Fruit secondary metabolites shape seed dispersal effectiveness

High-Resolution LC-MS Simultaneous Quantification of Forty-Six Compounds from Jatropha podagrica Fruit Recommends Four Top Antioxidant Contributors as Q-Markers

There has been no chemical analysis of the fruit of medicinal plant Jatropha podagrica until now. The current study aimed to qualitatively and quantitatively analyze the J. podagrica fruit using a high-resolution LC-MS strategy, i.e., library-comparison ultra-high-performance liquid chromatography-Quadrupole-Orbitrap-tandem mass spectrometry. The strategy putatively identified 46 compounds from fresh fruit. During the putative identification, 10 isomers (e.g., (vitexin vs. isovitexin) were completely distinguished from each other. Thereafter, all 46 compounds were simultaneously quantified using authentic standard comparison method. Finally, they were also subjected to the 2,2'-azino bis (3-ethylbenzothiazolin-6-sulfonic acid radical (ABTS+•)-scavenging assay to characterize their relative antioxidant capacities. Their antioxidant capacities were thus multiplied by chemical contents to calculate their antioxidant contribution values, respectively. Corilagin, gallic acid, ellagic acid, and phillygenin exhibited the highest antioxidant contribution percentages and thereby were suggested as the four top antioxidant contributors. The four are recommended to build up a quality-markers (Q-markers) system of J. podagrica fruits. All these findings can help to develop J. podagrica fruits as a potential resource of natural medicine.

Paralogous Gene Recruitment in Multiple Families Constitutes Genetic Architecture and Robustness of Pod Dehiscence in Legumes

Pod dehiscence facilitates seed dispersal in wild legumes while indehiscence is a key domestication trait in cultivated ones. However, the evolutionary genetic mechanisms underlying its diversity are largely unclear. In this study, we compared transcriptomes of two warm-season (Glycine spp. and Phaseolus spp.) and two cool-season (Pisum spp. and Medicago ruthenica) legumes in analysis of dehiscent and indehiscent pod genotypes. Differentially expressed genes in AP2/ERF-like transcription factors and seven structural gene families, including lactoperoxidase, laccase, and cellulose synthase-interactive proteins, which are involved in secondary cell wall component accumulation, were identified to exert key roles in pod dehiscence variation. In accordance with this, higher lignin and cellulose contents were observed in pod secondary cell wall of dehiscent accessions of soybean and pea; however, the variation patterns of lignin polymers in soybean (accumulation) and pea (proportion) differed between dehiscent and indehiscent pods. Moreover, genome-wide comparative analysis revealed that orthogroups represented <1% of all identified differentially expressed genes could be traced among the four genera of legumes, while recruiting paralogous members may constitute the genetic robustness of legume pod dehiscence. This study compared the genetic mechanism among several legumes in pod dehiscence formation and revealed a compensating role of paralogous redundancy of involved gene families in seed dispersal, which can guide crop breeding.

Extensive Local Geographic Variation in Locoweed Toxin Produced by a Fungal Endophyte

Legumes are notorious for coevolutionary arms races where chemical defenses are employed to ward off herbivores-particularly insect seed predators. Locoweeds are legumes containing the toxic alkaloid swainsonine which can poison livestock, but its role as a deterrent for insects is unknown. Swainsonine is produced by the fungal endophyte Alternaria section Undifilum, and the chemical composition of the toxin has been well characterized. Despite this knowledge, the ecological roles and evolutionary drivers of swainsonine toxins in locoweeds remain uncertain. Here, we quantify swainsonine concentrations and herbivory levels in the hyper-diverse locoweed Astragalus lentiginosus to evaluate its role as an evolved chemical defense. We found that A. lentiginosus shows considerable variation in swainsonine concentrations according to variety, in particular showing presence/absence variation at both population and local geographic scales. Surprisingly, herbivory levels from presumed generalist insects emerging from fruits showed no correlation with swainsonine concentrations. Conversely, seed and fruit herbivory levels linked to specialist Acanthoscelides seed beetles increased with concentrations of swainsonine-suggesting a possible coevolutionary arms race. Our results highlight that variation in endophyte-produced toxin systems may not follow classical expectations for geographic variation and ecological roles of plant chemicals. We discuss the implications of these results on plant-endophytic toxin systems and coevolutionary dynamics more broadly, highlighting a considerable need for more research in these systems.

