Effects of soil abiotic factors and plant chemical defences on seed predation on sea fennel (Crithmum maritimum)

Abstract

 Aims: Soil abiotic factors commonly influence plant defensive traits by shaping the costs of defence production and these bottom-up effects on plants can in turn affect insect herbivory. However, few studies have disentangled direct and indirect effects of soil abiotic factors on plant defences and insect herbivory. Methods: To address this gap, we tested the influence of soil abiotic factors on seed predation via changes in plant defences for sea fennel (Crithmum maritimum), a common coastal plant in southern Spain whose seeds are consumed by specialist caterpillars (Aethes species). To this end, we estimated seed predation on plants across several sea fennel populations, as well as measured different types of putative chemical seed defences (phenolics, terpenes) and soil abiotic factors (macro-and micro-elements, physiochemical variables). Results: We found a positive association between seed chemical defences (terpenes such as α-thujene, α-pinene, β-pinene, β-myrcene, α-terpinene, y-terpinene, and thymol methylether) and seed predation. In addition, a few macro-and microelements such as Ca, S and Sr negatively correlated with seed defences (terpenes); other macro-and micro-elements or physiochemical variables had no detectable association with defences. Despite observed effects of soil abiotic factors on defences and of the latter on seed predation, there was no detectable indirect effect of soil abiotic factors on seed attack. Conclusions: Our findings suggest that variation in a few key soil macro-and microelements in these coastal environments can exert an important influence on seed chemical defences in sea fennel, with potential consequences for interactions between sea fennel and seed predators.

Soil physicochemical properties associated with the yield and phytochemical composition of the edible halophyte Crithmum maritimum

“…Phenolic compounds were extracted from 20 mg of dried material (leaves or seeds) with 0.25 mL of 70 % methanol in an ultrasonic bath for 15 min, followed by centrifugation. The supernatant was filtered through a 0.20-μm micropore PTFE membrane and placed in vials for chromatographic analysis (Moreira et al, 2021). For chemical identification of the polyphenol composition we used ultra-performance liquid chromatography coupled with an electrospray ionization quadrupole (Thermo Dionex Ultimate 3000 LC) time-of-flight mass spectrometry (UPLC-Q-TOF-MS/MS) (Compact™) (Bruker Daltonics GmbH, Germany).…”

“…For the quantitative analysis of phenolic compounds, 10 μL of each sample was then analysed using the column and conditions described previously, in an UHPLC (Nexera LC-30 AD; Shimadzu) with a Nexera SIL-30 AC injector and one SPD-M20A UV/VIS photodiode array detector (Shimadzu, Japan); see Moreira et al (2021) for more details of the chromatographic analyses. Recording of chromatograms was performed at 330 nm.…”

Volatiles from French and Croatian Sea Fennel Ecotypes: Chemical Profiles and the Antioxidant, Antimicrobial and Antiageing Activity of Essential Oils and Hydrolates

“…It is hard to draw general conclusions about the causes of the differences in the chemical composition of sea fennel EOs, as they may be due to the different abiotic and biotic factors that affect the synthesis and accumulation of plant secondary metabolites, such as the harvest location or geographical variations [ 24 , 29 , 31 ], plant vegetation/harvest period/growth cycle [ 16 , 20 , 28 , 39 , 45 ], plant part used [ 16 , 43 , 44 ], climatological factors [ 16 , 20 ], soil abiotic factors [ 26 , 39 ], etc. However, our results agreed with the conclusions of other authors [ 12 , 16 , 22 ], according to which the main reason is simply the existence of different plant chemotypes (intraspecific variability).…”

“…Moreover, according to Renna [ 17 ], there are four main chemotypes of sea fennel based on the compounds prevalent in the EOs, namely aromatic monoterpenes, monoterpene hydrocarbons, phenylpropanoids and their intermediate forms. While the EOs from sea fennel in Mediterranean populations are well studied, like those from Turkey [ 18 , 19 , 20 , 21 , 22 ], Italy [ 23 , 24 , 25 ], Tunisia [ 12 ], Spain [ 26 ], Algeria [ 27 ], Greece [ 28 ] and France [ 29 ], there are few reports on volatiles from sea fennel populations on the Atlantic coasts of Portugal [ 9 , 13 , 16 , 26 , 30 ] and France [ 24 , 29 , 31 ].…”

Rock Samphire, a Candidate Crop for Saline Agriculture: Cropping Practices, Chemical Composition and Health Effects

“…Sea fennel can either be grown in the field or in pots (Figure 2) with different growth substrates such as a mixture of peat with perlite or vermiculite and a pH of up to 8.1 [50,[60][61][62]. When grown in the wild, plants prefer alkaline soils with a pH of up to 9.5 [63]. Under commercial cultivation conditions, the soil should be prepared in the fall with the main tillage where the field is plowed with a multiple moldboard plow at a depth of 40 cm, while the secondary tillage is carried out for seed-bed preparation and is performed with harrows [62].…”