many of which remain under-explored. Some research teams have made progress in studying seed dormancy, germination characteristics, and interspecific hybridization barriers of _Iris sativa_[9]. As a traditional folk medicine, Iris plants have a long history of medicinal use and are mainly employed to treat various diseases, such as cancer, inflammation, and bacterial and viral infections [10]. Extracts from Iris plants are also utilized in treating atherosclerosis and osteoporosis [11]. Some Iris plants' roots, stems, and leaves contain precious essence, which can be ground into powder to obtain high-quality fragrance powder. _Iris uniflora_ stands out for its unique sweet and fragment rhizome extract, making it a valuable raw material for perfume [12]. The floral fragrance characteristics of _Iris typifolia_ are primarily provided by its pistil, giving rise to a distinctive fresh aroma. [13]. The stems and leaves of _Iris sanguinea_ can be used to make paper, while the flowers, with their large and colorful appearance, hold high ornamental value, and their rhizomes are used medicinally. For this study, three types of Iris flowers in the bud stage, bloom stage, and decay stage are selected. It has been observed that the aroma of each flower stage can be significantly distinguished using an electronic nose, and there are notable differences in aroma components [14].