Animal pollination shapes fruits market features, seeds functional traits and modulates their chemistry

In this study, we experimentally addressed the impact of different pollination treatments on the morphological, reproductive and chemical traits of fruits and seeds of two crop species, the wild strawberry (Fragaria vesca L.) and cowpea (Vigna unguiculata (L.) Walp.). Multiple flowers from each plant were exposed to different pollination treatments: (1) self pollination, (2) hand cross pollination and (3) open pollination. Both crops were positively affected by open pollination in terms of morpho-chemical parameters concerning the marketability (e.g., 35% decrease in sugar/acid ratio in open pollinated strawberries compared to the autogamous ones) and the seed germination rate as a proxy of reproduction efficiency (e.g., the almost complete absence of seed abortion in the open pollination treatment). Remarkably, the pollination treatment also strongly influenced the phytochemical composition. Open-pollinated strawberries exhibited a higher relative concentration of compounds endowed with nutraceutical properties such as anthocyanins, ellagic acid derivatives and flavonoids. At the same time, cowpea seeds displayed higher concentrations of anti-nutrients in the self pollination treatments, such as saponins, compared to the open and hand cross pollinated seeds. This study suggests the presence of a link between the pollination mechanism, market quality, plant reproduction and chemical properties of fruits and seeds, supporting the intricate interplay between pollinators, plants and human nutrition, highlighting the crucial importance of animal pollination in the ecological and dietary contexts.

Importance of plant and fruit traits on the structure of bird seed dispersal networks in different disturbed habitats

Species functional traits can influence seed dispersal processes and consequently affect species' role in the mutualistic network. Although the effect of animal traits on the structure of the seed dispersal network is well explored, it remains poorly understood how plant and fruit traits contribute to the structure. We here studied the effects of plant and fruit traits on the structure of bird seed dispersal networks across different disturbed habitats in the Meihua Mountain National Nature Reserve, Southeastern China. During the study period, 16, 20, 13, and 15 bird species were recorded foraging on 10, 11, 12, and 8 plant species, resulting in 511, 312, 265, and 201 foraging events in the protected forest, natural forest, village, and bamboo forest, respectively. The composition of these seed dispersal networks is not primarily influenced by a specific group of bulbul species, but rather by the presence of an endangered plant species, Taxus chinensis. As we expected, the structure of the four networks was different among the four disturbed habitats. Furthermore, our results also showed tree height and canopy density were the most important plant traits for structuring the seed dispersal network, while sugar, amylase, dry matter, and alkaloids were identified as significant fruit traits. Overall, our findings highlight the value of integrating trait-based ecology into the framework of the seed dispersal network and provide new insights for mutualistic network conservation in disturbed habitats.

A multiplex approach of MS, 1D-, and 2D-NMR metabolomics in plant ontogeny: A case study on Clusia minor L. organs (leaf, flower, fruit, and seed)

INTRODUCTION

The genus Clusia L. is mostly recognised for the production of prenylated benzophenones and tocotrienol derivatives.

OBJECTIVES

The objective of this study was to map metabolome variation within Clusia minor organs at different developmental stages.

MATERIAL AND METHODS

In total 15 organs/stages (leaf, flower, fruit, and seed) were analysed by UPLC-MS and 1H- and heteronuclear multiple-bond correlation (HMBC)-NMR-based metabolomics.

RESULTS

This work led to the assignment of 46 metabolites, belonging to organic acids(1), sugars(2) phenolic acids(1), flavonoids(3) prenylated xanthones(1) benzophenones(4) and tocotrienols(2). Multivariate data analyses explained the variability and classification of samples, highlighting chemical markers that discriminate each organ/stage. Leaves were found to be rich in 5-hydroxy-8-methyltocotrienol (8.5 μg/mg f.w.), while flowers were abundant in the polyprenylated benzophenone nemorosone with maximum level detected in the fully mature flower bud (43 μg/mg f.w.). Nemorosone and 5-hydroxy tocotrienoloic acid were isolated from FL6 for full structural characterisation. This is the first report of the NMR assignments of 5-hydroxy tocotrienoloic acid, and its maximum level was detected in the mature fruit at 50 μg/mg f.w. Seeds as typical storage organ were rich in sugars and omega-6 fatty acids.

