Multifunctional Contribution of the Inflated Fruiting Calyx: Implication for Cuticular Barrier Profiles of the Solanaceous Genera Physalis, Alkekengi, and Nicandra

Abstract

Pivotal barrier properties of the hydrophobic plant cuticle covering aerial plant surfaces depend on its physicochemical composition. Among plant species and organs, compounds of this boundary layer between the plant interior and the environment vary considerably but cuticle-related studies comparing different organs from the same plant species are still scarce. Thus, this study focused on the cuticle profiles of Physalis peruviana, Physalis ixocarpa, Alkekengi officinarum, and Nicandra physalodes species. Inflated fruiting calyces enveloping fruits make Physalis, Alkekengi, and Nicandra highly recognizable genera among the Solanoideae subfamily. Although the inflation of fruiting calyces is well discussed in the literature still little is known about their post-floral functionalities. Cuticular composition, surface structure, and barrier function were examined and compared in fully expanded amphistomatous leaves, ripe astomatous fruits, and fully inflated hypostomatous fruiting calyces. Species- and organ-specific abundances of non-glandular and glandular trichomes revealed high structural diversity, covering not only abaxial and adaxial leaf surfaces but also fruiting calyx surfaces, whereas fruits were glabrous. Cuticular waxes, which limit non-stomatal transpiration, ranged from <1 μg cm−2 on P. peruviana fruiting calyces and N. physalodes fruits to 22 μg cm−2 on P. peruviana fruits. Very-long-chain aliphatic compounds, notably n-alkanes, iso-, and anteiso-branched alkanes, alkanols, alkanoic acids, and alkyl esters, dominated the cuticular wax coverages (≥86%). Diversity of cuticular wax patterns rose from leaves to fruiting calyces and peaked in fruits. The polymeric cutin matrix providing the structural framework for cuticular waxes was determined to range from 81 μg cm−2 for N. physalodes to 571 μg cm−2 for A. officinarum fruits. Cuticular transpiration barriers were highly efficient, with water permeabilities being ≤5 × 10−5 m s−1. Only the cuticular water permeability of N. physalodes fruits was 10 × 10−5 m s−1 leading to their early desiccation and fruits that easily split, whereas P. peruviana, P. ixocarpa, and A. officinarum bore fleshy fruits for extended periods after maturation. Regarding the functional significance, fruiting calyces establish a physicochemical shield that reduces water loss and enables fruit maturation within a protective microclimate, and promotes different seed dispersal strategies among plant species investigated.

Cuticle deposition ceases during strawberry fruit development

“…Third, characteristic of strawberry wax are esters ranging from C38 to C46. These are found in smaller quantities in apples [ 61 ] but not in sweet cherries [ 24 ], peaches [ 58 ] or pears [ 59 ] The alkanes found in strawberry wax are dominated by C27, C29 and C31 chain lengths, similar to those of Gaultheria mucronata [ 62 ] , Nicandra physalodes , Physalis peruviana and Physalis ixocarpa [ 63 ]. The decrease of wax mass per unit surface area in strawberry results primarily from decreases in alkanes, primary alcohols and esters caused by straining of the CM.…”

Advances in Physalis molecular research: applications in authentication, genetic diversity, phylogenetics, functional genes, and omics

“…The inflated calyx syndrome, also known as the Chinese lantern, is a post-floral morphological novelty in Physalis plants ( Hu and Saedler, 2007 ). During the fruit ripening process, the green calyx expands, inflates, and completely envelops the fruit ( de Souza et al., 2022 ). Despite extensive research on this morphological feature of Physalis plants, only a limited number of functional genes involved in its development have been investigated and cloned from Physalis plants ( Wilf et al., 2017 ).…”

Extraction and characterisation of cuticular waxes from Physalis peruviana calyx

“…Goldenberry fruits have a natural, protective waxy layer on the surface, which acts as a barrier to prevent moisture loss and provides sensory attributes such as a shiny appearance (Firdous et al ., 2023). Moreover, fruiting produces a cuticular barrier with properties that serve as a protective and supportive wrapper for the fruits (Ballesteros‐Vivas et al ., 2019a; de Souza et al ., 2022). The cuticle is a hydrophobic layer composed of two lipophilic moieties, namely, cuticular waxes and cutin (Canizares et al ., 2019; Wu et al ., 2023).…”

“…Even the citrus by‐product lemon wax was examined using a novel application of solid‐phase microextraction‐gas chromatography and ultra‐high performance liquid chromatography (SPME‐GC and UHPLC) to evaluate the possible use of a discarded fraction from citrus fruit processing (Costa et al ., 2019). The cuticular composition, surface structure, and barrier function of PPC have been examined and compared with other genera in the Solanoideae subfamily (de Souza et al ., 2022) using gas chromatography–mass spectrometry (GC–MS). There is an urgent need to explore biodegradable, eco‐friendly, sustainable, and safe hydrophobic materials (Sharma et al ., 2019).…”