The morphoanatomy of Serjania erecta Radlk (Sapindaceae) provides evidence of biotrophic interactions by endophytic fungi within leaves.

Background: The leaves of Serjania erecta Radlk (Sapindaceae) are renowned in ethnobotany for their medicinal properties and are significant as a medicinal resource for traditional Brazilian communities. As necrotic spots are common on these leaves, indicating interaction with phytopathogenic fungi, it was hypothesized that biotrophic fungal species colonize the leaf tissues of S. erecta. Methods: To test this hypothesis, we employed standard techniques in plant anatomy, which enabled us to investigate the interaction of fungal structures with plant tissues and describe the morphoanatomical and histochemical characteristics of the epidermis and limbus of S. erecta. Results: The anatomical analysis showed the existence of leaf teeth on the leaf tips. Additionally, hyphae, conidiospores, and spores of Bipolaris/Curvularia species were detected on the adaxial epidermis. Moreover, melanized microsclerotia were found in glandular areas of the leaf teeth and the phloem, providing evidence of biotrophic behavior. The hypothesis that biotrophic phytopathogenic fungi interact with S. erecta leaf tissues was confirmed, despite the presence of many bioactive compounds (such as flavonoids, alkaloids, and essential oils), as evidenced by histochemical analyses. The presence of tector, glandular, and scabiform trichomes on the leaf teeth and epidermis was also revealed. This study presents, for the first time, the synthesis of essential oils and alkaloids in the leaves of S. erecta. Additionally, it investigates previously unexplained aspects of the anatomy and histochemistry of the species, as well as its interaction with resident microorganisms. Therefore, it is recommended that future research focus on extracting and characterizing the oils and alkaloids of S. erecta, as well as exploring other aspects related to its microbiome and its relationship.

Inhibitory effects of Serjania erecta on the development of Chrysodeixis includens.

The soybean looper, Chrysodeixis includens, is a primary soybean pest that reduces crop productivity. This work examined control of C. includens populations with methanolic extract of Serjania erecta, a native Cerrado plant, while minimizing risks to pollinators, natural enemies and the environment. Serjania erecta specimens were collected, identified, and subjected to methanol extraction. Bioassays were performed using newly hatched and second-instar caterpillars and different extract concentrations on the diet surface to obtain IC50 values. Two replicates, containing 10 caterpillars, were established in triplicate. The IC50 values were 4.15 and 6.24 mg of extract mL-1 for first-instar and second-instar caterpillars, respectively. These growth inhibition results informed the extract concentrations assessed in subsequent development inhibition assays, in which the pupal weight was higher under the control than under the treatments. Extract treatments increased the duration of the larval, pupal and total development. The potential of different concentrations of S. erecta extract to inhibit the enzymes carboxylesterases was also evaluated. Carboxylesterases activity decreased by 41.96 and 43.43% at 7.8 and 15.6 µg mL-1 extract, respectively. At 31.3 µg mL-1 extract, enzymatic activity was not detected. Overall, S. erecta leaf methanolic extract showed inhibitory potential against carboxylesterases.

Expression in Escherichia coli of cysteine protease inhibitors from cowpea (Vigna unguiculata): The crystal structure of a single-domain cystatin gives insights on its thermal and pH stability.

Two cysteine proteinase inhibitors from cowpea, VuCys1 and VuCys2, were produced in E. coli ArcticExpress (DE3). The recombinant products strongly inhibited papain and chymopapain as well as the midgut proteases from Callosobruchus maculatus larvae, a bruchid that uses cysteine proteases as major digestive enzymes. Heat treatment at 100°C for up to 60min or incubation at various pH values caused little reduction in the papain inhibitory activity of both inhibitors. Moreover, minor conformational variations, as probed by circular dichroism spectroscopy, were observed after VuCys1 and VuCys2 were subjected to these treatments. The crystal structure of VuCys1 was determined at a resolution of 1.95Å, revealing a domain-swapped dimer in the asymmetric unit. However, the two lobes of the domain-swapped dimer are positioned closer to each other in VuCys1 in comparison to other similar cystatin structures. Moreover, some polar residues from opposite lobes recruit water molecules, forming a hydrogen bond network that mediates contacts between the lobes, thus generating an extended open interface. Due to the closer distance between the lobes, a small hydrophobic core is also formed, further stabilizing the folded domain-swapped dimer. These structural features might account for the extraordinary thermal and pH stability of VuCys1.