Capsicum waste as a sustainable source of capsaicinoids for metabolic diseases

Capsaicinoids are pungent alkaloid compounds enriched with antioxidants, anti-microbial, anti-inflammatory, analgesics, anti-carcinogenic, anti-obesity and anti-diabetic properties. These compounds are primarily synthesised in the placenta of the fruit and then transported to other vegetative parts. Different varieties of capsicum and chillies contain different capsaicinoid concentrations. As capsicums and chillies are grown extensively throughout the world, their agricultural and horticultural production leads to significant amount of waste generation, in the form of fruits and plant biomass. Fruit wastes (placenta, seeds and unused fruits) and plant biowaste (stems and leaves) can serve as sources of capsaicinoids which can provide opportunities to extract these compounds for development of nutraceutical products using conventional or advanced extraction techniques. Capsaicin and dihydrocapsaicin are two most abundantly found pungent compounds. Considering the health benefits of capsaicinoids, these compounds can help in reducing metabolic disease complications. The development of an advanced encapsulation therapy of safe and clinically effective oral capsaicinoid/capsaicin formulation seem to require evaluation of strategies to address challenges related to the dosage, limited half-life and bioavailability, adverse effects and pungency, and the impacts of other ligands antagonising the major capsaicinoid receptor

Molecular interaction and evolution of jasmonate signaling with transport and detoxification of heavy metals and metalloids in plants

An increase in environmental pollution resulting from toxic heavy metals and metalloids [e.g., cadmium (Cd), arsenic (As), and lead (Pb)] causes serious health risks to humans and animals. Mitigation strategies need to be developed to reduce the accumulation of the toxic elements in plant-derived foods. Natural and genetically-engineered plants with hyper-tolerant and hyper-accumulating capacity of toxic minerals are valuable for phytoremediation. However, the molecular mechanisms of detoxification and accumulation in plants have only been demonstrated in very few plant species such as Arabidopsis and rice. Here, we review the physiological and molecular aspects of jasmonic acid and the jasmonate derivatives (JAs) in response to toxic heavy metals and metalloids. Jasmonates have been identified in, limiting the accumulation and enhancing the tolerance to the toxic elements, by coordinating the ion transport system, the activity of antioxidant enzymes, and the chelating capacity in plants. We also propose the potential involvement of Ca2+ signaling in the stress-induced production of jasmonates. Comparative transcriptomics analyses using the public datasets reveal the key gene families involved in the JA-responsive routes. Furthermore, we show that JAs may function as a fundamental phytohormone that protects plants from heavy metals and metalloids as demonstrated by the evolutionary conservation and diversity of these gene families in a large number of species of the major green plant lineages. Using ATP-Binding Cassette G (ABCG) transporter subfamily of six representative green plant species, we propose that JA transporters in Subgroup 4 of ABCGs may also have roles in heavy metal detoxification. Our paper may provide guidance toward the selection and development of suitable plant and crop species that are tolerant to toxic heavy metals and metalloids

Proto Kranz-like leaf traits and cellular ionic regulation are associated with salinity tolerance in a halophytic wild rice

Species of wild rice (Oryza spp.) possess a wide range of stress tolerance traits that can be potentially utilized in breeding climate-resilient cultivated rice cultivars (Oryza sativa) thereby aiding global food security. In this study, we conducted a greenhouse trial to evaluate the salinity tolerance of six wild rice species, one cultivated rice cultivar (IR64) and one landrace (Pokkali) using a range of electrophysiological, imaging, and whole-plant physiological techniques. Three wild species (O. latifolia, O. officinalis and O. coarctata) were found to possess superior salinity stress tolerance. The underlying mechanisms, however, were strikingly different. Na+ accumulation in leaves of O. latifolia, O. officinalis and O. coarctata were significantly higher than the tolerant landrace, Pokkali. Na+ accumulation in mesophyll cells was only observed in O. coarctata, suggesting that O. officinalis and O. latifolia avoid Na+ accumulation in mesophyll by allocating Na+ to other parts of the leaf. The finding also suggests that O. coarctata might be able to employ Na+ as osmolyte without affecting its growth. Further study of Na+ allocation in leaves will be helpful to understand the mechanisms of Na+ accumulation in these species. In addition, O. coarctata showed Proto Kranz-like leaf anatomy (enlarged bundle sheath cells and lower numbers of mesophyll cells), and higher expression of C4-related genes (e.g., NADPME, PPDK) and was a clear outlier with respect to salinity tolerance among the studied wild and cultivated Oryza species. The unique phylogenetic relationship of O. coarctata with C4 grasses suggests the potential of this species for breeding rice with high photosynthetic rate under salinity stress in the future

Biological control of arthropod pests in protected cropping by employing entomopathogens : efficiency, production and safety

