Metabolomics of early blight (Alternaria solani) susceptible tomato (Solanum lycopersicum) unfolds key biomarker metabolites and involved metabolic pathways

Impact of cultivar types and thermal processing methods on sweet potato metabolome, a comparative analysis via a multiplex approach of NIR and GC-MS based metabolomics coupled with chemometrics

This study comprehensively analyzes the primary metabolites of sweet potato peels and pulps from four cultivars and assesses the impact of four different processing methods on pulp metabolome using a multiplex metabolomics approach of GC-MS and NIR. A total of 69 metabolites were identified. Beauregard cv. showed the highest sugar content (387.85 mg/g), whereas Sahrawy cv. was higher in alcohols (24.63 mg/g) and organic acids (2.98 mg/g). The chemometric analysis identified key markers that distinguished each cv. represented by its pulp, peel, and processed pulp. KEGG enrichment analysis pinpointed key metabolic pathways leading to the metabolic discrepancy of the specimens. Sugars were the most altered class by processing as manifested by a 5 to 11-fold increase, notably in the air-fried pulp. Air-frying also increased alcohol and organic acid contents. NIR analysis revealed that air-frying was the preferred method of processing, preserving the majority of pulp's metabolites, including β-carotene and phenolics.

Differential impact of impaired steryl ester biosynthesis on the metabolome of tomato fruits and seeds

Steryl esters (SE) are a storage pool of sterols that accumulates in cytoplasmic lipid droplets and helps to maintain plasma membrane sterol homeostasis throughout plant growth and development. Ester formation in plant SE is catalyzed by phospholipid:sterol acyltransferase (PSAT) and acyl-CoA:sterol acyltransferase (ASAT), which transfer long-chain fatty acid groups to free sterols from phospholipids and acyl-CoA, respectively. Comparative mass spectrometry-based metabolomic analysis between ripe fruits and seeds of a tomato (Solanum lycopersicum cv Micro-Tom) mutant lacking functional PSAT and ASAT enzymes (slasat1xslpsat1) shows that disruption of SE biosynthesis has a differential impact on the metabolome of these organs, including changes in the composition of free and glycosylated sterols. Significant perturbations were observed in the fruit lipidome in contrast to the mild effect detected in the lipidome of seeds. A contrasting response was also observed in phenylpropanoid metabolism, which is down-regulated in fruits and appears to be stimulated in seeds. Comparison of global metabolic changes using volcano plot analysis suggests that disruption of SE biosynthesis favours a general state of metabolic activation that is more evident in seeds than fruits. Interestingly, there is an induction of autophagy in both tissues, which may contribute along with other metabolic changes to the phenotypes of early seed germination and enhanced fruit tolerance to Botrytis cinerea displayed by the slasat1xslpsat1 mutant. The results of this study reveal unreported connections between SE metabolism and the metabolic status of plant cells and lay the basis for further studies aimed at elucidating the mechanisms underlying the observed effects.

Metabolite profiling of chickpea (Cicer arietinum) in response to necrotrophic fungus Ascochyta rabiei

Introduction

Ascochyta blight (AB) caused by the necrotrophic fungus Ascochyta rabiei is one of the most significant diseases that limit the production of chickpea. Understanding the metabolic mechanisms underlying chickpea-A.rabiei interactions will provide important clues to develop novel approaches to manage this disease.

Methods

We performed metabolite profiling of the aerial tissue (leaf and stem) of two chickpea accessions comprising a moderately resistant breeding line (CICA1841) and a highly susceptible cultivar (Kyabra) in response to one of the highly aggressive Australian A. rabiei isolates TR9571 via non-targeted metabolomics analysis using liquid chromatography-mass spectrometry.

