The aim of this study was to determine the allelopathic effects of Azadirachta indica oil and aqueous extracts of Tithonia diversifolia and Thevetia peruviana on the growth and stimulation of metabolites involved in tomato plant resistance. Randomized in blocks within a shaded area, the different treatments prepared at 10% and 15% (v/v and w/v) in water were subsequently applied on tomatoes seeds to monitor the effect on germination, and on tomatoes leaves to monitor the effect on growth and resilience of the plants. The result showed that in stressful conditions all the treatments significantly inhibit (p < 0.05) the germination capacity of the seeds from 21.22% to 92.61%, the germination rate from 39.82% to 92.76% and the germination viability of the seedlings from 64.67% to 100%. However, the negative allelopathic effect of the treatment was significantly reduced (p < 0.05) when used for germination initiation by botanical priming. In addition, while T. diversifolia at 10% promotes a better aerial and root growth in tomato plants, T. peruviana at 15% induces the activation of resistance mechanisms in tomato plants by increasing protein levels to 104.5%, phenol levels to 183.

La présente étude analyse au moyen d’une enquête réalisée auprès de 167 maraîchers de bas-fonds marécageux de la ville de Yaoundé (Cameroun) quelques aspects de l’utilisation des pesticides de synthèse et la perception de l’utilisation des extraits de plantes sauvages dans la lutte contre les ravageurs et les maladies des cultures. L’analyse descriptive des données montre que 85% des maraîchers enquêté n’ont pas été formés en agriculture, et 59% n’ont pas reçu de conseils sur l’utilisation des pesticides de synthèse. Par ailleurs, seuls 29% d’entre eux ont fait des études universitaires. En conséquence, même s’ils déclarent connaître que les pesticides de synthèse sont dangereux pour la santé (97%), ils ne respectent pas les bonnes pratiques phytosanitaires et manifestent de nombreux symptômes à l’instar du picotement du nez, la fatigue et le larmoiement. Toutefois, tous reconnaissent que les extraits de plantes sauvages peuvent être utilisés pour la protection des cultures contre les risques liés aux ravageurs et aux parasites. Cependant, seuls 43% y ont souvent recours, et parmi ces personnes, 71% ont déclaré les utiliser en cas de manque d’argent pour l’achat des pesticides de synthèse. De plus, 66% d’entre eux pensent que les extraits de plantes sauvages ne sont pas susceptibles de remplacer les pesticides de synthèse en agriculture. Ainsi, cette étude met en exergue la problématique de l’orientation des approches de la protection des cultures vers la voie de l’écologie.

IntroductionProtein carbonylation is a non-enzymatic and irreversible post-translational modification that occurs naturally in living organisms under the direct or indirect effect of reactive oxygen species (ROS). In animals, signaling pathways involving numerous carbonylated proteins have been identified, highlighting the dual role of these molecules in ROS signal transduction. In plants, studies on phytohormone signaling (auxin, methyl jasmonate, abscisic acid) have shown that reactive carbonyl species (RCS: acrolein, malondialdehyde, 4-hydroxynonenal, etc.), derived from the action of ROS on lipids, play important roles in secondary root formation and stomatal closure. However, the carbonylated proteins involved in these signaling pathways remain to be identified.MethodsIn this study, we analyzed proteins responsive to carbonylation by exogenous hydrogen peroxide (H2O2) by profiling the carbonyl proteome extracted from Arabidopsis thaliana leaves after H2O2 treatment. Carbonylated proteins were enriched at the peptide level and analyzed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS).Results and discussionWe identified 35 and 39 uniquely carbonylated proteins in the untreated and the H2O2-treated plant samples, respectively. In comparison to the control treatment, gene ontology enrichment analysis revealed that most of the carbonylated proteins identified in the H2O2-treated plant samples are related to sulfate adenylyl transferases and amidophosphoribosyl transferases involved in the immune system response, defense response, and external stimulus-response. These results indicated that exogenous H2O2 caused a change in the pattern of protein carbonylation in A. thaliana leaves. Protein carbonylation may thus influence the plant transcriptome and metabolism in response to H2O2 and ROS-triggering external stimuli.

This study aimed to determine the effect of 10 and 15% concentrations of Azadirachta indica oil (v/v) and Tithonia diversifolia and Thevetia peruviana liquid manure (w/v) on some key characteristics of tomato fruits. For this purpose, the extracts were sprayed on the tomato plants every two weeks until the fruits were harvested. The results show that the 15% T. diversifolia mash had the most significant positive impact (p < 0.05) on the size, weight, and ability of tomato fruits to protect DNA from denaturation. Indeed, compared to fruits harvested from untreated plants, this treatment increased the surface area by 75.38%, the weight by 72.74%, and the protective capacity of fruits against hydrogen peroxide-induced DNA denaturation by 82.96%. On the other hand, the highest lycopene content was obtained with A. indica at 10% (139.13 ± 4.35 μg/g MF), and that of phenols was observed with T. peruviana at 10% (31.07 ± 1.06 mg eq catechin/g MF). Also, there is a positive and significant correlation (p < 0.05) between phenol content and DPPH (2.2-diphenyl-1-picrylhydrazyl) and FRAP (ferric reducing antioxidant power) free radical scavenging activities of tomato fruits. Thus, this study shows that wild plant extracts are able to improve fruit quality.