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An oil palm (Elaeis guineensis Jacq.) bud rod disorder of unknown etiology, named Fatal Yellowing (FY) disease, is regarded as one of the top constraints with respect to the growth of the palm oil industry in Brazil. FY etiology has been a challenge embraced by several research groups in plant pathology throughout the last 50 years in Brazil, with no success in completing Koch's postulates. Most recently, the hypothesis of having an abiotic stressor as the initial cause of FY has gained ground, and oxygen deficiency (hypoxia) damaging the root system has become a candidate for stress. Here, a comprehensive, large-scale, single- and multi-omics integration analysis of the metabolome and transcriptome profiles on the leaves of oil palm plants contrasting in terms of FY symptomatology—asymptomatic and symptomatic—and collected in two distinct seasons—dry and rainy—is reported. The changes observed in the physicochemical attributes of the soil and the chemical attributes and metabolome profiles of the leaves did not allow the discrimination of plants which were asymptomatic or symptomatic for this disease, not even in the rainy season, when the soil became waterlogged. However, the multi-omics integration analysis of enzymes and metabolites differentially expressed in asymptomatic and/or symptomatic plants in the rainy season compared to the dry season allowed the identification of the metabolic pathways most affected by the changes in the environment, opening an opportunity for additional characterization of the role of hypoxia in FY symptom intensification. Finally, the initial analysis of a set of 56 proteins/genes differentially expressed in symptomatic plants compared to the asymptomatic ones, independent of the season, has presented pieces of evidence suggesting that breaks in the non-host resistance to non-adapted pathogens and the basal immunity to adapted pathogens, caused by the anaerobic conditions experienced by the plants, might be linked to the onset of this disease. This set of genes might offer the opportunity to develop biomarkers for selecting oil palm plants resistant to this disease and to help pave the way to employing strategies to keep the safety barriers raised and strong. [ABSTRACT FROM AUTHOR]

Drought and salinity are two of the most severe abiotic stresses affecting agriculture worldwide and bear some similarities regarding the responses of plants to them. The first is also known as osmotic stress and shows similarities mainly with the osmotic effect, the first phase of salinity stress. Multi-Omics Integration (MOI) offers a new opportunity for the non-trivial challenge of unraveling the mechanisms behind multigenic traits, such as drought and salinity resistance. The current study carried out a comprehensive, large-scale, single-omics analysis (SOA) and MOI studies on the leaves of young oil palm plants submitted to water deprivation. After performing SOA, 1955 DE enzymes from transcriptomics analysis, 131 DE enzymes from proteomics analysis, and 269 DE metabolites underwent MOI analysis, revealing several pathways affected by this stress, with at least one DE molecule in all three omics platforms used. Moreover, the similarities and dissimilarities in the molecular response of those plants to those two abiotic stresses underwent mapping. Cysteine and methionine metabolism (map00270) was the most affected pathway in all scenarios evaluated. The correlation analysis revealed that 91.55% of those enzymes expressed under both stresses had similar qualitative profiles, corroborating the already known fact that plant responses to drought and salinity show several similarities. At last, the results shed light on some candidate genes for engineering crop species resilient to both abiotic stresses. [ABSTRACT FROM AUTHOR]

Oil palm (Elaeis guineensis Jacq.) is a oilseed crop of great economic importance drastically affected by abiotic stresses. MicroRNAs (miRNAs) play crucial roles in transcription and post-transcription regulation of gene expression, being essential molecules in the response of plants to abiotic stress. To better understand the molecular mechanisms behind the response of young oil palm plants to drought stress, this study reports on the prediction and characterization of miRNAs and their putative target genes in the apical leaf of plants subjected to 14 days of water deprivation. Then, the data from this study were compared to the data from a similar study that focused on salinity stress. Both, the drought-and salt-responsive miRNAs and their putative target genes underwent correlation analysis to identify similarities and dissimilarities among them. Among the 81 identified miRNAs, 29 are specific for oil palm, including two (egu-miR28ds and egu-miR29ds) new ones -- described for the first time. As for the expression profile, 62 miRNAs were significantly differentially expressed under drought stress, being five up-regulated (miR396e, miR159b, miR529b, egu-miR19sds, and egu-miR29ds) and 57 down-regulated. Transcription factors, such as MYBs, HOXs, and NFYs, were predicted as putative miRNA-target genes in oil palm under water deprivation; making them the most predominant group of such genes. Finally, the correlation analysis study revealed a group of putative target genes with similar behavior under salt and drought stresses. Those genes that are upregulated by these two abiotic stresses encode lncRNAs and proteins linked to stress tolerance, stress memory, modulation of ROS signaling, and defense response regulation to abiotic and biotic stresses. In summary, this study provides molecular evidence for the possible involvement of miRNAs in the drought stress response in oil palm. Besides, it shows that, at the molecular level, there are many similarities in the response of young oil palm plants to these two abiotic stresses. [ABSTRACT FROM AUTHOR]