CONCLUSION

To the best of our knowledge, this is the first report on a comparative 1D-/2D-NMR approach to assess compositional differences in ontogeny studies compared with LC-MS exemplified by Clusia organs. Results derived from this study provide better understanding of the stages at which maximal production of natural compounds occur and elucidate in which developmental stages the enzymes responsible for the production of such metabolites are preferentially expressed.

Quercetin stimulates an accelerated burst of oviposition-based reproductive strategy in codling moth controlled by juvenile hormone signaling pathway

The advantageous characteristics of invasive pests, particularly their ability to reproduce and adapt to the environment, have been observed. However, it remains unclear what specific inherent superiority enables fruit pests to successfully invade and dominate in interactions with other species. In this study, we report that Cydia pomonella (Linnaeus), a notorious invasive pest of pome fruits and walnuts globally, employs unique reproductive strategies in response to quercetin, a plant compound in host fruits. By monitoring adult dynamics and fruit infestation rates, we observed a competitive relationship between C. pomonella and the native species Grapholita molesta (Busck). C. pomonella was able to occupy vacant niches to ensure its population growth. We also found that quercetin had different effects on the reproductive capacity and population growth of C. pomonella and G. molesta. While quercetin stimulated the fecundity and population growth of G. molesta, it inhibited C. pomonella. However, C. pomonella was able to rapidly increase its population after exposure to quercetin by adopting an 'accelerated burst' of oviposition strategy, with each individual making a greater reproductive contribution compared to the control. We further demonstrated that the effect of quercetin on oviposition is regulated by the juvenile hormone (JH) signaling pathway in C. pomonella, allowing it to prioritize survival. The enhanced reproductive fitness of G. molesta in response to quercetin is attributed to the regulation of JH titers and key genes such as Met and Kr-h1, which in turn up-regulate reproduction-related genes Vg and VgR. In contrast, C. pomonella is inhibited. These findings shed light on the mechanisms interspecific competition and help to improve our understanding of the global spread of C. pomonella, which can be attributed to its inherent superiority in terms of reproductive strategy.

Linking pollen limitation and seed dispersal effectiveness

Seed production and dispersal are crucial ecological processes impacting plant demography, species distributions and community assembly. Plant-animal interactions commonly mediate both seed production and seed dispersal, but current research often examines pollination and seed dispersal separately, which hinders our understanding of how pollination services affect downstream dispersal services. To fill this gap, we propose a conceptual framework exploring how pollen limitation can impact the effectiveness of seed dispersal for endozoochorous and myrmecochorous plant species. We summarize the quantitative and qualitative effects of pollen limitation on plant reproduction and use Optimal Foraging Theory to predict its impact on the foraging behaviour of seed dispersers. In doing so, we offer a new framework that poses numerous hypotheses and empirical tests to investigate links between pollen limitation and seed dispersal effectiveness and, consequently, post-dispersal ecological processes occurring at different levels of biological organization. Finally, considering the importance of pollination and seed dispersal outcomes to plant eco-evolutionary dynamics, we discussed the implications of our framework for future studies exploring the demographic and evolutionary impacts of pollen limitation for animal-dispersed plants.

Population-Related Variability in Qualitative and Quantitative Secondary Metabolite Profile of Gentianella austriaca (A. & J. Kern.) Holub

Phytochemical profiling of six natural populations of Gentianella austriaca was performed by HPLC identification and quantification of a number of secondary metabolites, and evaluation of time series of peak areas by chemometric analysis. Phytochemical analysis of G. austriaca revealed the presence of iridoids, flavone-C-glucosides and xanthones. Twelve secondary metabolites were identified in the aerial parts, roots and seeds, including swertiamarin (SWM), gentiopicrin (GP), sweroside (SWZ), isoorientin (ISOOR), swertisin (SWE), demethylbellidifolin-8-O-glucoside (DMB-8-O-glc), bellidifolin-8-O-glucoside (BDF-8-O-glc), mangiferin (MGF), corymbiferin (CBF), corymbiferin-1-O-glucoside (CBF-1-O-glc), bellidifolin (BDF) and campestroside. Multivariate statistical analyses showed relatively low variability among populations according to secondary metabolite content. However, some pharmacologically important compounds were found in higher amounts in a few populations, which could be useful for conservation and future biotechnological procedures.