The increasing adoption of environmentally friendly agricultural pesticides can be attributed to the continuous development and optimisation of both strategies and availability of products for pest management. This aligns with the increase in global population, decline of arable land and health concerns about synthetic pesticides. One outcome has been the development of protected cropping for enhancing productivity and quality of horticultural products worldwide. In 2020, biopesticides represented 6 % of the global pesticide market, but their share is expected to double and reach nearly 15 % by 2031. Microbial products have been mainly based on a limited number of pathogenic species, including Bacillus thuringiensis, Beauveria bassiana and Metarizhium anisopliae. Here, we review the current progress of biopesticide products for agriculture. In particular, we explore opportunities to utilise entomopathogens in protected cropping (controlled environment agriculture), where they have several advantages for integrated pest management (IPM) in these systems. There are a range of candidate entomopathogens such as Paenibacillus elgii, Pseudomonas spp., Aspergillus spp. and Cladosporum spp. that may be employed as biological control agents (BCAs) in protected cropping. Furthermore, the use of endophytic entomopathogenic fungi (EPF) is a promising alternative strategy for IPM in protected cropping. Also, we review the future strategies for IPM in protected cropping systems, including the combination of different BCAs. We suggest that interactions between combinations of BCAs, particularly EPF-Entomopathogenic bacteria (EPB) and EPFbeneficial arthropods, can offer promising IPM strategies, providing opportunities towards sustainable food production in the future

Linking high light-induced cellular ionic and oxidative responses in leaves to fruit quality in tomato

Light regulates cellular responses in leaves through a myriad of signalling cascades that control the growth and fruit quality of tomatoes. The relationships between high light-induced cellular hydrogen peroxide (H2O2) production and Ca2+ signalling in leaves (source) and fruits (sink) are rarely investigated. Experiments were conducted in two greenhouse trials to study the effects of high light on tomatoes at the plant-, organ-, cellular-, and molecular-levels. Short-term (1-week) and long-term (7-weeks) high light treatment led to a significant increase of H2O2 whereas, the accumulation of Ca2+ in leaf mesophyll cells was decreased significantly after 1- and 2-weeks of high light. Furthermore, photoreceptor genes (e.g., PHYB2, CRY2) were significantly downregulated in the leaves, however, Ca2+ and K+ transporter genes were not affected in the long-term, high light treatment. Notably, high light significantly improved the total soluble solids in tomato fruit without affecting fruit firmness, pH, and titratable acidity. Interestingly, we found a significant correlation between leaf mesophyll H2O2 production and fruit colour, fruit fresh weight, and titratable acidity, in addition to a correlation between leaf mesophyll Ca2+ concentration and fruit firmness. This study proposed that leaf mesophyll H2O2 and Ca2+ may be linked to fruit quality under high light conditions, which is useful for the early prediction of yield and postharvest quality of tomatoes in protected horticultural production. We suggest that light-induced fruit development and fruit quality, and their synchronisation with light signals in the leaf should be investigated to elucidate long-distant light signalling transduction in plants

[In Press] Molecular regulation and evolution of cytokinin signaling in plant abiotic stresses

The sustainable production of crops faces increasing challenges from global climate change and human activities, which leads to increasing instances of many abiotic stressors to plants. Among the abiotic stressors, drought, salinity and excessive levels of toxic metals cause reductions in global agricultural productivity and serious health risks for humans. Cytokinins (CKs) are key phytohormones functioning in both normal development and stress responses in plants. Here, we summarize the molecular mechanisms on the biosynthesis, metabolism, transport and signaling transduction pathways of CKs. CKs act as negative regulators of both root system architecture plasticity and root sodium exclusion in response to salt stress. The functions of CKs in mineral-toxicity tolerance and their detoxification in plants are reviewed. Comparative genomic analyses were performed to trace the origin, evolution and diversification of the critical regulatory networks linking CK signaling and abiotic stress. We found that the production of CKs and their derivatives, pathways of signal transduction and drought-response root growth regulation are evolutionarily conserved in land plants. In addition, the mechanisms of CK-mediated sodium exclusion under salt stress are suggested for further investigations. In summary, we propose that the manipulation of CK levels and their signaling pathways is important for plant abiotic stress and is, therefore, a potential strategy for meeting the increasing demand for global food production under changing climatic conditions

Triangulation of methods using insect cell lines to investigate insecticidal mode-of-action

This study investigated three in vitro models to assist in elucidating possible mode‐of‐action, which could be adopted to evaluate insecticidal activity of complex, unknown, or multi‐constituent formulations. We used a combination of absorbance spectrometry, confocal scanning laser microscopy and microelectrode ion flux estimation (MIFE) to provide insight into potential target sites for insecticides. This study used two insect cell lines and evaluated three pyrethroid insecticides