Inflorescence Scents of Calendula maritima, Calendula suffruticosa subsp. fulgida, and Their Hybrid

Abstract

Premise of research. Hybridization is an important driver of plant evolutionary processes. By attracting the same pollinators to different species, floral scents may be involved in the formation of hybrids and breakdown of species boundaries. In contrast, by attracting a different suite of pollinators to hybrids and their parents, floral scents are believed to contribute to speciation processes initiated by hybridization events. Scents may or may not differ between the hybrids and their parents, but little is known about the scent chemistry of parental species and their hybrids. Methodology. We studied the inflorescence scents of parental Calendula maritima and C. suffruticosa subsp. fulgida (henceforth, C. fulgida) and a morphologically intermediate hybrid. Scents were collected by dynamic headspace and analyzed by thermal desorption-gas chromatography/mass spectrometry. Insects visiting inflorescences of the three taxa were also captured. Pivotal results. Calendula maritima and C. fulgida emitted different absolute amounts of scent; the hybrid released intermediate amounts of scent. The scents of the parental and hybrid taxa were all dominated by monoterpenes, with several compounds in common among the taxa. Nevertheless, the three taxa showed differences in qualitative and semiquantitative scent patterns. Calendula maritima emitted more and a higher amount of sesquiterpenes than the other taxa. The hybrid was overall more similar in scent properties to C. fulgida than it was to C. maritima. Conclusions. The overlap in scent compounds among the taxa may be responsible for attraction of the same insect pollinators, resulting in interspecific pollen transfer between the parents and the formation of hybrids. Indeed, preliminary observations revealed that all three taxa are visited by Panurgus siculus bees (Andrenidae).

Chemical Diversity of Volatiles From Parents, Rootstock and Atemoya Hybrid

“…However, our results reveal that atemoya also present a chemical profile intermediate to the rootstock. These results are in agreement with studies in literature, which report that the majority of specialized metabolites can be expressed in similar concentrations or even intermediate to those ones from its parents (Zito et al, 2018). Besides, in hybrid, substances may have its relative percentages raised or even suppressed (Cheng et al, 2011;López-Caamal & Tovar-Sánchez, 2014), condition that can contribute with the intermediate chemical profile.…”

“…Although it was not possible to identify and confirm the origin of substances presented in hybrid from its parents and rootstock, hybridization and grafting associated to both environment and intraspecific conditions, may contribute to variations in the expression of the volatile profile (Selmar & Kleinwächter, 2013;Zito et al, 2018). This variation can provide greater resistance to pathogens, allowing a better environment adaptation in different climatic conditions (Baron et al, 2019;Chezem & Clay, 2016).…”

“…Chemical profile of essential oils can variate between parents and hybrid, being that the latter produces higher diversity of substances, (Alzogaray, Lucia, Zerba, & Masuh, 2011) or present a similar and closer profile concerning to one of its parents (Vereecken, Cozzolino, & Schiestl, 2010;Zito, Tavella, Sajeva, Carimi, & Dötterl, 2018). Typically, hybrid shows an intermediate chemical profile from its parents (Herraiz-Peñalver et al, 2015;Ruberto & Rapisarda, 2002;Zito et al, 2018).…”

“…The expression of specialized metabolites is frequently regulated by different genes, which could explain an intermediate chemical volatile profile in hybrids and its parents (Cheng, Vrieling, & Klinkhamer, 2011;López-Caamal & Tovar-Sánchez, 2014). Variations in genetic expression of specialized metabolites could be linked to changing of its epigenome (Greaves et al, 2015), indicating an inheritance complex pattern from this trait (Cheng et al, 2011;Zito et al, 2018).…”

“…Once insects may be the main allies for several species pollination, as well as in the interaction between plants and defense against herbivores and pathogens (Alzogaray et al, 2011;Hommel et al, 2016;Wang, Liu, Wei, & Yan, 2012;Zito et al, 2018), the fluctuations in chemical profile could be important for comprehending plant survival strategies, defense and reproduction.…”