The domestication-associated L1 gene encodes a eucomic acid synthase pleiotropically modulating pod pigmentation and shattering in soybean

Pod coloration is a domestication-related trait in soybean, with modern cultivars typically displaying brown or tan pods, while their wild relative, Glycine soja, possesses black pods. However, the factors regulating this color variation remain unknown. In this study, we cloned and characterized L1, the classical locus responsible for black pods in soybean. By using map-based cloning and genetic analyses, we identified the causal gene of L1 and revealed that it encodes a hydroxymethylglutaryl-coenzyme A (CoA) lyase-like (HMGL-like) domain protein. Biochemical assays showed that L1 functions as a eucomic acid synthase and facilitates the synthesis of eucomic acid and piscidic acid, both of which contribute to coloration of pods and seed coats in soybean. Interestingly, we found that L1 plants are more prone to pod shattering under light exposure than l1 null mutants because dark pigmentation increases photothermal efficiency. Hence, pleiotropic effects of L1 on pod color and shattering, as well as seed pigmentation, likely contributed to the preference for l1 alleles during soybean domestication and improvement. Collectively, our study provides new insights into the mechanism of pod coloration and identifies a new target for future de novo domestication of legume crops.

Notes to the Taxonomic Affiliation of the Bulbophyllym Sect. Physometra (Orchidaceae, Epidendroideae) Based on Molecular Phylogenetic Analyses

To solve the taxonomic affiliation of Bulbophyllum physometrum, the only known species of the Bulbophyllym sect. Physometra (Orchidaceae, Epidendroideae), we conducted phylogenetic analyses based on nuclear markers, i.e., ITS and the low-copy gene Xdh, and the plastid region matK. We used Asian Bulbophyllum taxa, with a special focus on species from the sections Lemniscata and Blepharistes, i.e., the only Asian sections of this genus with bifoliate pseudobulbs, as in B. physometrum. Unexpectedly, the results of molecular phylogenetic analyses showed that B. physometrum is most probably more related to the representatives of the sections Hirtula and Sestochilos than Blepharistes or Lemniscata.

On the adequacy of fruit removal as a proxy for fitness in studies of bird-mediated phenotypic selection

PREMISE

In fleshy-fruited plants, fruit removal is widely used as a proxy for plant reproductive success. Nevertheless, this proxy may not accurately reflect the number of seeds dispersed, an assumed better proxy for total fitness (fruit removal × mean number of seeds dispersed per fruit).

METHODS

We examined under what circumstances fruit removal can be reliable as a proxy for total fitness when assessing bird-mediated selection on fruit traits. In three populations of the Blue Passionflower (Passiflora caerulea), we used the number of fruits pecked per plant as a surrogate for fruit removal to estimate phenotypic selection on fruit and seed traits, and simulations of the effect of the fruit-seed number trade-off on the number of fruits removed.

RESULTS

Fruit removal was a good indicator of fitness, accounting for 55 to 68% of the variability in total fitness, measured as total number of seeds removed. Moreover, multivariate selection analyses on fruit crop size, mean fruit diameter and mean seed number using fruit removal as a fitness proxy yielded similar selection regimes to those using total fitness. Simulations showed that producing more fruits, a lower number of seeds per fruit, and a higher variability in seed number can result in a negative relationship between fruit removal and total fitness.

CONCLUSIONS

Our results suggest that fruit removal can be reliably used as a proxy for total fitness when (1) there is a weak fruit number-seed number trade-off, (2) fruit crop size and fruit removal correlate positively, and (3) seed number variability does not largely exceed fruit number variability.