ARTICLE | doi:10.20944/preprints201811.0408.v1
Subject: Biology, Plant Sciences Keywords: red raspberry; cuticle; stomata; micromorphology; anatomy; ultrastructure elements
Online: 16 November 2018 (11:32:10 CET)
Leaves of Rubus idaeus are a raw material, ingredients of herbal blend and a source of antioxidants. There are no data concerning histochemistry of trichomes and little is known about the leaves structure of this species. The aim of this study was to determine the histochemistry of active compounds and the structure of glandular trichomes, micromorphology, anatomy and ultrastructure of leaves as well as content of elements. To determine the histochemistry of glandular trichomes different chemical compounds were used. The leaves structure was analysed using light, scanning, and transmission electron microscopes. The content of elements was determined with atomic absorption spectrometry and the microanalysis of the epidermis ultrastructure was carried out with transmission electron microscope equipped with a digital X-ray analyser. In glandular trichomes: polyphenols, terpenes, lipids, proteins, and carbohydrates were identified. The main elements in the ultrastructure of the epidermis were: Na, S, Ca, Mg, B, Mo, and Se. In dry matter of leaves K, Mg, Ca, P, and Fe were dominant. Infusions from leaves are safe for health in terms of the Cd and Pb concentrations. Leaves can be a valuable raw material. Non-glandular trichomes prevent clumping of mixed raw materials in herbal mixtures.
ARTICLE | doi:10.20944/preprints202103.0004.v1
Subject: Life Sciences, Biochemistry Keywords: root-lesion nematode; suppressive soil; antagonistic microbes; rhizosphere; cuticle
Online: 1 March 2021 (12:48:25 CET)
Plant-parasitic nematodes are a major constraint for agricultural production. They significantly impede crop yield. To complete their parasitism, they need to locate, disguise, and interact with plant signals exuded in the rhizosphere of the host plant. A specific subset of the soil microbiome can attach to the surface of nematodes in a specific manner. We hypothesized that host plants recruit species of microbes as helpers against attacking nematode species, and that these helpers differ among plant species. We investigated to what extend the attached microbial species are determined by plant species, their root exudates, and how these microbes affect nematodes. We conditioned the soil microbiome in the rhizosphere of different plant species, then employed culture-independent and culture-dependent methods to study the microbial attachment to the cuticle of the phytonematode Pratylenchus penetrans. Community fingerprints of nematode-attached fungi and bacteria showed that the plant species govern the microbiome associated with nematode cuticle. Bacteria isolated from the cuticle belonged to Actinobacteria, Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Sphingobacteria, and Firmicutes. The isolates Microbacterium sp. i.14, Lysobacter capsici i.17, and Alcaligenes sp. i.37 showed the highest attachment rates to the cuticle. The isolates Bacillus cereus i.24 and L. capsici i.17 significantly antagonized P. penetrans after attachment. Significantly more bacteria attached to P. penetrans in microbiome suspensions from bulk soil or oat rhizosphere compared to Ethiopian mustard rhizosphere. However, the latter caused a better suppression of the nematode. Conditioning the cuticle of P. penetrans with root exudates significantly decreased the number of Microbacterium sp. i.14 attaching to the cuticle, suggesting induced changes of the cuticle structure. These findings will lead to a more knowledge-driven exploitation of microbial antagonists of plant-parasitic nematodes for plant protection.
REVIEW | doi:10.20944/preprints202009.0696.v1
Subject: Life Sciences, Biochemistry Keywords: Beauveria bassiana; cuticle degrading enzymes; entomopathogenic fungi; pathogenesis; virulence
Online: 29 September 2020 (08:57:33 CEST)
Intensive crop production and extensive use of harmful synthetic chemical pesticides create numerous socio-economic problems worldwide. Therefore, sustainable solutions are needed for insect pest control, such as biological control agents. The fungal insect pathogen Beauveria bassiana has shown considerable potential as a biological control agent against a broad range of insects. The insights into virulence mechanism of B. bassiana is essential to show the robustness of its use. B. bassiana has several determinants of virulence, including the production of cuticle-degrading enzymes (CDEs), such as proteases, chitinases, and lipases. CDEs are essential in the infection process as they hydrolyze the significant components of the insect's cuticle. Moreover, B. bassiana has evolved effective antioxidant mechanisms that include enzyme families that act as ROS scavengers, e.g., superoxide dismutases, catalases, peroxidases, and thioredoxins. In B. bassiana, the number of CDEs and antioxidant enzymes characterized in recent years. The enzymatic activities are crucial for the biological control potential and significantly advanced our understanding of the infection mechanism of B. bassiana. This review focuses on the progress detailed in the studies of these enzymes and provides an overview of enzymatic activities and their contributions to virulence.