Evolutionary dynamics of interactions between plants and their enemies: comparison of herbivorous insects and pathogens

Genome-Wide Transcriptional Response of Avocado to Fusarium sp. Infection

The avocado crop is relevant for its economic importance and because of its unique evolutionary history. However, there is a lack of information regarding the molecular processes during the defense response against fungal pathogens. Therefore, using a genome-wide approach in this work, we investigated the transcriptional response of the Mexican horticultural race of avocado (Persea americana var. drymifolia), including miRNAs profile and their possible targets. For that, we established an avocado-Fusarium hydroponic pathosystem and studied the response for 21 days. To guarantee robustness in the analysis, first, we improved the avocado genome assembly available for this variety, resulting in 822.49 Mbp in length with 36,200 gene models. Then, using an RNA-seq approach, we identified 13,778 genes differentially expressed in response to the Fusarium infection. According to their expression profile across time, these genes can be clustered into six groups, each associated with specific biological processes. Regarding non-coding RNAs, 8 of the 57 mature miRNAs identified in the avocado genome are responsive to infection caused by Fusarium, and the analysis revealed a total of 569 target genes whose transcript could be post-transcriptionally regulated. This study represents the first research in avocados to comprehensively explore the role of miRNAs in orchestrating defense responses against Fusarium spp. Also, this work provides valuable data about the genes involved in the intricate response of the avocado during fungal infection.

Review: Mechanism of herbivores synergistically metabolizing toxic plants through liver and intestinal microbiota

Interspecific interactions are central to ecological research. Plants produce toxic plant secondary metabolites (PSMs) as a defense mechanism against herbivore overgrazing, prompting their gradual adaptation to toxic substances for tolerance or detoxification. P450 enzymes in herbivore livers bind to PSMs, whereas UDP-glucuronosyltransferase and glutathione S-transferase increase the hydrophobicity of the bound PSMs for detoxification. Intestinal microorganisms such as Bacteroidetes metabolize cellulase and other macromolecules to break down toxic components. However, detoxification is an overall response of the animal body, necessitating coordination among various organs to detoxify ingested PSMs. PSMs undergo detoxification metabolism through the liver and gut microbiota, evidenced by increased signaling processes of bile acids, inflammatory signaling molecules, and aromatic hydrocarbon receptors. In this context, we offer a succinct overview of how metabolites from the liver and gut microbiota of herbivores contribute to enhancing metabolic PSMs. We focused mainly on elucidating the molecular communication between the liver and gut microbiota involving endocrine, immune, and metabolic processes in detoxification. We have also discussed the potential for future alterations in the gut of herbivores to enhance the metabolic effects of the liver and boost the detoxification and metabolic abilities of PSMs.

Untargeted Metabolome Analyses Revealed Potential Metabolic Mechanisms of Leymus chinensis in Response to Simulated Animal Feeding

Leymus chinensis (Trin.) Tzvel., also known as the "Alkali Grass", is a major forage grass in the eastern and northeastern steppe vegetation in the Songnen Prairie. It is of great practical significance for grassland management to understand the influence of animal saliva on L. chinensis during animal feeding. In this study, we used clipping and daubing animal saliva to simulate responses to grazing by L. chinensis, and analyzed the physiological and metabolomic changes in response to simulated animal feeding. Results showed that the effects of animal saliva on physiological and metabolic processes of the treated plants produced a recovery phenomenon. Moreover, the effects of animal saliva produced a large number of differential metabolites related to several known metabolic pathways, among which the flavonoid biosynthesis pathway has undergone significant and persistent changes. We posit that the potential metabolic mechanisms of L. chinensis in response to simulated animal feeding are closely related to flavonoid biosynthesis.