Results

The results revealed resistance and susceptibility-associated constitutive metabolites for example the moderately resistant breeding line had a higher mass abundance of ferulic acid while the levels of catechins, phthalic acid, and nicotinic acid were high in the susceptible cultivar. Further, the host-pathogen interaction resulted in the altered levels of various metabolites (induced and suppressed), especially in the susceptible cultivar revealing a possible reason for susceptibility against A.r abiei. Noticeably, the mass abundance of salicylic acid was induced in the aerial tissue of the susceptible cultivar after fungus colonization, while methyl jasmonate (MeJA) was suppressed, elucidating the key role of phytohormones in chickpea-A. rabiei interaction. Many differential metabolites in flavonoid biosynthesis, phenylalanine, Aminoacyl-tRNA biosynthesis, pentose and glucuronate interconversions, arginine biosynthesis, valine, leucine, and isoleucine biosynthesis, and alanine, aspartate, and glutamate metabolism pathways were up- and down-regulated showing the involvement of these metabolic pathways in chickpea-A. rabiei interaction.

Discussion

Taken together, this study highlights the chickpea - A. rabiei interaction at a metabolite level and shows how A. rabiei differentially alters the metabolite profile of moderately resistant and susceptible chickpea accessions and is probably exploiting the chickpea defense pathways in its favour.

The hidden treasures in endophytic fungi: a comprehensive review on the diversity of fungal bioactive metabolites, usual analytical methodologies, and applications

This review provides a comprehensive overview of the key aspects of the natural metabolite production by endophytic fungi, which has attracted significant attention due to its diverse biological activities and wide range of applications. Synthesized by various fungal species, these metabolites encompass compounds with therapeutic, agricultural, and commercial significance. We delved into strategies and advancements aimed at optimizing fungal metabolite production. Fungal cultivation, especially by Aspergillus, Penicillium, and Fusarium, plays a pivotal role in metabolite biosynthesis, and researchers have explored both submerged and solid-state cultivation processes to harness the full potential of fungal species. Nutrient optimization, pH, and temperature control are critical factors in ensuring high yields of the targeted bioactive metabolites especially for scaling up processes. Analytical methods that includes High-Performance Liquid Chromatography (HPLC), Liquid Chromatography-Mass Spectrometry (LC-MS), Gas Chromatography-Mass Spectrometry (GC-MS), Nuclear Magnetic Resonance (NMR), and Mass Spectrometry (MS), are indispensable for the identification and quantification of the compounds. Moreover, genetic engineering and metabolic pathway manipulation have emerged as powerful tools to enhance metabolite production and develop novel fungal strains with increased yields. Regulation and control mechanisms at the genetic, epigenetic, and metabolic levels are explored to fine-tune the biosynthesis of fungal metabolites. Ongoing research aims to overcome the complexity of the steps involved to ensure the efficient production and utilization of fungal metabolites.

A nondestructive asymptomatic early disease prediction method employing ROS-induced differential volatile emissions from dry rot-infected potatoes

Potatoes are a staple crop with many health benefits. Postharvest storage of potatoes takes a considerable amount of time. Potato dry rot is one of the most serious postharvest storage diseases, caused primarily by the fungus Fusarium sambucinum. It is possible to minimize losses if disease is detected early, which allows it to be controlled promptly. A phytopathogen infection can alter the volatile profile of plants. Identifying unique volatile organic compounds (VOCs) as biomarkers for early disease detection is an area of considerable research interest. In this study, we compared the VOC profiles of healthy and dry rot inoculated potatoes (cv. "Kufri Pukhraj") over a time course using gas chromatography-mass spectrometry (GC-MS). There were 29 differentially emitting VOCs between healthy and dry rot inoculated potatoes. Nevertheless, only four of these compounds (linalool tetrahydride, γ-muurolene, alloaromadendrene, and α-isomethyl ionone) were exclusively found in dry rot inoculated potatoes, and hence they were considered biomarkers. Furthermore, reactive oxygen species (ROS) levels were altered in potatoes that were inoculated with dry rot, suggesting a role for ROS signaling in differential VOC emissions. In the early stages of dry rot infection, when symptoms were barely visible, these four biomarker VOCs were robustly useful in distinguishing healthy and dry rot-infected potatoes. These novel biomarkers associated with this disease are promising candidates for non-destructive detection of dry rot in stored potatoes at an early asymptomatic stage. These biomarkers can be used to develop an e-nose sensor to predict dry rot in the future.