Oil palm (Elaeis guineensis Jacq.) is the number one source of consumed vegetable oil nowadays. It is cultivated in areas of tropical rainforest, where it meets its natural condition of high rainfall throughout the year. The palm oil industry faces criticism due to a series of practices that was considered not environmentally sustainable, and it finds itself under pressure to adopt new and innovative procedures to reverse this negative public perception. Cultivating this oilseed crop outside the rainforest zone is only possible using artificial irrigation. Close to 30% of the world's irrigated agricultural lands also face problems due to salinity stress. Consequently, the research community must consider drought and salinity together when studying to empower breeding programs in order to develop superior genotypes adapted to those potential new areas for oil palm cultivation. Multi-Omics Integration (MOI) offers a new window of opportunity for the non-trivial challenge of unraveling the mechanisms behind multigenic traits, such as drought and salinity tolerance. The current study carried out a comprehensive, large-scale, single-omics analysis (SOA), and MOI study on the leaves of young oil palm plants submitted to very high salinity stress. Taken together, a total of 1239 proteins were positively regulated, and 1660 were negatively regulated in transcriptomics and proteomics analyses. Meanwhile, the metabolomics analysis revealed 37 metabolites that were upregulated and 92 that were downregulated. After performing SOA, 436 differentially expressed (DE) full-length transcripts, 74 DE proteins, and 19 DE metabolites underwent MOI analysis, revealing several pathways affected by this stress, with at least one DE molecule in all three omics platforms used. The Cysteine and methionine metabolism (map00270) and Glycolysis/Gluconeogenesis (map00010) pathways were the most affected ones, each one with 20 DE molecules. [ABSTRACT FROM AUTHOR]

The multipurpose tree Gliricidia sepium (Jacq.) Walp. adapts to a very high level of salt stress (≥20 dS m−1) and resumes the production of new leaves around 2 weeks after losing all leaves due to abrupt salinity stress. The integration of metabolome and transcriptome profiles from gliricidia leaves points to a central role of the phenylpropanoid biosynthesis pathway in the short-term response to salinity stress. In this study, a deeper untargeted metabolomics analysis of the leaves and roots of young gliricidia plants was conducted to characterize the mechanism(s) behind this adaptation response. The polar and lipidic fractions from leaf and root samples were extracted and analyzed on a UHPLC.ESI.Q-TOF.HRMS system. Acquired data were analyzed using the XCMS Online, and MetaboAnalyst platforms, via three distinct and complementary strategies. Together, the results obtained first led us to postulate that these plants are salt-excluding plants, which adapted to high salinity stress via two salt-excluding mechanisms, starting in the canopy—severe defoliation—and concluding in the roots—limited entry of Na. Besides that, it was possible to show that the phenylpropanoid biosynthesis pathway plays a role throughout the entire adaptation response, starting in the short term and continuing in the long one. The roots metabolome analysis revealed 11 distinct metabolic pathways affected by salt stress, and the initial analysis of the two most affected ones—steroid biosynthesis and lysine biosynthesis—led us also to postulate that the accumulation of lignin and some phytosterols, as well as lysine biosynthesis—but not degradation, play a role in promoting the adaptation response. However, additional studies are necessary to investigate these hypotheses. [ABSTRACT FROM AUTHOR]